JP7277659B1 - Manufacturing method for recycled plastic base material - Google Patents

Abstract

An object of the present invention is to separate a plastic substrate from a plastic laminate for packaging material by applying a shearing force high enough not to crush it in a liquid medium, and to separate only the substrate without being affected by bubbles. Thus, it is an object of the present invention to provide a production method for obtaining a high-quality recycled base material while efficiently separating it from ink flakes. A step (A) of detaching a coating layer from a laminate having at least a plastic substrate and a coating layer using a liquid medium in a desorption tank, and recovering the detached plastic substrate. A method for producing a recycled plastic base material, comprising a step (B), wherein the step (A) has the characteristics of (1) and (2), and the step (B) has the characteristics of (3). (1) The desorption tank has a clearance of 20 mm or less through which the processing liquid and/or the laminate can pass. (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 recovered recycled plastic substrate is 1 mm or more. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a method for producing a recycled plastic substrate by recovering a plastic substrate from a laminate containing the plastic substrate.

In recent years, packages, plastic bottles, and other plastic products made from plastic film have been discarded or dumped into the ocean as garbage, causing environmental pollution problems. These plastic products are decomposed in seawater to become submicron-sized fragments (microplastics) and float in seawater. When these microplastics are ingested by marine organisms such as fish, they are concentrated in the bodies of the organisms, and there is concern that they may affect the health of seabirds and humans who consume these marine organisms as food.

Examples of the plastic products include multi-layered food packaging packages using plastic films. In such food packaging packages, polyester base material, nylon base material (NY), polypropylene base material ( PP), polyethylene substrates (PE), etc., are used. These film substrates are printed with printing ink, bonded to other film substrates or hot-melt resin substrates via an adhesive or the like, cut and heat-sealed to form a package. However, such a multi-layered food packaging package has a problem that material recycling cannot be performed as it is because a plurality of incompatible different materials are mixed.

Regarding the material recycling of packaging materials with such a multilayer structure, for example, Patent Documents 1 and 2 disclose that a cleaning agent is brought into contact with a roll-shaped printed material, and the printed layer is rubbed off using a non-abrasive cloth, a brush, or the like. Techniques for removing and regenerating rolls of transparent film have been disclosed.

Further, in Patent Documents 3 and 4, by treating a laminate provided with a release layer containing a polyurethane resin having a predetermined acid value with an alkaline aqueous solution, not only a surface printing structure but also a multilayer structure can be converted into a printed layer. is disclosed.

Patent Literature 5 discloses a technique of removing ink printed on a substrate using a cleaning agent containing a nonionic surfactant and water.

Patent Literature 6 discloses a technique for simplifying the recycling process by crushing a laminated film in a cleaning liquid so that the laminated body is peeled off at the same time as the crushing.

Patent Literature 7 discloses a technique of crushing a laminated film in a washing liquid, peeling the laminated body at the same time as the crushing, and performing the detachment process again.

Japanese Patent Publication No. 2016-509613 Japanese Patent Publication No. 2018-514384 JP 2020-090627 A JP 2021-098294 A International publication 2021-230032 International publication 2021-230033 International publication 2022-190872

However, in Patent Documents 1 and 2, although the printing ink can be removed by rubbing off from the surface of the roll-shaped printed film, it is difficult to remove the printed layer arranged between the layers of the laminated film or to separate the laminated films. Not applicable. In addition, it cannot be used for packaging materials processed and bagged into various sizes and shapes from rolls.

The detachment techniques described in Patent Documents 3 and 4 create a laminate using an ink layer having an acidic group, a primer layer, an adhesive layer, etc. as a detachment layer for peeling the laminate with an alkaline cleaning liquid. There is a problem that the quality of recycled materials cannot be improved unless only packaging materials suitable for such detachment are separated from general packaging materials and then recycled.

In the desorption method described in Patent Document 5, if the processing amount of the laminate with respect to the cleaning liquid is increased in order to improve the processing efficiency, the detachability and the quality of the recycled material deteriorate. Further, in the prior art, when recycling a large amount of packaging materials using olefin base material, which has a low specific gravity and floats in the cleaning liquid, stirring is essential for the purpose of immersing the packaging materials in the cleaning liquid. Surfactants contained in cleaning liquids, surfactants such as antistatic agents contained in films, surfactants in ink and adhesive ingredients, and surfactants contained in the contents of packaging materials, etc. It foams at the air-liquid interface. The presence of bubbles makes it difficult to separate and recover the removed ink or film pieces and reduces the quality of the recycled material. Foaming can be suppressed to some extent by adding anti-foaming agents, alcohol-based or glycol-based solvents, etc. to the cleaning solution, but if the composition of the cleaning solution becomes complicated, it becomes difficult to reuse the cleaning solution, resulting in environmental impact and economic impact. Not the best option from a sexual point of view.

In the detachment method described in Patent Document 6, since the ink is removed and crushed simultaneously in the washing liquid, the detached fine ink pieces and detergent components are buried in the fractured surface of the base material, and the recycled resin is colored and It causes deterioration of mechanical properties.

The desorption method described in Patent Document 7 is intended to improve the coloring of the recycled resin, but the cause of the deterioration of the mechanical properties has not been eliminated.

Therefore, an object of the present invention is to easily peel off a plastic substrate from a general-purpose plastic laminate for packaging materials by applying a shearing force high enough not to crush it in a liquid medium (hereinafter also referred to as a treatment liquid), To provide a manufacturing method for obtaining a high-quality recycled plastic base material by separating only the plastic base material without being affected by bubbles.

The present invention removes components other than the plastic base material from a laminate containing the plastic base material without crushing the plastic base material more than necessary.

That is, the present invention includes a step (A) of desorbing a coating layer from a laminate having at least a plastic substrate and a coating layer using a liquid medium in a desorption tank;
including a step (B) of recovering the detached plastic substrate,
The step (A) relates to a method for producing a recycled plastic base material, wherein the step (A) has the following features (1) to (2), and the step (B) has the following feature (3).
(1) The desorption tank has a clearance of 20 mm or less through which the processing liquid and/or the laminate can pass.
(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 recovered recycled plastic substrate is 1 mm or more.

The present invention also relates to the above-described method for producing a recycled plastic base material, wherein the step (A) has the following characteristics of (4).
(4) The desorption tank has a rotary stirring device, and the stirring Froude number (Fr) during stirring is 2 or more and 16 or less.

The present invention also relates to the above-described method for producing a recycled plastic base material, wherein the step (A) has the following characteristics of (5).
(5) The desorption tank has means for applying a shearing force to the laminate, and the shearing force has a shear rate (D) of 500 to 200,000 s ^-1 .

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

The present invention also relates to the above method for producing a recycled plastic base material, wherein the treatment liquid contains water and a surfactant.

The present invention also relates to the above method for producing a recycled plastic base material, wherein the surfactant contains at least one selected from the group consisting of anionic surfactants, nonionic surfactants and amphoteric surfactants.

