JP7196900B2 - Polyester film recovery method, recovery device and functional layer remover - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyester film recovery method, a recycled polyester product, a polyester film recovery device, and a polyester film functional layer removing agent.

Conventionally, waste plastics have been disposed of by landfill, ocean dumping, incineration, etc., but it is becoming difficult to secure a landfill site, and ocean dumping is becoming an environmental problem because plastics do not decompose. In addition, although it can be used as heat by incineration, there is a problem that it leads to global warming due to the emission of carbon dioxide gas.

Therefore, due to the recent heightening of environmental problems, there is a need for recycling such as reuse and regeneration of waste plastics, and research and development for this purpose are being actively carried out. In addition, most plastics are produced using fossil fuels, and from the point of view of effective use of resources, construction of a recycling method is required.

By the way, a polyester film, which is a type of plastic film, is useful as a base film and is often used as a laminated film in which various functional layers are laminated on one side or both sides. There are various functional layers such as hard coat layer, adhesive layer, decorative layer, light shielding layer, polarizing layer, and UV shielding layer. is used.

Such laminated films are hardly reused after use, and are discarded, incinerated, or the like.

Even if you attempt to re-melt and recycle the laminated film with the functional layer laminated as it is, the materials that make up the functional layer will be mixed into the molten polymer, causing an offensive odor during extrusion and a decrease in the melt viscosity of the polymer. As a result, it causes breakage during film formation.
In addition, even if the film can be formed, it is inevitable that the resulting film will be colored and the quality will be deteriorated due to contamination with foreign matter.

In addition, even if the functional layer is removed physically by scraping it off and then melted and extruded, the remaining functional layer clogs the filter during the filtration process during extrusion, making normal film formation impossible. problem arises.

As a method for recycling laminated films, for example, there is a technique disclosed in Patent Document 1. This technique is a laminated film formed by laminating a readily soluble resin layer and a surface functional layer in this order on at least one side of a substrate film. With such a structure, after use, the substrate film is separated and recovered from the laminated film by washing with a solvent that can dissolve only the easily soluble resin layer but does not dissolve the substrate film. be. The separated and collected material is remelted, making it possible to regenerate the resin composition constituting the base film.

Japanese Patent Application Laid-Open No. 2004-169005

As described above, the method disclosed in Patent Document 1 is based on the premise of a laminated film in which a readily soluble resin layer and a surface functional layer are laminated in this order on the surface of a base film. is intended to remove the functional layer by dissolving the
That is, it cannot be used for most laminated polyester films that do not have a readily soluble resin layer, and it is a technique without versatility.
In view of the above circumstances, it is an object of the present invention to propose a polyester film recovery method capable of peeling off the functional layer and recovering the base film even in the case of a laminated polyester film that does not have a readily soluble resin layer. do.

As a result of extensive studies, the present inventors have found that the functional layer can be removed by using a cleaning agent containing an alcohol having an acidity constant (pKa) of 8.0 or more and 20.0 or less. It was found that the base polyester film can be efficiently recovered. The present invention has been completed based on such findings. That is, the present invention has the following aspects.
(1) A laminated polyester film having a functional layer on the surface of the polyester film is washed with a detergent containing an alcohol having an acidity constant (pKa) of 8.0 or more and 20.0 or less to remove the functional layer. A method for recovering a polyester film comprising a functional layer removing step (A) and a recovering step (B) for recovering the polyester film from which the functional layer has been removed.
(2) The method for recovering a polyester film according to (1) above, wherein the cleaning agent is a water-based cleaning agent.
(3) The method for recovering a polyester film according to (1) or (2) above, wherein the cleaning agent further contains an alkalinizing agent.
(4) The method for recovering a polyester film according to (3) above, wherein the alkalinizing agent contains an alkali metal hydroxide.
(5) The method for recovering a polyester film according to (4) above, wherein the alkali metal hydroxide contains potassium hydroxide.
(6) The polyester film recovery method according to any one of (1) to (5) above, wherein two or more of the alcohols are used in combination.
(7) The method for recovering a polyester film according to (6) above, wherein the acidity constant (pKa) of at least one of the alcohols is 9.0 or more and 10.0 or less.
(8) The polyester film recovery method according to any one of (1) to (7) above, wherein the temperature of the cleaning agent in the functional layer removing step (A) is 20° C. or higher.
(9) A recycled polyester product containing, as a raw material, at least a part of the polyester film recovered by the recovering method according to any one of (1) to (8) above.
(10) A polyester film recovery apparatus having a washing device, in which a laminated polyester film having a functional layer on the surface of the polyester film is washed with an acidity constant (pKa) of 8.0 or more and 20.0 or less. A recovery apparatus for a polyester film, which recovers a polyester film from which a functional layer has been removed by cleaning with a cleaning agent containing an alcohol.
(11) The apparatus for recovering a polyester film according to (10) above, further comprising a rinsing device for washing off the cleaning agent adhering to the polyester film from which the functional layer has been removed.
(12) The polyester film recovery apparatus according to (11) above, wherein the cleaning agent is a water-based cleaning agent, and the water-based cleaning agent is washed away with water in the rinsing device.
(13) The apparatus for recovering a polyester film according to any one of (10) to (12) above, comprising a drying device for drying the polyester film from which the functional layer has been removed.
(14) The polyester film collecting apparatus according to any one of (10) to (13) above, which has an unwinding device in the preceding stage of the washing device.
(15) The apparatus for recovering the polyester film according to (14) above, which is recovered by a roll-to-roll system.
(16) The polyester film recovery apparatus according to any one of (10) to (13) above, further comprising a cutting device in a stage preceding the cleaning device.
(17) A remover for removing a functional layer from a laminated polyester film having a functional layer on the surface of the polyester film, and an alcohol having an acidity constant (pKa) of 8.0 or more and 20.0 or less. Functional layer remover for polyester film containing.
(18) The functional layer removing agent for a polyester film as described in (17) above, wherein the removing agent is a water-based removing agent.
(19) The functional layer removing agent for a polyester film as described in (17) or (18) above, which further contains an alkalinizing agent.
(20) The functional layer removing agent for a polyester film as described in (19) above, wherein the alkaline agent contains an alkali metal hydroxide.
(21) The functional layer removing agent for polyester film as described in (20) above, wherein the alkali metal hydroxide contains potassium hydroxide.
(22) The functional layer removing agent for polyester film as described in any one of (17) to (21) above, wherein two or more of the alcohols are used in combination.
(23) The functional layer removing agent for a polyester film as described in (22) above, wherein the acidity constant (pKa) of at least one of the alcohols is 9.0 or more and 10.0 or less.

