Method for separating and recovering plastic film and method for producing reprocessed plastic pellets

Abstract

Provided is a method for easily separating and recovering a variety of plastic films having at least a printed layer, and a method for manufacturing high-quality recycled plastic pellets using crushed plastic materials recovered by the method, the method for separating and recovering a plastic film having at least a printed layer, the method comprises: a step 1 in which the plastic film is crushed; a step 2 in which the plastic film is immersed in a cleaning solution; and a step (3) for separating the plastic film by stirring the crushed plastic film in water.

Description

Technical Field

[0001] The present invention relates to a method for separating and recovering plastic films and a method for producing recycled plastic particles using plastic crushed materials recovered by the method. Background Art

[0002] At present, the recycling rate of classified recycling of plastic waste is 9% of the plastics manufactured worldwide. Among the 91% of plastics that become garbage, 12% are incinerated, and 79% are landfilled or leaked into the environment (Non-Patent Literature 1). As one of the reasons for the continuation of such a low recycling rate, the difficulty of the classified recycling system can be cited. In order to recycle plastics, it is necessary to separate and recycle waste plastics that are integrated with different types of plastic materials such as polyethylene (PE) and polypropylene (PP). However, most plastic products represented by laminated films are made by bonding and stacking different types of plastic materials, so it is difficult to separate and recycle them by material. Therefore, there is a strong demand for the construction of a recycling system that can easily separate and recycle waste plastics.

[0003] In addition, from the perspective of cost, it is difficult to restore recycled plastic products to the same products. Basically, they deteriorate every time they are recycled, so they have to become products with degraded quality. As a reason for the deterioration of the quality of recycled plastics, it can be cited that inks and pigments are mixed in plastics as impurities. However, since most plastic products are printed on their surfaces, they are difficult to decolorize in the recycling process, resulting in the coloring of recycled plastic products. Recycled plastics containing pigments, inks, etc. are not only significantly low in product value due to coloring, but in reality they can only become plastics whose physical properties deteriorate starting from impurities, and a recycling method for recycled plastics with good quality is needed.

[0004] In response to such issues, Patent Document 1 proposes a method of dissolving the aluminum layer from a crushed multilayer film with an alkali, separating the multilayer films by specific gravity difference, and then selectively melting them in a solvent to separate the valuable components for recycling. Patent Document 2 proposes a process of crushing the printed film, removing the ink, rinsing, and drying, but the processes are long and complicated.

[0005] In addition, Patent Document 3 provides a method for removing ink from a printed film in a roller state using a solvent and a non-abrasive cloth, and Patent Document 4 provides a method for removing ink from a printed film in a roller state using a solvent, a brush, and a scraper, but only a non-printed film is produced by removing the ink from the film in a roller state.

[0006] In recent years, in particular, with the diversification of packaging materials, there are further requirements for high functionality of packaging materials, improved adhesion of ink films to plastic substrates, and high design of printed materials, which promotes the diversification of types of packaging materials and inks. At the same time, it has become more difficult to peel off the ink layer. For example, in a laminated film formed by stacking multiple films, or in a laminated body formed by stacking other films and laminating after an ink layer is provided on a film via an adhesive layer, in the case of a laminated film in which an ink layer is provided between multiple films (back printing), in order to remove the ink layer, it is necessary to separate the multiple films, so the peeling of the ink layer becomes more difficult. It is desired to have a method for peeling off the ink layer of these various plastic films.

[0007] Prior art literature

[0008] Non-patent literature

[0009] Non-patent literature 1: Science Advances 19Jul 2017: Vol.3, no.7, e1700782

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2006-205160

[0012] Patent Document 2: Japanese Patent Application No. 2015-520684

[0013] Patent Document 3: Japanese Patent Application No. 2016-509613

[0014] Patent Document 4: Japanese Patent Application No. 2018-514384 Summary of the invention

[0015] Problems to be solved by the invention

[0016] The separation of laminated films in the prior art is carried out by performing a step of removing ink or a separation step after a step of dry crushing the laminated film, which is a common step, and the step is long and complicated. In addition, in the prior art method, since it is difficult to recycle laminated films of various structures, the quality and product value of the recycled plastic are reduced.

[0017] Therefore, the problem to be solved by the present invention is to provide a method for easily separating and recovering various plastic films having at least an ink layer, and a method for producing high-quality recycled plastic particles using plastic crushed products recovered by the method.

[0018] Methods for solving problems

[0019] The inventors of the present invention have repeatedly conducted in-depth research to solve the above-mentioned problems, and as a result, have discovered a method for easily regenerating a plastic laminate into a high-quality recycling raw material, which is a separation and recovery method for a plastic film having at least an ink layer, comprising: step 1 of crushing the above-mentioned plastic film, step 2 of immersing the above-mentioned plastic film in a cleaning liquid, and step 3 of separating the above-mentioned plastic film by stirring the crushed above-mentioned plastic film in water.

[0020] That is, the present invention provides a method for separating and recovering a plastic film, which is a method for separating and recovering a plastic film having at least an ink layer, comprising: step 1 of crushing the aforementioned plastic film; step 2 of immersing the aforementioned plastic film in a cleaning liquid; and step 3 of separating the aforementioned plastic film by stirring the crushed aforementioned plastic film in water.

[0021] In addition, the present invention provides a method for producing recycled plastic particles, wherein the plastic crushed materials separated by the above-described method are recovered in single layers, and the recovered materials are melted and then molded by a molding machine.

[0022] Effects of the Invention

[0023] According to the present invention, various plastic films having at least an ink layer can be separated into single layers, and the broken single-layer films can be easily recycled and classified for reuse. According to the method of the present invention, not only a plastic film having an ink layer exposed on the film surface (front surface printing) but also a plastic laminate having an ink layer between multiple films (back surface printing) can be separated into single layers, and the ink layer can be easily peeled off. That is, regardless of the type of plastic laminate, the film can be separated into single layers, and the ink layer can be easily peeled off, so the separation and recovery method of the plastic laminate can be facilitated, and the recovered plastic can be reused as a high-quality recycled plastic raw material. DETAILED DESCRIPTION

[0024] <About Process 1>

[0025] The method for separating and recovering a plastic film of the present invention comprises a step 1 of crushing the plastic film. In step 1, the method for crushing the plastic film is not particularly limited and can be carried out by a known method. In addition, the crushing can be carried out in an air atmosphere without the presence of liquids such as solvents, or in water or a cleaning liquid. When crushing is carried out in an air atmosphere, a dry crusher can be used. In addition, when crushing is carried out in water or a cleaning liquid, a wet crusher that can perform pressure feeding while crushing can be used. When a wet crusher is used, the plastic film can be effectively crushed, and the laminated plastic film can be peeled off at each layer.

[0026] By breaking the plastic film in step 1, the plastic film can be easily completely peeled off into single layers in the later-described steps 2 and 3. In step 1, the plastic film may be broken, and the broken plastic film may be in a state where at least a portion of the edge portion and the like is partially peeled off, each layer may be completely peeled off, or each layer may not be peeled off.

[0027] The long side of the plastic film after being broken in step 1 is preferably 1 mm to 30 mm, more preferably 1 mm to 20 mm, and even more preferably 1 mm to 10 mm. If it is within the above range, in step 2 of immersing the plastic film in the cleaning liquid, the time for the treatment liquid to penetrate from the end surface of the fluff to the center is shortened, and the plastic film can be easily and completely peeled off into a single layer.

[0028] In order to shorten the time for the treatment liquid to penetrate from the end surface of the fluff to the center, it is more preferable to open holes or cuts in the broken plastic film. The diameter of the hole or the length of the cut is preferably 0.5 mm or more, more preferably 0.8 mm or more, and more preferably 1.0 mm or more.

[0029] (Dry Crusher)

[0030] The dry crusher used in step 1 is not particularly limited, and for example, a jaw crusher, an impact crusher, a cutting mill, a pounding mill, a ring mill, a roller mill, a jet mill, a hammer mill, a colloid mill, a rotary cutter, a micron pulverizer, a particle pulverizer, a ball mill, a power mill, a pin mill, an air flow pulverizer (jet mill), a shear friction pulverizer, a cutting pulverizer, an impact pulverizer (hammer mill, ball mill), a roller pulverizer, a homogenizer, an ultrasonic pulverizer, etc., which are known techniques for pulverizing solids or cutting films, can be applied. In order to prevent the substrate or the ink layer from softening due to the friction heat during pulverization and thus fusing the laminate cross section, it is preferred to pulverize and crush the laminate or the crushing device in a cooled state.

[0031] The aforementioned dry crusher can be preferably used for separating and recovering a plastic film with an ink layer (front surface printing) exposed on the film surface, and a plastic film with an ink layer and a coating covering the ink layer on the film surface. In addition, it can also be preferably used in the case of performing separation and recovery of process 1 to process 4. The ink layer applied to the plastic film is a display and decorative printing ink layer for giving a trade name, etc., and most of them use gravure printing presses, flexographic printing presses, offset printing presses, inkjet printers, etc. to print organic solvent-based printing inks, water-based or active energy ray-curable inks. In such a plastic film provided with an ink layer, when a dry crusher is used in process 1, the film and the printed surface will not be completely separated, but in the present invention, the film and the printed surface can be completely separated in process 2 and process 3 described later. In a laminated film in which an ink layer is provided between multiple films (back printing), in addition to the aforementioned dry crusher, a wet crusher can also be used.

[0032] (Wet Crusher)

[0033] The wet crusher used in step 1 is not particularly limited, but is preferably a wet crusher capable of simultaneously crushing, dispersing, mixing, and pressurizing solid matter in a liquid. Specifically, a crusher having a mechanism for crushing solid matter in a liquid by shear force and / or friction force is preferred, and a crusher having a mechanism for crushing and pressurizing a plastic film is preferred. Examples of such a wet crusher include a wet crushing pump, a colloid mill, a grinder, a beater, and the like.

[0034] (Wet Breaker Pump)

[0035] The wet crushing pump preferably has a mechanism for crushing the solid matter by fixed blades and rotating blades while pressurizing the solid matter in the liquid. A more preferred mechanism is a mechanism for crushing in three stages by a combination of four parts: a cutting edge, a crushing impeller, a hoop, and a grille.

[0036] The plastic film is broken in three stages by the wet crushing pump. The plastic film is roughly cut by the cutting edge of the fixed blade and the edge of the inlet of the crushing impeller of the rotating blade, and then stirred and pressed by the axial flow type crushing impeller. A part of the plastic film contacts the blade of the hoop of the fixed blade and is cut. The laminated film that has passed through the crushing impeller is further finely crushed and stirred between the grid, and is pressurized by the pressurizing impeller through the grid and pressed to the next process.

[0037] The pressure feeding speed is not particularly limited, but is preferably 0.03 m / s when considering the peeling of the ink layer or the peeling and separation efficiency when separating the plastic film into each layer. 3 The upper limit of the pressure delivery speed is not particularly limited, and even the standard operating speed of the device, such as 1.4 m / min, 3 / min, the ink can be fully peeled off and the plastic film can be separated into a single layer.

[0038] The grid shape is not particularly limited. The grid aperture is related to the size of the laminated film after shredding, and is preferably 0.1 to 50 mm, and more preferably 1 to 20 mm in consideration of shredding efficiency and the size of the laminated film after shredding.

[0039] Specific examples of wet crushing pumps include KD series from Husqvarna-Zenoah, Suncutter series from Nikuni, Disintegrator series from Furukawa Industrial Machinery Systems, In-crusher series or Refiner from Aikawa Iron Works, Scatter from Sanwa Hydrotec, and Trigonal from Nippon Coke.

[0040] (Colloid mill)

[0041] The colloid mill used in the present invention is an apparatus used to reduce the particle size in a dispersed system in which particles are suspended in a liquid. The colloid mill is composed of a rotor and a stator combination, and the rotor rotates at high speed relative to a fixed stator. It is used to reduce the particle size in the liquid by a high level of shear generated by high-speed rotation.

[0042] The crushing part of the colloid mill is composed of a combination of a truncated cone-shaped rotor and a stator, which are formed into a conical shape that narrows as it approaches the discharge port. The laminated film is repeatedly sheared, compressed, and impacted in the annular gap that narrows as it approaches the discharge port, causing it to be crushed.

[0043] The specific colloid mill is not particularly limited as long as it is a disperser generally called a colloid mill, and examples thereof include the colloid mill MK series manufactured by IKA, the WCM series manufactured by IWAKI, the PUC colloid mill series manufactured by Mountech, and the Cavitron manufactured by Eurotech.

[0044] (Grinder)

[0045] The grinding machine preferably has a mechanism for crushing solid matter put between the stone mills by shearing and friction while rotating a set of upper and lower stone mills in a liquid, and preferably has a mechanism for crushing solid matter into a fine powder while flowing water.

[0046] By adjusting the interval between the upper and lower sets of millstones, the size of the crushed material can be adjusted, usually finely crushed to less than 500 μm, preferably less than 300 μm, and more preferably less than 200 μm. By reducing the size of the crushed material in this way, the layers of the plastic film are separated into single layers. In addition, the storage space of the crushed material can be reduced, making inventory management easier. In addition, when making recycled plastics from the crushed material, it can be put into a mixer without going through a compressor, etc., so the process can be simplified. On the other hand, in order to facilitate recycling, the lower limit of the size of the crushed material is preferably 10 μm or more, preferably 30 μm or more, and more preferably 50 μm or more.

[0047] There is no particular restriction on the rotation speed or water flow speed.

[0048] As a specific grinding device, an ultrafine pulverizer manufactured by Masuko Sangyo Co., Ltd. and the like can be exemplified.

[0049] As described above, the wet crusher can be preferably used in the case of separating and recovering a laminated plastic film having an ink layer (back surface printing) provided between a plurality of films.

[0050] In the laminated plastic film printed on the back, in addition to the adhesive, most of them are provided with a display and decorative printing ink layer for giving a product name, etc., but regarding the ink layer, most of them use gravure printing machines, flexographic printing machines, offset printing machines, inkjet printers, etc. to print organic solvent-based printing inks, water-based or active energy ray-curable inks. In the plastic film provided with such an ink layer, in order to more effectively peel off and remove the ink layer, the plastic film can be crushed in a cleaning solution containing a cleaning component and a stripping component in water. By crushing the plastic film in a cleaning solution containing a cleaning component and a stripping component in water, the stripping removal of the ink layer provided on the plastic film and the single-layer separation of the plastic film can be performed simultaneously. For example, the most commonly used ink in the plastic laminated film represented by food packaging is gravure ink or flexographic ink, but in the wet crushing process using a cleaning solution, the printing ink layer can also be peeled off, so it is effective. In addition, sometimes a metal foil or a vapor-deposited film such as aluminum is laminated on the laminated film, but in the present invention, the metal foil or the vapor-deposited film can also be peeled off or dissolved. It should be noted that, as described above, the layers constituting the plastic film may be peeled off into a single layer by breaking in water, or a portion of the broken plastic film may be partially peeled off. In addition, the ink layer provided on the plastic film does not need to be completely removed from the plastic film in step 1, and may be partially attached or may not be removed from the ink layer.

