Production method of recycled plastic base material

Abstract

To provide a production method for obtaining high-quality recycled base material while efficiently separating from ink pieces by: peeling a plastic base material from a plastic laminate for a packaging material in a liquid medium by applying a high but not fragmenting shear force.; and separating only the base material without being affected by foam.SOLUTION: A production method of a recycled plastic base material includes a step (A) of removing a coating layer from a laminate having at least a plastic base material and the coating layer using a liquid medium in a removing tank, and a step (B) of collecting the removed plastic base material, where the step (A) has features (1) and (2) and the step (B) has a feature (3) in the following: (1) the removing tank has a clearance of 20 mm or less through which a process liquid and / or the laminate can pass; (2) an area change rate of the plastic base material between before and after the step (A) is 70% or less; and (3) the long side of the collected recycled plastic base material is 1 mm or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a recycled plastic substrate material, in which a plastic substrate material is recovered from a laminate containing a plastic substrate material. [Background technology]

[0002] In recent years, packaging made from plastic film, plastic bottles, and other plastic products have been discarded and dumped as garbage in the ocean, causing environmental pollution. These plastic products break down in seawater and become submicron-sized fragments (microplastics), which float in the seawater. When these microplastics are ingested by marine organisms such as fish, they become concentrated in the organisms' bodies, and there are concerns that they may affect the health of seabirds and humans who consume these marine organisms as food.

[0003] The plastic products include food packaging packages having a multi-layer structure using plastic films, and various plastic substrates such as polyester substrates, nylon substrates (NY), polypropylene substrates (PP), and polyethylene substrates (PE) are used as film substrates in such food packaging packages. These film substrates are printed with printing ink, bonded to other film substrates or heat-melting resin substrates via adhesives, and then cut and heat-sealed to form packages. However, such food packaging packages having a multi-layer structure contain multiple incompatible materials, and therefore have the problem that they cannot be recycled as they are.

[0004] Regarding material recycling of such multi-layered packaging materials, for example, Patent Documents 1 and 2 disclose a technology in which a roll of printed material is brought into contact with a cleaning agent, and the printed layer is rubbed off and removed using a non-abrasive cloth, brush, or the like, to regenerate a roll of transparent film.

[0005] Furthermore, Patent Documents 3 and 4 disclose a technique for removing a printed layer from not only surface-printed laminates but also laminates having a multi-layer structure by treating a laminate having a removal layer containing a polyurethane resin having a predetermined acid value with an alkaline aqueous solution.

[0006] Patent Document 5 discloses a technique for removing ink printed on a substrate using a cleaning agent containing a nonionic surfactant and water.

[0007] Patent Document 6 discloses a technique for simplifying the recycling process by crushing a laminated film in a cleaning solution and simultaneously peeling off the laminate.

[0008] Patent Document 7 discloses a technique in which a laminated film is crushed in a cleaning solution, and the laminate is peeled off at the same time as the crushing, and then a removal step is carried out once more. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Special Publication No. 2016-509613 [Patent Document 2] Special Publication No. 2018-514384 [Patent Document 3] JP 2020-090627 A [Patent Document 4] Patent Publication No. 2021-098294 [Patent Document 5] International Publication No. 2021-230032 [Patent Document 6] International Publication No. 2021-230033 [Patent Document 7] International Publication No. 2022-190872 Summary of the Invention [Problem to be solved by the invention]

[0010] However, although Patent Documents 1 and 2 can scrape off and remove printing ink from the surface of a rolled printed film, they cannot be applied to removing a printed layer disposed between layers of a laminated film or peeling laminated films apart from each other. In addition, they cannot be used for packaging materials that have been processed and made into bags of various sizes and shapes from a roll.

[0011] The removal techniques described in Patent Documents 3 and 4 require the creation of a laminate using an ink layer, a primer layer, an adhesive layer, or the like having acidic groups as a removal layer for peeling off the laminate with an alkaline cleaning solution. Unless only such packaging materials suitable for removal are separated from general packaging materials and then recycled, there is a problem in that the quality of the recycled materials cannot be improved.

[0012] In the desorption method described in Patent Document 5, if the amount of laminate treated with the cleaning solution is increased to improve the processing efficiency, the desorption property and the quality of the recycled material decrease. In addition, in the conventional technology, when a large amount of packaging material using an olefin base material that has a low specific gravity and floats in the cleaning solution is recycled, stirring is essential in order to immerse the packaging material in the cleaning solution. Foaming occurs at the gas-liquid interface due to surfactants contained in the cleaning solution, surfactants such as antistatic agents contained in the film, surfactants in the ink and adhesive components, or surfactants contained in the contents of the packaging material. The presence of bubbles makes it difficult to separate and recover the removed ink pieces or film pieces, and the quality of the recycled material decreases. Although foaming can be suppressed to some extent by adding an antifoaming agent, an alcohol-based or glycol-based solvent, etc. to the cleaning solution, reuse of the cleaning agent becomes difficult when the composition of the cleaning agent becomes complex, and this is not the best means in terms of environmental load and economic efficiency.

[0013] In the deinking method described in Patent Document 6, the ink is removed and crushed simultaneously in a cleaning solution, so that fine ink particles and cleaning agent components that have been deinked become embedded in the fracture surfaces of the substrate, causing discoloration of the recycled resin and deterioration of its mechanical properties.

[0014] The desorption method described in Patent Document 7 improves the coloring of the recycled resin, but does not eliminate the cause of the deterioration of mechanical properties.

[0015] Therefore, an object of the present invention is to provide a manufacturing method for obtaining high-quality recycled plastic substrate material by easily peeling a plastic substrate from a general-purpose plastic laminate for packaging material by applying a high shear force in a liquid medium (hereinafter also referred to as a treatment liquid) that does not cause crushing, and separating only the plastic substrate material without being affected by bubbles. [Means for solving the problem]

[0016] The present invention relates to a method for removing components other than a plastic substrate from a laminate containing a plastic substrate without crushing the plastic substrate more than necessary.

[0017] That is, the present invention relates to a process for removing a coating layer from a laminate having at least a plastic substrate and a coating layer by using a liquid medium in a removal tank; A step (B) of recovering the detached plastic substrate, The step (A) has the following characteristics (1) and (2), The process (B) relates to a method for producing a recycled plastic substrate having the following feature (3). (1) The desorption tank has a clearance of 20 mm or less to allow the passage of the treatment liquid and / or the laminate. (2) The area change rate of the plastic substrate before and after the step (A) is 70% or less. (3) The long side of the collected recycled plastic substrate is 1 mm or more.

[0018] The present invention also relates to the method for producing the above recycled plastic substrate, in which step (A) has the following feature (4): (4) The desorption tank has a rotating agitator and the Froude number (Fr) during agitation is between 2 and 16. Below.

[0019] The present invention also relates to the method for producing the above recycled plastic substrate, in which step (A) has the following feature (5): (5) The desorption tank has a means for applying a shear force to the laminate, and the shear rate (D) of the shear force is 500 to 200,000 s -1 It is.

[0020] The present invention also relates to the above-mentioned method for producing a recycled plastic substrate, wherein the treatment liquid contains water and a basic compound and has a pH of 10 or higher.

[0021] The present invention also relates to the above-mentioned method for producing a recycled plastic substrate, in which the treatment liquid contains water and a surfactant.

[0022] The present invention also relates to the above-mentioned method for producing a recycled plastic substrate, wherein the surfactant contains at least one selected from the group consisting of anionic surfactants, nonionic surfactants, and amphoteric surfactants. Effect of the Invention

[0023] The present invention provides a manufacturing method for obtaining high-quality recycled plastic substrates by easily peeling a plastic substrate from a general-purpose plastic laminate for packaging material by applying a high shear force in a liquid medium but not causing crushing, and separating only the plastic substrate without being affected by bubbles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The following describes in detail the embodiments of the present invention. However, the following description of the embodiments or requirements is merely an example of the embodiments of the present invention, and the present invention is not limited to these contents as long as it does not exceed the gist of the present invention.