According to the recovery method of the present invention, the functional layer can be easily removed from the laminated polyester film having the functional layer, and the base film (polyester film) can be efficiently recovered.

[Method for collecting laminated polyester film]
A method for recovering a laminated polyester film of the present invention comprises washing a laminated polyester film having a functional layer on the surface of the polyester film with a cleaning agent containing an alcohol having an acidity constant (pKa) of 8.0 or more and 20.0 or less. and a functional layer removing step (A) for removing the functional layer, and a recovering step (B) for recovering the polyester film from which the functional layer has been removed.
Here, in the functional layer removing step (A), it is important to use an alcohol having an acidity constant (pKa) of 8.0 or more and 20.0 or less, so that the functional layer on the polyester film can be effectively removed.

The mechanism by which the functional layer can be effectively removed by using the above-mentioned alcohols is not clear, but is presumed as follows.

When a functional layer that undergoes hydrolysis, such as a laminated film having an acrylic adhesive layer or an acrylic hard coat layer, is washed, an alkoxide generated from the hydroxyl group of an alcohol causes transesterification at the functional layer and/or the ester bond of the base material. It is presumed that the functional layer laminated on the film can be peeled off and removed due to the occurrence of reaction, reduction in molecular weight, saponification, and elution due to the transesterification reaction.
Alcohols with an acidity constant (pKa) of 8.0 or more and 20.0 or less are thought to efficiently generate the alkoxide, thereby facilitating the separation of the functional layer.

<Laminated polyester film>
The laminated polyester film in the present invention means a film in which a functional layer such as a resin layer is laminated on the surface of a polyester film which is a base film.
The polyester film may have a single layer structure or a multilayer structure. In the case of a multilayer structure, it may be a two-layer structure, a three-layer structure, or a multilayer structure of four or more layers, and the number of layers is not particularly limited. Moreover, the polyester film may be a stretched film such as a biaxially stretched film or an unstretched film.

The polyester constituting the polyester film is not particularly limited, and those commercially available can be appropriately used. Specific examples thereof include polyesters obtained by polycondensation of dicarboxylic acids and diols. Dicarboxylic acids are preferably aromatic dicarboxylic acids, and diols are preferably aliphatic glycols.
Examples of the aromatic dicarboxylic acid include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, and phthalic acid. Examples of the aliphatic glycol include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like.
The polyester may be a homopolyester or a copolyester. Moreover, the polyester may contain a third component other than the aromatic dicarboxylic acid and the glycol as a copolymer component.

Specific examples of polyester include polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polybutylene-2,6-naphthalate, etc. Among these, polyethylene terephthalate is preferred. These may also be copolymer polyesters. For example, polyethylene terephthalate has dicarboxylic acid units other than terephthalic acid at about 30 mol % or less of the dicarboxylic acid units, and 30 mol % of the diol units. It may have diol units other than ethylene glycol to some extent.

The constituents of the functional layer are not particularly limited, but from the viewpoint of removal by the recovery method of the present invention, the functional layer is preferably made of a resin. Functional layers include, for example, a hard coat layer, an adhesive layer, a release layer, a decorative layer, a light shielding layer, an ultraviolet shielding layer, an easy adhesion layer (primer layer), an antistatic layer, a refractive index adjusting layer, an oligomer sealing layer, stopping layer, and the like.

The hard coat layer is a layer provided to impart abrasion resistance and the like to the polyester film, and the material forming the hard coat layer is not particularly limited, but examples include monofunctional (meth)acrylates, polyfunctional ( Examples include cured products of reactive silicon compounds such as meth)acrylates and tetraethoxysilane.

The adhesive layer is a layer provided for adhesion to other devices or the like, and the material constituting the adhesive layer is not particularly limited, but for example, known acrylic, rubber, silicone A tackifying resin such as a system can be used.

The release layer is a layer provided to impart releasability to the polyester film. For example, it is used in the production of flat panel displays such as green sheet forming process paper, polarizing plates, and optical filters used in the production of ceramic electronic components. It is a layer that is provided on a release film that is used as an adhesive separator for optical members that are sometimes used. The material constituting the release layer is not particularly limited. For example, a material containing a curable silicone resin as a main component, a modified silicone resin obtained by graft polymerization with a urethane resin, an epoxy resin, or the like, a long-chain alkyl group, etc. Containing compounds, fluorine compounds, hydrocarbon waxes and the like can be mentioned.

The decorative layer is a layer provided for imparting design properties, and the material constituting the decorative layer is not particularly limited, but examples thereof include polyurethane-based resins, vinyl-based resins, polyamide-based resins, and polyester-based resins. , acrylic resins, polyvinyl acetal resins, and the like. Pigments and dyes are added to these resins for decoration.

The light-shielding layer or ultraviolet light-shielding layer is a layer provided to protect the contents from ultraviolet rays, visible light, etc., and the material constituting the light-shielding layer or ultraviolet light-shielding layer is not particularly limited, but for example, a decorative layer , inorganic fillers such as calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth and barium sulfate, organic fillers such as wood powder, pulp powder and cellulose powder.

The easy-adhesion layer (primer layer) is a layer provided for adhering other layers or films onto the polyester film, and is not particularly limited, but may be polyurethane-based resin, vinyl-based resin, polyamide-based resin, polyester-based resin, Examples include acrylic resins, polyvinyl acetal resins, various cross-linking agents, and particles.

The antistatic layer is a layer provided to prevent electrification caused by contact with or peeling off from other materials. The antistatic agent used in the antistatic layer is not particularly limited, but nonionic, cationic, anionic, amphoteric surfactants, polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene), poly( 4-styrene sulfonate), conductive polymers such as SnO ₂ (Sb-doped), In ₂ O ₃ (Sn-doped), metal oxide fillers such as ZnO (Al-doped), graphene, carbon black, carbon nanotubes ( CNT) and other carbon compounds. These may be used alone or in combination of two or more. Also, the antistatic layer may be formed from a resin composition containing an antistatic agent. Examples of resins contained in the resin composition include polyester resins, acrylic resins, and urethane resins.

