JP2023079089A - Method for removing functional layer of laminated polyester film - Google Patents

Abstract

To provide a method for removing a functional layer from a laminated polyester film provided with a functional layer on the surface of the polyester film, and a method for removing a functional layer from a laminated polyester film that can contribute to improvement of the removal rate of the functional layer, among others.SOLUTION: A method for removing a functional layer from a laminated polyester film includes: an irradiation step (A) in which a laminated polyester film provided with a functional layer on at least one surface of the polyester film is irradiated with an active energy beam; and a cleaning step (B) in which the laminated polyester film is cleaned with a cleaning agent containing an alkalizing agent (a).SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a method for removing a functional layer from a laminated polyester film.

Conventionally, waste plastics were disposed of by landfilling, ocean dumping, incineration, etc., but it is becoming difficult to secure landfill sites, and ocean dumping is becoming an environmental problem because plastics do not decompose. there is
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 polyester film in which various functional layers are laminated on one or both sides thereof.
As functional layers, there are various functional layers such as hard coat layer, adhesive layer, release layer, decorative layer, light shielding layer, UV shielding layer, and easy adhesion layer. Laminated polyester film is used.

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

Even if you try to re-melt and recycle the laminated polyester 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 offensive odors during extrusion and lowering of the melt viscosity of the polymer. Problems such as causing breakage during film formation arise.
Moreover, even if a film can be formed, it is inevitable that the quality of the resulting film will be deteriorated due to coloration and inclusion of foreign matter.

Furthermore, even if the functional layer is removed physically by scraping off and melt-extruded, for example, in the filtration process during extrusion, the remaining functional layer causes clogging of the filter, preventing normal film formation. Problems such as disappearance may occur.

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

Further, Patent Document 2 discloses a method for removing a functional layer provided on at least one surface of a substrate film, wherein the substrate film wound into a roll is exposed to an alkaline treatment liquid in a long state. A method of removing a functional layer is disclosed, characterized in that it includes a contacting step.

Patent Document 3 discloses a method for cleaning a release film having a base film and a release layer formed on the base film, wherein the release film having a foreign substance on the release layer is washed with an alkaline substance. A method for cleaning a release film is disclosed, which has a removing step of removing the release layer from the base film by contacting the release layer with an organic solvent after contacting with a solution containing alcohol.

Japanese Patent Application Laid-Open No. 2004-169005 JP 2020-090094 A JP 2009-291690 A

As described above, the method disclosed in Patent Document 1 is based on the premise of a laminated polyester film formed by laminating an easily soluble resin layer and a surface functional layer on the surface of a base film in this order. It is intended to remove the functional layer by dissolving the layer.
That is, it cannot be used for most laminated polyester films that do not have a readily soluble resin layer, and is inferior in versatility.

The methods disclosed in Patent Documents 2 and 3 remove the functional layer by bringing it into contact with an alkaline solution such as an alkaline processing liquid or an alkaline substance. was not sufficiently removed.
Polyester films are used in various fields such as industrial materials, optical materials, electronic component materials, and packaging materials, and in recent years, the demand for quality has been extremely high.
Therefore, if the removal of the functional layer is not sufficient, there remains the problem of contamination of recycled raw materials and recycled products.

In view of the above circumstances, the present invention provides a functional layer removing method for removing a functional layer from a laminated polyester film having a functional layer on the surface of the polyester film, even if the laminated polyester film does not have a readily soluble resin layer. It is therefore an object of the present invention to propose a method for removing a functional layer from a laminated polyester film, which can contribute to improving the removal rate of the functional layer.

As a result of intensive studies, the inventors have found that the above problems can be solved by having the following configuration.
The present invention has the following aspects.