According to the present invention, a plastic substrate can be easily peeled off from a general-purpose plastic laminate for packaging materials by applying a shearing force high enough not to crush it in a liquid medium. was able to provide a manufacturing method for obtaining a high-quality recycled plastic base material.

Embodiments of the present invention will be described in detail below, but the description of the embodiments or requirements described below is an example of the embodiments of the present invention, and the present invention does not exceed the gist thereof. Not limited.

The method for producing a recycled plastic base material (hereinafter also referred to as a recycled base material) in the present invention comprises:
including a step (A) of desorbing the coating layer from the laminate having at least the plastic substrate and the coating layer using a liquid medium in the desorption tank;
The step (A) has the following features (1) to (2), and the step (B) has the following feature (3).
(1) including a step of passing the treatment liquid and/or laminate 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) recovered The long side of the recycled plastic base material is 1 mm or more.

In the present invention, "detachment" refers to separation of the laminated coating layer and the plastic substrate (hereinafter also referred to as "substrate"), and any of the following (1) to (4) Any form is acceptable.
(1) The coating layer dissolves in the treatment liquid (2) The coating layer swells with the treatment liquid and peels off (3) The interfacial adhesive strength between the substrate and the coating layer decreases due to penetration of the treatment liquid and the coating layer peels off (4) ) Peeling occurs when a physical shear stress is applied to the coating layer or substrate.

Since the object of the present invention is to obtain a substrate after detachment as a recycled substrate or a recycled substrate, it is preferable to remove as many coating layers and the like as possible from the substrate. Specifically, it is preferable that 50% by mass or more of 100% by mass of the coating layer is desorbed. More preferably 60% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more are desorbed. It is not essential that the coating layer is detached from the interface between the substrate and the coating layer.

<Step (A)>
The step of removing the coating layer from the laminate performed 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. .
The conventional desorption process using a stirring device requires time until desorption, and the desorption process using a device having a passable clearance of 20 mm or less is accompanied by crushing, and preferable recycled plastic substrates cannot be recovered. .

<Processing liquid>
The treatment liquid may be selected appropriately as long as it is a liquid medium that is compatible with, permeates, swells, or dissolves the coating layer. Examples of such a treatment liquid include organic solvents, water, surfactant solutions, basic aqueous solutions, acidic aqueous solutions, etc. The treatment liquid may be heated. In the recycling of 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 preferable in terms of excellent releasability of urethane-based inks and urethane-based adhesives used in the coating layer.

[Basic compound]
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 examples thereof include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), ammonia, barium hydroxide (Ba(OH) ₂ ), Sodium carbonate _{( Na2CO3} ) is preferably used. More preferably, it is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide.
There is no particular limitation on the content of the basic compound in the basic aqueous solution, and it is preferably within a range in which the pH of the treatment liquid is 10 or higher, more preferably 12 or higher, and even more preferably 13 or higher. When the basic aqueous solution has a pH of 10 or higher, sufficient basicity is maintained for desorption of the urethane-based ink and urethane-based adhesive described above.

[Surfactant]
The treatment liquid preferably contains water and a surfactant. A surfactant mainly plays a role of improving the releasability of the coating layer. This is presumably because the action of the surfactant facilitates penetration of the treatment liquid between the layers of the laminate, thereby promoting releasability. In addition, the detached coating layer is made finer and dispersed and stabilized in the treatment liquid by the surfactant, thereby greatly preventing reattachment to the substrate.

The HLB value is an index value related to the affinity of a surfactant for water and oil, and is divided equally by setting the HLB value of a substance having no hydrophilic group to 0 and the HLB value of a substance having only a hydrophilic group to 20. be. The concept of HLB was proposed by William Griffin of the Atlas Powder Company in 1949, and several calculation methods have been proposed.
Formula) HLB = 20 x [(molecular weight of hydrophilic group contained in surfactant)/(molecular weight of surfactant)]
Hydrophilic groups contained in surfactants include, for example, hydroxyl groups and ethyleneoxy groups.

The HLB value of the surfactant in the present invention is preferably 7 or more. When the HLB is 7 or more, excellent deinking properties and reattaching properties are exhibited. The HLB value of the surfactant is preferably 8 or higher, more preferably 10 or higher. The HLB value of the surfactant is preferably 20 or less, more preferably 19 or less, and even more preferably 17 or less. When the HLB value is 20 or less, the defoaming property is excellent, which is preferable.

Types of surfactants include, for example, nonionic, anionic, cationic, and amphoteric surfactants, and suitable types and blending amounts can be appropriately selected and used according to required properties. At least one selected from the group consisting of anionic surfactants, nonionic surfactants and amphoteric surfactants is preferred from the viewpoint of releasability and foamability.
Further, the surfactant has a structure to which an alkylene oxide (hereinafter also referred to as AO) is added, so that deinking property and reattachment property are improved, which is preferable.

(Nonionic surfactant)
Although the nonionic surfactant is not particularly limited, it is preferably an alkylene oxide adduct to which alkylene oxide is added. More preferred are compounds obtained by adding alkylene oxide to alcohols having active hydrogen, compounds obtained by adding alkylene oxide to amines, or compounds obtained by adding alkylene oxide to fatty acids. The addition may be either random addition or block addition. Also, the carbon number of the alkylene oxide is preferably 2 to 4 carbon atoms.
More preferred nonionic surfactants are alcohol-based nonionic surfactants obtained by adding an alkylene oxide having 2 to 4 carbon atoms to an alcohol.

[Alcohol-based nonionic surfactant]
Examples of alcohol-based nonionic surfactants include alkylene oxide adducts of primary or secondary alcohols having a total carbon number of 8 to 24, or alkylene oxide adducts of alkylphenols having a total carbon number of 8 to 12. be done. The primary or secondary alcohol having a total carbon number of 8 to 24 may be either saturated or unsaturated.
Examples of primary or secondary alcohols having a total carbon number of 8 to 24 include lauryl alcohol, stearyl alcohol, oleyl alcohol, dodecyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, and myristyl alcohol.
Examples of the alkylene oxide to be added to the alcohol include ethylene oxide, propylene oxide and butylene oxide, and ethylene oxide is preferably essential. The number of moles of alkylene oxide to be added is preferably 1 to 100 mol, more preferably 2 to 50 mol, per 1 mol of alcohol or alkylphenol. It is preferable that it is in the above range because it is particularly excellent in releasability.

[Fatty acid-based nonionic surfactant]
The structure of the fatty acid-based nonionic surfactant is not particularly limited. Examples include oils and fats composed of esters of higher fatty acids and glycerin, and alkylene oxide adducts of mixtures of the above oils and fats and 2 to 10 polyhydric alcohols. The higher fatty acid having 10 to 24 total carbon atoms may be either saturated or unsaturated.
Examples of the higher fatty acids having 10 to 24 carbon atoms in total include saturated higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid; palmitoleic acid, oleic acid, elaidic acid, linoleic acid, unsaturated higher fatty acids such as linolenic acid, erucic acid and ricinoleic acid; Dihydric to decahydric polyhydric alcohols include ethylene glycol, propylene glycol, glycerin, polyglycerin, sorbitol, sorbitan, sucrose and the like. The type and number of moles of alkylene oxide to be added are the same as those described in the section [Alcoholic Nonionic Surfactant] above.