[0051] When a wet crusher is used in step 1, water or a cleaning liquid containing a cleaning or peeling component such as an inorganic base, a surfactant, or other components in water can be used as a solvent for crushing. The cleaning liquid can be a cleaning liquid containing one or more of the following components in water in appropriate combination.

[0052] (Inorganic base)

[0053] As the aqueous cleaning liquid that can be used in step 1, an aqueous cleaning liquid containing an inorganic base in water can be used. As the inorganic base, specifically, sodium hydroxide and potassium hydroxide can be mentioned. These inorganic bases are contained in a concentration of 0.1 to 10% by weight relative to the total amount of the aqueous cleaning liquid, and more preferably in a concentration of 0.1 to 5% by weight. In addition, the pH is preferably 10 or more.

[0054] (Surfactant)

[0055] As the aqueous cleaning liquid that can be used in step 1, an aqueous cleaning liquid containing a surfactant in water can be used. The surfactant is not particularly limited, and a known surfactant can be used, for example, anionic surfactants, nonionic surfactants, amphoteric surfactants, cationic surfactants, etc.

[0056] Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, glycerol fatty acid esters, polyoxyethylene glycerol fatty acid esters, polyglycerol fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, fatty acid alkanolamides, alkyl alkanolamides, acetylene glycols, oxyethylene adducts of acetylene glycols, and polyethylene glycol polypropylene glycol block copolymers. Examples of the nonionic surfactant include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkanolamides, acetylene glycols, oxyethylene adducts of acetylene glycols, and polyethylene glycol polypropylene glycol block copolymers.

[0057] In the present invention, an aqueous cleaning liquid containing 0.01 to 5% by weight of a polyoxyalkylene alkyl ether surfactant containing 50% by weight or more of water and at least one compound represented by the general formula (1) is preferred.

[0058] R 1 -O-[CH2-CH(X 1 )-O]n 1 -H(1)

[0059] In the general formula (1), R 1 represents a straight-chain or branched alkyl, alkenyl or octylphenol group, n 1 represents the average number of added moles, X 1 represents hydrogen or a short-chain alkyl group.

[0060] More preferably, R in the general formula (1) is 1 The carbon number of the alkyl group is a straight chain or branched chain alkyl or alkenyl group having 10 or more carbon atoms. The more the carbon number exceeds 10, the better the ink releasability is, and the more preferred it is. Specific examples of the carbon number include decyl having 10 carbon atoms, lauryl having 12 carbon atoms, tridecyl having 13 carbon atoms, myristyl having 14 carbon atoms, cetyl having 16 carbon atoms, oleyl having 18 carbon atoms, and stearyl.

[0061] As specific products, among the NOIGEN series, DSK NL-Dash series, DKS-NL series manufactured by Daiichi Kogyo Seiyaku Co., Ltd., the nonionic series manufactured by NOF Corporation, the EMULGEN series manufactured by Kao Corporation, the LEOX series, LEOCOL series, and LIONOL series manufactured by Lion Corporation, as long as R in the nonionic surfactant represented by the general formula (1) is 1 The number of carbon atoms shown is 10 or more, but it is not limited thereto.

[0062] The HLB value of the polyoxyalkylene alkyl ether surfactant represented by the general formula (1) is not particularly limited. It should be noted that the HLB value referred to herein is a value indicating the degree of affinity of the surfactant for water and oil (water-insoluble organic compound), and is defined by the Griffin method (HLB value = 20 × sum of the formula weights of the hydrophilic part / molecular weight).

[0063] Regarding the nonionic surfactant represented by the general formula (1), R 1As specific surfactants having 10 or more carbon atoms and an HLB value of less than 12.5, examples thereof include NOIGEN XL-41, NOIGEN LF-40X, NOIGEN TDS-30, NOIGEN TDS-50, NOIGEN TDS-70, NOIGEN TDX-50, NOIGEN SD-30, NOIGEN SD-60, DKS NL-15, DKS NL-30, DKS NL-40, DKS NL-50, DKS NL-60, DKS NL-70, NOIGEN ET-83, NOIGEN ET-102, DSK Dash400, DSK Dash403, DSK Dash404, DSK Dash408, NOIGEN LP-55, NOIGEN LP-70, NOIGEN ET-65, NOIGEN ET-95, NOIGEN Examples of the nonionic K-204, PERSOFT NK-60, nonionic P-208, nonionic P-210, nonionic E-202, nonionic E-202S, nonionic E-205, nonionic E-205S, nonionic S-202, nonionic S-207, nonionic EH-204, nonionic ID-203, nonionic HT-505, nonionic HT-507, nonionic HT-510, nonionic HT-512 manufactured by Kao Corporation; examples of the nonionic K-204, PERSOFT NK-60, nonionic P-208, nonionic P-210, nonionic E-202, nonionic E-202S, nonionic E-205, nonionic E-205S, nonionic S-202, nonionic S-207, nonionic EH-204, nonionic ID-203, nonionic HT-505, nonionic HT-507, nonionic HT-510, nonionic HT-512 manufactured by Kao Corporation Examples of the LEOX 106, EMULGEN 108, EMULGEN 210P, EMULGEN 404, EMULGEN 408, EMULGEN 409PV, EMULGEN 705, and EMULGEN 707 manufactured by LION include LEOX CL-30, LEOX CL-40, LEOX CL-50, LEOX CL-60, LEOCOL NL-30C, LEOCOL TD-50, LEOCOL TD-70, LEOCOL SC-50, and LEOCOL SC-70, but are not limited thereto.

[0064] Among the nonionic surfactants represented by the general formula (1), specific surfactants in which R1 has a linear or branched alkyl or alkenyl group with 10 or more carbon atoms and an HLB value of 12.5 or more include NOIGEN XL-61, NOIGEN XL-6190, NOIGEN XL-70, NOIGEN XL-80, NOIGEN XL-100, NOIGEN XL-140, NOIGEN XL-160, XL-400D, NOIGEN XL-1000, NOIGEN LF-60X, NOIGEN LF-80X, NOIGEN LF-100X, NOIGEN TDS-80, NOIGEN TDS-100, NOIGEN TDS-120, NOIGEN TDS-200D, NOIGEN TDS-500F, NOIGEN TDX-80, NOIGEN TDX-80D, NOIGEN TDX-100D, NOIGEN TDX-120D, NOIGEN SD-70, NOIGEN SD-80, NOIGEN SD-110, NOIGEN SD-150, DKS NL-80, DKS NL-90, DKS NL-100, DKS NL-110, DKS NL-180, DKS NL-250, DKS NL-450F, DKS NL-600F, NOIGENET-160, NOIGEN ET-170, NOIGEN ET-190, DSK Dash410,Noigen LP-80, Noigen LP-100, Noigen LP-180, Noigen ET-135, Noigen ET-165, Noigen ET-159, Noigen ET-189, and nonionic K-220, nonionic K-230, nonionic K-2100W, PERSOFT NH-90C, PERSOFT NK-100, PERSOFT NK-100C, nonionic P-210, nonionic P-213, nonionic E-212, nonionic E-215, nonionic E-230, nonionic S-215, nonionic S-220, nonionic B-250, nonionic ID-206, nonionic ID-209, DISPANOLTOC, nonionic HT-515, nonionic HT-518, and examples of those manufactured by Kao Corporation include EMULGEN 109P, EMULGEN 120, EMULGEN 123P, EMULGEN 130K, EMULGEN 147, EMULGEN 150, EMULGEN 220, EMULGEN 320P, EMULGEN 350, EMULGEN 420, EMULGEN 430, EMULGEN 709, EMULGEN 1108, and EMULGEN Examples of the products manufactured by LION include LEOX CL-90, LEOX CL-230, LEOCOL TD-90, LEOCOL TD-90D, LEOCOL TDA-90-25, LEOCOL TDN-90-80, LEOCOL TD-120, LEOCOL TD-200, LEOCOL TDA-400-75, LEOCOL SC-80, LEOCOL SC-90, LEOCOL SC-120, LEOCOL SC-150, LEOCOL SC-200, LEOCOL SC-300, LEOCOL SC-400, etc., but are not limited to these. ,

[0065] In the general formula (1), R 1 In the case of an octylphenol group, octylphenol ethoxylate is preferred.

[0066] Specific products include, but are not limited to, TRITON (registered trademark) series from Dow Chemical, Igepal CA series from Rhodia, Nonidet P series from Shell Chemicals, and Nikkol OP series from Nikko Chemicals.

[0067] Specifically, the amphoteric surfactant is preferably a betaine-type double surfactant, and more preferably an amphoteric surfactant having an alkylcarboxybetaine skeleton or an alkylamidecarboxybetaine skeleton containing at least one compound represented by the general formula (2a).

[0068] R1-R2-N + (CH3)2CH2COO - (2a)

[0069] (In the general formula (2a), R1 represents hydrogen or C(=O)R3-NH- (R3 represents a linear or branched alkyl or alkenyl group), and R2 represents an alkylene group or an alkenylene group.)

[0070] In the general formula (2a), R1 preferably represents a hydrogen atom.

[0071] The compound represented by the general formula (2a) is preferably an amphoteric surfactant having an alkylcarboxybetaine skeleton represented by the general formula (2a-1).

[0072] C n H 2n+1 N + (CH3)2CH2COO - (2a-1)

[0073] (In the general formula (2a-1), n ​​represents the average number of added moles.)

[0074] In the general formula (2a-1), n ​​is preferably 8 or more, preferably 10 or more, and preferably 11 or more.

[0075] Specific products corresponding to the general formula (2a) include NISSAN ANON BDF (registered trademark)-R, NISSAN ANON BDF (registered trademark)-SF, NISSAN ANON BDC-SF, and NISSAN ANON BDL-SF manufactured by NOF Corporation; AMOGEN CB-H and AMOGEN HB-C manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; RIKABION B-200 and RIKABION B-300 manufactured by Shin Nippon Chemical Co., Ltd.; and OBAZOLIN CAB-30 and OBAZOLIN ISAB manufactured by Toho Chemical Industry Co., Ltd. Specific products corresponding to the general formula (1a-1) include AMOGEN S, AMOGEN SH and AMOGEN K manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., AMPHITOL 20BS, AMPHITOL 24B and AMPHITOL 86B manufactured by Kao Corporation, NISSAN ANON BF, NISSAN ANON BL and NISSAN ANON BL-SF manufactured by NOF Corporation, RIKABION A-100, RIKABION A-200 and RIKABION A-700 manufactured by Shin Nippon Chemical Co., Ltd., and OBAZOLIN LB and OBAZOLIN LB-SF manufactured by Toho Chemical Co., Ltd., but the present invention is not limited to these.

[0076] In addition, the betaine-type amphoteric surfactant may be a substance having an imidazoline betaine skeleton. Specific products thereof include NISSAN ANON GLM-R and NISSAN ANON GLM-R-LV manufactured by NOF Corporation and AMPHITOL 20Y-B manufactured by Kao Corporation, but are not limited to these.

[0077] In addition, the amphoteric surfactant may be a surfactant represented by the following general formula (2b).

[0078] R4-(NHC2H4) nb -N(R5)2(2b)

[0079] (In the general formula (2b), R4 represents a linear or branched alkyl or alkenyl group, nb represents an integer from 0 to 5, R5 represents hydrogen, -CH2COONa or -CH2COOH, the two R5s present may be the same or different, and at least one R5 represents -CH2COONa.)

[0080] In the general formula (2b), R4 preferably represents a linear alkyl group, and the number of carbon atoms in R4 is preferably 8 or more, preferably 10 or more, and preferably 12 or more.

[0081] Specific products corresponding to the general formula (2b) include NISSAN ANON LG-R and NISSAN ANON LA manufactured by NOF Corporation, but are not limited to these.

[0082] In addition, the amphoteric surfactant may be an amine oxide type surfactant represented by the following general formula (2c).

[0083] R6-N + (CH3)2O - (2c)

[0084] (In the general formula (2c), R6 represents a linear or branched alkyl or alkenyl group.)

[0085] In the general formula (2c), R6 preferably represents a linear alkyl group, and the number of carbon atoms of R6 is preferably 8 or more, preferably 10 or more, and preferably 12 or more.

[0086] Specific products corresponding to the general formula (2c) include AMOGEN AOL manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. and AMPHITOL 20N manufactured by Kao Corporation, but are not limited to these.

[0087] Specifically, the cationic surfactant is preferably a cationic surfactant having a quaternary ammonium skeleton, and more preferably a cationic surfactant having a quaternary ammonium skeleton containing at least one compound represented by the general formula (3a).

[0088] R1-N + (R2R3)-R4(3a)

[0089] (In the general formula (3a), R1 represents a straight-chain or branched alkyl group, or a straight-chain or branched alkenyl group, and the -CH2- in the alkyl group or alkenyl group may be substituted by -C(=O)-, -NH- or -C(=O)-NH-; R2 and R3 represent a hydrogen atom, a straight-chain or branched alkyl group, or a straight-chain or branched alkenyl group; R4 represents a hydrogen atom, a straight-chain or branched alkyl group, a straight-chain or branched alkenyl group or a phenyl group, and the terminal -CH3 in the alkyl group or alkenyl group may be substituted by a carboxyl group or a phenyl group.)

[0090] In the general formula (3a), in order to further improve the releasability of the ink, R1 is preferably a long-chain alkyl or alkenyl group, specifically, preferably an alkyl or alkenyl group having 8 to 30 carbon atoms, preferably an alkyl group having 10 to 25 carbon atoms, and preferably an alkyl or alkenyl group having 12 to 22 carbon atoms. The alkyl or alkenyl group may be straight chain or branched, preferably a straight chain, and more preferably a straight chain alkyl group.

[0091] R1 may be an alkyl or alkenyl group in which at least one -CH2- is substituted by -C(=O)-, -NH- or -C(=O)-NH-. Preferably, at least one -CH2- in the alkyl or alkenyl group is substituted by -C(=O)-NH- or -NH-C(=O), preferably, one -CH2- in the alkyl group is substituted by -C(=O)-NH- or -NH-C(=O), and more preferably, R1 has an amidopropyl skeleton.

[0092] R2 and R3 preferably represent a linear or branched alkyl group or a linear or branched alkenyl group, preferably a linear or branched alkyl group, preferably a linear alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

[0093] R4 preferably represents a linear or branched alkyl group, a linear or branched alkenyl group or a phenyl group, and more preferably represents a linear or branched alkyl group. In addition, the terminal -CH3 in the alkyl group or alkenyl group is preferably substituted with a carboxyl group or a phenyl group.

[0094] The number of carbon atoms in R4 is preferably 1 to 8, preferably 1 to 5, preferably 1 to 3, and more preferably 1 or 2.