The refractive index adjusting layer is a layer provided for adjusting the refractive index, and the material constituting the refractive index adjusting layer is not particularly limited, but polyester resin, acrylic resin, urethane resin, polycarbonate resin, epoxy resin, Examples include alkyd resins, urea resins, fluorine resins, and metal oxides such as zirconium oxide and titanium oxide. These may be used alone or in combination of two or more.

The oligomer sealing layer is a layer provided to prevent film whitening and foreign matter prevention after a heating process, and is not particularly limited. Examples of materials constituting the oligomer sealing layer include amine compounds and ionic resins. mentioned. Also, the oligomer sealing layer may be a highly crosslinked coating film or the like.

The oligomer sealing layer is a layer provided to prevent film whitening and foreign substances after the heating process, and is not particularly limited, but examples thereof include amine compounds, ionic resins, highly crosslinked coating films, and the like.

A single layer may be sufficient as these functional layers, and two or more types of layers may be laminated|stacked.
When two or more layers are laminated, at least one layer is preferably a layer made of resin.

<Cleaning agent>
In the method of the present invention, in the functional layer removing step (A), cleaning is performed with a cleaning agent containing an alcohol having an acidity constant (pKa) of 8.0 or more and 20.0 or less.
When the acidity constant (pKa) of the alcohol is within the above range, the alkoxide is generated without impairing the liquid properties of the cleaning agent, thereby improving the cleaning ability of the cleaning agent. From the viewpoint of detergency, the acidity constant (pKa) of the alcohol is more preferably 8.0 or more and 18.0 or less, more preferably 9.0 or more and 16.0 or less, and 9.0 or more and 15.6. The following ranges are particularly preferred, and 9.3 or more and 15.4 or less are most preferred.

(alcohol)
Examples of alcohols having an acidity constant (pKa) of 8.0 or more and 20.0 or less include hexafluoro-2-propanol (pKa = 9.3), benzyl alcohol (pKa = 15.4), methanol (pKa = 15.5), ethanol (pKa = 16.0), 1-propanol (pKa = 16.1), 2-propanol (pKa = 17.1), 1-butanol (pKa = 16.1), tert-butanol (pKa=18.0) and the like.
Of these, hexafluoro-2-propanol, methyl alcohol, ethyl alcohol, propyl alcohol and benzyl alcohol, which have a suitable acidity constant (pKa), are more preferred. Among them, hexafluoro-2-propanol, which has high detergency, is particularly preferable.

The above alcohols may be used singly or in combination of two or more. In particular, from the viewpoint of enhancing the peeling and cleaning effect, it is preferable to use two or more in combination.
When two or more alcohols are used in combination, it is preferable that at least one alcohol having an acidity constant (pKa) of 9.0 or more and 10.0 or less is included from the viewpoint of adjusting the cleaning ability. Combinations of hexafluoro-2-propanol (pKa=9.3) and methyl alcohol, hexafluoro-2-propanol and ethyl alcohol, and hexafluoro-2-propanol and benzyl alcohol are preferred. Among them, combined use of hexafluoro-2-propanol and benzyl alcohol is particularly preferable from the viewpoint of low volatility and usable temperature range.

When two or more of the above alcohols are used in combination, the blending ratio is, from the viewpoint of particularly enhancing the peeling and cleaning effect, an alcohol having an acidity constant (pKa) of 9.0 or more and 10.0 or less: other suitable alcohols is preferably 1:1 to 1:100, more preferably 1:3 to 1:41, even more preferably 1:4 to 1:20, and 1:5 to A ratio of 1:10 is particularly preferred.
In addition, phenols other than the above or alcohols other than the above-mentioned suitable alcohols may be used in combination, and specific examples include the following.

Phenols include phenol, xylenol, salicylic acid, picric acid, naphthol, catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, dibutylhydroxytoluene, bisphenol A, cresol, estradil, eugenol, gallic acid, guaiacol, phenolphthalein. , serotonin, dopamine, adrenaline, noradrenaline, thymol, tyrosine, hexahydroxybenzene and the like.

Examples of alcohols other than the above preferred alcohols include monovalent alcohols such as ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether and propylene glycol monoethyl ether; dihydric alcohols such as ethylene glycol, diethylene glycol and propylene glycol; glycerin. and polyhydric alcohols such as

The content of alcohols and phenols (hereinafter also individually or collectively referred to as "component (a)") in the detergent is preferably 10 to 99% by mass, more preferably 20 to 98% by mass, and 30 to 97% by mass. % by mass is more preferred. Within the above range, the quality of the recycled polyester film can be maintained.
The content of alcohols having an acidity constant (pKa) of 8.0 or more and 20.0 or less in component (a) is preferably 50 to 100% by mass, more preferably 60 to 100% by mass. and more preferably 70 to 100% by mass.

The cleaning agent according to the present invention preferably contains an alkalinizing agent.
(Alkalizing agent)
The alkalinizing agent (hereinafter also referred to as "(b) component") makes the cleaning solution alkaline, and can also be called an alkaline agent. The alkalizing agent may be an inorganic alkalizing agent or an organic alkalizing agent.

Examples of inorganic alkalinizing agents include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide; Alkali metal carbonates such as sodium and potassium carbonate; Alkali metal phosphates such as trisodium phosphate, sodium pyrophosphate, sodium tripolyphosphate, sodium tetrapolyphosphate, tripotassium phosphate, potassium pyrophosphate and potassium tripolyphosphate alkali metal silicates such as sodium orthosilicate, sodium metasilicate and potassium silicate; and ammonia.

Of the inorganic alkalinizing agents in the cleaning agent, alkali metal hydroxides are preferred, sodium hydroxide and potassium hydroxide are more preferred from the standpoint of availability, and potassium hydroxide is particularly preferred from the standpoint of detergency.

As the inorganic alkalinizing agent in the cleaning agent, one kind can be used alone or two or more kinds can be used in combination. In particular, it is preferable to use potassium hydroxide and sodium hydroxide in combination from the viewpoint of effect and handling.

Examples of organic alkalinizing agents include N,N-bis(2-hydroxyethyl)-N-cyclohexylamine, diazabicycloundecene, diazabicyclononene, monomethylamine, dimethylamine, trimethylamine, monoethanolamine, diethanolamine, tri Examples include organic amine compounds such as ethanolamine, morpholine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 1-amino-2-propanol, triisopropanolamine, and the like.