[1] An irradiation step (A) of irradiating a laminated polyester film having a functional layer on at least one surface of the polyester film with an active energy ray, and a cleaning agent containing an alkalinizing agent (a), the laminated polyester film A method for removing a functional layer of a laminated polyester film, comprising a washing step (B) for washing.
[2] The method for removing a functional layer of a laminated polyester film according to [1] above, wherein the active energy ray is a vacuum ultraviolet ray.
[3] The method for removing a functional layer of a laminated polyester film according to [2] above, wherein the vacuum ultraviolet rays are excimer light.
[4] The method for removing a functional layer of a laminated polyester film according to any one of [1] to [3] above, wherein the irradiation step (A) is performed in a nitrogen atmosphere.
[5] The method for removing a functional layer of a laminated polyester film according to any one of [1] to [4] above, wherein the cleaning agent further contains a compound (b) having at least one hydroxyl group.
[6] The method for removing a functional layer of a laminated polyester film according to any one of [1] to [5] above, wherein the functional layer contains (meth)acrylate.
[7] The method for removing a functional layer of a laminated polyester film according to [6] above, wherein urethane acrylate is contained as the (meth)acrylate.
[8] The functional layer of the laminated polyester film according to any one of [1] to [7] above, further comprising a rinsing step to wash off the cleaning agent adhering to the polyester film after removing the functional layer. removal method.
[9] A recycled polyester product containing, as a raw material, at least a part of the polyester film from which the functional layer has been removed by the method for removing the functional layer according to any one of [1] to [8] above.
[10] A recovery step of recovering the polyester film from which the functional layer has been removed by the method for removing the functional layer according to any one of [1] to [8] above, and recycling the recovered polyester film as a raw material. A manufacturing process for manufacturing a polyester product, and a method for manufacturing a recycled polyester product.
[11] A laminated polyester film having a functional layer on at least one surface of the polyester film is provided with an irradiation device for irradiating an active energy ray and a cleaning agent containing an alkalinizing agent (a), and the lamination is performed with the cleaning agent. A functional layer removing device for a laminated polyester film, comprising: a cleaning device for cleaning the polyester film.
[12] The functional layer removing apparatus for a laminated polyester film according to [11] above, further comprising a rinsing device for washing away the cleaning agent adhering to the polyester film from which the functional layer has been removed.
[13] The functional layer removing device according to [11] or [12] above, a recovery device for recovering the polyester film from which the functional layer has been removed by the functional layer removing device, and the recovered polyester film as a raw material , a manufacturing device that manufactures recycled polyester products.

According to the method for removing the functional layer of the laminated polyester film of the present invention, the functional layer can be sufficiently removed from the laminated polyester film having the functional layer, and in particular, the removal rate of the functional layer can be improved.

It is a schematic diagram showing an example of a recycling device provided with the functional layer removing device of the present invention.

Next, an example of an embodiment of the invention will be described. However, the present invention is not limited to the embodiments described below.

In the method for removing the functional layer of the laminated polyester film of the present invention (hereinafter also referred to as "this method for removing the functional layer"), a laminated polyester film having a functional layer on at least one surface of the polyester film is irradiated with an active energy ray. It comprises an irradiation step (A) and a washing step (B) of washing the laminated polyester film with a washing agent containing an alkalinizing agent (a).

<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 at least one surface of a polyester film which is a base film.

(polyester 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 include polyesters obtained by polycondensation of dicarboxylic acids and diols. The dicarboxylic acid is preferably an aromatic dicarboxylic acid, and the diol is preferably an aliphatic glycol.

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.

Specific examples of polyester include polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polybutylene-2,6-naphthalate, etc. Among these, polyethylene terephthalate is preferred.
In addition, the above polyester is a dicarboxylic acid constituting the polyester, preferably a compound that is a main component of an aromatic dicarboxylic acid, and a diol, preferably a third component other than a compound that is a main component of an aliphatic glycol. may be included as an ingredient.
For example, polyethylene terephthalate has dicarboxylic acid units other than terephthalic acid in about 30 mol% or less of the dicarboxylic acid units, and diol units other than ethylene glycol in about 30 mol% or less of the diol units. good.