[0095] When R4 represents a methyl group, R2 and R3 also represent a methyl group, and preferably the general formula (3a) represents an alkyltrimethylammonium skeleton.

[0096] When R4 represents an ethyl group, the terminal -CH3 in the ethyl group is preferably substituted with a carboxyl group or a phenyl group. That is, R4 preferably represents -CH2-(C(=O)OH or a benzyl group.

[0097] The compound represented by the general formula (3a) is preferably a cationic surfactant having a quaternary ammonium skeleton represented by the general formula (3a-1).

[0098] C n H 2n+1 N + (CH3)2R4(3a-1)

[0099] (In the general formula (3a-1), n ​​represents the average number of added moles, and R4 represents the same meaning as R4 in the general formula (3a) described in claim 3.)

[0100] In the general formula (3a-1), the number of carbon atoms represented by n is preferably 8 or more. The more the number of carbon atoms exceeds 8, the better the ink releasability is, and the more preferred it is. Specific examples of the number of carbon atoms include octyl with 8 carbon atoms, nonyl with 9 carbon atoms, decyl with 10 carbon atoms, undecyl with 11 carbon atoms, lauryl with 12 carbon atoms, tridecyl with 13 carbon atoms, myristyl with 14 carbon atoms, pentadecyl with 15 carbon atoms, cetyl with 16 carbon atoms, oleyl with 18 carbon atoms, and stearyl.

[0101] Preferred groups for R4 are the same as those in the general formula (3a).

[0102] The cationic surfactants of these quaternary ammonium skeletons are preferably quaternary ammonium skeleton salts that form salts with halogens, preferably with Cl - Forming a salt, more preferably with Br - Forming a salt, further preferably with I - It is believed that the quaternary ammonium skeleton salt that forms a salt with the halogen promotes the hydrolysis of the ink film by the nucleophilic action of the halogen, thereby improving the releasability of the ink.

[0103] Among them, alkyltrimethylammonium chloride type, dialkyldimethylammonium chloride type, and alkylbenzalkonium chloride type compounds are preferred.

[0104] Specific products corresponding to the general formula (3a) or (3a-1) include DEHA, NISSAN CATION MA, NISSAN CATION SA, NISSAN CATION BB, NISSAN CATION FB, NISSAN CATION PB-300, NISSAN CATION ABT2-500, NISSAN CATION AB, NISSAN CATION AB-600, NISSAN CATION VB-M fragment, NISSAN CATION VB-F, NISSAN CATION 2-DB-500E, NISSAN CATION 2-DB-800E, NISSAN CATION 2ABT, NISSAN CATION 2-OLR, NISSAN CATION F2-50R, and NISSAN CATION M2-100R manufactured by NOF Corporation; and CATIOGEN TML, CATIOGEN TMP, CATIOGEN TMS, CATIOGEN Examples of the products include DDM-PG, CATIOGEN BC-50, and CATIOGEN TBB. Examples of the products manufactured by Kao Corporation include Quartamin 24P, Quartamin 86P CONC, Quartamin 60W, Quartamin 86W, SANISOL C, and SANISOL B-50. Examples of the products manufactured by Lion Corporation include LIPOGARD C-50, LIPOGARD T-28, LIPOGARD T-30, LIPOGARD T-50, LIPOGARD T-800, LIPOGARD 16-29, LIPOGARD 16-50E, LIPOGARD 18-63, LIPOGARD 22-80, LIPOGARD CB-50, LIPOGARD 210-80E, LIPOGARD 2C-75, LIPOGARD 2HP-75, LIPOGARD 2HP Flakes, and LIPOGARD 2HT-75, LIPOGARD 2HT fragment, LIPOGARD 20-751, LIPOGARD 41-50, TMAC-50, TPAH-40, TBAB-50A, TBAB-100A, TBAH-40, LIPOGARD PH-100, BTMAC-50, BTMAC-100A, BTEAC-50, BTEAC-100A, BTBAC-50A, etc., but are not limited to these.

[0105] The cationic surfactant preferably contains at least one compound represented by a primary to secondary alkanolamine skeleton, and preferably contains at least one compound represented by a monoalkanolamine skeleton.

[0106] As the primary monoalkanolamine, a lower alkanol having 1 to 4 carbon atoms is preferred, and specifically, monoethanolamine, 2-aminoisobutanol, etc. can be cited. As the secondary monoalkanolamine, N-methylethanolamine, 2-ethylaminoethanol, isopropanolamine, etc. can be cited, but substances other than those exemplified can also be used appropriately. In addition, these monoalkanolamine compounds can be used alone or in combination of two or more, or mixed with water. The cationic surfactants of these monoalkanolamine skeletons are preferably monoalkanolamine salts that form salts with halogens, preferably with Cl - A salt is formed.

[0107] These surfactants can be used alone or in combination of two or more. The amount added is preferably in the range of 5% by weight or less, preferably 2% by weight or less, relative to the total amount of the aqueous cleaning solution. The lower limit of the surfactant is not particularly limited, and may be 0% by weight. In the case of containing a surfactant, it is preferably 0.1% by weight or more.

[0108] (Water-insoluble alcohol)

[0109] As the cleaning liquid that can be used in step 1, a cleaning liquid containing a water-insoluble primary alcohol in water can be used. The water-insoluble primary alcohol is preferably contained in an amount of 20% by weight or less based on water.

[0110] Examples of the water-insoluble primary alcohol include butane-1-ol, pentane-1-ol, hexane-1-ol, heptane-1-ol, octane-1-ol, nonane-1-ol, decane-1-ol, undecan-1-ol, dodecan-1-ol, tridecan-1-ol, tetradecan-1-ol, pentadecane-1-ol, hexadecan-1-ol, heptadecan-1-ol, octadecan-1-ol, nonadecan-1-ol, eicosan-1-ol, heneicosan-1-ol, docosan-1-ol, tricosan-1-ol, tetracosan-1-ol, pentacosan-1-ol, hexacosan-1-ol, heptacosan-1-ol, octacosan-1-ol, nonacosan-1-ol, triacontan-1-ol, octacosan-1-ol, 2-methylpropane-1-ol and benzyl alcohol. Among them, butane-1-ol and benzyl alcohol are preferred.

[0111] (Water-soluble alcohol)

[0112] As a cleaning liquid that can be used in step 1, a cleaning liquid containing a water-soluble primary alcohol in water can be used. Examples of the water-soluble primary alcohol include methanol, ethanol, and propane-1-ol. As industrial alcohol, any mixture of these alcohols can also be used. The water-soluble primary alcohol preferably contains 20% by weight or more relative to water.

[0113] (Water-insoluble glycol ether organic solvent)

[0114] A cleaning liquid containing a water-insoluble glycol ether organic solvent in water can be used as the cleaning liquid that can be used in step 1. An aqueous cleaning liquid containing a water-insoluble glycol ether organic solvent in an amount of 20% by weight or less based on water is preferred.

[0115] Examples of the water-insoluble glycol ether-based organic solvent include aromatic glycol ethers.

[0116] (Aromatic glycol ether solvent)

[0117] As the cleaning liquid that can be used in step 1, a cleaning liquid containing an aromatic glycol ether solvent in water can be used. As the aromatic glycol ether solvent, for example, as examples of aromatic glycol ethers, ethylene glycol monophenyl ether (phenoxyethanol), ethylene glycol monobenzyl ether, ethylene glycol dibenzyl ether, diethylene glycol monophenyl ether, diethylene glycol diphenyl ether, propylene glycol monophenyl ether, etc. can be mentioned. As examples of ester glycol ethers, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-butyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, etc. can be mentioned. Among them, ethylene glycol monophenyl ether (phenoxyethanol) is more preferred.

[0118] (Water-soluble glycol ether organic solvent)

[0119] A washing liquid containing a water-soluble glycol ether-based organic solvent in water can be used as the washing liquid that can be used in step 1. An aqueous washing liquid containing a water-soluble glycol ether-based organic solvent in an amount of 20% by weight or more based on water is preferred.

[0120] Examples of the water-soluble glycol ether-based organic solvent include alkylene glycol alkyl ethers.

[0121] (Water-soluble alkylene glycol alkyl ether solvent)

[0122] R 1 -O-[CH2-CH(X)-O]n 1 -R 2 (4)

[0123] (In general formula (4), R 1 represents an alkyl group having 1 or more carbon atoms, R 2 represents an alkyl group with 1 or more carbon atoms or hydrogen, n 1 represents an integer of 1 to 3, and X represents hydrogen or methyl. )

[0124] Among the alkylene glycol alkyl ethers represented by the general formula (4), water-soluble alkylene glycol alkyl ethers are more preferred.

[0125] Examples of the alkylene glycol alkyl ether represented by the general formula (4) include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol methyl ethyl ether, ethylene glycol methyl propyl ether, ethylene glycol ethyl propyl ether, ethylene glycol monobutyl ether, ethylene glycol tert-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl propyl ether, diethylene glycol ethyl propyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether and the like.

[0126] These alkylene glycol alkyl ethers can be used alone or in combination of two or more, or can be mixed with water. There is no particular problem as long as the content of the alkylene glycol alkyl ether is more than 20% by weight. When water is used as a medium, it is preferably more than 30% by weight, and most preferably more than 40% by weight. On the other hand, the upper limit can be 100% by weight, but from the perspective of environmental impact and safety, water is preferably used as a medium.

[0127] Among the water-soluble alkylene glycol alkyl ethers represented by the general formula (4), the alkylene glycol monoalkyl ethers represented by the general formula (5) are more preferred.

[0128] R 2 -O-[CH2-CH(X)-O]n 2 -H(5)

[0129] (In general formula (5), R 2 represents an alkyl group with 1 or more carbon atoms, n 2 represents an integer of 1 to 3, and X represents hydrogen or methyl. )

[0130] Examples of the water-soluble alkylene glycol alkyl ether represented by the general formula (5) include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether, ethylene glycol tert-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and the like.

[0131] Furthermore, in the aqueous cleaning liquid containing the water-soluble alkylene glycol alkyl ether represented by the general formula (5), from the viewpoint that the composition can maintain the peeling property even when the water content is much higher than 50 wt %. 2 is an alkyl group having 3 or more carbon atoms, n 2 1~3, X 2It is hydrogen or methyl.

[0132] Specifically, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol tert-butyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, etc. can be exemplified. These alkylene glycol alkyl ethers can be used alone or in combination of two or more, or can be mixed with water.

[0133] Among them, diethylene glycol monobutyl ether, ethylene glycol mono-tert-butyl ether, and propylene glycol monopropyl ether are particularly preferred from the viewpoints of environmental characteristics, flammability, and defoaming properties.

[0134] (Water-soluble monoalkanolamine organic solvent)

[0135] A cleaning liquid containing a water-soluble alkanolamine organic solvent in water can be used as the cleaning liquid that can be used in step 1. Preferably, the cleaning liquid contains 20% by weight or more of the water-soluble alkanolamine organic solvent based on water.

[0136] The primary or secondary monoalkanolamine having a boiling point of 150 to 200° C. may be contained in an amount of 10% to 50% by weight based on the total amount of the cleaning liquid.

[0137] Examples of primary monoalkanolamines include monoethanolamine, 2-aminoisobutanol, isopropanolamine, etc., and examples of secondary monoalkanolamines include N-methylethanolamine, 2-ethylaminoethanol, dimethylaminoethanol, etc. Among primary and secondary monoalkanolamines, any other than those listed above may be used as appropriate as long as the boiling point is within the range of 150 to 200° C. In addition, these monoalkanolamine compounds may be used alone or in combination of two or more thereof, or may be mixed with water.

[0138] (Defoaming Agent)

[0139] The water used in step 1 may contain a defoaming agent. In step 1, a large amount of bubbles may be generated in the stirring and breaking step. If bubbles remain, the bubbles may overflow in the plastic film recovery step. In addition, in the plastic film breaking step, if a large amount of bubbles are involved in the washing liquid, the plastic substrate may not be broken into a desired size.

[0140] As compounds generally used as defoamers, water-soluble organic solvents and nonionic surfactants with low HLB values ​​in the range of 1 to 3 are used. Silicone compounds are particularly preferred from the perspective of high defoaming ability. Among them, emulsion-type and self-emulsifying silicone compounds are preferred.

[0141] Specific defoaming agents include X-50-1176, KS-530, and KS-537 manufactured by Shin-Etsu Chemical Co., Ltd. as self-emulsifying types, KM-7750D, KM-7752, and KM-98 manufactured by Shin-Etsu Chemical Co., Ltd., FS Antifoam 025, FS Antifoam 80, FS Antifoam 92, FS Antifoam 93, DKQ1-1183, and DKQ1-1247 manufactured by Nagase Chem Spec, but are not limited to these.

[0142] The defoaming agent may be used alone or in combination of two or more. The amount of the cleaning liquid used in step 1 is preferably in the range of 0.01 to 5 wt %, more preferably in the range of 0.02 to 4 wt %, and even more preferably in the range of 0.03 to 3 wt %.

[0143] (liquid temperature)

[0144] The liquid temperature of the water or cleaning liquid used in step 1 is not particularly limited as long as it is kept in a liquid state, and is generally preferably performed at a liquid temperature of 15 to 90°C. In the case of using an aqueous cleaning liquid in which a surfactant or the like is added to water, it is preferred to adjust the liquid temperature according to the type of surfactant. The optimal temperature for excellent cleaning effect varies depending on the type of surfactant, and is, for example, preferably 40°C or higher, preferably 65°C or higher, and preferably 85°C or higher.

[0145] On the other hand, when it is desired to improve the crushability of the plastic film, that is, to crush the plastic film more finely, the liquid temperature is preferably not too high, and is preferably 40° C. or lower, preferably 30° C. or lower, and preferably 20° C. or lower. The smaller the size of the crushed plastic film, the larger the cross-sectional area, so that in step 2, each layer constituting the plastic film is easily swelled into a single layer.

[0146] <About Process 2>

[0147] The method for separating and recovering a plastic film of the present invention comprises step 2 of immersing the plastic film crushed in step 1 in a cleaning liquid. In step 2, each layer constituting the plastic film and the ink layer can be easily swollen.

[0148] (Immersion time)

[0149] In step 2, the immersion time is preferably a time for the crushed plastic film to swell sufficiently, specifically, preferably 30 minutes or more. More specifically, it is in the range of 30 minutes to 48 hours. When the lower limit is less than 30 minutes, it is difficult to swell sufficiently in step 2. On the other hand, when the upper limit exceeds 48 hours, the separation and recovery of the present invention takes too much time.

[0150] In addition, the immersion time can be appropriately adjusted by combining the liquid temperature and stirring described later. The higher the liquid temperature, the shorter the immersion time. In the case of constructing a practical recycling system, it is preferred to set the upper limit of the immersion time to about 4 hours while warming the liquid temperature.