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

(Anionic surfactant)
The anionic surfactant is preferably a non-soap surfactant, such as a sulfonate anionic surfactant, a sulfate ester anionic surfactant, a carboxylic acid anionic surfactant, a phosphate ester anionic surfactant. active agents.

[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 these. salt of Specific examples include hexanesulfonic acid, octanesulfonic acid, decanesulfonic acid, dodecanesulfonic acid, toluenesulfonic acid, cumenesulfonic acid, octylbenzenesulfonic acid, dodecylbenzenesulfonic acid, dinitrobenzenesulfonic acid, and lauryldodecylphenyl ether disulfone. An acid or the like can be used.

[Sulfuric Acid Ester-Based Anionic Surfactant]
Examples of the above-mentioned sulfate ester-based anionic surfactants include sulfate esters (alkyl ether sulfate esters), alkylene oxide adducts of sulfate esters, and salts thereof. Specific examples include lauryl sulfuric acid, myristyl sulfuric acid, polyoxyethylene lauryl ether sulfuric acid, and the like.

[Carboxylic acid-based anionic surfactant]
Examples of the carboxylic acid-based anionic surfactants include alkylcarboxylic acids, alkylbenzenecarboxylic acids, alkylene oxide adducts of carboxylic acids, and salts thereof. Specific examples include lauric acid, myristic acid, palmitic acid, stearic acid, polyoxyethylene lauryl ether acetic acid, and polyoxyethylene tridecyl ether acetic acid.

[Phosphate Ester Anionic Surfactant]
Examples of the phosphate ester-based anionic surfactants include phosphate esters (alkyl ether phosphate esters), alkylene oxide adducts of phosphate esters, and salts thereof. Specific examples include octyl phosphate, lauryl phosphate, tridecyl phosphate, myristyl phosphate, cetyl phosphate, stearyl phosphate, polyoxyethylene octyl ether phosphate, and polyoxyethylene lauryl ether phosphate. etc. can be used.

The anionic surfactant preferably has an alkyl group of 2 to 24 carbon atoms or an alkenyl group of 2 to 24 carbon atoms, more preferably an alkyl group of 8 to 18 carbon atoms. The alkyl group or alkenyl group may be linear or branched.
When the anionic surfactant is an alkylene oxide adduct, examples of the alkylene oxide include ethylene oxide, propylene oxide and butylene oxide, with ethylene oxide being preferred. The number of moles of alkylene oxide to be added is preferably 1 to 12 mol, more preferably 1 to 8 mol, per 1 mol of alcohol or alkylphenol. It is preferable that it is in the above range because it is particularly excellent in releasability.

Examples of salts constituting the above-mentioned anionic surfactants include metal salts of sodium, potassium, magnesium, calcium and the like. These salts may be used individually by 1 type, and may be used in combination of 2 or more type.
Among them, the anionic surfactant is preferably a sulfonate type or a phosphate type, more preferably an alkyl sulfonate or a polyoxyalkylene alkyl ether sulfonate, from the viewpoint of desorption and reattachment properties. , polyoxyalkylene alkyl ether phosphate, and the like.

(Cationic surfactant)
Examples of cationic surfactants include alkylamine salts and quaternary ammonium salts. Specifically, stearylamine acetate, trimethylyac ammonium chloride, trimethyl tallow ammonium chloride, dimethyldioleyl ammonium chloride, methyloleyl diethanol chloride, tetramethylammonium chloride, laurylpyridinium chloride, laurylpyridinium bromide, laurylpyridinium disulfate, cetylpyridinium bromide. , 4-alkylmercaptopyridine, poly(vinylpyridine)-dodecyl bromide, dodecylbenzyltriethylammonium chloride and the like can be used.

(Amphoteric surfactant)
Examples of amphoteric surfactants include betaine lauryldimethylaminoacetate, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, betaine coconut fatty acid amidopropyldimethylaminoacetate, polyoctylpolyaminoethylglycine, and imidazoline. derivatives.

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% by mass, more preferably in the range of 0.005 to 7% by mass, based on the mass of the treatment liquid. It is preferably 0.03 to 5% by mass, more preferably 0.05 to 3% by mass. A content of 0.001% by mass or more is preferable because it is advantageous for promotion of detachment and prevention of reattachment of the released ink flakes to the substrate, and a content of 10% by mass or less is preferable from the viewpoint of antifoaming properties.

[Antifoaming agent]
In the present invention, it is also preferred that the treatment liquid further contains an antifoaming agent. By using the antifoaming agent in combination with the surfactant described above, good antifoaming properties can be exhibited without deteriorating the detachability and reattachment properties, and foaming due to the surfactant can be suppressed. Antifoaming agents include, for example, silicone compounds and non-silicone compounds.

(Silicone-based compound)
Examples of the silicone compound include emulsion type, self-emulsifying type, oil type, oil compound type, and solvent type.
Emulsion type is a silicone antifoaming agent made into an O / W type emulsion by emulsifying a silicone oil compound with an active agent. Examples include “FC2913” and “SILFOAMSE47” manufactured by Wacker Silicone, and “BYK-015” and “BYK-1640” manufactured by BYK-Chemie Japan.
The self-emulsifying type is a silicone-based antifoaming agent containing 100% active ingredients that becomes an emulsion state by diluting and mixing with water. , "SILFOAM SD670" and "SILFOAM SD850" manufactured by Asahi Kasei Wacker Silicone.
The oil type is a 100% silicone oil defoaming agent that does not contain solvents or additives. AK12500” and “BYK-1770” manufactured by BYK-Chemie Japan.
The oil compound type is a silicone antifoaming agent in which silica particles are blended with silicone oil. "PULPSIL22274VP", BYK-Chemie Japan's "BYK-017" and "BYK-018" are mentioned.
The solvent type is a silicone antifoaming agent obtained by dissolving silicone oil in a solvent. and "BYK-025".

(Non-silicone compound)
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, and amide polymers. mineral oil emulsified type, polysiloxane adduct, fluorine compound, vinyl polymer, acetylene alcohol, acrylic polymer, special vinyl polymer, ethylene glycol, higher alcohol (octyl alcohol, cyclohexanol, etc.).

An antifoaming agent may be used individually by 1 type, and may use 2 or more types together. The content of the antifoaming agent in the treatment liquid is preferably in the range of 0.0001 to 5% by mass, more preferably in the range of 0.001 to 4.5% by mass, based on the mass of the treatment liquid. , more preferably 0.01 to 4% by mass, still more preferably 0.02 to 3.5% by mass, and particularly preferably 0.03 to 3% by mass. When it is 0.0001% by mass or more, the antifoaming property is excellent, and when it is 5% by mass or less, the deinking property and reattachment property are excellent.