[0025] The method for producing the recycled plastic substrate (hereinafter also referred to as the recycled substrate) in the present invention is as follows: The method includes a step (A) of removing the coating layer from a laminate having at least a plastic substrate and a coating layer by using a liquid medium in a removal tank, The step (A) has the following characteristics (1) and (2), and the step (B) has the following characteristic (3). (1) The method includes a step in which the treatment liquid and / or the laminate passes through a clearance of 20 mm or less. (2) The area change rate of the substrate before and after the step (A) is 70% or less. (3) The long side of the collected recycled plastic substrate is 1 mm or more.

[0026] In the present invention, "detachment" refers to separation of a laminated coating layer from a plastic substrate (hereinafter also referred to as "substrate"), and may take any of the following forms (1) to (4). (1) The coating layer dissolves in the treatment liquid. (2) The coating layer swells and peels off due to the treatment liquid. (3) The interfacial adhesive strength between the substrate and coating layer decreases due to penetration of the treatment liquid, causing peeling. (4) Peeling occurs due to physical shear stress applied to the coating layer or substrate.

[0027] Since the present invention aims to obtain the substrate after detachment as a recycled substrate or regenerated substrate, an embodiment in which as much of the coating layer, etc., has been removed from the substrate is preferred. Specifically, it is preferred that 50% by mass or more of the coating layer, which is 100% by mass, has been detached. More preferably, it is preferred that 60% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more has been detached. It is not essential that the coating layer is detached from the interface between the substrate and the coating layer.

[0028] <Process (A)> The step of removing the coating layer from the laminate carried out in the present invention is characterized by having a clearance of 20 mm or less through which the treatment liquid and / or the laminate can pass without changing the size of the laminate. Conventional desorption processes using agitation devices require time until desorption is complete, and desorption processes using devices with a passable clearance of 20 mm or less involve crushing, making it difficult to recover desirable recycled plastic substrates.

[0029] <Processing solution> The treatment liquid may be any liquid medium that has affinity for the coating layer and penetrates, swells or dissolves the coating layer, and may be appropriately selected. Examples of such treatment liquids include organic solvents, water, surfactant solutions, basic aqueous solutions, acidic aqueous solutions, etc., and the treatment liquid may be heated. In recycling packaging materials, a basic aqueous solution or a surfactant solution is particularly preferably used from the viewpoint of washing the remaining contents. A basic aqueous solution is also preferred in that it has excellent releasability of the urethane ink or urethane adhesive used in the coating layer.

[0030] [Basic compounds] As described above, the treatment liquid used in the present invention is preferably a basic aqueous solution containing a basic compound. The basic compound is not particularly limited, and for example, sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), ammonia, barium hydroxide (Ba(OH)2), and sodium carbonate (Na2CO3) are preferably used. More preferably, it is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide. There is no particular restriction on the content of the basic compound in the basic aqueous solution, and the pH of the treatment liquid is preferably in a range of 10 or more, more preferably 12 or more, and even more preferably 13 or more. By having the pH of the basic aqueous solution be 10 or more, sufficient basicity for the release of the above-mentioned urethane-based ink and urethane-based adhesive can be maintained.

[0031] [Surfactants] The treatment liquid preferably contains water and a surfactant. The surfactant mainly plays a role in improving the releasability of the coating layer. This is believed to be because the action of the surfactant makes it easier for the treatment liquid to penetrate between the layers of the laminate, promoting the releasability. In addition, the detached coating layer is finely divided and the surfactant stabilizes the dispersion in the treatment liquid, which is highly effective in preventing reattachment to the substrate.

[0032] The HLB value is an index value relating to the affinity of a surfactant for water and oil, with the HLB value of a substance with no hydrophilic groups being 0 and the HLB value of a substance with only hydrophilic groups being 20. The concept of HLB was proposed by William Griffin of the Atlas Powder Company in 1949, and several methods for determining the HLB value by calculation have been proposed, but in the present invention, the HLB value can be calculated using the Griffin method from the following formula. Formula) HLB = 20 x [(molecular weight of hydrophilic group contained in surfactant) / (molecular weight of surfactant)] Examples of the hydrophilic group contained in the surfactant include a hydroxyl group and an ethyleneoxy group.

[0033] The HLB value of the surfactant in the present invention is preferably 7 or more. With an HLB value of 7 or more, excellent deinking properties and re-adhesion properties are exhibited. The HLB value of the surfactant is preferably 8 or more, more preferably 10 or more. The HLB value of the surfactant is preferably 20 or less, more preferably 19 or less, and even more preferably 17 or less. An HLB value of 20 or less is preferable because it provides excellent defoaming properties.

[0034] The type of surfactant may be, for example, nonionic, anionic, cationic, or amphoteric, and the type and amount of the surfactant may be appropriately selected according to the required properties. From the viewpoint of releasing property and foaming property, the surfactant is preferably at least one selected from the group consisting of anionic surfactants, nonionic surfactants, and amphoteric surfactants. Moreover, the surfactant preferably has a structure to which alkylene oxide (hereinafter, also referred to as AO) is added, since this improves the deinking property and re-adhesion property.

[0035] (Nonionic surfactant) The nonionic surfactant is not particularly limited, but is preferably an alkylene oxide adduct in which an alkylene oxide is added. More preferably, it is a compound obtained by adding an alkylene oxide to an alcohol having active hydrogen, a compound obtained by adding an alkylene oxide to an amine, or a compound obtained by adding an alkylene oxide to a fatty acid. The above addition may be either random addition or block addition. In addition, the number of carbon atoms of the alkylene oxide is preferably 2 to 4. The nonionic surfactant is more preferably an alcohol-based nonionic surfactant in which an alkylene oxide having 2 to 4 carbon atoms is added to an alcohol.

[0036] [Alcohol-based nonionic surfactant] Examples of the alcohol-based nonionic surfactant include alkylene oxide adducts of primary or secondary alcohols having a total of 8 to 24 carbon atoms, and alkylene oxide adducts of alkylphenols having a total of 8 to 12 carbon atoms. The primary or secondary alcohols having a total of 8 to 24 carbon atoms may be either saturated or unsaturated. Examples of the primary or secondary alcohol having a total of 8 to 24 carbon atoms include lauryl alcohol, stearyl alcohol, oleyl alcohol, dodecyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, and myristyl alcohol. Examples of the alkylene oxide added to the alcohol include ethylene oxide, propylene oxide, and butylene oxide, and it is preferable to use ethylene oxide as an essential component. The number of moles of the alkylene oxide added is preferably 1 to 100 moles, more preferably 2 to 50 moles, per mole of the alcohol or alkylphenol. The above range is preferable because it has excellent elimination properties.

[0037] [Fatty acid-based nonionic surfactant] The structure of the fatty acid-based nonionic surfactant is not particularly limited, and examples thereof include alkylene oxide adducts of higher fatty acids having a total of 10 to 24 carbon atoms, fats and oils consisting of esters of the above-mentioned saturated or unsaturated higher fatty acids having a total of 10 to 24 carbon atoms and glycerin, and further, alkylene oxide adducts of mixtures of the above-mentioned fats and oils and polyhydric alcohols having 2 to 10 carbon atoms. The above-mentioned higher fatty acids having a total of 10 to 24 carbon atoms may be either saturated or unsaturated. Examples of the higher fatty acid having a total carbon number of 10 to 24 include saturated higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid; and unsaturated higher fatty acids such as palmitoleic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, erucic acid, and ricinoleic acid. Examples of the dihydric to decahydric polyhydric alcohol include ethylene glycol, propylene glycol, glycerin, polyglycerin, sorbitol, sorbitan, and sucrose. The type and molar number of the alkylene oxide are the same as those described in the above section on [Alcohol-based nonionic surfactants].

[0038] [Amine-based nonionic surfactant] Examples of the amine-based nonionic surfactant include AO adducts of saturated or unsaturated primary or secondary amines having a total carbon number of 8 to 36. Examples of the amine include 2-ethylhexylamine, di-2-ethylhexylamine, laurylamine, dilaurylamine, tetradecylamine, ditetradecylamine, hexadecylamine, dihexadecylamine, stearylamine, distearylamine, oleylamine, dioleylamine, etc. The type and number of moles of AO added are the same as above.