Of the organic alkalinizing agents in the cleaning agent, monoethanolamine, diethanolamine and triethanolamine are preferred from the viewpoint of versatility, monoethanolamine and diethanolamine are more preferred from the viewpoint of availability, and monoethanolamine is particularly preferred from the viewpoint of detergency.

Furthermore, it is also preferable to use an inorganic alkalinizing agent together with an organic alkalinizing agent from the viewpoint of cleanability. Specifically, at least one inorganic alkalinizing agent selected from sodium hydroxide and potassium hydroxide and monoethanolamine , diethanolamine, triethanolamine, morpholine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 1-amino-2-propanol, triisopropanolamine. More preferably, a combination of at least one inorganic alkalinizing agent selected from sodium hydroxide and potassium hydroxide and at least one organic alkalinizing agent selected from monoethanolamine and diethanolamine is particularly preferred.

The content of the alkalinizing agent in the entire cleaning agent is preferably 1 to 50% by mass, more preferably 2 to 45% by mass, and even more preferably 3 to 40% by mass. Within the above range, a sufficient effect as a cleaning agent can be obtained.

The cleaning agent according to the present invention is preferably a water-based cleaning agent. The water-based detergent is prepared by dissolving and diluting the components (a) and/or (b) in water. Aqueous detergents are relatively safe because they can raise the flash point, and are advantageous in that water can be used in the rinse step described later.

In addition to the components (a) and/or (b) described above, the cleaning agent according to the present invention may contain various additives such as surfactants, antioxidants, rust inhibitors, and pH adjusters. , preservatives, viscosity modifiers, antifoaming agents and the like can be added.

(Surfactant)
A surfactant is a component that solubilizes the components (a) and/or (b) and other optional additives, and typical examples thereof include the compounds described below.

The surfactant is not particularly limited, and any of anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants can be used.

Examples of anionic surfactants include alkylsulfonic acids, alkylbenzenesulfonic acids, alkylcarboxylic acids, alkylnaphthalenesulfonic acids, α-olefinsulfonic acids, dialkylsulfosuccinic acids, α-sulfonated fatty acids, N-methyl-N-oleyl taurine, Petroleum sulfonic acid, alkyl sulfuric acid, sulfated oil, polyoxyethylene alkyl ether sulfuric acid, polyoxyethylene styrenated phenyl ether sulfuric acid, alkyl phosphoric acid, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl phenyl ether phosphate, naphthalene sulfone acid-formaldehyde condensates, salts thereof, and the like;

Cationic surfactants include quaternary ammonium, tetraalkylammonium, trialkylbenzylammonium, alkylpyridinium, 2-alkyl-1-alkyl-1-hydroxyethylimidazolinium, N,N-dialkylmorpholinium, polyethylene Polyamine fatty acid amide, urea condensate of polyethylene polyamine fatty acid amide, quaternary ammonium of urea condensate of polyethylene polyamine fatty acid amide, salts thereof and the like.

Nonionic surfactants include polyoxyalkylene ethers such as polyoxyethylene alkyl ether, polyoxyethylene-polyoxypropylene alkyl ether; polyoxyethylene alkylphenyl ether, polyoxyethylene polystyrylphenyl ether, polyoxyethylene-poly Oxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, polyoxyethylenated castor oil, fatty acid diethanolamide, polyoxyethylene alkylamine, tri Examples include ethanolamine fatty acid partial esters, trialkylamine oxides, and the like.

Amphoteric surfactants include N,N-dimethyl-N-alkyl-N-carboxymethylammonium betaine, N,N,N-trialkyl-N-sulfoalkylene ammonium betaine, N,N-dialkyl-N,N- Examples include betaines such as bispolyoxyethylene ammonium sulfate betaine and 2-alkyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine, and aminocarboxylic acids such as N,N-dialkylaminoalkylene carboxylates.

(Antioxidant)
The antioxidant is not particularly limited, and amine-based antioxidants, phenol-based antioxidants, and the like can be used.

(anti-rust)
Rust inhibitors include inorganic compounds such as chromates, molybdates, and sodium nitrite.

(pH adjuster)
Examples of pH adjusters include lactic acid, carbon dioxide, succinic acid, gluconic acid, citric acid, trisodium citrate, malic acid, phosphoric acid, and the like.

(Preservative)
Examples of preservatives include parabens, benzoic acid, sodium benzoate, sorbic acid, propionate, dehydroacetic acid, sulfur dioxide and sodium pyrosulfite.

(Viscosity modifier)
Viscosity modifiers include polymer compounds and layered inorganic particles.

(Antifoaming agent)
Antifoaming agents include fluorine-based compounds, silicone-based compounds, polyether-based compounds, acetylene glycol-based compounds, and chelating agents represented by EDTA.

<Functional layer removal step (A)>
The functional layer removing step according to the present invention is a step of removing the functional layer of the laminated film using the cleaning agent. Examples of removal methods include an immersion method of immersing in a cleaning bath containing a cleaning agent, a coating method of applying a cleaning agent in a solution state, and a spraying method of spraying a cleaning agent in a solution state or a vaporized cleaning agent. . Among these methods, the immersion method is preferable from the viewpoint of penetration of the cleaning agent into the functional layer.

The temperature of the cleaning agent in the immersion method is preferably room temperature (20° C.) or higher. When the temperature is above room temperature (20° C.), the viscosity of the cleaning liquid is low and it easily permeates into the functional layer, so good cleaning properties can be obtained. From the above viewpoints, the temperature of the cleaning agent in the immersion method is more preferably 40° C. or higher, further preferably 50° C. or higher, and particularly preferably 60° C. or higher.
As for the upper limit of the temperature of the cleaning agent, when the cleaning agent is used in the form of a solution, a temperature below the boiling point is preferable. In the case of a water-based cleaning agent, which is a preferred embodiment of the present application, the temperature is preferably 100°C or lower, more preferably 90°C or lower.
In addition, the temperature of the cleaning liquid during cleaning is the same as described above even in methods other than the immersion method. Further, in the peeling cleaning in the immersion method, microwave irradiation may be performed for the purpose of advancing the hydrolysis reaction.

The pH of the cleaning agent is preferably 12 or higher, more preferably 13 or higher, from the viewpoint of detergency.

The immersion time is preferably adjusted as follows depending on the type of object to be cleaned.