The polyester polymerization catalyst is not particularly limited, and conventionally known compounds can be used, such as titanium compounds, germanium compounds, antimony compounds, manganese compounds, aluminum compounds, magnesium compounds and calcium compounds.

In order to suppress the precipitation amount of the oligomer component, the polyester film may be produced using a polyester having a low content of the oligomer component as a raw material. As a method for producing a polyester having a low content of oligomer components, various known methods can be used.
The polyester film may have a structure of three or more layers, and the outermost layer of the polyester film may be a layer using a polyester raw material having a low content of the oligomer component, thereby suppressing the precipitation amount of the oligomer component.
The polyester may be obtained by further raising the reaction temperature and subjecting it to melt polycondensation under reduced pressure after the esterification or transesterification reaction.

Particles can be incorporated into the polyester film for the main purpose of imparting slipperiness and preventing scratches in each step. The type of particles is not particularly limited as long as they can impart easy lubricity. Specific examples include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, acrylic resins, styrene resins, urea resins, phenol resins, Examples include organic particles such as epoxy resin and benzoguanamine resin.
Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

The shape of the particles to be used is also not particularly limited, and any of spherical, massive, rod-like, flattened and the like may be used.
Moreover, there are no particular restrictions on its hardness, specific gravity, color, and the like. One type of these series of particles may be used alone, or two or more types may be used in combination, if necessary.

The average particle diameter of the particles used is usually in the range of 0.05 to 5 μm, preferably 0.1 to 4 μm, more preferably 0.1 to 3.5 μm, in consideration of both transparency and handleability of the film. is good.

When the polyester film has a multilayer structure and contains particles, the particles are preferably contained in at least one of the layers. When the polyester film has a surface layer and an intermediate layer, the particles are preferably contained in the surface layer. The particles may be contained in one surface layer or in both surface layers. By including particles in the surface layer, it is possible to effectively impart lubricity and the like while reducing the content of particles in the entire polyester film.

The content of particles in the layer containing particles is usually in the range of 0.010% by mass or more and less than 10% by mass, preferably 0.015 to 5% by mass, more preferably 0.015 to 3% by mass. When there are no particles or when there are few particles, the transparency of the polyester film is high, and a good polyester film is obtained from the viewpoint of transparency. On the other hand, by containing the particles in the above range, the lubricity is also improved.
The layer containing the particles is preferably the surface layer when the polyester film has a multi-layer structure, but is the entire polyester film when the polyester film has a single-layer structure.

The method of adding particles to the polyester film is not particularly limited, and conventionally known methods can be employed. For example, it can be added at any stage of polyester production. For example, it is preferable to add the particles after the completion of the esterification or transesterification reaction during polyester production.

In addition to the particles described above, conventionally known additives such as antioxidants, antistatic agents, ultraviolet absorbers, heat stabilizers, lubricants, dyes, and pigments can be added to the polyester film as necessary. . When the substrate film has a multilayer structure, each additive may be added to at least one of the layers.

The thickness of the polyester film is not particularly limited as long as it can be formed into a film. When the polyester film has a multilayer structure, the thickness of the polyester film as a whole shall be within the above range.

(functional layer)
The component of the functional layer is not particularly limited, but from the viewpoint of removal by the functional layer removing method, it 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 for imparting abrasion resistance and the like to the polyester film. Materials for forming the hard coat layer are not particularly limited, but examples thereof include cured products of reactive silicon compounds such as (meth)acrylate and tetraethoxysilane. Among them, (meth)acrylate is preferred. The (meth)acrylate may be a monofunctional (meth)acrylate or a polyfunctional (meth)acrylate. More preferably, the (meth)acrylate is urethane acrylate.

The adhesive layer is a layer provided for adhesion to other equipment or the like. Although the material constituting the adhesive layer is not particularly limited, for example, known acrylic, rubber, silicone, or other adhesive resins 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 molding 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. Examples include various release agents such as containing compounds, fluorine compounds, hydrocarbon waxes, olefin release layers, and urethane acrylate release layers.