[0039] (anionic surfactant) The anionic surfactant is preferably a non-soap type, and examples thereof include sulfonic acid type anionic surfactants, sulfate ester type anionic surfactants, carboxylate type anionic surfactants, and phosphate ester type anionic surfactants.

[0040] [Sulfonic acid-based anionic surfactant] Examples of the sulfonic acid anionic surfactant include alkylsulfonic acid, alkylbenzenesulfonic acid, alkylnaphthalenesulfonic acid, alkyldiphenyletherdisulfonic acid, alkylmethyltaurine, sulfosuccinic acid diester, alkylene oxide adduct of sulfonic acid, and salts thereof.Specific examples include hexanesulfonic acid, octanesulfonic acid, decanesulfonic acid, dodecanesulfonic acid, toluenesulfonic acid, cumenesulfonic acid, octylbenzenesulfonic acid, dodecylbenzenesulfonic acid, dinitrobenzenesulfonic acid, and lauryldodecylphenyletherdisulfonic acid.

[0041] [Sulfate ester-based anionic surfactants] Examples of the sulfate anionic surfactant include sulfate (alkyl ether sulfate), alkylene oxide adduct of sulfate, and salts thereof. Specific examples include lauryl sulfate, myristyl sulfate, and polyoxyethylene lauryl ether sulfate.

[0042] [Carboxylic acid type anionic surfactant] Examples of the carboxylic acid-based anionic surfactant include alkyl carboxylic acids, alkyl benzene carboxylic acids, alkylene oxide adducts of carboxylic acids, and salts thereof. Specific examples of the surfactant that can be used include lauric acid, myristic acid, palmitic acid, stearic acid, polyoxyethylene lauryl ether acetic acid, and polyoxyethylene tridecyl ether acetic acid.

[0043] [Phosphate-based anionic surfactant] Examples of the phosphate anionic surfactant include phosphate (alkyl ether phosphate), alkylene oxide adduct of phosphate, and salts thereof.Specific examples include octyl phosphate, lauryl phosphate, tridecyl phosphate, myristyl phosphate, cetyl phosphate, stearyl phosphate, polyoxyethylene octyl ether phosphate, polyoxyethylene lauryl ether phosphate, etc.

[0044] The anionic surfactant preferably has an alkyl group having 2 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, and more preferably has an alkyl group having 8 to 18 carbon atoms. The alkyl group or the alkenyl group may be linear or branched. In addition, when the anionic surfactant is an alkylene oxide adduct, the alkylene oxide may be, for example, ethylene oxide, propylene oxide, or butylene oxide, with ethylene oxide being preferred. The number of moles of alkylene oxide added is preferably 1 to 12 moles, more preferably 1 to 8 moles, per mole of alcohol or alkylphenol. The above range is particularly preferred because of excellent releasability.

[0045] Examples of the salt constituting the anionic surfactant include metal salts such as sodium, potassium, magnesium, calcium, etc. These salts may be used alone or in combination of two or more. Among these, from the viewpoint of releasability and reattachment, preferred anionic surfactants are sulfonate type and phosphate type, and more preferred are alkyl sulfonate, polyoxyalkylene alkyl ether sulfonate, polyoxyalkylene alkyl ether phosphate, etc.

[0046] (Cationic Surfactant) Examples of cationic surfactants include alkylamine salts and quaternary ammonium salts.Specific examples of usable surfactants include stearylamine acetate, trimethyl coconut ammonium chloride, trimethyl beef tallow ammonium chloride, dimethyldioleyl ammonium chloride, methyl oleyl diethanol chloride, tetramethyl ammonium chloride, lauryl pyridinium chloride, lauryl pyridinium bromide, lauryl pyridinium disulfate, cetyl pyridinium bromide, 4-alkyl mercaptopyridine, poly(vinylpyridine)-dodecyl bromide, and dodecyl benzyl triethyl ammonium chloride.

[0047] (Amphoteric surfactant) Examples of amphoteric surfactants include lauryl dimethylaminoacetate betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, coconut oil fatty acid amidopropyl dimethylaminoacetate betaine, polyoctyl polyaminoethyl glycine, and imidazoline derivatives.

[0048] These surfactants may be used alone or in combination of two or more. The content of the surfactant in the treatment liquid is preferably in the range of 0.001 to 10 mass%, more preferably in the range of 0.005 to 7 mass%, further preferably in the range of 0.03 to 5 mass%, and still more preferably in the range of 0.05 to 3 mass%, based on the mass of the treatment liquid. A content of 0.001 mass% or more is preferable because it is advantageous for promoting detachment and preventing the detached ink particles from reattaching to the substrate, and a content of 10 mass% or less is preferable from the viewpoint of defoaming properties.

[0049] [Antifoaming agent] In the present invention, it is also preferable that the treatment liquid further contains a defoaming agent.By using the defoaming agent in combination with the above-mentioned surfactant, it is possible to exhibit good defoaming properties without reducing the detachment and reattachment properties, and to suppress foaming caused by the surfactant.As the defoaming agent, for example, a silicone-based compound and a non-silicone-based compound can be mentioned.

[0050] (Silicone compounds) Examples of the silicone-based compound include emulsion type, self-emulsifying type, oil type, oil compound type, and solvent type. Emulsion type is a silicone-based defoamer in which a silicone oil compound is emulsified with an activator to form an O / W type emulsion. Examples include "KM-89" and "KM-98" manufactured by Shin-Etsu Chemical Co., Ltd., "FC2913" and "SILFOAMSE47" manufactured by Asahi Kasei Wacker Silicone Co., Ltd., and "BYK-015" and "BYK-1640" manufactured by BYK Japan. The self-emulsifying type is a silicone-based defoamer that is 100% active ingredient and becomes an emulsion when diluted and mixed with water. Examples include "KS-540" and "X-50-1176" manufactured by Shin-Etsu Chemical Co., Ltd., and "SILFOAM SD670" and "SILFOAM SD850" manufactured by Wacker Asahi Kasei Silicones. Oil-type defoamers are 100% silicone oil defoamers that do not contain solvents or additives. Examples include "KM-89" and "KM-98" made by Shin-Etsu Chemical Co., Ltd., "AK350" and "AK12500" made by Asahi Kasei Wacker Silicone, and "BYK-1770" made by BYK Japan. Oil compound type is a silicone-based defoamer that combines silica particles with silicone oil. Examples include "KM-89" and "KM-98" manufactured by Shin-Etsu Chemical Co., Ltd., "SILFOAM SC370" and "PULPSIL22274VP" manufactured by Asahi Kasei Wacker Silicone, and "BYK-017" and "BYK-018" manufactured by BYK Japan. Solvent-type defoamers are silicone-based defoamers in which silicone oil is dissolved in a solvent. Examples include "KM-89" and "KM-98" manufactured by Shin-Etsu Chemical Co., Ltd., and "BYK-019" and "BYK-025" manufactured by BYK Japan.

[0051] (Non-silicone compounds) Examples of the non-silicone compounds include fatty acid ester compounds, urea resin compounds, paraffin compounds, polyoxyalkylene glycol compounds, acrylic ester copolymers, ester polymers, ether polymers, amide polymers, emulsion types of mineral oils, polysiloxane adducts, fluorine compounds, vinyl polymers, acetylene alcohol, acrylic polymers, special vinyl polymers, ethylene glycol, and higher alcohols (such as octyl alcohol and cyclohexanol).

[0052] The defoaming agent may be used alone or in combination of two or more. The content of the defoaming agent in the treatment liquid is preferably in the range of 0.0001 to 5 mass%, more preferably in the range of 0.001 to 4.5 mass%, further preferably 0.01 to 4 mass%, still more preferably 0.02 to 3.5 mass%, and particularly preferably 0.03 to 3 mass%, based on the mass of the treatment liquid. When it is 0.0001 mass% or more, the defoaming property is excellent, and when it is 5 mass% or less, the deinking property and the re-adhesion property are excellent.