When a polyester film provided with an acrylic pressure-sensitive adhesive layer as a functional layer is to be cleaned, the cleaning time is preferably 1 second or more and 30 minutes or less. When the time is 1 second or more, the cleaning agent sufficiently permeates into the functional layer, and cleaning performance can be exhibited. On the other hand, when it is within 30 minutes, the amount of polyester obtained when recovered can be ensured without excessive dissolution of the polyester film as the substrate. From the above viewpoints, it is more preferably 15 seconds or more and 20 minutes or less, further preferably 30 seconds or more and 15 minutes or less, and particularly preferably 1 minute or more and 10 minutes or less.

When a polyester film provided with an acrylic hard coat layer as a functional layer is to be washed, it is preferably 1 second or more and 30 minutes or less. When the time is 1 second or more, the cleaning agent sufficiently permeates into the functional layer, and cleaning performance can be exhibited. On the other hand, when it is within 30 minutes, the amount of polyester obtained when recovered can be ensured without excessive dissolution of the polyester film as the substrate. From the above viewpoints, the time is more preferably 15 seconds or more and 30 minutes or less, more preferably 30 seconds or more and 25 minutes or less, and particularly preferably 1 minute or more and 20 minutes or less.

When a polyester film provided with a silicone release layer as a functional layer is to be cleaned, the cleaning time is preferably 1 second or more and 30 minutes or less. When the time is 1 second or more, the cleaning agent sufficiently permeates into the functional layer, and cleaning performance can be exhibited. On the other hand, when it is within 30 minutes, the amount of polyester obtained when recovered can be ensured without excessive dissolution of the polyester film as the substrate. From the above viewpoints, the time is more preferably 15 seconds or more and 20 minutes or less, more preferably 30 seconds or more and 10 minutes or less, and particularly preferably 1 minute or more and 5 minutes or less.

A specific aspect of the functional layer removing step depends on the shape of the laminated film, which is a waste material.

When the waste laminated polyester film is in the form of a roll, an unwinding device is installed in front of the cleaning tank containing the detergent, and the laminated film is unwound from the device and introduced into the cleaning tank. It is preferable to wash with And the aspect which transfers to the following collection|recovery process (B) continuously is preferable.
In addition, in the rinsing process to be described later from the functional layer removal process, equipment equipped with physical means such as roll brushes, ultrasonic waves, micro/nano bubbles, water flow, compressed cold air, etc. for the purpose of efficiently removing the functional layer from the laminated polyester film. may be provided.

When the waste laminated polyester film is in the form of lumps, it is preferable to set up a cutting device before the washing step to make flakes and introduce them into the washing tank. By forming flakes, the contact area between the laminated polyester film and the cleaning agent is increased, the cleaning agent can easily permeate, and the functional layer can be removed efficiently. In this embodiment, it is preferable to use a belt conveyor or the like to continuously introduce the flaky laminated polyester film into the washing tank. By adopting such an aspect, cleaning can be performed with high productivity. In addition, in the case of this aspect, cleaning can also be performed in a batch system.

<Recovery step (B)>
After the functional layer removing step (A), the polyester film as the base film is recovered. It is preferable to have a rinsing process and a drying process, which will be described later, before the recovery process. As a method of collection, an appropriate method can be selected according to the shape of the laminated polyester film which is a waste material.

When the waste laminated polyester film is in the form of a roll, it can be efficiently collected by continuously performing a roll-to-roll process, appropriately washing, rinsing, and drying, and then winding it up.

When the waste laminated polyester film is in the form of a block, it is preferable to have a cutting step before the functional layer removing step, as described above. In the case of this embodiment, it is preferable to use a belt conveyor or the like to continuously pass through the rinsing process and the drying process to recover the polyester flakes.

It is advantageous in terms of handling that the polyester film recovered as described above is pelletized after recovery.

<Rinse process>
In the present invention, after the functional layer removing step (A) and before the recovering step (B), it is preferable to have a rinsing step for washing away the cleaning agent. Specifically, it refers to the step of washing off the cleaning agent adhering to the polyester film from which the functional layer has been removed, with a rinsing liquid.

The rinsing liquid is not particularly limited as long as it can wash away the cleaning agent, but water can be used in the rinsing step when using an aqueous cleaning agent, which is a preferred embodiment of the present invention.

The temperature in the rinsing step is preferably around room temperature, specifically preferably 5 to 50°C, more preferably 5 to 30°C, from the viewpoint of efficient rinsing.

Examples of the method for washing away the cleaning agent include a spraying method of spraying a rinse liquid onto the polyester film from which the functional layer has been removed, and an immersion method of immersing the polyester film in a rinse tank containing the rinse liquid. However, the rinsing step can be omitted when using a cleaning agent that does not require rinsing.

<Drying process>
After the rinsing process, it is preferable to pass through a drying process. The drying process can remove the detergent and/or rinse liquid remaining on the polyester film. When the rinsing process is omitted, the drying process is preferably performed after the functional layer removing process (A).

Conditions for the drying step are not particularly limited, and drying is usually carried out at 70 to 150° C. for about 1 to 30 minutes. As a drying method, general methods such as heat drying using an infrared heater or an oven, hot air drying using a hot air dryer or the like, and microwave heat drying can be used.

[Recycled polyester products]
The polyester film obtained by the recovery method of the present invention can be used as a polyester raw material, and can be reused as a so-called recycled polyester product. Specifically, the recovered polyester can be pelletized and stored as pelleted polyester (polyester product). The recovered polyester can also be molded into various polyester products such as polyester films by melt extrusion or the like.
In view of ease of production, the recovered polyester is preferably pelletized once and then molded into various products.

It can be used for the same purposes as ordinary polyester products, for example, it can be used as a polyester film that is a base film. By forming a functional layer on the base film, it can be reused as a laminated film.

Recycled polyester can be used by mixing with conventionally produced polyester, or a multilayer film using recycled polyester and conventionally produced polyester can be used.

Recycled polyester products can be used for various purposes other than films, such as PET bottles, polyester fibers, polyester sheets, and polyester containers.

It should be noted that the separated functional layer can also be recovered and reused as necessary.