The antifoaming agent has good alkali resistance, and when combined with the surfactant, it is difficult to reduce the deinking property and reattachment property. , and non-silicone compounds.

In the method for producing a recycled base material in the present invention, it is preferable not to crush the base material in the treatment liquid. When the base material is crushed in the treatment liquid, the coating layer peels off at the same time as the crushing progresses, and the coating layer that has detached and becomes finer, especially the printing ink layer has detached and becomes finer ink particles on the cross section of the base material. This is because reattachment and burial in the base material due to crushing pressure cause coloring and deterioration of physical properties of the recycled base material. In the method for producing a recycled base material of the present invention, the area change rate of the base material is 70% or less before and after the step (A) of removing the coating layer by mixing and stirring the treatment liquid, which is a liquid medium, and the laminate. It is characterized by When the area change rate is 70% or less, the substrate is not broken in the treatment liquid, reattachment of coating layer components to the cross section is suppressed, and a high-quality recycled substrate can be obtained.

On the other hand, the treatment liquid permeates from the end portion of the laminate, contacts the coating layer and the interface between the coating layer and the base material, and separates the base material and the coating layer. Therefore, in order to proceed with the desorption process efficiently, the laminate is subjected to a minimum amount of cutting or crushing (hereinafter also referred to as crushing) before contact with the treatment liquid, and the interface between the coating layer and the substrate is observed in the cross section. is exposed (hereinafter, the state in which the laminate is crushed from the sheet shape is referred to as "fluff" in this specification).

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. Before and after the desorption step, the size of the fluff does not change much due to heating or desorption treatment.
When desorption is performed in a batch process, there is an upper limit on the long side of the fluff due to restrictions on the desorption tank. The size of the fluff during batch processing is preferably 1 to 50 mm in long side, more preferably 1 to 40 mm, further preferably 1 to 30 mm. Within the above range, the time required for the treatment liquid to permeate the fluff from the end face to the center during batch processing is shortened, and the detachment between the coating layer and the substrate proceeds efficiently. In the case of continuous treatment, the size of the short side may be restricted by the desorption tank, but theoretically there is no upper limit on the long side.
When the long side is not cut or when it is cut into a shape other than a quadrangle, it is measured by applying a quadrangle that the outer periphery touches. If it is a collection of fluff with different long sides, the numerical average value is adopted.
Even if the fluff contains a large number of fluff less than 1 mm, it is removed from the recovered recycled plastic substrate together with detached ink pieces, etc., so the long side of the recovered recycled plastic substrate is uniform. can be measured to

The method of crushing the laminate to create fluff is not particularly limited, and examples include jaw crushers, impact crushers, cutter mills, stamp mills, ring mills, roller mills, jet mills, hammer mills, colloid mills, rotary cutters, and the like. , any known technique for grinding solids or cutting films can be applied. It is preferable that the laminate or the crushing device is cooled in order to prevent the base material or the coating layer from softening due to frictional heat during crushing and the cross section of the laminate from fusing.

Moreover, it is also preferable to perform preliminary cleaning for the purpose of cleaning stains such as contents adhering to the laminate. The pre-washing method is also not particularly limited, and pre-washing can be performed by a known method. It is also common to perform the above-described crushing of the laminate and pre-cleaning at the same time. The pre-cleaning step is a step of removing the contents adhering to the laminate to the extent that the subsequent steps are not affected, and does not include a step of detaching the coating layer from the substrate.

The desorption step (A) in the present invention is characterized by including a step of passing the treatment liquid and/or the laminate through a clearance of 20 mm or less. By passing through a clearance of 20 mm or less, it is possible to apply a high shearing force to the extent that the laminate does not break, for example, the effect of scraping off the coating layer exposed on the substrate surface, or the presence of two or more types of film between the layers. It has the effect of applying a shear stress to the coating layer, and can promote the peeling of the laminate.

Moreover, by having a step of passing through a clearance of 20 mm or less, a high shearing force can be obtained even at a low stirring rotation speed, and foaming at the gas-liquid interface can be suppressed. The bubbles envelop fine fragments of the coating layer that have detached from the base material, and are present at the gas-liquid interface, and adhere to the base material again, making separation difficult. Therefore, due to less foaming in the step (A), coloring of the recycled base material is suppressed, and high mechanical properties are maintained.

As a method of applying high shear with a clearance of 20 mm or less, a distance of 20 mm or less from the tank wall by controlling the size gap between the inner wall of the processing tank for stirring the laminate and/or the processing liquid and the stirring blade to 20 mm or less. Install a baffle plate in the stack, design the laminate and / or processing liquid to pass through a screen with holes of 20 mm or less in diameter, pass between two rolls with a gap of 20 mm or less, laminate using a ball mill, etc. For example, a fixed blade is provided outside the rotary blade like a homogenizer and the gap between the rotary blade and the fixed blade is controlled to 20 mm or less.

Examples of equipment that can provide a clearance of 20 mm or less include IKA MDH2000, Silverson High Shear Inline Mixer, Ystral Conti-TDS, Inoue Seisakusho Planetary Mixer, Nippon Coke Industry Co. Wet Attritor, Nippon Coke Industry Trigonal. , and so on.

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, relative to the mass of the treatment liquid. , more preferably 1.5% by mass or more and 7% by mass or less, still more preferably 2% by mass or more and 6% by mass or less. A content of 0.1% by mass or more is preferable from the viewpoint of treatment efficiency. A content of 10% by mass or less is preferable from the viewpoint of releasability.

The temperature of the treatment liquid when the laminate is immersed is preferably 25 to 120.degree. C., more preferably 30 to 120.degree. C., and particularly preferably 30 to 80.degree. The immersion time in the treatment solution is preferably 1 minute to 12 hours, more preferably 1 minute to 6 hours, still more preferably 1 minute to 3 hours.

In order to promote contact between the treatment liquid and the laminate, the treatment liquid is preferably mixed by convection such as stirring, vibration, or circulation.

In the method for producing a recycled base material of the present invention, the step (A) preferably has a rotary stirring mechanism, and the stirring Froude number (Fr) is 2 or more and less than 20. The agitation Froude number (Fr) is a numerical value representing the ratio of the inertial force of the fluid to the gravity, and is a dimensionless number that does not depend on the amount of the processing liquid or the laminate and the scale of the apparatus. By equalizing the stirring Froude number, the shape of the vortex on the liquid surface becomes similar. Several definitions of the stirring Froude number have been proposed in the literature. In the present invention, the stirring Froude number (Fr) in an apparatus equipped with a rotating stirring mechanism using stirring blades is defined as follows.
Fr={(n/60) ² }×R2/g
n: rotation speed of stirring blade (rpm)
R2: Diameter of stirring blade (m)
g: gravitational acceleration = 9.8 (m/s ² )

When the agitation fluid number is 2 or more, a sufficient laminar flow is provided in the system, the laminate and the treatment liquid come into contact with each other, and a sufficient flow rate can be obtained when passing through the clearance. Predominance. Further, when the agitation fluid number is 20 or less, foaming of the treatment liquid at the gas-liquid interface is suppressed, which is advantageous for separating and recovering the substrate. Therefore, when the agitation Froude number is within the above range, coloring of the recycled base material is reduced, and physical properties are improved, which is preferable. The range of the stirring Froude number is more preferably 3 or more and less than 16.