[0053] The above-mentioned defoaming agent is preferably at least one selected from the group consisting of emulsion-type silicone compounds, self-emulsifying silicone compounds, and non-silicone compounds, from the viewpoints that it has good alkali resistance and is less likely to reduce deinking properties and re-adhesion properties when combined with the above-mentioned surfactant.

[0054] In the method for producing a recycled substrate in the present invention, it is preferable not to crush the substrate in the treatment liquid. If the substrate is crushed in the treatment liquid, peeling of the coating layer proceeds at the same time as the crushing, and the coating layer that has been detached and made fine, especially the ink particles that have been detached and made fine from the printing ink layer, reattaches to the cross section of the substrate and is embedded in the substrate due to the pressure of the crushing, causing coloring and deterioration of the physical properties of the recycled substrate. The method for producing a recycled substrate in the present invention is characterized in that the area change rate of the substrate is 70% or less before and after step (A) in which the coating layer is detached by mixing and stirring the treatment liquid, which is a liquid medium, and the laminate. If the area change rate is 70% or less, the substrate is not broken in the treatment liquid, and reattachment of the coating layer components to the cross section is suppressed, and a high-quality recycled substrate can be obtained.

[0055] On the other hand, the treatment liquid permeates the end portion of the laminate, contacts the coating layer and the interface between the coating layer and the substrate, and separates the substrate from the coating layer. Therefore, in order to efficiently proceed with the detachment process, it is preferable that the laminate is cut or crushed to a minimum extent (hereinafter also referred to as crushing) before contacting with the treatment liquid, so that the interface between the coating layer and the substrate is exposed on the cross section (hereinafter, in this specification, the state in which the laminate is crushed from a sheet-like form is referred to as "fluff").

[0056] The long side of the recovered recycled plastic substrate is 1 mm or more, preferably 5 mm or more, and more preferably 10 mm or more. Since there is little change in the size of the fluff due to heating or the desorption treatment before and after the desorption step, the long side of the fluff before desorption in the desorption tank should be 1 mm or more as a guideline. When the detachment is performed by batch processing, there is an upper limit to the long side of the fluff due to the constraints of the detachment tank. The size of the fluff during batch processing is preferably 1 to 50 mm in long side, more preferably 1 to 40 mm, and even more preferably 1 to 30 mm. Within the above range, the time required for the treatment liquid to penetrate from the end face of the fluff to the center during batch processing is shortened, and detachment between the coating layer and the substrate proceeds efficiently. In the case of continuous processing, the size of the short side may be restricted by the detachment tank, but there is no theoretical upper limit to the long side. In addition, when the long side is not cut or is cut into a shape other than a rectangle, the measurement is made by applying a rectangle where the periphery is in contact. In the case of an aggregate of fluffs with different long sides, the number average value is used. Even if the fluff contains a large number of fluffs smaller than 1 mm, they are removed from the recovered recycled plastic substrate together with detached ink particles, etc., so the long side of the recovered recycled plastic substrate can be measured uniformly.

[0057] The method for crushing the laminate to prepare fluff is not particularly limited, and any known technique for crushing a solid or cutting a film can be applied, such as a jaw crusher, impact crusher, cutter mill, stamp mill, ring mill, roller mill, jet mill, hammer mill, colloid mill, rotary cutter, etc. In order to prevent the substrate or coating layer from softening due to frictional heat during crushing and the cross section of the laminate from fusing, it is preferable that the laminate or crushing device is cooled.

[0058] It is also preferable to perform pre-cleaning for the purpose of cleaning dirt such as contents attached to the laminate. There is no particular restriction on the method of pre-cleaning, and pre-cleaning can be performed by a known method. It is also common to simultaneously perform the crushing of the laminate described above and pre-cleaning, for example, a method of crushing while running water or a cleaning liquid through a rotary cutter. The above pre-cleaning step is a step of removing the contents attached to the laminate to a level that does not affect the subsequent steps, and does not include a step of detaching the coating layer from the substrate.

[0059] The detachment step (A) in the present invention is characterized by including a step in which the treatment liquid and / or the laminate passes through a clearance of 20 mm or less. By passing through a clearance of 20 mm or less, a high shear force can be applied to the laminate without breaking it, which has the effect of, for example, scraping off the coating layer exposed on the substrate surface and applying a shear stress to the coating layer present between two or more types of film layers, thereby facilitating peeling of the laminate.

[0060] In addition, by having a process of passing through a clearance of 20 mm or less, high shear force can be obtained even at a low stirring rotation speed, and foaming at the gas-liquid interface can be suppressed. The bubbles exist at the gas-liquid interface, enveloping fine fragments of the coating layer that have detached from the substrate, and they reattach to the substrate, making separation difficult. Therefore, by reducing foaming in process (A), coloring of the recycled substrate is suppressed and mechanical properties are maintained at a high level.

[0061] Methods for applying high shear with a clearance of 20 mm or less include controlling the size gap between the inner tank wall of the processing tank in which the laminate and / or processing liquid is stirred and the stirring blades to 20 mm or less, installing a baffle plate at a distance of 20 mm or less from the tank wall, designing the laminate and / or processing liquid to pass through a screen with holes of 20 mm or less in diameter, passing the laminate between two rolls with a gap of 20 mm or less, using a ball mill or the like to sandwich the laminate between the media and collide them, and controlling the gap between the rotating blade and the fixed blade to 20 mm or less, for example, as in a homogenizer, by installing a fixed blade on the outside of the rotating blade.

[0062] Examples of equipment that can provide a clearance of 20 mm or less include IKA MDH2000, Silverson High Shear In-line Mixer, Ystral Conti-TDS, Inoue Seisakusho Planetary Mixer, Nippon Coke and Oxford Wet Attritor, and Nippon Coke and Oxford Trigonal.

[0063] The content of the laminate when the laminate is separated in the treatment liquid is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 8% by mass or less, further preferably 1.5% by mass or more and 7% by mass or less, and even more preferably 2% by mass or more and 6% by mass or less, based on the mass of the treatment liquid. 0.1% by mass or more is preferable from the viewpoint of treatment efficiency. 10% by mass or less is preferable from the viewpoint of detachment property.

[0064] The temperature of the treatment liquid when the laminate is immersed is preferably in the range of 25 to 120° C., more preferably 30 to 120° C., and particularly preferably 30 to 80° C. The immersion time in the treatment liquid is preferably 1 minute to 12 hours, more preferably 1 minute to 6 hours, and even more preferably 1 minute to 3 hours. It is a range of time.

[0065] In order to promote contact between the treatment liquid and the laminate, the treatment liquid is preferably in a mixed state by stirring, vibration, circulation or other convection.

[0066] In the manufacturing method of the recycled substrate in the present invention, it is preferable that the step (A) has a rotary stirring mechanism, and the Froude number (Fr) of the stirring is 2 or more and less than 20. The Froude number (Fr) of the stirring is a value that represents the ratio of the inertial force of the fluid to gravity, and is a dimensionless number that does not depend on the amount of the treatment liquid or laminate, or the scale of the device. By making the Froude number of the stirring equal, the shape of the vortex on the liquid surface becomes similar. Several definitions of the Froude number of the stirring are proposed in the literature, but in the present invention, the Froude number of the stirring in a device equipped with a rotary stirring mechanism using a stirring blade is defined as follows. Fr = {(n / 60) 2}×R2 / g n: Rotation speed of the stirring blade (rpm) R2: Diameter of the stirring blade (m) g:Gravity acceleration=9.8(m / s 2 )

[0067] By having a Froude number of 2 or more, sufficient laminar flow is provided in the system, and sufficient flow speed can be obtained when the laminate and the treatment liquid come into contact and pass through the clearance, which is advantageous in terms of desorption. In addition, by having a Froude number of 20 or less, foaming of the treatment liquid at the gas-liquid interface is suppressed, which is advantageous in terms of separation and recovery of the substrate. Therefore, by having a Froude number of 20 or less, coloring of the recycled substrate is reduced and the physical properties are improved, which is preferable. The Froude number of 3 or more and less than 16 is more preferable as the range of the Froude number of 20 or less.