[Functional layer removing agent]
According to another aspect of the present invention, there is provided a removing agent (hereinafter also referred to as "removing agent") for removing a functional layer from a laminated polyester film having a functional layer on the surface of the polyester film.
The polyester film functional layer removing agent according to the present invention uses the cleaning agent used in the functional layer removing step (A) in the polyester film recovery method described above to remove the functional layer from the polyester film. is.
Specific aspects and preferred aspects of the present removing agent are the same as those of the cleaning agent described above, and all of these can be used.
This remover can easily remove the functional layer from the polyester film and efficiently recover the polyester film from the laminated polyester film.

[Polyester film recovery device]
The polyester film collecting device according to the present invention has a washing device. The collecting device collects the polyester film from which the functional layer has been removed by washing with the washing device.

The means for collecting the polyester film is not particularly limited, but in the case of a roll, a take-up roll for collecting the polyester film from which the functional layer has been removed may be used.
In the case of lumps, the polyester film from which the functional layer has been removed may be transported to a predetermined collection position by a conveying device such as a belt conveyor and collected.

The means for unwinding and cutting the polyester film is not particularly limited, but in the case of a roll, it is preferable to have an unwinding device, and further, the so-called roll-to-roll system in which winding is also performed by a roll. is preferable in that the polyester film can be recovered efficiently.
In the case of lumps, it is preferable to have a cutting device. Shredding flakes the waste material and, as mentioned above, makes the cleaning process more efficient.

The recovering device preferably also has a pelletizing device, and the recovered polyester film is preferably pelletized by the pelletizing device in order to facilitate handling. In particular, the polyester film recovered from bulky waste materials can be pelletized to make it easier to handle.

Furthermore, the recovery device preferably comprises a rinsing device and a drying device, as detailed below.

(Washing equipment)
The cleaning device is a device for cleaning with a cleaning agent containing an alcohol having an acidity constant (pKa) of 8.0 or more and 20.0 or less. Typically, the washing tank includes a washing tank filled with the above cleaning agent, and the waste laminated polyester film is introduced into the washing tank and immersed therein for washing. In addition, there are a coating device that applies a cleaning agent in a solution state, and a spraying device that forms a mist of a cleaning agent in a solution state or vaporized state and sprays the mist.

The cleaning agent is as described above, and the cleaning agent is preferably a water-based cleaning agent. By using a water-based cleaning agent, rinsing with water can be performed by a rinsing device to be described later, which is preferable.

(Rinse device)
The rinsing device is a device for washing off the detergent adhering to the polyester film after removing the functional layer with the detergent. Specifically, a spraying device for spraying the rinse solution, an immersion device for immersing the substrate in the rinse solution, and the like can be used. As described above, by using a water-based cleaning agent as the cleaning agent, it is possible to use water in the rinsing process, which is highly safe, and is preferable in terms of cost because an explosion-proof device is unnecessary.

In some cases, the functional layer peeled off from the polyester film is also washed away together with the detergent. The water and the material that made up the functional layer are then separated, the water can be reused in the rinsing step, and the material that made up the functional layer can also be reused. Also, the rinse device may be omitted.

(Drying device)
The drying device is for drying the polyester film from which the functional layer has been peeled off and the cleaning agent has been washed away, and the drying conditions are as described above. Drying devices include infrared heaters, ovens, hot air dryers, microwave heating dryers, and the like. The polyester base material is recovered through the drying process in the drying device. Even if the rinsing device is omitted, the drying device may dry the polyester film from which the functional layer has been removed.

Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples described below.

<Evaluation method>
(1) Immersion test The cleaning agent prepared in each example and comparative example was placed in a 30 ml water tank, and the laminated film was immersed. The cleaning agent temperature, immersion time, and sample size are as described in the table.

(2) Detachment evaluation of functional layer (2-1) Visual observation (laminated polyester film having an adhesive layer and laminated polyester film having a hard coat layer)
The immersed laminated film was taken out, and the surface was visually observed and evaluated according to the following criteria.
⊚ (very good): The functional layer is dissolved or peeled off, and the polyester film as the base material is not significantly damaged, which is particularly preferable for practical use.
○ (good); the functional layer is partially dissolved or peeled off, and there is no practical problem.
Δ (fair); A small part of the functional layer is dissolved or peeled off.
x (bad); the functional layer remains and is problematic in practice.

(2-2) X-ray fluorescence analysis (laminated polyester film with silicone release layer)
The surface of the laminated film after washing was quantitatively analyzed for Si element using an X-ray fluorescence spectrometer (XRF, "XRF-1800" manufactured by Shimadzu Corporation).
The removal rate of the functional layer was measured by setting the Si element content of the surface of the laminated polyester film before washing to 100% and the Si element content of the plain film not coated with the functional layer of the laminated film to 0%.
◎ (very good); removal rate 90-100%
○ (good); removal rate 70 to 89%
× (bad); removal rate 0 to 69%

(3) Intrinsic viscosity 1 g of polyester was precisely weighed, dissolved in 100 ml of a mixed solvent of phenol/tetrachloroethane = 50/50 (mass ratio), and measured at 30°C.

(Laminated polyester film having a functional layer)
A laminated polyester film having the following functional layers (I) to (III) was prepared as a sample.
(I) laminated film (laminated polyester film having an acrylic adhesive layer);
Commercial product (“PET75-H120 (10) Blue” manufactured by Nisei Shinka Co., Ltd.), thickness of polyethylene terephthalate film: 75 μm, thickness of acrylic adhesive layer: 10 μm

(II) laminated film (laminated polyester film having an acrylic hard coat layer);
A laminated polyester film having an acrylic hard coat layer was obtained by the following procedure.
(Preparation of acrylic hard coat solution)
Dipentaerythritol hexaacrylate 24 parts by mass, 2-hydroxy-3-phenoxypropyl acrylate 6 parts by mass, photopolymerization initiator (trade name: Omnirad 184, manufactured by IGM Resins B.V.) 1.5 parts by mass, toluene 70 parts by mass to obtain an acrylic hard coating solution.
(Preparation of acrylic hard coat film)
Polyethylene terephthalate film; commercially available product (Mitsubishi Chemical Co., Ltd. "Diafoil"), the above acrylic hard coat solution is applied so that the dry film thickness is about 9 μm, and cured by irradiating ultraviolet rays to form an acrylic film. A laminated polyester film having a hard coat layer was obtained.

(III) Laminated film (laminated polyester film having a silicone release layer); commercially available product ("MRF38" manufactured by Mitsubishi Chemical Corporation), thickness of polyethylene terephthalate film; 38 µm, intrinsic viscosity of polyethylene terephthalate film of 0.67 Met.