[0151] For example, when the immersion is performed at room temperature, the immersion can be performed for more than 24 hours to fully swell the granules. In addition, when the liquid temperature is set to 40°C, the immersion can be performed for 16 hours to fully swell the granules. In addition, when the liquid temperature is set to 75°C, the immersion can be performed for 2 hours to fully swell the granules.

[0152] (temperature)

[0153] In step 2, the liquid temperature of the cleaning liquid is not particularly limited as long as it maintains a liquid state. If it is carried out at room temperature, the liquid temperature does not need to be heated, so it can help reduce CO2 emissions and is preferred. On the other hand, in the case of giving priority to efficiency as a practical recycling system, a method of shortening the immersion time while heating the liquid temperature is preferred. That is, it is usually preferably carried out at a liquid temperature of 15 to 90°C. In the case of using an aqueous cleaning liquid in which a surfactant or the like is added to water, it is preferably to adjust the liquid temperature according to the type of surfactant. The optimal temperature for excellent cleaning effect varies depending on the type of surfactant, and is preferably above 40°C, preferably above 50°C, and preferably above 60°C. The upper limit of the liquid temperature is not particularly limited as long as it maintains a liquid state, and is usually preferably below 90°C.

[0154] On the other hand, when it is desired to improve the crushability of the plastic film, that is, to crush the plastic film more finely, the liquid temperature is preferably not too high, and is therefore preferably 40° C. or lower, preferably 30° C. or lower, and preferably 20° C. or lower. The smaller the size of the crushed plastic film, the greater the cross-sectional area, so that the layers constituting the plastic film are easily separated into single layers in step 3, and the peeling and colorization of the ink layer are facilitated.

[0155] (Stirring)

[0156] In step 2, stirring is not essential and may be optional, but stirring can more effectively cause swelling. Stirring is preferably performed at a stirring speed that hardly generates foaming even without adding a defoaming agent.

[0157] The device and method for stirring during stirring are not particularly limited, and a known method can be used. Specifically, a device having a motor with stirring wings capable of stirring the cleaning liquid in a container, a device having a device for generating ultrasonic waves, a device capable of oscillating together with the container, a wet crusher, etc. can be mentioned. The wet crusher can be the same crusher as that described in step 1.

[0158] (Cleaning fluid)

[0159] The cleaning liquid used in step 2 may be directly used as the cleaning liquid used when the wet crusher is used in step 1. Specifically, it is preferable to use a cleaning liquid containing water, the inorganic base described in step 1, and the surfactant described in step 1.

[0160] In addition, the cleaning liquid used in step 2 may contain an appropriate amount of an organic solvent. As the organic solvent, for example, one or more water-soluble alcohols and a water-soluble solvent having a flash point of 21° C. or higher are preferably contained. By using a water-soluble solvent in the cleaning liquid, hydroxide ions generated from the inorganic base contained in the cleaning liquid are difficult to hydrate, so the nucleophilicity of the hydroxide ions becomes higher, and the ink layer peeling reaction can be carried out under the hydrophobic field environment, which is effective for peeling the ink film.

[0161] The water-soluble solvent having a flash point of 21° C. or higher is preferably an organic solvent corresponding to the second petroleum type and the third petroleum type specified in the Fire Protection Act, and examples thereof include diethylene glycol butyl ether, propylene glycol propyl ether, and 3-methoxy-3-methyl-1-butanol.

[0162] In addition, examples of water-soluble alcohols include alcohols specified in the Fire Protection Act, and specifically include methanol, ethanol, 1-propanol, 2-propanol, etc. These can be used alone or in combination.

[0163] In addition, as an organic solvent, the water-insoluble alcohol and water-insoluble glycol ether organic solvent described in the above step 1 may be preferably contained. Among them, butane-1-ol, benzyl alcohol, and ethylene glycol monophenyl ether (phenoxyethanol) are particularly preferred.

[0164] In step 2, the plastic film that has been broken in step 1 is fully swollen, so that the plastic film can be easily and completely peeled off into a single layer even if only water is used in step 3. In particular, when the plastic film has an ink layer, it is difficult to colorize the plastic depending on the type of ink and the structure of the plastic film. However, in the present invention, by performing steps 1 and 2, a base is prepared that allows at least a part of each layer of the plastic film to be peeled off or easily peeled off, and in step 3 described later, the plastic film is separated into single layers and the ink layer is peeled off, so that the ink layer can be easily peeled off regardless of the type of ink and the structure of the plastic film.

[0165] In particular, from the perspective of the removability of the ink layer, the cleaning liquid used in step 2 preferably contains a large amount of a water-soluble solvent in the cleaning liquid. Specifically, the water-soluble solvent is preferably 30% by mass or more, preferably 40% by mass or more, preferably 50% by mass or more, preferably 60% by mass or more, preferably 70% by mass or more, preferably 80% by mass or more, preferably 90% by mass or more, and preferably 95% by mass or more.

[0166] In addition, the cleaning liquid used in step 2 preferably contains an inorganic base. Specifically, the inorganic base includes sodium hydroxide and potassium hydroxide. These inorganic bases are preferably contained in a concentration of 0.1 to 10% by weight relative to the total amount of the ink cleaning liquid, and more preferably in a concentration of 0.1% to 5% by weight. In addition, the pH is preferably above 10, preferably above 11, and more preferably above 12. Sodium hydroxide is poorly soluble in organic solvents, so when sodium hydroxide is used, it is preferably used in combination with a cationic surfactant. Specifically, a cleaning liquid containing sodium hydroxide, a cationic surfactant, a water-insoluble aromatic glycol ether solvent, a water-soluble alcohol or a water-soluble alkanolamine solvent can be used. On the other hand, when potassium hydroxide is used, in order to be easily soluble in an organic solvent, a cationic surfactant may not be used in combination. Specifically, for example, a cleaning liquid containing potassium hydroxide and a water-soluble alcohol or an aromatic glycol ether solvent can be used.

[0167] In addition, the cleaning liquid used in the step 2 may contain water. When the cleaning liquid in the step 2 contains water, the operation stability and environmental stability in the step 2 can be improved.

[0168] In addition, the cleaning liquid used in step 2 may contain a surfactant. The surfactant is not particularly limited, and known surfactants can be used, for example, anionic surfactants, nonionic surfactants, amphoteric surfactants, cationic surfactants, etc. As specific types of these surfactants, the same surfactants as those described as surfactants that can be contained in water in step 1 can be used.

[0169] In the cleaning solution of step 2, the surfactant may be used alone or in combination of two or more. The amount added is preferably in the range of 5% by weight or less, preferably 2% by weight or less, relative to the total amount of the cleaning solution. The lower limit of the surfactant is not particularly limited, and may be 0% by weight. When a surfactant is contained, it is preferably 0.01% by weight or more.

[0170] <About Process 3>

[0171] The method for separating and recovering a plastic film of the present invention comprises, after the steps 1 and 2, a step 3 of separating the plastic film by stirring the crushed and swollen plastic film in water.

[0172] (Stirring)

[0173] In step 3, the stirring device and method during stirring are not particularly limited, and a known method can be used. Specifically, there can be mentioned a device having a motor with stirring wings capable of stirring the cleaning liquid in the container, a device having a device for generating ultrasonic waves, a device capable of oscillating together with the container, a wet crusher, etc. The wet crusher can use the same crusher as the crusher described in step 1.

[0174] Step 3 preferably includes a step of passing the plastic film after being crushed in step 1 through a gap of 30 mm or less. The gap is more preferably 20 mm or less, and more preferably 10 mm or less. Passing through a gap of 10 mm or less can exert a high shear force on the plastic film, for example, it has an effect of wiping off the ink from the plastic film with the ink layer provided on the exposed part, and an effect of exerting a shear stress on the plastic film with the ink layer provided between a plurality of films, and can promote the peeling of the laminate.

[0175] The wet crusher has a mechanism for crushing with a fixed blade and a rotating blade, so the gap can be easily controlled according to its operating conditions. The narrower the gap, the higher the shear force can be applied to the plastic film, but the narrower the gap, the easier it is for the plastic film to be clogged, and the liquid temperature of water or cleaning liquid to rise rapidly, so it is preferably 0.1 mm or more.

[0176] Specifically, the gap through which the plastic film passes is set by setting a gap of a predetermined size or less and applying high shear. The design can be made, for example, by controlling the gap between the inner wall of the tank for stirring the plastic film and / or water and the stirring blade to a predetermined size or less, providing a baffle at a distance of a predetermined size or less from the tank wall, designing the plastic film and / or water to pass through a sieve having holes of a predetermined size or less, passing between two rollers having a gap of a predetermined size or less, using a ball mill or the like to sandwich a laminate so that the media collide with each other, for example, providing a fixed blade on the outside of a rotating blade like a homogenizer and controlling the gap between the rotating blade and the fixed blade to a predetermined size or less.

[0177] The shear rate in step 3 is preferably 2,000 s -1 The faster the shear rate, the higher the effect of scraping the ink off the plastic film and the effect of applying shear stress to the plastic film having the ink layer provided between the plurality of films, so there is no upper limit.

[0178] In addition, the shear rate (D) mentioned here is defined by the following formula.

[0179] D=v / Δy

[0180] v: Flow velocity (m / s), calculated as v = π × R × (n / 60)

[0181] π: Pi

[0182] R: Diameter of rotating blade (m)

[0183] n: Rotating blade speed (rpm)

[0184] Δy: Gap (m), here refers to the gap (m) between the rotating blade and the fixed blade.

[0185] The larger the diameter of the fixed blade of the wet crusher, the higher the flow rate. Therefore, the larger the size of the fixed blade of the wet crusher, the more preferable it is. The narrower the gap, the higher the shear rate. Therefore, the narrower the gap, the more preferable it is.

[0186] The blade design of the fixed blade and the rotating blade is preferably such that at least a portion of the blade is arranged in a radial direction, and the blade arranged in the radial direction is preferably inclined at 2° to 60° from the radial direction, and more preferably at 5° to 45°.

[0187] When a plurality of cutters are arranged in parallel on the rotary blade, the blade width of the rotary blade is preferably 0.5 to 5.0 mm, the groove width between the cutters is preferably 0.5 to 5.0 mm, and the height of the cutters is preferably 1.0 to 5.0 mm.

[0188] The stirring Froude number (Fr) in step 3 is preferably not less than 10. The faster the stirring Froude number, the greater the effect of scraping ink off the plastic film and the effect of applying shear stress to the plastic film having the ink layer provided between the plurality of films, so there is no upper limit.

[0189] In addition, the stirring Froude number (Fr) mentioned here is defined by the following formula.

[0190] Fr = {(n / 60) 2}×R / g

[0191] n: Rotating blade speed (rpm)

[0192] R: Diameter of rotating blade (m)

[0193] g: Gravitational acceleration = 9.8 (m / s 2 )

[0194] Step 3 is a step of peeling off the adhesive, ink layer, etc. from the plastic film swollen in water, so it is preferable to use a wet crusher that can obtain high shear force and / or high friction force. Examples of such wet crushers include KD series from Husqvarna-Zenoah, Suncutter series from Nikuni, Disintegrator series from Furukawa Industrial Machinery Systems, In-crusher series or Refiner from Aikawa Iron Works, Scatter from Sanwa Hydrotech, Trigonal manufactured by COKE Japan, alkali cleaning / cleaning deinking equipment manufactured by CIM Japan, and cleaning crusher Scissors Cutter series.

[0195] (Ink removability)

[0196] The ink removability of the plastic film after step 3 is preferably 50% or more, more preferably 75% or more, and particularly preferably 90% or more.

[0197] The ink removability was measured as follows.

[0198] After the film was washed and dried after the stirring step in step 3, the ink removability of the printed portion was determined by calculating the area by image processing of a photograph taken with an optical microscope and determining the ink removal rate using the following formula.

[0199] Ink removal rate (%) = (1-ink adhesion area after cleaning / ink adhesion area before cleaning) × 100

[0200] (Surface roughness)

[0201] The surface roughness of the plastic film after step 3 is preferably 0.7 μm or more. By using the wet crushing equipment as described above to set the surface roughness of the crushed product to 0.7 μm or more, the plastic film laminate can be separated into single layers, and not only the ink layer provided on the surface of the plastic film laminate can be removed, but also the ink layer provided between the laminates can be removed, so the recovered crushed product is suitable as a raw material for manufacturing high-quality recycled plastics.

[0202] The surface roughness of the crushed product is preferably 0.7 μm or more, more preferably 0.8 μm or more, and further preferably 0.9 μm or more. On the other hand, the upper limit is not particularly limited and can be appropriately adjusted according to the conditions of the wet crushing equipment.

[0203] The surface roughness of the film was determined by measuring the surface roughness Sa of 500 μm×600 μm using a white interference microscope manufactured by Ryoka Systems Co., Ltd. Sa is not a value obtained from a cross section like Ra, but represents the value of the entire in-plane area, so the evaluation range is wider and the overall surface roughness can be evaluated.

[0204] (Size of diaphragm)

[0205] The size of the plastic film after step 3 is preferably 20 mm or less in the long side direction, more preferably 10 mm or less, and further preferably 5 mm or less. In addition, the length in the short side direction is preferably 20 mm or less, preferably 10 mm or less, preferably 5 mm or less, and preferably 3 mm or less. There is no particular lower limit on the size of the broken object, but if it is too small, the recyclability decreases, so it is preferred that the length in the long side direction is 1 mm or more.

[0206] (water)

[0207] In step 3, water is used as a solvent. After step 3, the plastic crushed products are collected in single layers. However, when the cleaning liquid with a pH of 10 or higher used in step 2 is used in step 3, the obtained plastic crushed products often require a cleaning step in order to make the pH neutral. In addition, the cleaning liquid with a pH of 10 or higher may sometimes cause corrosion to the device itself. In the present invention, neutral water is used as a solvent in step 3, so such a problem is less likely to occur.

[0208] (Recycling Equipment)

[0209] The plastic crushed material separated into single layers in step 3 can be recovered as a single layer. The equipment and method for recovering the plastic crushed material are not particularly limited, and for example, a filter, a centrifugal separator, an automatic scraping rod screen, an inclined mesh screen, a drum screen, etc. can be used.

[0210] <About Process 4>

[0211] The method for separating and recovering plastic films of the present invention preferably comprises, after the steps 1, 2 and 3, a step 4 in which the plastic films recovered by layer are stirred in a rinse liquid to perform fine washing on the plastic films.

[0212] (Stirring)

[0213] In step 4, the stirring device and method during stirring are not particularly limited, and a known method can be used. Specifically, there can be mentioned a device having a motor with stirring wings capable of stirring the cleaning liquid in the container, a device having a device for generating ultrasonic waves, a device capable of oscillating together with the container, a wet crusher, a kneader, etc. The wet crusher can be the same crusher as the crusher described in step 1.