[0068] In the method for producing the recycled substrate of the present invention, the shear rate (D) in the step (A) is 500 S^-1 or more and 200,000 S -1 In the present invention, the shear rate (D) is defined by the following formula. D=v / Δy v: flow velocity (m / s), calculated as v = π × R2 × (n / 60) π: circumference constant R2: Diameter of the stirring blade (m) Δy: Clearance (m), calculated as Δy=(R1-R2) / 2 R1: Tank inner wall diameter

[0069] The higher the shear rate, the greater the shear force applied to the fluid. The faster the flow velocity and the smaller the clearance through which the fluid passes, the larger the value. -1 The shear rate (D) of 200,000 S or more is favorable for the desorption property, and in particular, the desorption progresses quickly. -1 By being less than or equal to 1,000, the physical properties of the recycled base material tend to be good. The shear rate (D) is more preferably in the range of 1,000 to 200,000 S -1 , more preferably 10,000 to 200,000S -1 It is.

[0070] The coating layer is detached from the laminate, and the substrate is recovered, and then the substrate is washed with water and dried to obtain a regenerated substrate. The removal rate of the detached layer on the surface of the substrate is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more, of the area of ​​the coating layer before detachment. The resulting recycled base material can be processed into pellets using an extruder or the like and reused as recycled resin.

[0071] <Process (B)> In step (A), the recycled plastic substrate is detached from the laminate, and in step (B), the recycled plastic substrate and detached ink particles and the like are removed to recover the recycled plastic substrate. The removal method can be based on differences in specific gravity or size, as is well known. Even when separating based on differences in specific gravity, if the long side of the fluff is 1 mm or more, separation can be performed with little adhesion or contamination. The long side of the resulting recycled plastic substrate is also 1 mm or more.

[0072] <Laminate> The laminate used in the present invention includes at least a substrate layer and a coating layer. The coating layer in contact with the substrate is detached, so that the substrate can be recovered and recycled.

[0073] <Coating layer> The coating layer in the present invention refers to a layer applied to a substrate, and includes a "printing ink layer," an "adhesive layer," a "primer layer," a "detachment layer," and the like. The coating layer may be colorless or colored. The coating layer may be provided in contact with the substrate, or may be provided via an inorganic vapor deposition layer or the like in contact with the substrate. The coating layer may be in the form of a laminate of different coating layers. There is no particular restriction on the thickness of the coating layer, but it 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 even more preferably 1 μm or more and 5 μm or less.

[0074] The "printed ink layer" in this application is intended to provide decoration, aesthetics, display contents, expiration date, manufacturer or seller, and protect the surface of packaging materials, and includes solid printed layers and transparent printed layers. The printed ink layer can be formed using a conventionally known ink composition, and the method of formation is not particularly limited. The printed ink layer may be formed of a single layer or multiple layers.

[0075] The ink composition used to form the printed ink layer can be produced by dissolving and / or dispersing a colorant and a dispersant in a binder resin or a solvent, and may contain other components as necessary. Examples of the solvent include aromatic organic solvents such as toluene and xylene, ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester organic solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, and isobutyl acetate, alcohol organic solvents such as methanol, ethanol, n-propanol, isopropanol, and n-butanol, glycol ether solvents such as ethylene glycol monopropyl ether and propylene glycol monomethyl ether, and water. These solvents can be used alone or in combination. Examples of the binder resin include fibrous materials such as nitrocellulose and cellulose acetate propionate, chlorinated polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, acrylic, urethane resin, and acrylic urethane, polyamide, polybutyral, cyclized rubber, chlorinated rubber, or a combination of these. The method for applying the ink composition to form a printed ink layer is not particularly limited, and the ink composition can be applied by a method such as gravure coating, flexo coating, roll coating, bar coating, die coating, curtain coating, spin coating, inkjet, etc. The printed ink layer can be formed by leaving the ink composition alone or, if necessary, blowing air, heating, drying under reduced pressure, irradiating with ultraviolet light, etc.

[0076] The "adhesive layer" in the present application is a layer disposed for the purpose of bonding and laminating the substrate layer and / or coating layer, and a conventionally known adhesive can be used. It is preferable that the adhesive layer is a cured product of an adhesive containing a polyester polyol and at least one polyisocyanate selected from the group consisting of an aliphatic polyisocyanate and an araliphatic polyisocyanate. The method for forming the adhesive layer is not limited, and the adhesive layer can be formed using a known method. Examples of the method for forming the adhesive layer include a dry lamination method, a solventless lamination method, and an extrusion lamination method.

[0077] The "primer layer" in this application refers to a layer provided for the purposes of providing a base effect for a printing ink layer, aiding adhesion between a film and a coating layer, etc., and is preferably provided in contact with the substrate.

[0078] The "detachment layer" in the present application may be any layer that facilitates the detachment of the coating layer from the substrate by the treatment liquid, and is preferably a layer containing a water-soluble resin or a compound having an acidic group, and more preferably a layer containing a compound having an acidic group. The "detachment layer" is preferably at least one layer selected from the group consisting of a primer layer, a print layer, and an adhesive layer. That is, at least one layer selected from the group consisting of a primer layer, a print layer, and an adhesive layer is preferably a layer containing a water-soluble resin or a compound having an acidic group (excluding water-soluble resins), and more preferably a layer containing a compound having an acidic group. The compound having an acidic group may be a resin or a low molecular weight compound. These water-soluble resins or compounds having an acidic group may be used alone or in combination of two or more. The laminate including the detachment layer as the coating layer has an advantage in the detachment property between the substrate and the coating layer, and the coloring of the recycled substrate obtained by the manufacturing method of the recycled substrate in the present invention is suppressed, and the physical properties are improved.

[0079] (Water-soluble resin) The water-soluble resin may be any resin that swells or dissolves in water. The water may be heated to a temperature of about 25 to 100°C. Such resins may be selected from known resins as long as they do not impair water solubility, and examples of such resins include water-soluble polyester resins, water-soluble polyamide resins, water-soluble polyimide resins, water-soluble acrylic resins, water-soluble polyurethane resins, water-soluble polyallylamine resins, water-soluble phenolic resins, water-soluble epoxy resins, water-soluble phenoxy resins, water-soluble urea resins, water-soluble melamine resins, polyvinyl alcohol resins, and modified products of these resins. These may be used alone or in combination of two or more. Among them, polyvinyl alcohol (PVA) resins are preferably used from the viewpoints of availability and release properties.

[0080] (Compounds having an acidic group) The compound having an acidic group may be a resin having an acidic group or a low molecular weight compound having an acidic group. Examples of the resin having an acidic group include cellulose resin, urethane resin, polyamide resin, vinyl chloride / vinyl acetate copolymer, ketone resin, polyester resin, and (meth)acrylic resin. Examples of the acidic group include a carboxy group, a phosphoric acid group, a sulfo group, a sulfino group, or the like, or an ester or salt thereof. Furthermore, as the resin having an acidic group, a rosin-modified resin having an acid value, such as maleic rosin or fumaric rosin, can be used. In addition, examples of resins having an acidic group that can be used include radical copolymers such as styrene-(meth)acrylic resins, styrene-maleic acid (anhydride) resins, and terpene-maleic acid (anhydride) resins, which are copolymerized with polymerizable monomers having an acidic group, such as polymerizable monomers having a carboxy group, such as itaconic acid, maleic acid, fumaric acid, and cinnamic acid; polymerizable monomers which are acid anhydrides, such as itaconic acid anhydride and maleic acid anhydride; polymerizable monomers having a sulfonic acid group, such as sulfonated styrene; and polymerizable monomers having a sulfonamide group, such as vinylbenzenesulfonamide; and acid-modified polyolefin resins. These may be used alone or in combination of two or more.