[Example 1]
40 parts by mass of benzyl alcohol and 10 parts by mass of xylenol as components (a), 5 parts by mass of potassium hydroxide as component (b), and 45 parts by mass of water as other components were mixed to obtain a cleaning agent (pH = 13). above) were prepared.
Washability was evaluated under the conditions shown in Table 1 using the laminated films (I) to (III). Table 1 shows the results.

[Example 2]
40 parts by mass of benzyl alcohol and 1 part by mass of propylene glycol as components (a), 5 parts by mass of potassium hydroxide, 5 parts by mass of sodium hydroxide and 19 parts by mass of monoethanolamine as components (b), and 30 parts by mass of water as other components A cleaning agent (pH = 13 or higher) was prepared by mixing so as to make parts by mass.
Washability was evaluated under the conditions shown in Table 1 using the laminated films (I) to (III). Table 1 shows the results.
Laminated film (III) was immersed for 1 minute and washed at a temperature of 60 ° C., and the intrinsic viscosity of the polyester film after removing the silicone release layer was measured. As a result, the intrinsic viscosity was 0.67. The intrinsic viscosity of the film was unchanged.

[Example 3]
16 parts by mass of benzyl alcohol as component (a), 5 parts by mass of potassium hydroxide, 5 parts by mass of sodium hydroxide and 10 parts by mass of diethanolamine as components (b), and 64 parts by mass of water as other components. and a cleaning agent (pH=13 or more) was prepared.
Detergency evaluation was performed under the conditions shown in Table 1 using the laminated films (I) and (III). Table 1 shows the results.

[Example 4]
95 parts by mass of benzyl alcohol as component (a) and 5 parts by mass of potassium hydroxide as component (b) were mixed to prepare a detergent (pH=13 or higher).
Detergency evaluation was performed under the conditions shown in Table 1 using the laminated films (I) and (III). Table 1 shows the results.

[Example 5]
95 parts by mass of methanol as component (a) and 5 parts by mass of potassium hydroxide as component (b) were mixed to prepare a cleaning agent (pH=13 or more).
Washability was evaluated under the conditions shown in Table 1 using the laminated film (III). Table 1 shows the results.

[Example 6]
95 parts by mass of ethanol as component (a) and 5 parts by mass of potassium hydroxide as component (b) were dissolved in water to prepare a cleaning agent.
Detergency evaluation was performed under the conditions shown in Table 1 using the laminated films (I) and (III). Table 1 shows the results.

[Example 7]
33.8 parts by mass of benzyl alcohol, 3.8 parts by mass of hexafluoro-2-propanol, and 2.9 parts by mass of propylene glycol as components (a), 5 parts by mass of potassium hydroxide and 5 parts by mass of sodium hydroxide as components (b) Parts by mass, 17.9 parts by mass of monoethanolamine, and 31.6 parts by mass of water as another component were mixed to prepare a cleaning agent.
Washability was evaluated under the conditions shown in Table 1 using the laminated film (III). Table 1 shows the results.

[Example 8]
28.1 parts by mass of benzyl alcohol, 9.4 parts by mass of hexafluoro-2-propanol, and 2.9 parts by mass of propylene glycol as components (a), 5 parts by mass of potassium hydroxide and 5 parts by mass of sodium hydroxide as components (b) Parts by mass, 17.9 parts by mass of monoethanolamine, and 31.6 parts by mass of water as another component were mixed to prepare a cleaning agent.
Washability was evaluated under the conditions shown in Table 1 using the laminated film (III). Table 1 shows the results.

[Example 9]
18.8 parts by mass of benzyl alcohol, 18.8 parts by mass of hexafluoro-2-propanol, and 2.9 parts by mass of propylene glycol as components (a), 5 parts by mass of potassium hydroxide and 5 parts by mass of sodium hydroxide as components (b) Parts by mass, 17.9 parts by mass of monoethanolamine, and 31.6 parts by mass of water as another component were mixed to prepare a cleaning agent.
Washability was evaluated under the conditions shown in Table 1 using the laminated film (III). Table 1 shows the results.

[Comparative Example 1]
A detergent was prepared by mixing 30 parts by mass of potassium hydroxide as the component (b) and 70 parts by mass of water as the other component. Detergency evaluation was performed under the conditions shown in Table 1 using the laminated films (I) and (III). Table 1 shows the results.

[Comparative Example 2]
Detergency evaluation was carried out in the same manner as in Comparative Example 1, except that the temperature conditions were changed as shown in Table 1. Table 1 shows the results.

As reference examples, a substrate film (IV) (polyethylene terephthalate film, thickness 52 μm) having no functional layer and a substrate film (V) (unstretched polypropylene film, thickness 56 μm) were prepared as samples.
The sample was immersed in the cleaning agent for 5 minutes, and the thickness was measured by Mitutoyo's "Thickness Gauge ID-C112X/1012X" to measure the thickness change of the substrate.
A was given when the thickness change was 3 μm or more, and B was given when the thickness change was less than 3 μm.

[Reference example 1]
A cleaning test was performed on the substrate film (IV) and the substrate film (V) under the conditions shown in Table 1 using the cleaning agent having the same composition as in Example 1, and the thickness after cleaning was measured. Table 1 shows the results.

[Reference example 2]
A cleaning test was performed on the substrate film (IV) and the substrate film (V) under the conditions shown in Table 1 using the cleaning agent having the same composition as in Example 2, and the thickness after cleaning was measured. Table 1 shows the results.

[Reference example 3]
In order to confirm the best form of alcohol in the detergent, the washing temperature was changed to 40°C and the immersion time was changed to 1.2 minutes in Examples 2, 7, 8 and 9. cleaning evaluation. Table 2 shows the results.
In the same manner as described above, cleaning evaluation was performed by quantitatively analyzing the Si element on the surface of the laminated film after cleaning using a fluorescent X-ray spectrometer.
The removal rate of the functional layer was judged according to the following criteria.
○ (good); removal rate 50 to 100%
△ (fair); removal rate 0 to 49%

From the results shown in Table 1, according to the method of the present invention, the functional layer can be peeled off from any of the adhesive film, the hard coat film, and the release film, and the polyester film can be recovered. .
Further, from the results of Example 2, according to the method of the present invention, the intrinsic viscosity (IV) of the polyester film before and after the functional layer removal step (washing step) does not decrease, so the recovered polyester film is used as a raw material. Recycled polyester products are also highly likely to have excellent mechanical properties.
Furthermore, from the results of Examples 7, 8 and 9, according to the method of the present invention, two or more alcohols having an acidity constant (pKa) of 8.0 or more and 20.0 or less are used in combination, and at least When the acidity constant (pKa) of one type is 9.0 or more and 10.0 or less, it is possible to peel off the functional layer at a lower temperature and in a shorter time with a low possibility of affecting the film. I found out.