In the method for producing a recycled base material of the present invention, the shear rate (D) in the step (A) is preferably 500S^-1 or more and 200,000S ^-1 or less. The shear rate (D) in the present invention is defined by the following formula.
D=v/Δy
v; flow velocity (m/s), calculated as v = π x R2 x (n/60) π; circumference ratio R2; stirring blade diameter (m)
Δy; clearance (m), calculated as Δy=(R1-R2)/2 R1: Tank inner wall diameter

The higher the shear rate, the greater the shear force applied to the fluid. A shear rate (D) of 500 S ⁻¹ or more is advantageous for the detachability, and particularly accelerates the progress of detachment. Further, when the shear rate (D) is 200,000 S ⁻¹ or less, the physical properties of the recycled base material tend to be good. The range of shear rate (D) is more preferably 1,000 to 200,000 S ^-1 , still more preferably 10,000 to 200,000 S ^-1 .

After removing the coating layer from the laminate and recovering the base material, the recycled base material can be obtained through the steps of washing and drying the obtained base material. The removal rate of the detachable layer on the surface of the substrate is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more, relative to the area of the coating layer before detachment.
In addition, the obtained recycled base material can be processed into pellets using an extruder or the like and reused as a recycled resin.

<Step (B)>
In step (A), the recycled plastic substrate is detached from the laminate, and in step (B), the recycled plastic substrate and the detached ink pieces are removed to recover the recycled plastic substrate.
As for the removal method, it can be removed by a known difference in specific gravity or a difference in size. Even when the separation is based on the difference in specific gravity, if the long side of the fluff is 1 mm or more, the separation can be performed with little adhesion or contamination. The long side of the obtained recycled plastic base material is also 1 mm or more.

<Laminate>
The laminate used in the present invention includes at least a substrate layer and a coating layer. By detachment of the coating layer in contact with the base material, the base material can be recovered and recycled.

<Coating layer>
The coating layer in the present invention refers to a layer applied to a substrate, and includes "printing ink layer", "adhesive layer", "primer layer", "release layer" and the like. The coating layer may be colorless or colored. The coating layer may be provided in contact with the base material, or may be provided via an inorganic deposition layer or the like in contact with the base material. The coating layer may be in the form of laminating different coating layers. Although the thickness of the coating layer is not particularly limited, 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 still more preferably 1 μm or more and 5 μm or less.

The "printing ink layer" in this application is for the purpose of decoration, imparting aesthetics, content, expiration date, indication of manufacturer or seller, surface protection of packaging material, etc., and is a solid printing layer or transparent printing layer Also includes The printing ink layer can be formed using a conventionally known ink composition, and the forming method is not particularly limited. The printing ink layer may consist of a single layer or multiple layers.

The ink composition used to form the printing 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. You may
Examples of solvents 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-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and n-butanol; glycol ether-based solvents such as ethylene glycol monopropyl ether and propylene glycol monomethyl ether; and known solvents such as water. Two or more kinds can be mixed and used. Examples of binder resins include fibrous materials such as nitrocellulose, cellulose acetate and propionate, chlorinated polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, acrylic, urethane resin, acrylic urethane, and polyamide. , polybutyral-based, cyclized rubber-based, chlorinated rubber-based binders, or a suitable combination of these binders can be used. The method of applying the ink composition to form a printing ink layer is not particularly limited, and includes a gravure coating method, a flexo coating method, a roll coating method, a bar coating method, a die coating method, a curtain coating method, a spin coating method, and an inkjet method. It can be applied by a method such as the following. A printing ink layer can be formed by leaving this as it is, or if necessary, blowing air, heating, drying under reduced pressure, irradiating with ultraviolet rays, or the like.

The "adhesive layer" in the present application is a layer arranged for the purpose of laminating each layer of the substrate layer and/or the coating layer by adhesion, and conventionally known adhesives can be used. It is preferably a cured adhesive containing a polyester polyol and at least one polyisocyanate selected from the group consisting of aliphatic polyisocyanates and araliphatic polyisocyanates. A method for forming the adhesive layer is not limited, and it can be formed using a known method. Examples of methods for forming the adhesive layer include a dry lamination method, a solventless lamination method, and an extrusion lamination method.

The "primer layer" in the present application is a layer provided for the purpose of providing a base effect for the printing ink layer, assisting adhesion between the film and the coating layer, and the like, and is preferably provided in contact with the base material.

The "detachment layer" in the present application may be a layer that facilitates detachment of the coating layer from the substrate by the treatment liquid, preferably a layer containing a water-soluble resin or a compound having an acidic group, more preferably an acidic layer. It is a layer containing a compound having a group. The "release layer" is preferably at least one layer selected from the group consisting of a primer layer, a printing layer and an adhesive layer. That is, at least one layer selected from the group consisting of a primer layer, a printed layer and an adhesive layer is preferably a layer containing a water-soluble resin or a compound having an acidic group (excluding a water-soluble resin). , 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. One of these water-soluble resins or compounds having an acidic group may be used alone, or two or more thereof may be used in combination. By using a laminate containing a detachable layer as a coating layer, the detachability between the substrate and the coating layer is superior, and coloring of the recycled substrate obtained by the method for producing a recycled substrate according to the present invention is suppressed. and good physical properties.

(Water-soluble resin)
As the water-soluble resin, any resin that swells or dissolves in water may be used. The water may be heated to a temperature of about 25-100°C. Such resins can be selected from known resins as long as they do not impair water solubility. polyallylamine resins, water-soluble phenol 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 can be used singly or in combination of two or more. Among them, polyvinyl alcohol (PVA) resin is preferably used from the viewpoint of availability and releasability.

(Compound having an acidic group)
As the compound having an acidic group, a resin having an acidic group or a low-molecular-weight compound having an acidic group may be used. Examples of resins having an acidic group include cellulose resins, urethane resins, polyamide resins, vinyl chloride/vinyl acetate copolymers, ketone resins, polyester resins, and (meth)acrylic resins. Examples of the acidic group include a carboxy group, a phosphoric acid group, a sulfo group, a sulfino group, etc., or an ester or salt thereof.
As the resin having an acidic group, a rosin-modified resin having an acid value such as maleated rosin and fumarated rosin can be used.
In addition, as the resin having an acidic group, a polymerizable monomer having a carboxy group such as itaconic acid, maleic acid, fumaric acid, and cinnamic acid; a polymerizable monomer that is an acid anhydride such as itaconic anhydride and maleic anhydride; Polymerizable monomers having a sulfonic acid group such as styrene; Polymerizable monomers having a sulfonamide group such as vinylbenzenesulfonamide; Polymerizable monomers having an acidic group such as styrene-(meth)acryl Resins, radical copolymers such as styrene-(anhydride) maleic acid resins and terpene-(anhydride) maleic acid resins, and acid-modified polyolefin resins can be used.
These may be used individually by 1 type, and may use 2 or more types together.