[0214] The purpose of step 4 is to remove a small amount of ink flakes remaining on the surface of the plastic film, so a known dispersing device using a medium such as beads can be used. Examples of a dispersing machine having a medium include a disperser, a dispersing machine having stirring blades such as turbine blades, a paint stirrer, a roll mill, a ball mill, a grinder, a sand mill, a bead mill, and the like. As the medium used, salt, glass beads, zirconium oxide beads, and the like are preferably used.

[0215] The ball diameter of the medium used is preferably 0.5 to 20 mm, more preferably 1 to 10 mm, and further preferably 2 to 5 mm. As the material of the medium, steel, zirconium oxide, aluminum oxide, glass, etc. can be cited, which can be used separately according to the properties of the selected flushing liquid. If the medium diameter is less than 0.2 mm, it is difficult to handle and difficult to recover the beads. If it exceeds 5 mm, it becomes easy to handle, but a large amount of flushing time is required, causing a decrease in productivity. The device residence time in step 4 is preferably 1 to 30 minutes.

[0216] Examples of the disperser with a medium include StarMill manufactured by Ashizawa Finetech Co., Ltd., MSC-MILL, SC-MILL, and Attritor MA01SC manufactured by Mitsui Mining Co., Ltd., Nano Glen Mill, Piko Glen Mill, Pure Glen Mill, Megacapper Glen Mill, Cera PowerGlen Mill, Dual Glen Mill, AD Mill, Twin AD Mill, Basket Mill, and Tuin Basket Mill manufactured by Asada Iron Works Co., Ltd., and Apex Mill, Ultra Apex Mill, and Super Apex Mill manufactured by Kotobukiya Kogyo Co., Ltd.

[0217] (Rinsing fluid)

[0218] The rinse liquid used in step 4 may directly adopt the cleaning liquid used when using the wet crusher in step 1. Specifically, it may contain an appropriate amount of organic solvent, which is preferred. As the organic solvent, for example, it is preferred to contain one or more water-soluble alcohols and a water-soluble solvent with a flash point of 21°C or more. By using a water-soluble solvent in the rinse liquid, it is effective for peeling off the ink film that slightly remains on the surface of the plastic film after step 3. The water-soluble solvent with a flash point of 21°C or more is preferably a water-soluble solvent among the organic solvents equivalent to the second petroleum type and the third petroleum type specified in the Fire Protection Act. In addition, as water-soluble alcohols, alcohols specified in the Fire Protection Act can be cited. As them, specifically, as the second petroleum and the third petroleum, there can be mentioned 3-methoxy-3-methyl-1-butanol, diethylene glycol monobutyl ether, propylene glycol propyl ether, N-methylethanolamine, 2-ethylaminoethanol, isopropanolamine, and as alcohols, there can be mentioned methanol, ethanol, 1-propanol, 2-propanol, etc., and the industrial ethanol contained in them can be used alone or as a mixture.

[0219] In addition, as the organic solvent, the water-insoluble alcohol and water-insoluble glycol ether organic solvents described in the above step 1 may be preferably contained. Among them, butane-1-ol, benzyl alcohol, and ethylene glycol monophenyl ether (phenoxyethanol) are particularly preferred.

[0220] In particular, from the viewpoint of the removability of a small amount of residual ink layer, the rinsing liquid used in step 4 preferably contains a large amount of so-called water-soluble solvents including alcohols in the cleaning liquid. Specifically, the water-soluble solvent is preferably 30% by mass or more, preferably 40% by mass or more, preferably 50% by mass or more, preferably 60% by mass or more, preferably 70% by mass or more, preferably 80% by mass or more, preferably 90% by mass or more, and preferably 95% by mass or more.

[0221] In step 4, when a rinse liquid mainly composed of a so-called water-soluble solvent containing alcohols and intentionally not containing water is used, an inorganic salt may be used.

[0222] (Inorganic salt)

[0223] The inorganic salt used in the present invention is not particularly limited as long as it can be used as a grinding aid. From the viewpoint of removing the inorganic salt in the subsequent process, it is preferably water-soluble to the extent that 10 g or more is dissolved in 100 g of water at room temperature. In addition, it is preferably insoluble to the extent that only 10 mg or less is dissolved in 100 g of the above-mentioned water-soluble organic solvent at room temperature, and it is more preferably substantially insoluble in the organic solvent. Specifically, sodium chloride, potassium chloride, calcium chloride, sodium sulfate, potassium sulfate, aluminum sulfate, etc. can be mentioned, and sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, etc. are more preferred. The above-mentioned inorganic salts can be used alone or in combination of two or more.

[0224] When an inorganic salt is used as a grinding aid, the inorganic salt is preferably 100 to 2000 mass%, more preferably 300 to 1500 mass%, relative to the plastic film 100. In addition, the amount of the rinse liquid is 5000 to 50000 mass%, preferably 10000 to 40000 mass%, relative to the plastic film 100. The more the inorganic salt is, the higher the peeling effect of the residual ink layer is, and the smaller the amount of the solvent is, the higher the effect is.

[0225] When an inorganic salt is used as a grinding aid, the treatment temperature is preferably 120° C. or lower, particularly preferably 20 to 70° C. The treatment time is preferably about 5 minutes to 3 hours.

[0226] The device for kneading the mixture of the plastic film, inorganic salt (grinding aid) and water-soluble organic solvent after process 3 can be any device that can mechanically grind the plastic film, and a kneader can be cited as a specific example. In addition, a super mixer made by KAWATA represented by a paint stirrer and a paint regulator, an FM mixer made by COKE of Japan, an intermittent kneading machine such as TRIMIX made by Inoue Manufacturing Co., Ltd., and a continuous kneading machine such as KCKMILL made by Asada Iron Works Co., Ltd. can also be used. In addition, devices other than these can also be used.

[0227] (Plastic film)

[0228] The plastic film separated and recovered by the present invention is a plastic film having at least an ink layer. Plastic films with an ink layer (front surface printing) exposed on the film surface, laminated films with an ink layer (back surface printing) between multiple films, single-layer films or laminated films that are usually circulated as packaging materials for food packaging or daily necessities, and various types of plastic films with resin layers that are discarded through recycling can be separated and recovered without special restrictions. That is, the separation and recovery method of the present invention is characterized in that it can be processed together without special re-separation.

[0229] In addition, in order to give a product name or other indication or decorative features to containers such as plastic bottles, a laminated film formed into a cylindrical shape, i.e., a shrink label, is used. During recycling, consumers often peel off the shrink label and discard the plastic bottle body and the shrink label separately. However, in the separation and recycling method of the present invention, even when the plastic bottle body and the shrink label are integrated, the shrink label can be separated from the plastic bottle body and the shrink label can be separated into individual single-layer films.

[0230] In the laminated film bonded by the reactive adhesive, an adhesive layer composed of the reactive adhesive is laminated between at least two resin film layers or metal foil or vapor-deposited film layers. Specifically, in the laminated film, when the resin film layer is represented as (F), the metal foil layer of the metal foil or vapor-deposited film layer is represented as (M), and the adhesive layer of the reactive adhesive or the like is represented as (AD), the following configurations can be considered as specific forms of the laminated film, but are of course not limited thereto.

[0231] (F) / (AD) / (F),

[0232] (F) / (AD) / (F) / (AD) / (F),

[0233] (F) / (AD) / (M) / (AD) / (F),

[0234] (F) / (AD) / (M),

[0235] (F) / (AD) / (M) / (F),

[0236] (F) / (AD) / (F) / (AD) / (M) / (AD) / (F)、

[0237] (F) / (AD) / (M) / (AD) / (F) / (AD) / (F)、

[0238] (M) / (AD) / (F) / (AD) / (M),

[0239] (AD) / (F) / (AD) / (M),

[0240] (AD) / (F) / (AD) / (F) / (AD), etc.

[0241] (coating)

[0242] The outermost surface of the laminated film may be a functional coating. The coating may be colorless or colored. The coating may be provided in contact with the substrate, or may be provided via an inorganic vapor-deposited layer or the like in contact with the substrate. The coating may also be in the form of stacking different coatings. The thickness of the coating is not particularly limited, but is preferably 0.1 μm or more and 100 μm or less, more preferably 0.1 μm or more and 10 μm or less, and further preferably 1 μm or more and 5 μm or less.

[0243] Functional coatings are formed for various purposes. Typical functions include hard coating, silicone peeling, IR cutoff, water and moisture proofing, antibacterial, UV cutoff, heat dissipation, photocatalyst, weather resistance, anti-fog, anti-fingerprint and anti-fouling, self-healing, water and oil repellency, etc.

[0244] The laminated film to be used as the subject of the present separation and recovery method may further include a paper layer, an oxygen absorbing layer, an anchor coating layer, an ink layer, a release primer layer provided to facilitate the removal of the ink, and the like.

[0245] (Base coating)

[0246] The aforementioned printing ink is usually printed on a resin film that becomes a substrate film layer (F1) in the aforementioned laminated film, and then the aforementioned reactive adhesive is applied to the printed surface, and laminated with another substrate film (F1) or a sealing layer (F2) or a metal foil or a metal foil layer (M) of a vapor-deposited film layer to form a laminated film. In the laminated film having such a layer structure, a primer layer may also be provided on the substrate film layer (F1) that becomes the printed surface. As the primer layer, since it is easily dissolved or hydrolyzed by an alkaline solution, it is preferable to contain a resin having an acidic group, so that the laminated film printed with the ink and then laminated with an adhesive can be easily separated into a single layer film.

[0247] The primer may be provided on the sealing layer (F2), or may be provided on both F1 and F2. If the primer is provided on both F1 and F2, separation into single-layer films can be made easier.

[0248] The primer layer can use resin and low molecular weight compound with acidic group separately. In addition, resin and low molecular weight compound with acidic group can be mixed in the resin without acidic group and used. As the resin with acidic group, for example, resin with acid value such as rosin-modified maleic acid resin, rosin-modified fumaric acid resin, etc., make acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, cinnamic acid or their anhydrides etc. have carboxyl polymerizable monomer, sulfonated styrene etc. have sulfonic acid group polymerizable monomer, vinylbenzenesulfonamide etc. have sulfonamide group polymerizable monomer etc. have acidic group polymerizable monomer copolymerization (methyl) acrylic resin, styrene-(methyl) acrylic resin, styrene-maleic acid (anhydride) resin, terpene-maleic acid (anhydride) resin etc. as free radical copolymer resin, acid-modified polyolefin resin etc., can use one among them or use multiple in combination.

[0249] In addition, the primer layer may be made of a resin having a low acid value and film-forming properties at room temperature, which is a low molecular weight compound having an acidic group, or a mixture of two or more thereof.

[0250] Examples of the low molecular weight compound having an acidic group include saturated fatty acids, unsaturated fatty acids, hydroxy acids, aromatic carboxylic acids, dicarboxylic acids, tricarboxylic acids, oxocarboxylic acids, carboxylic acid derivatives, and acid anhydrides, and they may be used alone or in combination of two or more.

[0251] Examples of saturated fatty acids include lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid. Examples of unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and sorbic acid. Examples of hydroxy acids include lactic acid, malic acid, and citric acid. Examples of aromatic carboxylic acids include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and cinnamic acid. Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, and maleic acid. Examples of tricarboxylic acids include aconitic acid. Examples of oxocarboxylic acids include pyruvic acid and oxaloacetic acid. Examples of carboxylic acid derivatives include amino acids and nitrocarboxylic acids. Examples of acid anhydrides include trimellitic anhydride and pyromellitic anhydride. One of these may be used alone or in combination.

[0252] As the aforementioned resins having film-forming properties at room temperature, there are various synthetic resins, for example, polyester, polyvinyl chloride, copolymers of vinyl chloride and other monomers containing unsaturated double bonds, homopolymers of (meth)acrylate, copolymers of (meth)acrylate and other monomers containing unsaturated double bonds, polystyrene, copolymers of styrene monomer and other monomers containing unsaturated double bonds, ketone-formaldehyde condensates, hydrogenated products thereof, multifunctional epoxy resins, polyvinyl alcohol acetals, polyurethanes, etc., which can be used alone or in combination with one or more selected from them. As multifunctional epoxy compounds, for example, bisphenol A novolac epoxy resins, bisphenol F novolac epoxy resins, bisphenol S novolac epoxy resins, biphenyl epoxy resins, and naphthalene epoxy resins can be mentioned.

[0253] When using a low molecular weight compound having an acidic group or a mixture of multiple compounds in the aforementioned resin with a low acid value and film-forming properties at room temperature, the amount added can be appropriately determined within a range that does not impair the printing adaptability or coating adaptability of the primer solution, and is preferably in the range of 0.5 to 50 weight %, more preferably in the range of 1.0 to 30 weight %, roughly relative to the solid content of the primer solution.

[0254] When the printed material is polypropylene (PP), for example, it is preferable to use, as a resin having film-forming properties, at least one thermoplastic resin selected from the group consisting of ketone-formaldehyde condensates or hydrogenated products thereof, polyesters, vinyl chloride-vinyl acetate copolymers, and polyvinyl acetals, which has good adhesion to PP and is solid at 50° C. Examples of such ketone-formaldehyde condensates or hydrogenated products thereof include Evonik Degussa Japan (KK) TEGO (registered trademark) VariPlus series (SK, AP, etc.), examples of polyesters include Toyobo Co., Ltd.'s Vylon (registered trademark) series (Vylon 200, etc.), examples of vinyl chloride-vinyl acetate copolymers include Nissin Chemical Industries, Ltd.'s Solbin (registered trademark) series (Solbin AL, etc.), and examples of polyvinyl acetals include Sekisui Chemical Co., Ltd.'s S-LEC (registered trademark) series (S-LEC KS-10, etc.).

[0255] In order to form a primer layer on a substrate, a solution prepared using the above-mentioned components is applied to the substrate and dried. The coating amount is about 0.1 to 5 μm (dry thickness), but if it is less than 0.1, it is difficult to apply evenly, and if it exceeds 5 μm, it is uneconomical and therefore impractical. The coating uses a common coating method, such as gravure, relief printing, flexographic printing, roller coater, reverse coater, spray method, etc. The formation of the primer layer and the printing thereon can be continuous (online), or the formation and printing of the primer layer can be performed separately.

[0256] When printing is performed immediately after primer coating in-line using a roll-to-roll printer, so-called blocking occurs, in which the printed surface and the back of the substrate stick together, depending on the solubility of the resin used in the primer in the ink solvent and the glass transition temperature (Tg) of the resin itself. In order to prevent such blocking, transparent particles of 0.1 μm to 10 μm such as silicon dioxide and titanium oxide can be mixed into the primer solvent at a rate of about 0.005 to 5% relative to the total amount of the primer as an anti-blocking agent.

[0257] In order to prevent blocking, the resin solution with a high acid value used in the primer may be neutralized with ammonia or the like before coating to prevent redissolution in the solvent contained in the printing ink.

[0258] The acid value of the compound having an acidic group is not particularly limited, but is preferably 150 mgKOH / g or more.