It can be seen that Comparative Examples 1 and 2, which do not contain alcohols having an acidity constant (pKa) of 8.0 or more and 20.0 or less as detergents, do not exhibit the effects of the present invention.

From the results of Reference Examples 1 and 2, the surface of the base film (IV), which is a polyester film, was partially melted and thinned, and the base film (V) having no ester bond was thinned without being melted on the surface. I know it's not. That is, it is considered that the cleaning agent according to the present invention effectively peels off the functional layer by partially dissolving the surface of the polyester film that is the substrate.

Further, from the results of Reference Example 3 (Table 2), monovalent alcohols with an acidity constant (pKa) of 9.0 or more and 10.0 or less are alcohols A, and the acidity constant (pKa) is 8.0 or more. , When alcohols with a unit price of 20.0 or less are alcohols B, the mass ratio of alcohols A and alcohols B (excluding alcohols A) is 1: 5 to 1: 10. It was found that a cleaning effect can be obtained.

As described above, according to the present invention, various functional layers can be peeled off with one kind of cleaning agent. It is possible to peel off the layers. In addition, for example, even with a laminated polyester film having a hard coat layer on the surface and an adhesive layer on the back surface, the functional layer can be peeled off from both sides by one washing operation, and the polyester film as the substrate can be removed. can be recovered.

Claims (21)

Having a functional layer removing step (A) and a recovering step (B),
The functional layer removing step (A) is a step of removing the functional layer of the laminated polyester film provided with the functional layer on the surface of the polyester film using a detergent,
The cleaning agent contains an alcohol having an acidity constant (pKa) of 8.0 or more and 15.4 or less, including benzyl alcohol and hexafluoro-2-propanol, and an inorganic alkalinizing agent,
The mass ratio of benzyl alcohol and hexafluoro-2-propanol is 18.8:18.8 to 33.8:3.8,
The recovery step (B) is a method for producing a recycled polyester product, wherein the polyester film from which the functional layer has been removed is recovered. 2. The method for producing recycled polyester products according to claim 1, wherein the cleaning agent is a water-based cleaning agent. The functional layer is any one of a hard coat layer, an adhesive layer and a release layer, the hard coat layer is an acrylic hard coat layer, and the adhesive layer is an acrylic adhesive layer. layer, and the release layer is a silicone release layer. The method for producing a recycled polyester product according to any one of claims 1 to 3, wherein the temperature of the cleaning agent in the functional layer removing step (A) is 20°C or higher. The method for producing a recycled polyester product according to any one of claims 1 to 4, wherein the polyester constituting the polyester film is polyethylene terephthalate. The method for producing recycled polyester products according to any one of claims 1 to 5, wherein the cleaning agent further comprises an organic alkalinizing agent. A polyester film recovery apparatus having a cleaning device, the cleaning device having a cleaning tank containing a cleaning agent, a laminated polyester film having a functional layer on the surface of the polyester film is washed with benzyl alcohol and hexafluoro-2 - An apparatus for washing by immersing in a cleaning agent containing propanol and containing alcohols and an inorganic alkalinizing agent having an acidity constant (pKa) of 8.0 or more and 15.4 or less,
The mass ratio of benzyl alcohol and hexafluoro-2-propanol is 18.8:18.8 to 33.8:3.8,
An apparatus for recovering a polyester film, which recovers the polyester film from which the functional layer has been removed by the cleaning apparatus. The functional layer is any one of a hard coat layer, an adhesive layer and a release layer, the hard coat layer is an acrylic hard coat layer, and the adhesive layer is an acrylic adhesive layer. layer, and the release layer is a silicone release layer. 9. The apparatus for recovering a polyester film according to claim 7 or 8, wherein the polyester constituting the polyester film is polyethylene terephthalate. The polyester film recovery apparatus according to any one of claims 7 to 9, wherein the cleaning agent further contains an organic alkalinizing agent. The polyester film recovering apparatus according to any one of claims 7 to 10, further comprising a rinsing device for washing off the cleaning agent adhering to the polyester film from which the functional layer has been removed. 12. The apparatus for recovering a polyester film according to claim 11, wherein the cleaning agent is a water-based cleaning agent, and the water-based cleaning agent is washed away with water in the rinsing device. The apparatus for recovering a polyester film according to any one of claims 7 to 12, further comprising a drying apparatus for drying the polyester film from which the functional layer has been removed. 14. The polyester film recovery apparatus according to any one of claims 7 to 13, further comprising an unwinding device in front of the cleaning device. 15. The apparatus for recovering a polyester film according to claim 14, wherein the polyester film is recovered by a roll-to-roll system. The polyester film recovery apparatus according to any one of claims 7 to 13, further comprising a cutting device in a stage preceding the cleaning device. A removing agent for removing a functional layer from a laminated polyester film having a functional layer on the surface of the polyester film,
The remover contains alcohols having an acidity constant (pKa) of 8.0 or more and 15.4 or less, including benzyl alcohol and hexafluoro -2-propanol, and an inorganic alkalinizing agent. - Functional layer removing agent for polyester film , wherein the mass ratio of 2-propanol is 18.8:18.8 to 33.8:3.8 . 18. The polyester film functional layer removing agent according to claim 17, wherein the removing agent is a water-based removing agent. The functional layer is any one of a hard coat layer, an adhesive layer and a release layer, the hard coat layer is an acrylic hard coat layer, and the adhesive layer is an acrylic adhesive layer. 19. The polyester film functional layer removing agent according to claim 17 or 18, wherein the release layer is a silicone release layer. The functional layer removing agent for a polyester film according to any one of claims 17 to 19, wherein the polyester constituting the polyester film is polyethylene terephthalate. The functional layer removing agent for polyester film according to any one of claims 17 to 20, wherein the removing agent further contains an organic alkalinizing agent.