A low-molecular-weight compound having an acidic group refers to a compound having no molecular weight distribution and having 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; 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; oxalic acid, Dicarboxylic acids such as 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.
A low-molecular-weight compound having an acidic group can be used in combination with a resin having an acidic group or a known binder resin constituting a known coating layer to form a release layer.

[Urethane resin having an acidic group]
The urethane resin having an acidic group is not particularly limited, and for example, a urethane resin obtained by reacting a polyol having an acidic group with a polyisocyanate, or a urethane resin obtained by reacting a polyol with a polyisocyanate, the hydroxyl groups in the urethane resin are acid-modified. and a resin obtained by acid-modifying the amino group in a urethane urea resin obtained by reacting an isocyanate group in a urethane resin obtained by reacting a polyol and a polyisocyanate with a polyamine.
As the urethane resin having an acidic group, a resin obtained by reacting a polyol containing a hydroxy acid and a polyisocyanate may be used. By using a hydroxy acid as a polyol, an acid value derived from a carboxy group can be imparted to the urethane resin, and the releasability can be improved. Further, when the urethane resin having an acidic group has an isocyanate group, a part of the isocyanate group may be reacted with a polyamine to introduce a urea bond to form a urethane urea.

[Acrylic resin having an acidic group]
The acrylic resin having an acidic group includes, for example, a polymer obtained by polymerizing a monomer containing a (meth)acrylic monomer having an acidic group such as (meth)acrylic acid and maleic acid; a (meth)acrylic monomer having a hydroxyl group or a glycidyl group. After polymerizing a monomer containing, the functional group is modified to introduce a carboxyl group (for example, a maleic anhydride-modified resin);
The acid value of the acrylic resin having acidic groups is preferably 50 mgKOH/g or more, more preferably 100 mgKOH/g or more.

[Rosin modified resin]
A rosin-modified resin is a resin prepared using rosin as one of raw materials. Rosin contains a mixture of resin acids such as abietic acid, parastric acid, isopimaric acid, levopimaric acid, etc. These resin acids contain hydrophilic and chemically active carboxyl groups, some of which have conjugated double bonds. Some are prepared. Therefore, polyhydric alcohols and polybasic acids are combined for condensation polymerization, phenolic condensate resol is added to the benzene ring contained in the rosin skeleton, and dienophile maleic anhydride and maleic acid undergo Diels-Alder reaction. Various rosin-modified resins have been prepared by adding a maleic acid or maleic anhydride skeleton by allowing the Various types of such rosin-modified resins are commercially available, and it is also possible to obtain and use them.

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. In the present invention, any rosin-modified resin may be used, but among these, at least one selected from the group consisting of maleic acid, maleic anhydride, fumaric acid and fumaric anhydride in its structure Those containing a portion to be used are preferably used. A resin that "contains a site derived from at least one selected from the group consisting of maleic acid, maleic anhydride, fumaric acid and fumaric anhydride in its structure" refers to maleic acid and maleic anhydride as part of raw materials. It is prepared using at least one selected from the group consisting of acid, fumaric acid and fumaric anhydride, for example, rosin-modified malein obtained by condensation polymerization of maleic acid or fumaric acid as part of the polybasic acid Acid resins, rosin-modified fumaric acid resins, maleic rosins and fumaric rosins having a structure obtained by adding maleic acid, maleic anhydride, fumaric acid, or fumaric anhydride as a dienophile by Diels-Alder reaction, fumaric rosins, and functional groups contained therein It means a resin or the like obtained by further polymerizing another chemical species using a group.

The acid value of the rosin-modified resin is preferably 10-400 mgKOH/g, more preferably 100-300 mgKOH/g.

<Base material>
Examples of the substrate include film-like or sheet-like plastic substrates generally used for packaging materials, gas barrier substrates such as metal foil, paper, and the like, and may be a laminate in which these are laminated.
Examples of the plastic substrate include films of thermoplastic resins and thermosetting resins, preferably films of thermoplastic resins. Examples of 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 plastics.

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; Nylon 6, nylon 6/ethylene-vinyl alcohol copolymer/nylon 6) and mixtures; Among them, those having mechanical strength and dimensional stability are preferable.
In addition, polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), acid-modified polyethylene, unstretched polypropylene (CPP), acid-modified polypropylene, copolymerized polypropylene, ethylene- Sealant base materials having sealant properties such as vinyl acetate copolymers, ethylene-(meth)acrylic ester copolymers, ethylene-(meth)acrylic acid copolymers, and ionomers are also suitably used.
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 still more preferably 10 μm or more and 50 μm or less.

Gas barrier substrates include, for example, aluminum foil; plastic substrates having an inorganic deposited layer of aluminum, silica, alumina, etc.; plastic substrates having an organic layer, such as polyvinyl alcohol; In the case of aluminum foil, the thickness in the range of 3 to 50 μm is preferable from an economical point of view. Examples of commercial products of plastic substrates having an inorganic deposition layer include "GL FILM" (manufactured by Toppan Printing Co., Ltd.) and IB-FILM (Oita), in which an inorganic deposition layer such as alumina is laminated on a plastic substrate. manufactured by Nippon Printing Co., Ltd.) and the like. In addition, since aluminum and alumina are soluble in a basic aqueous solution, they are dissolved in the later-described desorption step, and it is possible to recycle only the plastic substrate.

From the viewpoint of reuse as a recycled base material, the base material preferably contains a polyolefin resin film such as polyethylene or biaxially oriented polypropylene.

When the substrate is a laminate, the substrates are preferably laminated with an adhesive layer interposed therebetween. The method for forming the adhesive layer is not limited, and it can be formed by a known method using a known adhesive. The base material may contain additives such as an antistatic agent and an anti-ultraviolet agent as necessary, and the surface of the base material may be subjected to corona treatment or low-temperature plasma treatment.