[0081] The low molecular weight compound having an acidic group refers to a compound that does not have a molecular weight distribution and has a molecular weight of 1,000 or less. Examples of such compounds include saturated fatty acids such as lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid; unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and sorbic acid; hydroxy acids such as lactic acid, malic acid, and citric acid; aromatic carboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and cinnamic acid; dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, and maleic acid; tricarboxylic acids such as aconitic acid; oxocarboxylic acids such as pyruvic acid and oxaloacetic acid; carboxylic acid derivatives such as amino acids and nitrocarboxylic acids; and acid anhydrides such as trimellitic anhydride and pyromellitic anhydride. The low molecular weight compound having an acidic group can be used in combination with the above-mentioned resin having an acidic group or a known binder resin constituting a known coating layer to form a release layer.

[0082] [Urethane resin having acidic groups] The urethane resin having an acidic group is not particularly limited, and examples thereof include a urethane resin obtained by reacting a polyol having an acidic group with a polyisocyanate, a resin obtained by acid-modifying hydroxyl groups in a urethane resin obtained by reacting a polyol with a polyisocyanate, and a resin obtained by acid-modifying amino groups in a urethane urea resin obtained by reacting a polyamine with an isocyanate group in a urethane resin obtained by reacting a polyol with a polyisocyanate. In addition, as the urethane resin having an acidic group, a resin obtained by reacting a polyol containing a hydroxy acid with a polyisocyanate may be used. By using a hydroxy acid as the polyol, it is possible to impart an acid value derived from a carboxy group to the urethane resin, and it is possible to improve the releasability. In addition, when the urethane resin having an acidic group has an isocyanate group, a polyamine may be reacted with a part of the isocyanate group to introduce a urea bond, thereby forming a urethane urea.

[0083] [Acrylic resin having acidic group] Examples of acrylic resins having an acidic group include polymers obtained by polymerizing a monomer containing a (meth)acrylic monomer having an acidic group, such as (meth)acrylic acid or maleic acid; and resins obtained by polymerizing a monomer containing a (meth)acrylic monomer having a hydroxyl group or a glycidyl group, and then modifying the functional group to introduce a carboxyl group (e.g., maleic anhydride modified resin). The acid value of the acrylic resin having an acidic group is preferably 50 mgKOH / g or more, and more preferably 100 mgKOH / g or more.

[0084] [Rosin-modified resin] Rosin-modified resins are resins prepared using rosin as one of the raw materials. Rosin contains a mixture of resin acids such as abietic acid, palustric acid, isopimaric acid, and levopimaric acid, and these resin acids contain hydrophilic and chemically active carboxyl groups, some of which have conjugated double bonds. For this reason, various rosin-modified resins are prepared by combining polyhydric alcohols and polybasic acids and polycondensing them, adding resol, which is a condensate of phenol, to the benzene ring contained in the rosin skeleton, or by carrying out a Diels-Alder reaction with maleic anhydride or maleic acid, which is a dienophile, to add maleic acid or maleic anhydride skeletons. Various types of such rosin-modified resins are commercially available, and it is also possible to obtain and use them.

[0085] Examples of rosin-modified resins include maleated rosin, fumarated rosin, rosin-modified maleic acid resin, rosin-modified fumaric acid resin, rosin-modified phenolic resin, rosin-modified alkyd resin, and rosin-modified polyester resin. Any rosin-modified resin may be used in the present invention, but among these, those containing in their structure a moiety derived from at least one selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, and fumaric anhydride are preferably used. A resin "containing in its structure a moiety derived from at least one selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, and fumaric anhydride" is one prepared using at least one selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, and fumaric anhydride as part of a raw material, and means, for example, a rosin-modified maleic acid resin or rosin-modified fumaric acid resin obtained by condensation polymerization of maleic acid or fumaric acid as part of a polybasic acid, a maleated rosin or fumarated rosin having a structure in which maleic acid, maleic anhydride, fumaric acid, or fumaric anhydride is added as a dienophile by a Diels-Alder reaction, or a resin obtained by further polymerizing other chemical species using the functional groups contained in these.

[0086] The acid value of the rosin-modified resin is preferably from 10 to 400 mgKOH / g, and more preferably from 100 to 300 mgKOH / g.

[0087] <Base material> Examples of the substrate include film- or sheet-like plastic substrates that are generally used for packaging materials, gas barrier substrates such as metal foils, and paper, and the substrate may be a laminate of these. Examples of the plastic substrate include films of thermoplastic resins and thermosetting resins, and preferably films of thermoplastic resins. Examples of the thermoplastic resins include polyolefin resins, polyester resins, polyamide resins, polystyrene resins, vinyl chloride resins, vinyl acetate resins, ABS resins, acrylic resins, acetal resins, polycarbonate resins, and cellulose-based plastics.

[0088] More specifically, polyolefin resin films such as polyethylene (PE) and biaxially oriented polypropylene (OPP), polyester resin films such as polyethylene terephthalate, polyethylene naphthalate (PEN) and polylactic acid (PLA), polystyrene resin films, polyamide resin films such as nylon 6 and poly-p-xylylene adipamide (MXD6 nylon), polycarbonate resin films, polyacrylonitrile resin films, polyimide resin films, laminates thereof (for example, nylon 6 / MXD6 / nylon 6, nylon 6 / ethylene-vinyl alcohol copolymer / nylon 6) and mixtures thereof, etc. are used. Among them, those having mechanical strength and dimensional stability are preferred. Also preferably used are sealant base materials having sealant properties, such as polyethylenes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), acid-modified polyethylene, non-oriented polypropylene (CPP), acid-modified polypropylene, copolymerized polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, and ionomer. 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 further preferably 10 μm or more and 50 μm or less.

[0089] Examples of gas barrier substrates include aluminum foil; plastic substrates having an inorganic vapor deposition layer such as aluminum, silica, alumina, etc.; and plastic substrates having an organic layer such as polyvinyl alcohol. In the case of aluminum foil, a thickness in the range of 3 to 50 μm is preferable from an economical point of view. Examples of commercially available plastic substrates having an inorganic vapor deposition layer include "GL FILM" (manufactured by Toppan Printing Co., Ltd.) and IB-FILM (manufactured by Dai Nippon Printing Co., Ltd.), in which an inorganic vapor deposition layer such as alumina is laminated on a plastic substrate. Since aluminum and alumina are soluble in a basic aqueous solution, they dissolve in the desorption step described below, and it is possible to recycle only the plastic substrate.

[0090] From the viewpoint of reuse as a recycled substrate, the substrate preferably contains a polyolefin resin film such as polyethylene or biaxially oriented polypropylene.

[0091] When the substrate is a laminate, the substrates are preferably laminated with each other via an adhesive layer. The method of forming the adhesive layer is not limited, and it can be formed by a known method using a known adhesive. The substrate may contain additives such as an antistatic agent and an ultraviolet ray inhibitor as necessary, and the substrate surface may be corona-treated or low-temperature plasma-treated.

[0092] Examples of the laminate structure of the present invention are given below, but the present invention is not limited to these. In the following configuration, the "substrate layer" does not have to be a single layer, but may be a laminate of multiple substrates. In addition, at least one layer selected from a group consisting of a printing ink layer, a primer layer, and an adhesive layer may be a release layer. ·Base material layer / printing ink layer ·Base material layer / printing ink layer / adhesive layer / base material layer · Substrate layer / printing ink layer / adhesive layer / metal deposition layer / substrate layer ·Base material layer / adhesive layer / base material layer ·Base material layer / Primer layer / Printing ink layer ·Base layer / Primer layer / Printing ink layer / Adhesive layer / Base layer

[0093] <Method of manufacturing molding material> The recycled base material recovered by the above-mentioned method for producing recycled base material can be melt-kneaded to produce a molding material. The melt-kneading process refers to adding various additives and the like as necessary, mixing with a Henschel mixer, tumbler, disperser, etc., and then mixing and dispersing using a batch kneader such as a kneader, roll mill, super mixer, Henschel mixer, Shugi mixer, vertical granulator, high-speed mixer, fur matrix, ball mill, steel mill, sand mill, vibration mill, attritor, or Banbury mixer, a twin-screw extruder, a single-screw extruder, or a rotor-type twin-screw kneader. This results in a recycled resin, which is a resin composition. The shape of the recycled resin is not particularly limited, and may be pellet-shaped, powder-shaped, granular, or bead-shaped. The melt-kneading process is preferably performed using a twin-screw extruder. The molding material can further contain a masterbatch. The masterbatch is not particularly limited as long as it is compatible with the recycled resin, and generally, a mixture of a thermoplastic resin such as a polyethylene resin or a polypropylene resin and a colorant can be used. The thermoplastic resin contained in the masterbatch may be used alone or in combination of two or more kinds. The masterbatch may contain, within the range not impairing the effects of the present invention, metal soap of alkali metal, alkaline earth metal, or zinc, hydrotalcite, nonionic surfactant, cationic surfactant, anionic surfactant, amphoteric surfactant, antistatic agent, flame retardant such as halogen-based, phosphorus-based, or metal oxide, lubricant such as ethylene bis alkyl amide, antioxidant, ultraviolet absorber, and filler.