[0259] In the laminated film using the above-mentioned primer layer, when the printed design is based on white, the ink layer is mostly made of white ink, and the film laminated with an adhesive is sometimes difficult to peel off at low temperature or low concentration alkali solution. In this case, the peelability of the ink layer can be improved by introducing an intermediate layer used in printing ink between the primer layer and the white ink layer or between the white ink layer and the adhesive layer.

[0260] In the present invention, when the laminated film is a laminated film bonded by a reactive adhesive, the reactive adhesive preferably contains a compound having an acidic group. In addition, when the laminated film is a laminated film bonded by a reactive adhesive and has an ink layer and / or a primer layer, it is preferred that at least one of the reactive adhesive, the ink layer, and the primer layer contains a compound having an acidic group. When any layer contains a compound having an acidic group, separation and recovery are easier.

[0261] Among them, it is preferred that any one of the constituent components of the reactive adhesive has an ester bond, since it is easily dissolved or hydrolyzed by an alkaline solution, so that it can be easily separated into a single layer film in a short time in the above-mentioned steps 2 and 3. Regarding any one of the constituent components of the reactive adhesive having an ester bond, specifically, there can be mentioned a reactive adhesive containing either or both of the following polyol compositions and polyisocyanate compositions, wherein the polyol composition contains a polyol compound such as polyester polyol, polyether ester polyol, polyester (polyurethane) polyol, acrylic polyol, etc. having an ester bond, and the polyisocyanate composition contains a polyisocyanate compound, which is a reaction product of the above-mentioned polyol compound having an ester bond and the above-mentioned various polyisocyanates.

[0262] In addition to the aforementioned polyol composition and the aforementioned polyisocyanate composition, a reactive adhesive to which a resin or a low molecular compound having an acidic group is added can also be preferably used. As the resin or low molecular compound having an acidic group, any resin or low molecular compound having an acidic value that can be easily mixed with the aforementioned polyol composition or the aforementioned polyisocyanate composition as the main component of the reactive adhesive (in this case, a solvent described later can be used as needed) can be used without particular limitation.

[0263] Examples of the resin having an acidic group include resins having an acid value such as rosin-modified maleic acid resin and rosin-modified fumaric acid resin, (meth)acrylic resins obtained by copolymerizing polymerizable monomers having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, cinnamic acid or their anhydrides, polymerizable monomers having a sulfonic acid group such as sulfonated styrene, polymerizable monomers having a sulfonamide group such as vinylbenzenesulfonamide, resins in the form of free radical copolymers such as styrene-(meth)acrylic acid resin, styrene-maleic acid (anhydride) resin, terpene-maleic acid (anhydride) resin, acid-modified polyolefin resins, and the like. One of these may be used alone or a plurality of them may be used in combination.

[0264] In addition, examples of low molecular weight compounds having an acidic group include saturated fatty acids, unsaturated fatty acids, hydroxy acids, aromatic carboxylic acids, dicarboxylic acids, tricarboxylic acids, oxocarboxylic acids, carboxylic acid derivatives, and acid anhydrides, and these can be used alone or in combination.

[0265] Examples of saturated fatty acids include lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid. Examples of unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and sorbic acid. Examples of hydroxy acids include lactic acid, malic acid, and citric acid. Examples of aromatic carboxylic acids include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and cinnamic acid. Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, and maleic acid. Examples of tricarboxylic acids include aconitic acid. Examples of oxocarboxylic acids include pyruvic acid and oxaloacetic acid. Examples of carboxylic acid derivatives include amino acids and nitrocarboxylic acids. Examples of acid anhydrides include trimellitic anhydride and pyromellitic anhydride. One of these may be used alone or in combination.

[0266] The acid value of the resin or low molecular compound having an acidic group is not particularly limited, but is preferably 150 mgKOH / g or more.

[0267] Regarding the alkaline solution used in this separation and recovery method, it is presumed that it acts on the interface of the laminated film, the adhesive, and the printing ink as described above, so that its bonding force is significantly reduced, thereby causing interfacial peeling. On the other hand, the solubility of the alkaline solution itself is also high, so the uncrosslinked printing ink layer also dissolves. In addition, it is presumed that in the case where the printing ink layer itself is crosslinked, interfacial peeling is also produced in the present invention, so separation and recovery can be carried out efficiently in a short time.

[0268] (Ink layer)

[0269] The ink layer is, for example, a printing ink obtained by printing an organic solvent-based printing ink, a water-based printing ink, or an active energy ray-curable ink using a gravure printer, a flexographic printer, an offset printer, an inkjet printer, etc. It may also be an ink layer obtained by multicolor printing using a plurality of inks. In the present invention, by performing steps 1 and 2, the ink layer can be peeled off regardless of the type of ink.

[0270] Printing inks to which resins having acidic groups or low molecular weight compounds having acidic groups are added can also be preferably used. As the resins or low molecular weight compounds having acidic groups, any resins or low molecular weight compounds having acidic groups can be used without particular limitation as long as they can be easily mixed with the aforementioned binder resins, organic solvents, etc., which are the main components of the printing ink, and have acid values.

[0271] As the resin or low molecular weight compound having an acidic group, the same compounds as those described for the primer layer can be used.

[0272] The printing ink preferably contains the resin or low molecular weight compound having an acidic group. The amount of the resin or low molecular weight compound added may be appropriately determined within a range that does not impair the printing adaptability of the printing ink, and is preferably in the range of 0.5 to 50% by weight, more preferably in the range of 1.0 to 30% by weight, relative to the solid content of the printing ink.

[0273] The location where the ink layer is provided is not particularly limited. For example, the ink layer may be provided in the outermost layer of the laminated film, or may be provided between the resin film layer (F) and the adhesive layer (AD). In the case where there is an ink layer between the resin film layer (F) and the adhesive layer (AD) (back printing), the ink layer and the adhesive layer are more firmly bonded, so that it becomes more difficult to peel off the ink layer. However, the method of the present invention can effectively peel off the ink layer even in the configuration of back printing.

[0274] The ink layer may be a layer showing any patterns, designs, words, marks, etc., for the purpose of imparting decoration or beauty, contents, shelf life, and display of the manufacturer or seller. The ink layer may also be a solid color ink layer without patterns, designs, words, marks, etc. There is no particular limitation on the method for forming the ink layer, and it may be formed using known pigments and / or dyes. The ink layer may preferably be formed using a printing ink containing a pigment and / or dye. The ink layer may be a single-layer structure or a multi-layer structure. The thickness of the ink layer is preferably 0.1 to 10 μm, more preferably 1 to 5 μm.

[0275] The ink layer may contain a pigment derivative and / or a resin-type dispersant as a dispersant for the colorant. These may be used alone, but are preferably used in combination because dispersion stability and stability over time are further improved.

[0276] For example, in the case where the structure of the plastic film is (F1) / ink / (AD) / (M) / (F2) or (F1) / ink / (AD) / (F2), the ink layer exists between the layers constituting the plastic film, and the ink layer is more firmly bonded to the adhesive layer. Therefore, it is a structure of the plastic film that is difficult to separate them into single layers and remove the ink layer. However, if a part of the film F2 is peeled off in step 1 or F2 is made into a broken product in a state that is easy to peel off, the remaining layer structure can be easily peeled off in step 2, and the ink layer can be removed.

[0277] The resin film layer (F) is classified according to the required function and functions as a base film layer (F1), a sealant layer (F2) that becomes a heat-sealed portion when forming a packaging material, and the like.

[0278] For example, the resin film used as the substrate film layer (F1) may include polyolefin films such as low-density polyethylene, high-density polyethylene, linear low-density polyethylene, OPP (biaxially stretched polypropylene), CPP (unstretched polypropylene), polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, polyamide films such as nylon 6, nylon 6,6, meta-xylene adipamide (N-MXD6), biodegradable films such as polylactic acid, polyacrylonitrile films, poly(meth)acrylic acid films, polystyrene films, polycarbonate films, ethylene-vinyl acetate copolymer saponified product (EVOH) films, polyvinyl alcohol films, K coatings such as polyvinylidene chloride, etc., which contain pigments. Transparent vapor-deposited films in which aluminum oxide, silicon dioxide, etc. are vapor-deposited on these films may also be used.

[0279] In addition, the surface of the film material may be subjected to various surface treatments such as flame treatment, corona discharge treatment, or chemical treatment such as primer release treatment.

[0280] As the flexible polymer film that becomes the sealing layer (F2), preferably polyethylene film, polypropylene film, polyolefin-based films such as ethylene-vinyl acetate copolymer, ionomer resin, EAA resin, EMAA resin, EMA resin, EMMA resin, biodegradable resin film, etc. In terms of common name, CPP (unstretched polypropylene) film, VMCPP (aluminum vapor-deposited unstretched polypropylene film), LLDPE (straight-chain low-density polyethylene), LDPE (low-density polyethylene), HDPE (high-density polyethylene), VMPLDPE (aluminum vapor-deposited low-density polyethylene film) film, films containing these pigments, etc. The surface of the film can be subjected to various surface treatments such as flame treatment, corona discharge treatment, or chemical treatment such as detachment primer.

[0281] The thickness of the plastic film is preferably 5 μm or more and 200 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferably 10 μm or more and 50 μm or less.

[0282] From the viewpoint of reuse as a recycling base material, the base material preferably includes a polyolefin resin film such as polyethylene or biaxially stretched polypropylene.

[0283] Examples of the metal foil layer (M) include metal foils having excellent ductility, such as gold, silver, copper, zinc, iron, lead, tin, and alloys thereof, steel, stainless steel, and aluminum.

[0284] Examples of the paper layer include natural paper and synthetic paper. The first and second sealant layers may be formed of the same material as the sealant layer described above.

[0285] Other layers may also contain known additives and stabilizers, such as antistatic agents, non-reactive adhesives, easy-adhesion coating agents, plasticizers, lubricants, antioxidants, and the like.

[0286] <Particle Size Distribution of Desorbed Ink Components>

[0287] The median particle size (D50) of the detached ink component is preferably 1 μm or more. By setting the median particle size of the detached ink component to 1 μm or more, it is possible to suppress the detached ink component from reattaching to the substrate, thereby obtaining a colorless regenerated material. The median particle size of the detached ink component is preferably 5 μm or more, more preferably 10 μm or more, further preferably 15 μm or more, and particularly preferably 20 μm or more.

[0288] The span value A of the detached ink component represents the particle size distribution width of the detached ink component. The larger the value, the wider the particle size distribution width, and the more likely it is to contain fine ink components that are easily reattached to the substrate. The span value A is preferably 10 or less, more preferably 8 or less, and further preferably 5 or less. If the span value is 10 or less, it is possible to suppress the reattachment of the detached ink layer, so it is preferred.

[0289] In the present invention, the volume-based median diameter (D50) and span value A of the ink component released from the plastic substrate layer are measured by a laser diffraction particle size distribution analyzer. The span value A is represented by the following formula.

[0290] A=(D90-D10) / D50

[0291] D10: Cumulative 10% diameter of the volume-based particle size distribution of the separated ink component obtained by laser diffraction particle size distribution measurement

[0292] D90: Cumulative 90% diameter of the volume-based particle size distribution of the released ink component obtained by laser diffraction particle size distribution measurement

[0293] <Method for producing molding material>

[0294] By melt-kneading the recycled plastic film recovered by the manufacturing method of the above-mentioned recycled plastic film, molding particles can be manufactured. Various additives are added as needed in the melt-kneading process, and after mixing with a Henschel mixer, a roller, a disperser, etc., a kneader, a roller mill, a twin-screw extruder, a single-screw extruder, a rotor-type twin-screw mixer, etc. are used to mix and disperse. Thus, a recycled resin as a resin composition is obtained. The shape of the recycled resin is not particularly limited, and it can be granular, powdery, granular, or beaded. A twin-screw extruder is preferably used in the melt-kneading process. The molding material may further contain a masterbatch. As long as the masterbatch has compatibility with the recycled resin, there is no particular restriction, and a masterbatch formed by mixing thermoplastic resins such as polyethylene resins and polypropylene resins with colorants can usually be used. The thermoplastic resin contained in the masterbatch can be used alone or in combination of two or more. The masterbatch may contain metal soaps of alkali metals, alkaline earth metals or zinc, hydrotalcite, nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants, antistatic agents, flame retardants such as halogen-based, phosphorus-based or metal oxides, lubricants such as ethylenebisalkylamide, antioxidants, ultraviolet absorbers, fillers, and peroxides within a range that does not inhibit the effects of the present invention.

[0295] <Molding>

[0296] By heat-molding the molding material obtained by the above-mentioned manufacturing method, a molded body can be obtained. The heat molding method is not particularly limited, and examples thereof include injection molding, extrusion molding, blow molding, and compression molding. The molding material manufactured using the plastic substrate recovered by the separation and recovery method of the present invention is of high quality because the ink layer is separated, thereby inhibiting the re-adhesion of the adhesive component, and can be used in various fields such as household electrical appliances, stationery, automotive parts, toys and sporting goods, medical use, and materials for building / construction materials.

[0297] The additives that can be used in the manufacturing process of the recycled particles obtained by the manufacturing method of the recycled plastic film include at least one antioxidant selected from the group consisting of phenol and phosphorus, at least one lubricant selected from the group consisting of fatty acid amide, alkylene fatty acid amide, metal soap and ester, hindered amine weathering stabilizer, wax with an acid value of 5 mgKOH / g or less, at least one antistatic agent selected from the group consisting of fatty acid sulfonate and fatty acid ester, at least one peroxide selected from organic peroxides for polypropylene modification, etc.

[0298] Examples of phenolic antioxidants include 2,6-di-tert-butyl-p-cresol, butylated hydroxyaniline, 2,6-di-tert-butyl-4-ethylphenol, 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis-(4-ethyl-6-tert-butylphenol), 4,4'-thiobis-(3-methyl-6-tert-butylphenol), 4,4'-butylidene-bis-(3-methyl-6-tert-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-tert-butylphenol)] butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl}2,4,8,10-tetraoxaspiro〕5,5-undecane, 1,1,3-tris-(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis-{methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)butyrate}methane and bis{(3,3'-bis-4'-hydroxy-3'-tert-butylphenyl)butyrate}ethylene glycol ester.

[0299] Examples of the phosphorus antioxidant include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, 4,4'-butylidene-bis-(3-methyl-6-tert-butylphenyl-di-tridecyl)phosphite, cyclic neopentanetetraylbis(octadecylphosphite), tris(diphenyl)phosphite, diisodecyl pentaerythritol diphosphite, 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxo-10-phosphaphenanthrene, cyclic neopentanetetraylbis(2,4-di-tert-butylphenyl)phosphite, cyclic neopentanetetraylbis(2,6-di-tert-butylmethylphenyl)phosphite, and 2,2-methylenebis(4,6-tert-butylphenyl)octylphosphite.