Examples of the laminate structure of the present invention are shown below, but the present invention is not limited thereto. Further, in the configuration described below, the "substrate layer" does not have to be a single layer, and may be a laminate in which a plurality of substrates are laminated. At least one layer selected from the group consisting of the printing ink layer, the primer layer and the adhesive layer may be the release layer.
・Base layer/Printing ink layer ・Base layer/Printing ink layer/Adhesive layer/Base layer ・Base layer/Printing ink layer/Adhesive layer/Metal deposition layer/Base layer/Base layer/Adhesion Agent layer/Base layer/Base layer/Primer layer/Printing ink layer/Base layer/Primer layer/Printing ink layer/Adhesive layer/Base layer

<Method for manufacturing molding material>
A molding material can be produced by melt-kneading the recycled base material recovered by the above-described method for producing a recycled base material. In the melt-kneading process, various additives are added as necessary, mixed with a Henschel mixer, tumbler, disper, etc., then kneader, roll mill, super mixer, Henschel mixer, Sugi mixer, vertical granulator, high speed mixer, fur Mix and disperse using matrix, ball mill, steel mill, sand mill, vibration mill, attritor, batch kneader such as Banbury mixer, twin screw extruder, single screw extruder, rotor type twin screw kneader, etc. point to As a result, a recycled resin, which is a resin composition, is obtained. The shape of the recycled resin is not particularly limited, and may be in the form of pellets, powder, granules, or beads. The melt-kneading step preferably uses a twin-screw extruder. The molding material can additionally 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 polyethylene resin or polypropylene resin and a colorant kneaded can be used. The thermoplastic resin contained in the masterbatch may be used alone or in combination of two or more. The masterbatch contains alkali metal, alkaline earth metal, or zinc metallic soap, hydrotalcite, nonionic surfactant, cationic surfactant, anionic surfactant, amphoteric surfactant, as long as it does not impair the effects of the present invention. Surfactants, antistatic agents, flame retardants such as halogen-based, phosphorus-based or metal oxides, lubricants such as ethylenebisalkylamide, antioxidants, ultraviolet absorbers and fillers may be contained.

<Molded body>
A molded article can be obtained by heat-molding the molding material obtained by the manufacturing method described above. The thermoforming method is not particularly limited, and examples thereof include injection molding, extrusion molding, blow molding, and compression molding.
The molding material produced using the plastic base material recovered by the separation and recovery method of the present invention is of high quality because the printed layer is detached and reattachment of the detached component is suppressed. It can be used in various fields such as products, stationery, parts for automobiles, toys and sporting goods, materials for medical use, and building and construction materials.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these Examples. The compounding ratio, parts and % in the present invention represent the compounding mass ratio, parts by mass and mass% unless otherwise specified.

<Manufacture of primer composition>
[Synthesis Example 1] (Polyurethane resin P1 having an acidic group)
While introducing nitrogen gas in a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet tube, a stirrer, and a thermometer, PPA (consisting of a polycondensate of propylene glycol and adipic acid, having a number average molecular weight of 2, 000 polyester polyol), 135.7 parts of PPG (a polyether polyol having a number average molecular weight of 2,000 consisting of polypropylene glycol), 28.3 parts of DMPA (2,2-dimethylolpropanoic acid), IPDI 105.7 parts of (isophorone diisocyanate) and 200 parts of NPAC (n-propyl acetate) were charged and reacted at 90° C. for 5 hours to obtain a urethane prepolymer solution having terminal isocyanate groups.
Then, a mixture of 16.7 parts of AEA (2-(2-aminoethylamino) ethanol) and 350 parts of IPA (isopropyl alcohol) was added dropwise over 60 minutes at room temperature, followed by reaction at 70° C. for 3 hours. to obtain a polyurethane resin solution.
NPAC was added to the obtained polyurethane resin solution to adjust the solid content to obtain 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 JISK0070 (1992).

[Production Example 1] (Primer Composition AC1)
87 parts of a polyurethane resin P1 solution having an acidic group, 5 parts of EA, 5 parts of IPA, and 3 parts of silica particles (P-73 manufactured by Mizusawa Chemical Co., Ltd.: hydrophilic silica particles having an average particle diameter of 3.8 μm) were stirred and mixed using a disper. Thus, primer composition AC1 was obtained.

<Production of laminate>
A method for manufacturing a laminate will be described below. The printing ink and the primer composition were each prepared using a mixed solvent of EA/IPA (mass ratio: 70/30) so that the viscosity would be 15 seconds (25°C, Zahn cup #3 (manufactured by Rigosha)). was used after diluting to

[Production Example 2-1] (Laminate L1)
Diluted printing ink (INK1) was printed in this order on OPP (corona-treated oriented polypropylene film, thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm, and dried at 50°C. , and a laminate L1 having a structure of OPP/INK.

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

[Production Examples 2-3 to 5] (Laminates L2 to 5)
Laminates L2 to L5 were obtained in the same manner as in Production Examples 2-1 and 2-2, except that the coating layer and substrate were changed to those shown in Table 1.
The printing inks, adhesives and substrates used are as follows.
INK1: Toyo Ink General-Purpose Laminating Ink “LP Bio SX R39 Indigo”
AD1: Ester-based dry laminating adhesive "TOMOFLEX TM250 / isocyanate-based curing agent CAT-RT86" manufactured by Toyo-Morton
(Blending ratio TM250:CAT-RT86=10:1)
OPP: corona-treated oriented polypropylene film, thickness 20 μm
CPP: unstretched polypropylene film thickness 50 μm
VMCPP: aluminum deposition unstretched polypropylene thickness 30 μm

<Crushing the laminate and creating fluff>
[Fluff Production Example 3-1] (Fluff F1)
As a wet crusher, PFS-40 type manufactured by Nippon Seam Co., Ltd. (a vertical shredder equipped with a cutter mill and a circular screen whose diameter is arbitrarily controlled) was used to wet crush the laminate. The laminate L1 was charged from the hopper, and the crushing step was performed while water was introduced from the water inlet. When shredding progresses and the fluff size becomes less than a certain size, it passes through the screen provided at the bottom of the shredding section by its own weight together with water. The long side of the fluff can be adjusted according to 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 10 mm was obtained.

[Fluff Production Examples 3-2 to 3-6, 3-8, 3-9] (Fluff F2 to F6, F8, F9)
Fluff F2 to F6, F8, and F9 were obtained in the same manner as in Fluff Production Example 3-1, except that the laminate and the long side of the fluff, ie, the screen size, were changed to those shown in Table 2.

[Fluff Production Example 3-7] (Fluff F7)
As a dry crusher, Horai FG-2060 (equipped with a cutter mill and a circular screen with a diameter of 2 mm) was used to dry crush the laminate. The laminate L2 was put into the hopper and crushed to obtain a fluff F7 having a long side of 2 mm.

<Adjustment of treatment liquid>
Treatment liquids S1 to S6 were prepared by mixing and stirring at the following compounding ratios.
Treatment liquid 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 liquid S2: 97.5% by weight of water, 2% by weight of sodium hydroxide, 0.5% by weight of sodium lauryl sulfate
Treatment liquid 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 liquid S4: 98% by weight of water, 2% by weight of sodium hydroxide
Treatment liquid S5: 99.5% by weight of water, 0.5% by weight of polyoxyethylene stearyl ether (polyoxyethylene addition number: 12)
Treatment liquid S6: 99.5% by weight of water, 0.5% by weight of sodium hydroxide

[Example 1]
A tank containing 1000 L of treatment liquid S1 and 40 kg of fluff F1 was connected to MHD2000 manufactured by IKA, and mixed and stirred while being circulated at a discharge rate of 30 kg/min. The temperature of the treatment liquid S1 in the process was controlled at 50.degree. Thereafter, the base material was separated and recovered from the treatment liquid, and the coloration and melt mass flow rate of the recycled base material were measured and evaluated.