[0094] <Molded body> The molding material obtained by the above-mentioned production method can be heated and molded to obtain a molded article. The heating and molding method is not particularly limited, and examples thereof include injection molding, extrusion molding, blow molding, and compression molding. Molding materials produced using plastic substrates recovered by the separation and recovery method of the present invention are of high quality because the printed layer is detached and reattachment of the detached components is suppressed, and they can be used in a variety of fields, including home appliances, stationery, automobile parts, toys, sporting goods, medical materials, and building and construction materials. EXAMPLES

[0095] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, the blending ratio, parts, and % represent blending mass ratio, parts by mass, and % by mass unless otherwise noted.

[0096] <Production of primer composition> [Synthesis Example 1] (Polyurethane resin P1 having acidic groups) In a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet tube, a stirrer, and a thermometer, 135.7 parts of PPA (a polyester polyol having a number average molecular weight of 2,000 made from a polycondensation product of propylene glycol and adipic acid), 13.6 parts of PPG (a polyether polyol having a number average molecular weight of 2,000 made from polypropylene glycol), 28.3 parts of DMPA (2,2-dimethylolpropanoic acid), 105.7 parts of IPDI (isophorone diisocyanate), and 200 parts of NPAC (normal propyl acetate) were charged while introducing nitrogen gas, and the mixture was reacted at 90°C for 5 hours to obtain a urethane prepolymer solution having an isocyanate group at the end. Next, a mixture of 16.7 parts of AEA (2-(2-aminoethylamino)ethanol) and 350 parts of IPA (isopropyl alcohol) was added dropwise at room temperature over 60 minutes, and then reacted at 70°C for 3 hours to obtain a polyurethane resin solution. NPAC was added to the resulting polyurethane resin solution to adjust the solid content, thereby obtaining a solution of polyurethane resin P1 having an acidic group with a solid content concentration of 30% and an acid value of 39.3 mgKOH / g. The acid value was measured according to the method described in JIS K0070 (1992).

[0097] [Production Example 1] (Primer composition AC1) 87 parts of polyurethane resin P1 solution having acidic groups, 5 parts of EA, 5 parts of IPA, and 3 parts of silica particles (P-73 manufactured by Mizusawa Chemical Industries, Ltd.: hydrophilic silica particles having an average particle size of 3.8 μm) were stirred and mixed using a disper to obtain primer composition AC1.

[0098] <Production of Laminate> The method for producing the laminate is described below. The printing ink and primer composition were each diluted with a mixed solvent of EA / IPA (mass ratio 70 / 30) to a viscosity of 15 seconds (25°C, Zahn cup #3 (Rigo Co., Ltd.)) before use.

[0099] [Manufacturing Example 2-1] (Laminate L1) The diluted printing ink (INK1) was printed in this order onto OPP (corona-treated stretched polypropylene film, thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm, and then dried at 50°C to obtain a laminate L1 having a structure of OPP / INK.

[0100] [Manufacturing Example 2-2] (Laminate L2) Diluted printing ink (INK1) was printed on OPP (corona-treated stretched polypropylene film, thickness 20 μm) in this order using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm, and dried at 50° C. to obtain a laminate having a structure of base layer (OPP) / printed ink layer (INK1). Next, adhesive AD1 was applied and dried on the printed ink layer of the obtained laminate using a dry laminator so that the film thickness after drying was about 3 μm, and then it was laminated with CPP (unstretched polypropylene film, thickness 50 μm) to obtain a laminate L2 having a structure of base layer (OPP) / printed ink layer (INK1) / adhesive layer (AD1) / base layer (CPP).

[0101] [Manufacturing Examples 2-3 to 2-5] (Laminates L2 to L5) Except for changing the coating layer and the substrate as shown in Table 1, the same procedures as in Production Examples 2-1 and 2-2 were used to obtain laminates L2 to L5. The printing inks, adhesives and substrates used were as follows: INK1: Toyo Ink's general-purpose laminating ink "LP Bio SX R39 Indigo" AD1: Toyo Morton ester-based dry lamination adhesive "TOMOFLEX TM250 / isocyanate-based hardener CAT-RT86" (Mixing ratio TM250:CAT-RT86=10:1) OPP: Corona-treated oriented polypropylene film, thickness 20 μm CPP: Non-oriented polypropylene film, thickness 50 μm VMCPP: Aluminum-deposited non-oriented polypropylene, thickness 30μm

[0102] [Table 1]

[0103] <Crushing the laminate and creating fluff> [Fluff manufacturing example 3-1] (Fluff F1) The laminate was wet-shredded using a PFS-40 wet crusher manufactured by Nippon Seam (a vertical shredding device equipped with a cutter mill and a circular screen with a diameter that can be arbitrarily controlled). The laminate L1 was fed from a hopper, and the shredding process was carried out while water was flowing in from the water inlet. As the shredding progressed and the fluff size became smaller than a certain value, it passed through the screen installed at the bottom of the shredding section due to its own weight together with the water. The long side of the fluff can be adjusted by the size of the screen used, and by using a circular screen with a diameter of 10 mm, fluff F1 with a long side of the shredded material of 10 mm was obtained.

[0104] [Fluff manufacturing examples 3-2 to 3-6, 3-8, 3-9] (Fluff F2 to F6, F8, F9) Fluffs F2 to F6, F8, and F9 were obtained using the same equipment and method as in Fluff Production Example 3-1, except that the laminate and the fluff long sides, ie, the screen sizes, were changed to those shown in Table 2.

[0105] [Fluff Manufacturing Example 3-7] (Fluff F7) The laminate was dry-crushed using a Horai FG-2060 dry crusher (equipped with a cutter mill and a circular screen with a diameter of 2 mm). The laminate L2 was placed in the hopper and crushed to obtain fluff F7 with a long side of 2 mm.

[0106] [Table 2]

[0107] <Adjustment of processing solution> Treatment solutions S1 to S6 were prepared by mixing and stirring the following blending ratios. Treatment solution S1: 97.5% by weight of water, 2% by weight of sodium hydroxide, 0.5% by weight of polyoxyethylene stearyl ether (polyoxyethylene addition number: 12) Treatment solution S2: 97.5% by weight of water, 2% by weight of sodium hydroxide, 0.5% by weight of sodium lauryl sulfate Treatment solution S3: 97.5% by weight of water, 2% by weight of sodium hydroxide, 0.5% by weight of polyoxyethylene lauryl ether phosphate (polyoxyethylene addition number: 4) Treatment solution S4: 98% by weight of water, 2% by weight of sodium hydroxide Treatment solution S5: 99.5% by weight of water, 0.5% by weight of polyoxyethylene stearyl ether (polyoxyethylene addition number: 12) Treatment solution S6: 99.5% by weight water, 0.5% by weight sodium hydroxide

[0108] [Example 1] A tank containing 1000 L of treatment liquid S1 and 40 kg of fluff F1 was connected to an IKA MHD2000, and mixed and stirred while circulating at a discharge rate of 30 kg / min. The temperature of treatment liquid S1 in the process was controlled at 50°C. After that, the substrate was separated and recovered from the treatment liquid, and the coloration and melt mass flow rate of the recycled substrate were measured and evaluated.