[0300] These antioxidants can be used alone or in combination of two or more. Based on the mass of the molding material, the amount of the antioxidant added is preferably 0.01 to 1% by mass, and more preferably 0.03 to 0.5% by mass. When the amount added is 0.01% by mass or more, it is preferred in terms of antioxidant properties, and when it is 1% by mass or less, it is preferred in terms of processability.

[0301] Examples of fatty acid amide-based lubricants include aliphatic monocarboxylic acid amides such as lauric acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, ricinoleic acid amide, and hydroxystearic acid amide; N-substituted aliphatic monocarboxylic acid amides such as N-oleyloleic acid amide, N-oleylstearic acid amide, and N-stearyloleic acid amide; aliphatic dicarboxylic acid amides such as methylenebisstearic acid amide and ethylenebisstearic acid amide; N,N'-ethylene-bis-oleylamide, N,N'-ethylenebisstearic acid amide, and N,N'-methylenebisstearic acid amide.

[0302] Examples of the metal soap-based lubricant include calcium stearate, magnesium stearate, barium stearate, zinc stearate, aluminum stearate, lithium stearate, metal salts of higher fatty acids such as calcium laurate, magnesium laurate, barium laurate, zinc laurate, aluminum laurate, and lithium laurate, as well as calcium hydroxystearate, magnesium hydroxystearate, barium hydroxystearate, zinc hydroxystearate, aluminum hydroxystearate, and lithium hydroxystearate.

[0303] These lubricants can be used alone or in combination of two or more. The amount of lubricant added is based on the mass of the molding material, preferably 0.01 to 1% by mass, more preferably 0.03 to 0.5% by mass. When the amount is 0.01% by mass or more, it is preferred in terms of activity, and when it is 1% by mass or less, it is preferred in terms of processability.

[0304] Examples of hindered amine weathering stabilizers include dimethyl 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidinium succinate polycondensate, poly[{6-(1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidinyl)imino}hexamethylene{{2,2,6,6-tetramethyl-4-piperidinyl)imino}] , N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-piperidinyl)amino]-6-chloro-1,3,5-triazine condensate, bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate and 2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonic acid bis(1,2,2,6,6-pentamethyl-4-piperidinyl) ester.

[0305] As waxes having an acid value of 5 mgKOH / g or less, natural waxes and synthetic waxes can be cited. As natural waxes, plant waxes such as candelilla wax, carnauba wax, rice bran wax and wood wax, animal waxes such as beeswax, lanolin wax and spermaceti wax, mineral waxes such as montan wax, ozokerite and ceresin, and petroleum waxes such as paraffin, microcrystalline wax and mineral wax can be cited. As synthetic waxes, there are semi-synthetic waxes and fully synthetic waxes. Semi-synthetic waxes are obtained by modifying natural waxes or natural wax-like materials through chemical treatments such as esterification, amidation and neutralization using acid waxes. As synthetic waxes, synthetic hydrocarbons such as polyethylene waxes, polypropylene waxes and polystyrene waxes can be cited.

[0306] These waxes with an acid value of 5 mgKOH / g or less may be used alone or in combination of two or more. The amount of the wax with an acid value of 5 mgKOH / g or less is preferably 0.5 to 50% by mass, more preferably 1 to 30% by mass, based on the mass of the molding material. When the amount is 0.5% by mass or more, it is preferred in terms of adjusting fluidity, and when it is 50% by mass or less, it is preferred in terms of processability.

[0307] Examples of the anionic surfactant-based antistatic agent include carboxylates such as alkali metal salts of higher fatty acids, sulfate esters such as higher alcohol sulfate esters and higher alkyl ether sulfate esters, sulfonates such as alkylbenzene sulfonates, alkyl sulfonates and paraffin sulfonates, and phosphates such as higher alcohol phosphate esters.

[0308] Examples of the nonionic surfactant include polyethylene glycol-type nonionic surfactants such as higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, higher alkylamine ethylene oxide adducts, and polypropylene glycol ethylene oxide adducts; fatty acid esters of polyethylene oxide or glycerol, fatty acid esters of pentaerythritol, fatty acid esters of sorbitol or sorbitan, alkyl ethers of polyols, and polyol-type nonionic surfactants such as aliphatic amides of alkanolamines.

[0309] These antistatic agents may be used alone or in combination of two or more.

[0310] The amount of the antistatic agent added is preferably 0.05 to 1% by mass, more preferably 0.1 to 0.5% by mass, based on the mass of the molding material. When the amount is 0.05% by mass or more, it is preferred from the perspective of antistatic properties, and when it is 1% by mass or less, it is preferred from the perspective of transparency and low bleeding.

[0311] Examples of the organic peroxide include dicumyl peroxide, di(2-tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3-yl.

[0312] These organic peroxides may be used alone or in combination of two or more. They may be diluted with an inorganic filler and used.

[0313] In order to improve the physical properties of the recycled pellets obtained by the method for producing a recycled plastic film, at least one of an acid-modified polypropylene having a melting point of 130° C. or higher and a thermoplastic elastomer or a metallocene-catalyzed polyethylene having a density of 0.94 or less may be melt-kneaded.

[0314] The physical property modification of recycled pellets refers to changing the physical properties of the raw plastic film pellets of the plastic film before recycling. The purpose of modifying the physical properties is that when recycled pellets are produced from a film using film-grade plastic pellets, if the recycled pellets are directly used for molded products, various physical property values ​​are often insufficient.

[0315] The items for improving the physical property values ​​are various, including tensile strength, flexural strength, elongation at break, tensile elastic modulus, flexural elastic modulus, yield point stress, etc., but are not limited thereto.

[0316] Examples of commercially available acid-modified thermoplastic elastomers include maleic anhydride-modified isoprene rubbers such as LIR-403 manufactured by KURARAY, modified isoprene rubbers such as LIR-410 manufactured by KURARAY, carboxyl-modified nitrile rubbers such as KRYNAC 110, 221, and 231 manufactured by POLYSAR, maleic anhydride-modified polybutenes such as Nippon Oil & Gas Polybutene, ethylene methacrylic acid copolymers such as NUCREL manufactured by DuPont Mitsui Polychemicals, ethylene methacrylic acid copolymers such as YUKALON manufactured by Mitsubishi Chemical, maleic anhydride-modified ethylene-propylene rubbers such as TAFMER M (MA8510) manufactured by Mitsui Chemicals, TX-1215 manufactured by Mitsui Chemicals, and TAFMER manufactured by Mitsui Chemicals. Maleic anhydride-modified ethylene-butene rubber such as M (MH7020), HPR series (maleic anhydride-modified EEA) manufactured by Mitsui-DuPont Polychemicals, BONDINE (maleic anhydride-modified EEA) manufactured by ATOFINA, Tuftec (maleic anhydride-modified SEBS, M1943) manufactured by Asahi Kasei Corporation, Kraton (maleic anhydride-modified SEBS, FG1901X) manufactured by Kraton Polymer, Tufprene (maleic anhydride-modified SBS, 912) manufactured by Asahi Kasei Corporation, Septon (maleic anhydride-modified SEPS) manufactured by KURARAY, Rexpearl (maleic anhydride-modified EEA, ET-182G, 224M, 234M) manufactured by Japan Polyolefins, Auroren (maleic anhydride-modified EEA, 200S, 250S) manufactured by Nippon Paper Chemicals, etc.

[0317] As a particularly preferred example of the acid-modified thermoplastic elastomer, a styrene-ethylene-butadiene-styrene copolymer modified with maleic anhydride can be cited. As commercially available products of the acid-modified styrene-ethylene-butylene-styrene block copolymer, Tuftec M1911 manufactured by Asahi Kasei Chemicals, Tuftec M1913 manufactured by Asahi Kasei Chemicals, and Tuftec M1943 manufactured by Asahi Kasei Chemicals can be cited.

[0318] Examples of commercially available thermoplastic elastomers that are not acid-modified include ethylene methacrylic acid copolymers such as NUCREL manufactured by DuPont Mitsui Polychemicals, ethylene methacrylic acid copolymers such as YUKALON manufactured by Mitsubishi Chemical Corporation, α-olefin copolymers such as TAFMER manufactured by Mitsui Chemicals, SEBS such as Tuftec manufactured by Asahi Kasei Corporation, Tufprene manufactured by Asahi Kasei Corporation, SBS manufactured by KURARAY, SEPS such as Septon, and EEA such as Rexpearl manufactured by Japan Polyolefins Co., Ltd.

[0319] In the melt-kneading process, for example, when a single-screw or twin-screw extruder is used, general conditions can be used for the melt-kneading conditions. The kneading temperature is preferably 180 to 260°C, more preferably 190 to 250°C, and further preferably 200 to 240°C. In order to form a better melt-kneading state, the temperature on the raw material inlet side is preferably about -50 to -100°C from the center, and the temperature on the outlet side is also preferably about -50 to -100°C from the center. More preferably, the temperature is gradually increased from the raw material inlet temperature to the center, and the temperature is gradually decreased from the center to the outlet. In particular, when the set temperature of the extruder from the center to the vicinity of the outlet is lower than the melting point of the input plastic, if the mold temperature is set to be about 5 to 10°C higher than the melting point of the plastic, plastic streaks are easily formed.

[0320] When the central temperature is 180°C or lower, melt kneading is difficult, and when it is 260°C or higher, the physical properties of the produced regenerated pellets are significantly reduced. The temperature just below the film input is preferably 20°C to 100°C so that the film does not melt immediately and cause bridging.

[0321] The screw rotation speed is preferably 50 rpm to 500 rpm, more preferably 180 rpm to 400 rpm, and even more preferably 100 rpm to 300 rpm. If the rotation speed is too low, it is difficult to form uniform regenerated particles during melting, and if it is too high, the physical properties of the produced regenerated particles are significantly reduced due to the heat generated during kneading.

[0322] The speed of feeding the crushed plastic film into the extruder is preferably 5 to 100 kg / h, more preferably 5 to 50 kg / h, and further preferably 5 to 30 kg / h. The faster the feeding speed, the higher the resin pressure in the extruder, and a better mixing state can be formed. Therefore, in the case of mixing the recycled particles with the unused particles, or mixing the recycled particles with the modified resin, additives, etc., it is preferred to increase the resin pressure. The resin pressure is preferably 1 to 30 MPa, more preferably 1 to 25 MPa, and further preferably 1 to 20 MPa.

[0323] The melt mass flow rate (MFR) of the recycled pellets is preferably 2 to 50 g / 10 minutes, more preferably 3 to 40 g / 10 minutes, and more preferably 5 to 30 g / 10 minutes. By making the melt mass flow rate within the above range, a recycled molding material suitable for various moldings such as injection molding and extrusion molding can be provided.

[0324] (Decolorization evaluation of regenerated particles)

[0325] The plastic film sheets that have been through steps 1 to 4 were extruded at 200°C using a twin-screw extruder and pelletized to obtain recycled pellets. The recycled pellets were heated and pressed at 200°C using a hot press to produce a pressed plate with a thickness of 1 mm. The pressed plate was measured for color value L using a spectrophotometer (X-riteeXact manufactured by X-rite). * 、a * 、b * The raw material pellets of the plastic film were similarly subjected to a heating and pressing step to produce a pressed plate having a thickness of 1 mm, and the color difference ΔE was calculated using the following calculation formula.

[0326] ΔE=((L * xL * y) 2 +(a * x * y) 2 +(b * xb * y) 2 ) 1 / 2

[0327] x: raw material particles

[0328] y: Recycled particles

[0329] ΔE is preferably 30 or less, more preferably 20 or less, more preferably 10 or less, and even more preferably 5 or less. The less the color difference between the recycled pellets and the raw pellets, the more the ink can be decolorized by the washing process, and the higher the utilization value as recycled pellets. In addition, since many molded products are melt-kneaded with a masterbatch containing a colorant, as long as the target color tone can be obtained, ΔE of 30 or less can be fully used.

[0330] When the regenerated particles are made into a film with a thickness of about 100 μm, the total light transmittance is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more. The higher the total light transmittance, the more the ink is decolorized by the washing process, and the higher the utilization value of the regenerated particles.

[0331] (A mixture of recycled and unused pellets)

[0332] In the melt kneading process of the plastic film from which the ink layer has been removed, unused plastic pellets may be mixed in any proportion according to the purpose. For example, the mixing ratio of recycled pellets to unused pellets is 99.5:0.5 to 50:50 in terms of weight conversion. From the perspective of recyclability, it is preferred to increase the ratio of recycled pellets as much as possible.

[0333] The unused plastic particles used at this time may be polypropylene selected from block polymers, random polymers, and homopolymers. Alternatively, they may be selected from acid-modified polypropylene, thermoplastic elastomers, and polyethylene using a metallocene catalyst, or at least one of them may be mixed and used.

[0334] A specific example of the method for separating and recovering a plastic film of the present invention will be described.

[0335] (1) Step 1: Crushing the plastic film

[0336] First, the plastic film is sequentially put into a dry crusher or a wet crusher (hereinafter referred to as the crusher) to make a plastic crushed object. At this time, the plastic film can be cut into plastic pieces of a size of, for example, about 20 cm square or 30 cm square, and put into the crusher. By going through this cutting process, the crushing in the crusher in the next process can be carried out more effectively. Cutting can be performed using a known crusher, for example, impact crushers such as hammer crushers and rotary crushers, shredders, cutters, etc. The size and shape of the plastic film put in are not particularly limited, and the maximum length of the plastic piece is, for example, preferably less than 50 cm, preferably less than 30 cm, preferably less than 20 cm, and preferably less than 10 cm.

[0337] In the case where a sieve or net is used in the dry crusher in step 1, the aperture is preferably 30 mm or less, more preferably 20 mm or less, and further preferably 10 mm or less. When a 10 mm sieve or net is used, the size of the membrane after crushing is 0.5 to 10 mm on the long side. Regarding the immersion in the cleaning solution in step 2, the smaller the size of the membrane after crushing, the easier it is to obtain the effect, so the smaller the crushing size in step 1, the more preferred.

[0338] When a wet crusher is used in step 1, the laminated film roll is cut into pieces of about 20 cm square or 30 cm square, and is introduced into the crushing part by suction of the crusher, and is crushed into pieces of about 1 to 20 mm or about 5 to 20 mm, and then the pieces are crushed into pieces of 0.03 mm. 3 / min is pressed to the next process. At this time, the input film is subjected to high shear during crushing, so that at least a portion of the layers constituting the laminated film becomes easily separated into single layers. When an ink layer is provided on the laminated film, the ink layer is also easily peeled off and removed from the film due to the high shear caused by crushing, and preferably at least a portion of the ink layer is peeled off.

[0339] Even if the crushing target is not a laminated film roll but a single film bag collected from the market, it can be directly put into the crushing machine in a recovered state.

[0340] When a grinder is used as a crusher to pulverize the plastic film into powder, it is preferable to use a laminated film roll cut into small pieces of about 5 mm square. The plastic film pulverized by the grinder is pulverized to about 10 to 500 μm.

[0341] The crushing step in the above step 1 may be performed once or several times.