[Examples 2 to 20] [Comparative Examples 1 to 3]
The recycled base material 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. Table 3 shows the results.

<Step (A) of removing the coating layer>
The abbreviations in Table 3 are as follows for the step (A) of mixing and stirring the fluff or laminate with the treatment liquid using the following method to remove the coating layer.
Of the following PRO1 to PRO8, PRO3 to PRO8 have a step in which the laminate and/or the treatment liquid pass 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 processing liquid and/or laminate can pass.
PRO1: A stainless steel tank with a diameter of 1.2 m and a height of 1.4 m, equipped with a disper blade with a diameter of 300 mm in the center, is filled with a fluff or laminate and a treatment liquid, and mixed and stirred by rotating the disper blade at 200 rpm. did
PRO2: A stainless steel tank with a diameter of 1.2 m and a height of 1.4 m, equipped with a disper blade with a diameter of 300 mm in the center, is filled with a fluff or laminate and a treatment liquid, and mixed and stirred by rotating the disper blade at 1000 rpm. did
PRO3: Nikuni Sancutta C80H (a horizontal shredding device equipped with a cutter mill and a circular screen with a diameter of 10 mm) is filled with the fluff or laminate and the processing solution, and the processing solution is mixed and stirred while circulating at a rate of 60 kg/min. gone.
PRO4: Put the fluff or laminate and the treatment liquid into 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 1180 mm in the center, and mix and stir by rotating the disper blade at 600 rpm. did
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 was performed while circulating at a discharge rate of 30 kg/min.
PRO6: MHD2000 manufactured by IKA Co., Ltd. was connected to a tank containing the fluff or laminate and the treatment liquid, and mixing and stirring was performed while circulating at a discharge rate of 30 kg/min.
PRO7: Using a wet attritor manufactured by Nippon Coke Kogyo Co., Ltd., the fluff or laminate, the treatment liquid, and zirconia beads with a diameter of 10 mm were mixed and stirred.
PRO8: Using an Inoue Seisakusho planetary mixer, the fluff or laminate and the treatment liquid were rotationally stirred at 600 rpm.

(Production of recycled film and evaluation of recycled resin coloring)
After 2 hours from the start of stirring, the detached OPP base material and CPP base material were recovered, extruded at 200° C. with a single screw extruder, and pelletized to obtain recycled resin pellets. The recycled resin was extruded at 200° C. using a T-die film molding machine to produce a recycled film having a thickness of 50 μm.
Color values L ^* _x , a ^* _x , and b ^* _x of the recycled film were measured with a spectrophotometer (X-rite eXact, manufactured by X-rite). The OPP base material before printing was similarly subjected to the pelletizing process to prepare a recycled film having a thickness of 50 μm, and the color difference ΔE was obtained by the following formula.
(Formula) ΔE=((L ^* _x −L ^* _y ) ² +(a ^* _x −a ^* _y ) ² +(b ^* _x −b ^* _y ) ² ) ^1/2
Evaluation criteria are as follows. Evaluation C or higher is 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 (improper): other than A to C

(Recycled resin physical property evaluation)
The melt mass flow rate (MFR) of the recycled film was measured as a physical property value of the recycled film prepared above. A mixed film obtained by mixing the OPP base material and the CPP base material before printing at a weight ratio of 1:1 was similarly subjected to the pelletizing process to prepare a recycled film, and the MFR was measured.
Taking the MFR of the mixture of the OPP base material and the CPP base material before printing as 100%, the MFR increase rate of the obtained recycled film was evaluated according to the following criteria. Evaluation or higher is the usable range. The MFR was measured according to JIS K-7210.
A (excellent): less than +50% B (good): +50% or more and less than 100% C (acceptable): +100% or more and less than 200% D (improper): +200% or more

(Examples 1 to 20, Comparative Examples 1 to 3)

[Example 21]
At the center of a cylindrical tank with a diameter of 0.25 m, 5 L of treatment liquid S1 and 160 g of fluff F2 were charged into a rotary stirring device equipped with an anchor blade with a diameter of 0.21 m, and stirred while being heated to 50°C. By doing so, the step (A) was performed, and the separated and collected base material 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 process liquid and laminate to pass through.

[Examples 22-32] [Comparative Examples 4-10]
Evaluation was carried out in the same manner as in Example 21, except that the tank diameter, anchor blade diameter, treatment liquid amount, and fluff amount were changed to those shown in Table 4.
The abbreviations and parameter calculation methods shown in Table 4 are as follows.
R1: Diameter of cylindrical tank [m]
R2: Anchor wing diameter [m]
Δy: Clearance [mm] through which the treatment liquid and/or laminate passes in step (A)
n: Anchor blade rotation speed [rpm]
Fr: Stirring Froude number in step (A) D: Shear rate in step (A) [S^-1]

Δy=(R1−R2)/2
Fr={(n/60) ² }×R2/g
However, g: gravitational acceleration = 9.8 (m/s ² )
D=v/Δy
v; flow velocity (m/s), calculated as v = π x R2 x (n/60) where π: circular constant

(Examples 21-32, Comparative Examples 4-10)

In Comparative Example 1, the fluff area change rate before and after the step (A) was 70% or more,
The recycled base material exhibited marked coloration and tended to deteriorate in physical properties.
From the above evaluation results, it was shown that a high-quality molding material with little coloration and good physical properties can be obtained with the method for producing a recycled base material of the present invention.

Claims (6)

a step (A) of desorbing the coating layer from the laminate having at least the plastic substrate and the coating layer using a liquid medium in the desorption tank;
including a step (B) of recovering the detached plastic substrate,
A method for producing a recycled plastic base material, wherein the step (A) has the following features (1), (2) and (4), and the step (B) has the following feature (3).
(1) The desorption tank has a clearance of 20 mm or less through which the processing liquid and/or the laminate can pass.
(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 recovered recycled plastic substrate is 1 mm or more.
(4) The desorption tank has a rotary stirring device, and the stirring Froude number (Fr) during stirring is 2 or more and 16 or less. 2. The method for producing a recycled plastic base material according to claim 1, wherein step (A) has the following characteristics of (5).
(5) The desorption tank has means for applying a shearing force to the laminate, and the shearing force has a shear rate (D) of 500 to 200,000 s ^-1 . 3. The method for producing a recycled plastic substrate according to claim 1, wherein the treatment liquid contains water and a basic compound and has a pH of 10 or more. 3. The method for producing a recycled plastic substrate according to claim 1 , wherein the treatment liquid contains water and a surfactant. 4. The method for producing a recycled plastic substrate according to claim 3, wherein the treatment liquid contains water and a surfactant. 5. The method for producing a recycled base material according to claim 4, wherein the surfactant contains at least one selected from the group consisting of anionic surfactants, nonionic surfactants and amphoteric surfactants.