[0109] [Examples 2 to 20] [Comparative Examples 1 to 3] The recycled substrate was evaluated in the same manner as in Example 1, except that the treatment liquid, fluff, and step (A) were changed to those shown in Table 3. The results are shown in Table 3.

[0110] <Step (A) of removing the coating layer> For step (A) in which the fluff or laminate is mixed and stirred with a treatment liquid using the following method to remove the coating layer, the abbreviations listed in Table 3 are as follows. Among the following PRO1 to PRO8, PRO3 to PRO8 have a step in which the laminate and / or the treatment liquid passes through a clearance of 20 mm or less. In PRO1 and PRO2, the desorption tank does not have a clearance of 20 mm or less through which the treatment liquid and / or the laminate can pass. PRO1: The fluff or laminate and the treatment liquid were placed in a stainless steel tank having a diameter of 1.2 m and a height of 1.4 m, and equipped with a dispersing blade with a diameter of 300 mm at the center. The dispersing blade was rotated at 200 rpm to mix and stir the mixture. PRO2: The fluff or laminate and the treatment liquid were placed in a stainless steel tank with a diameter of 1.2 m and a height of 1.4 m, equipped with a dispersing blade with a diameter of 300 mm in the center, and the dispersing blade was rotated at 1000 rpm to mix and stir the mixture. PRO3: The fluff or laminate and processing liquid were placed in a Nikuni Sancutter C80H (a horizontal shredding device equipped with a cutter mill and a circular screen with a diameter of 10 mm), and the fluff or laminate and processing liquid were mixed and stirred while circulating the processing liquid at a speed of 60 kg / min. PRO4: The fluff or laminate and the treatment liquid were placed in a stainless steel tank with a diameter of 1.2 m and a height of 1.4 m, equipped with an anchor blade with a diameter of 1,180 mm in the center, and the fluff or laminate and the treatment liquid were placed in a stainless steel tank with a diameter of 1.2 m and a height of 1.4 m, and the fluff or laminate and the treatment liquid were mixed and stirred by rotating the disperser blade at 600 rpm. PRO5: A high shear in-line mixer equipped with a Silverson standard round head was connected to a tank containing the fluff or laminate and the treatment liquid, and mixing and stirring were performed while circulating at a discharge rate of 30 kg / min. PRO6: IKA MHD2000 was connected to a tank containing the fluff or laminate and the treatment liquid, and mixing and stirring were performed while circulating at a discharge rate of 30 kg / min. PRO7: Using a wet attritor manufactured by Nippon Coke & Co., the fluff or laminate, the treatment liquid, and zirconia beads having a diameter of 10 mm were mixed and stirred. PRO8: The fluff or laminate and the treatment solution were mixed by rotation at 600 rpm using a planetary mixer manufactured by Inoue Seisakusho.

[0111] (Manufacturing of recycled film and evaluation of coloring of recycled resin) Two hours after the start of stirring, the detached OPP and CPP substrates were collected and extruded at 200°C using a single-screw extruder, and pelletized to obtain pellets of recycled resin. The recycled resin was extruded at 200°C using a T-die film molding machine to produce a recycled film with a thickness of 50 μm. The color value L was measured using a spectrophotometer (X-rite eXact, manufactured by X-rite) for the recycled film. * x , a * x , b * x The OPP substrate before printing was also subjected to a pelletizing process to create a recycled film with a thickness of 50 μm, and the color difference ΔE was calculated using the following formula. (Formula)ΔE=((L * x -L * y ) 2 +(a * x -a * y ) 2 +(b * x -b * y ) 2 ) 1 / 2 The evaluation criteria are as follows: A rating of C or higher is within the usable range. A (Excellent): ΔE is less than 3 B (Good): ΔE is 3 or more and less than 10 C (Acceptable): ΔE is 10 or more and less than 20 D (not allowed): Other than A~C

[0112] (Evaluation of recycled resin properties) The melt mass flow rate (MFR) of the recycled film was measured as a physical property of the recycled film produced above. A mixed film in which the OPP substrate and CPP substrate before printing were mixed in a 1:1 weight ratio was also produced through a pelletizing process in the same way, and the MFR was measured. The MFR of the mixture of OPP and CPP substrates before printing was taken as 100%, and the MFR increase rate of the obtained recycled film was evaluated according to the following criteria. A rating of 0 or higher indicates the usable range. The MFR was measured in accordance with JIS K-7210. A (Excellent): Less than +50% B (Good): +50% or more but less than 100% C (Acceptable): +100% or more but less than 200% D (impossible): +200% or more

[0113] (Examples 1 to 20, Comparative Examples 1 to 3) [Table 3]

[0114] [Example 21] 5 L of treatment liquid S1 and 160 g of fluff F2 were placed in a rotary mixing device equipped with an anchor blade with a diameter of 0.21 m at the center of a cylindrical tank with a diameter of 0.25 m, and step (A) was performed by stirring while heating to 50°C, and the separated and recovered substrate was evaluated in the same manner as in Example 1. The desorption tank was custom-made to have a clearance of 20 mm or less between the tank wall and the anchor wings to allow the passage of the treatment liquid and the laminate.

[0115] [Examples 22 to 32] [Comparative Examples 4 to 10] The evaluation was carried out in the same manner as in Example 21, except that the tank diameter, anchor blade diameter, amount of treated liquid, and amount of fluff were changed to those shown in Table 4. The abbreviations and parameter calculation methods in Table 4 are as follows: R1: diameter of cylindrical tank [m] R2: Anchor blade diameter [m] Δy: clearance [mm] through which the treatment liquid and / or laminate passes in step (A) n: rotation speed [rpm] of the anchor blade Fr: Froude number of stirring in process (A) D: Shear rate in step (A) [S^-1] Δy=(R1-R2) / 2 Fr = {(n / 60) 2}×R2 / g Where, g: gravitational acceleration = 9.8 (m / s 2 ) D=v / Δy v: flow velocity (m / s), calculated as v = π × R2 × (n / 60) where π is the circumference of the

[0116] (Examples 21 to 32, Comparative Examples 4 to 10) [Table 4]

[0117] In Comparative Example 1, the change rate of the fluff area before and after step (A) was 70% or more. The recycled substrate showed noticeable discoloration and its physical properties tended to deteriorate. The above evaluation results show that the recycled substrate manufacturing method of the present invention can produce high-quality molding materials with little coloration and good physical properties.

Claims

1. (A) removing the coating layer from a laminate having at least a plastic substrate and a coating layer by using a liquid medium in a removal tank; and A step (B) of recovering the detached plastic substrate, The step (A) has the following characteristics (1) and (2), The method for producing a recycled plastic substrate, wherein the step (B) has the following feature (3): (1) The desorption tank has a clearance of 20 mm or less to allow the treatment liquid and / or the laminate to pass through. (2) The change in area of ​​the plastic substrate before and after the step (A) is 70% or less. (3) The long side of the collected recycled plastic substrate is 1 mm or more.

2. The method for producing a recycled plastic substrate according to claim 1, wherein the step (A) has the following characteristic (4): method. (4) The desorption tank has a rotating agitator and the Froude number (Fr) during agitation is 2 to 16. Below.

3. The method for producing a recycled plastic substrate according to claim 1, wherein the step (A) has the following characteristic (5): method. (5) The desorption tank has a means for applying a shear force to the laminate, and the shear rate (D) of the shear force is 500 to 200,000 s －１ It is.

4. The method for producing a recycled plastic substrate according to any one of claims 1 to 3, wherein the treatment liquid contains water and a basic compound and has a pH of 10 or higher.

5. The method for producing a recycled plastic substrate according to any one of claims 1 to 3, wherein the treatment liquid contains water and a surfactant.

6. 6. The method for producing a recycled substrate according to claim 5, wherein the surfactant comprises at least one selected from the group consisting of anionic surfactants, nonionic surfactants and amphoteric surfactants.