[0342] (2) Step 2: Immerse the plastic film in the cleaning solution

[0343] In step 2, the plastic crushed material crushed in step 1 may be left to stand in the washing liquid for immersion, or may be immersed in a known stirring device such as a homogenizer or a wet crusher similar to step 1, and stirred as needed. If the crushed plastic film is printed on the front surface, the ink layer on the surface is fully swollen, and if it is a laminated film including back printing, the ink layer and the adhesive layer are fully swollen.

[0344] The liquid temperature and stirring time during immersion in the cleaning liquid are not particularly limited and can be appropriately adjusted depending on various conditions such as the material of the cleaning liquid used and the structure of the plastic film.

[0345] (3) Step 3: Stirring the crushed plastic film in water to separate the plastic film

[0346] The plastic film is swollen by the steps 1 and 2, and then stirred in water to separate the plastic film. In the water after separation, the separated single-layer films are suspended or dissolved together with the residues such as adhesive, printing ink, and metal foil. After taking them out of the water, they are separated and recovered.

[0347] As an example of a specific method, for example, in flotation, light plastics (floating objects) such as polyolefins such as polypropylene and polyethylene, condensation synthetic films such as polyester and nylon, or heavy objects such as metal foils with a specific gravity heavier than polyolefins are screened, and the heavy objects are removed. Then, the plastics recovered in the washing and dehydration process are further washed and dehydrated as needed, and plastics with different specific gravities are separated by centrifugal separation. For example, it can be divided into plastic separations containing vinyl chloride resins and polyethylene terephthalate with a specific gravity of more than 1 that sink in water, and plastic separations containing olefin resins such as polyethylene and polypropylene that do not contain vinyl chloride resins. Further separation can be carried out by appropriately changing the liquid used in the suspension separation, such as the mixing ratio of water to an organic solvent or salt to change the specific gravity.

[0348] After roughly separating and recovering by gravity separation, high-level separation may be performed by electrostatic separation or the like utilizing the inherent charging characteristics of plastics.

[0349] As a specific example, a method of separating a plastic mixture charged in advance by dropping it between parallel plate electrodes to which a voltage is applied can be used. A combination of plastics with a small specific gravity difference that is difficult to separate by specific gravity separation can also be separated.

[0350] (4) Step 4: Clean the remaining ink on the washed plastic film in a rinse solution

[0351] For plastic film, after the ink layer is washed from the plastic crushed material through steps 1, 2, and 3, it is stirred in a rinse liquid to remove a small amount of ink flakes remaining on the film surface that were not completely removed in step 3, thereby greatly improving the quality of the recycled particles.

[0352] In step 4, in addition to a known stirring device such as a homodisperser and a wet crusher similar to step 1, a so-called mixer or kneader represented by a paint stirrer or a paint conditioner may be used. In addition, devices other than these may also be used.

[0353] (5) Recovery and reuse of cleaning solution (step 5)

[0354] The water, washing liquid, and rinse liquid used in steps 1 to 4 are supplied to one or more recycling machines selected from a filter, a centrifuge, and an ultrafilter in order to recover them, and are reused after removing solid matter. It is also possible to continuously operate the water, washing liquid, or the washing liquid reuse step while performing the wet crushing step and the specific gravity separation step in steps 1 to 4 to separate the solid matter from the water, washing liquid, and rinse liquid.

[0355] (6) Drying of plastic separation (step 6)

[0356] In order to remove residual moisture, the recovered plastic film separated and recovered in step 3 or 4 is dried by any one or more methods selected from reduced pressure heating drying, hot air drying, and pressurized compression drying. As a pretreatment for making recycled particles described later, a pressurized compressor such as a press dehydrator manufactured by CIM of Japan, a particle mill manufactured by Oike Iron Works, or STELLA manufactured by ELECOM, a briquetting machine can also be used to make lumps after or during the drying of the film as a recovered product. In the case of using a grinding mill as a wet crusher to crush the plastic film into a powder, the crushed material is crushed into about 10 to 500 μm, and the density of the crushed material is high, so the pressurized compression process can be omitted. The density varies depending on the material constituting the crushed material, but in order to be applied to a mixing mill, the greater the density, the easier it is to handle, so it is preferred. Specifically, it is preferably 0.03 kg or more in a dry state, more preferably 0.05 kg or more, more preferably 0.2 kg or more, and further preferably 0.3 kg or more.

[0357] (7) Production of Regenerated Pellets (Step 7)

[0358] The film sheet or agglomerate dried in step 6 is fed into a single-screw or twin-screw extruder to produce recycled pellets. When the film sheet is directly fed into the extruder without going through a pressurization and compression step, a bridging phenomenon in which the ink sheet is blocked at the feed port is likely to occur. In order to avoid bridging, the film sheet can be pressurized with a feeder or air can be pressed in. In addition, in order to avoid bridging, the screws of the extruder body can use twin-shaft screws that rotate in opposite directions, or can be pressed in with a side feeder. There are no special restrictions on the conditions of the mixer. In order not to significantly deteriorate the performance of the resin before recycling, it is preferably operated at 180 to 260°C.

[0359] Example

[0360] The content and effects of the present invention are described in more detail below by way of examples. In addition, the films, printing inks, reactive adhesives, and organic solvents used as raw materials in each of the examples and comparative examples are shown below.

[0361] (Film used in laminated film)

[0362] OPP: Biaxially oriented polypropylene film 20μm

[0363] CPP: Unstretched polypropylene film 35μm

[0364] (Printing ink)

[0365] Ink 1: Glosser 507 Primary Blue S2 manufactured by DIC Graphics

[0366] Ink 2: FINART R507 primary blue manufactured by DIC Graphics

[0367] Ink 3: FINART R794 White S manufactured by DIC Graphics

[0368] (Reactive Adhesive)

[0369] AD1: Two-component adhesive of solvent-based adhesive DICDRY LX-401 A and SP-60 (ether-based adhesive)

[0370] AD2: Two-component adhesive of solvent-free adhesive DICDRY 2K-SF-400 A and HA-400 B (ester adhesive)

[0371] (Method for producing laminated film)

[0372] The laminated film was produced by printing on a target film by a printing method described below, and then laminating the target film by a laminating method described below. The layer structure of the film, the reactive adhesive, and the type of printing ink were determined according to the combinations shown in Table 1.

[0373] (Printing method)

[0374] For the gravure inks used as printing inks, each ink was developed on the film "Film 1" using a proofing machine.

[0375] (Lamination method)

[0376] The printing ink-developed surface of the film "film 1" after the printing ink was developed was coated with a reactive adhesive "AD" by a laminator in such a manner that the solid content was 3 g / m2, and the film "film 2" was laminated. The laminated films were aged at 40° C. for 72 hours. The laminated films "LAM1" to "LAM2" shown in Table 1 were obtained. In addition, blank columns indicate that there is no structure.

[0377] [Table 1]

[0378] Table 1 Laminated film composition Membrane 1 Ink 1 Ink 2 Ad Membrane 2 Print 1 OPP Ink 1 LAM1 OPP Ink 1 Ink 3 AD1 CPP LAM2 OPP Ink 1 Ink 3 AD2 CPP

[0379] (Process 1 Crushing process)

[0380] Print 1 and LAM 1 and 2 were put into a wet crushing pump and wet-crushed until the crushed film had a short side of 5 to 10 mm and a long side of 10 to 20 mm.

[0381] (Step 2: Immersing Step)

[0382] PRO_A: 120 minutes, immerse in cleaning solution at room temperature.

[0383] PRO_B: 120 minutes, added to the cleaning solution at 75°C, and stirred at 300 rpm using a Three-One Motor.

[0384] PRO_C: 60 minutes, added to a cleaning solution at 75°C, and immersed in a 28kHz ultrasonic bath for 60 minutes.

[0385] (Step 3: Stirring and Separating Step)

[0386] PRO_1: Use IKA MultiDrive in room temperature water and run at 20,000 rpm for 2 minutes.

[0387] PRO_2: Using Suncutter C125H manufactured by Nikuni, pressure feeding was performed at 0.1 m3 / min in water at room temperature.

[0388] (Cleaning fluid)

[0389] Water, the solvent shown in Table 2 and 2% by weight of sodium hydroxide were mixed to prepare the cleaning solution shown in Table 3. In the cleaning solution composition, the components were added vertically, and water was added to make up the portion less than 100%. Benzalkonium chloride is a cationic surfactant.

[0390] [Table 2]

[0391] Table 2 Solvents Compound Name SOL1 Phenoxyethanol SOL2 Ethanol

[0392] [Table 3]

[0393]

[0394] (Ink removability from plastic film)

[0395] The results in Tables 4 and 5 show the state of ink removal from the plastic film. After washing and drying the film after the immersion step in step 2 and the stirring and separation step in step 3, the ink removal property of the printed part was determined by calculating the area by image processing of photographs taken with an optical microscope and determining the ink removal rate using the following formula.

[0396] Ink removal rate (%) = (1-ink adhesion area after cleaning / ink adhesion area before cleaning) × 100

[0397] ◎: 100% excluding the printed part.

[0398] ○: 75% or more and less than 100% of the printed part is removed.

[0399] ○△: 50% or more and less than 75% of the printed portion or the laminated portion is removed.

[0400] ×: No peeling at all - less than 50% removal.

[0401] In addition, ◎ and ○ are ranges with no practical problems.

[0402] [Table 4]

[0403]

[0404] [Table 5]

[0405]

[0406] In the above-mentioned embodiment, the cleaning liquid described in Table 7 containing the solvent described in Table 6 is used as the cleaning liquid in step 2 (immersion step), and the cleaning liquid heated to 50° C. is used in step 3 (agitation and separation step) instead of water at room temperature. Except for this, the ink from the plastic film is removed in the same manner as in the above-mentioned embodiment, and the ink removal rate is determined by the method of the above-mentioned embodiment.

[0407] [Table 6]

[0408] Table 6 Solvents Compound Name SOL3 2-Dimethylaminoethanol SOL4 Diethylene glycol monobutyl ether

[0409] [Table 7]

[0410]

[0411] [Table 8]

[0412]

[0413] [Table 9]

[0414]

[0415] According to the results, the examples of the present invention can peel off the plastic film and can also peel off the ink layer existing between the layers of the plastic film. In the methods of the examples, the films after step 2 all swelled.

[0416] Using Print 1, LAM1, and LAM2 shown in Table 1, the following treatments were performed.

[0417] (Process 1 Crushing process)

[0418] Print 1 and LAM 1 and 2 were put into a dry crusher equipped with a sieve with an aperture of 10 mm, and crushed until the crushed film had a short side direction of 5 to 10 mm and a long side direction of 10 to 20 mm.

[0419] (Step 2: Immersing Step)

[0420] PRO_2A: 240 minutes, immersed in the cleaning solution at 40°C.

[0421] PRO_2B: 120 minutes, added to the cleaning solution at 75°C, and stirred at 500 rpm using a Three-One Motor.

[0422] (Cleaning fluid)

[0423] Water, the solvent shown in Table 2 and 2 wt% of potassium hydroxide were mixed to prepare the cleaning solution shown in Table 3. In the cleaning solution composition, the components were added vertically, and water was added to make up the portion less than 100%.

[0424] [Table 10]

[0425] Solvents Compound Name SOL21 Ethanol SOL22 n-Propanol SOL23 Propylene glycol propyl ether

[0426] [Table 11]

[0427]

[0428] (Step 3: Stirring and Separating Step)

[0429] PRO_1: Use IKA MultiDrive in room temperature water and run at 20,000 rpm for 2 minutes.

[0430] PRO_2: Using Suncutter C125H manufactured by Nikuni, pressure feeding was performed at 0.1 m3 / min in water at room temperature.

[0431] (Process 4 finishing process)

[0432] PRO_W: 10 g of the plastic film obtained in step 3 was used in 300 mL of water, and the mixture was operated at 15,000 rpm for 5 minutes using a Mighty Blender manufactured by Osaka Gas Chemical.

[0433] PRO_X: 10 g of the plastic film obtained in step 3 was used in 300 mL of n-propanol and operated at 15,000 rpm for 5 minutes using a Mighty Blender manufactured by Osaka Gas Chemical.

[0434] PRO_Y: 10 g of the plastic film obtained in step 3 was used and the mixture was stirred at 500 rpm for 30 minutes using a three-one motor in 300 mL of diethylene glycol butyl ether containing 30 g of sodium chloride.

[0435] PRO_Z: 10 g of the plastic film obtained in step 3 was used and operated at 500 rpm for 30 minutes using a three-one motor in 300 mL of a liquid of n-propanol:water=60:40.

[0436] (Decolorization evaluation of regenerated particles)

[0437] The results in Tables 4 to 6 show the state of removing the ink from the plastic film. The plastic film sheets that have undergone steps 1 to 4 are extruded at 200°C using a twin-screw extruder to produce recycled particles. The obtained recycled particles are heated and pressed at 200°C using a hot press to form a pressed plate with a thickness of 1 mm. The pressed plate is measured for color values ​​L*, a*, and b* using a spectrophotometer (manufactured by X-rite, X-riteeXact). The raw material particles of the plastic film (non-recycled product F-300SP manufactured by Primen Polymers) are also subjected to the same heating and pressing process to determine the color difference ΔE.

[0438] ◎: ΔE is 10 or less

[0439] ○: ΔE is less than 20

[0440] △: ΔE is less than 30

[0441] ×: ΔE is 31 or more

[0442] [Table 12]

[0443]

[0444]

[0445] [Table 13]

[0446]

[0447] Comparative Examples are shown in Table 6. Blank columns in the table indicate that the comparative examples were not implemented.

[0448] [Table 6]

[0449]

[0450]

[0451] From these results, the examples of the present invention can peel off the plastic film and can also peel off the ink layer existing between the layers of the plastic film.

Claims

1. A method for separating and recovering a plastic film, which is a method for separating and recovering a plastic film having at least an ink layer, characterized in that: include: Step 1 of breaking the plastic film; Step 2 of immersing the plastic film in a cleaning solution; and Step 3 of separating the plastic film by stirring the crushed plastic film in water.

2. The method for separating and recovering plastic film according to claim 1, wherein: The cleaning solution contains (a) a water-soluble alcohol or water-soluble monoalkanolamine organic solvent or a water-insoluble aromatic glycol ether solvent, and (b) an inorganic base.

3. The method for separating and recovering plastic film according to claim 1, wherein: In the step 2, the plastic film is immersed in a cleaning solution to be swollen.

4. The method for separating and recovering plastic film according to claim 1, wherein: include: Step 4 is to wash the plastic film after step 3 in a rinse solution.

5. The method for separating and recovering plastic film according to claim 4, wherein: The flushing solution contains a water-soluble solvent.

6. A method for producing recycled plastic particles, comprising collecting the plastic crushed material separated by the method according to any one of claims 1 to 5 for each single layer, melting the recovered material and then molding it with a molding machine.

Images