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

A light shielding layer or an ultraviolet shielding layer is a layer provided to protect contents from ultraviolet rays, visible light, and the like. The material constituting the light shielding layer or the ultraviolet shielding layer is not particularly limited, but for example, various resins described in the decorative layer, calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth, inorganic fillers such as barium sulfate. , wood flour, pulp flour, etc., and organic fillers such as 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), poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), conductive polymers such as SnO ₂ (Sb-doped), In ₂ O ₃ (Sn-doped), Examples include metal oxide fillers such as ZnO (Al-doped), carbon compounds such as graphene, carbon black, and carbon nanotubes (CNT). 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 adjustment layer is a layer provided for adjusting the refractive index. Materials constituting the refractive index adjusting layer are not particularly limited, but include polyester resins, acrylic resins, urethane resins, polycarbonate resins, epoxy resins, alkyd resins, urea resins, fluorine resins, and metal oxides such as zirconium oxide and titanium oxide. etc. 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 substances after the heating process. For example, materials constituting the oligomer sealing layer are not particularly limited, but include amine compounds and ionic resins. Also, the oligomer sealing layer may be a highly crosslinked coating film or 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.

Moreover, the functional layer preferably contains (meth)acrylate from the viewpoint of effectively cutting the chemical bonds of the functional layer in the irradiation step (A) of irradiating the active energy ray, which will be described later. (Meth)acrylates are not particularly limited, and include monofunctional (meth)acrylates, bifunctional (meth)acrylates, trifunctional or higher polyfunctional (meth)acrylates, and the like.
In the present invention, "(meth)acrylate" is a generic term for acrylate or methacrylate.

Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and cyclohexyl (meth)acrylate. , Alkyl (meth)acrylates such as isobornyl (meth)acrylate, Hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate, Hydroxypropyl (meth)acrylate, Hydroxybutyl (meth)acrylate, Methoxyethyl (meth)acrylate, Ethoxy Alkoxyalkyl (meth)acrylates such as ethyl (meth)acrylate, methoxypropyl (meth)acrylate and ethoxypropyl (meth)acrylate, aromatic (meth)acrylates such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate, diamino amino group-containing (meth)acrylates such as ethyl (meth)acrylate and diethylaminoethyl (meth)acrylate; methoxyethylene glycol (meth)acrylates; phenoxypolyethylene glycol (meth)acrylates; Ethylene oxide-modified (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and urethane (meth)acrylate can be mentioned.

Examples of bifunctional (meth)acrylates include 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol. Alkanediol di(meth)acrylates such as di(meth)acrylate and tricyclodecanedimethylol di(meth)acrylate, bisphenols such as bisphenol A ethylene oxide-modified di(meth)acrylate and bisphenol F ethylene oxide-modified di(meth)acrylate Modified di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, urethane di(meth)acrylate, epoxy di(meth)acrylate.

Trifunctional or higher polyfunctional (meth)acrylates include, for example, dipentaerythritol hexa(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, tri Ethylene oxide-modified (meth)acrylates such as methylolpropane tri(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, ethylene oxide-modified tri(meth)acrylate isocyanurate , isocyanuric acid-modified tri(meth)acrylates such as ε-caprolactone-modified tris(acryloxyethyl) isocyanurate, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate Urethane acrylates such as hexamethylene diisocyanate urethane prepolymers can be mentioned.

Among these, the functional layer preferably contains urethane acrylate as the (meth)acrylate from the viewpoint that the functional layer can be easily removed by breaking the chemical bond of the functional layer. The urethane acrylate is as exemplified as a monofunctional, difunctional or trifunctional or higher polyfunctional acrylate as described above.

<Irradiation step (A)>
This functional layer removing method includes an irradiation step (A) of irradiating a laminated polyester film having a functional layer on at least one surface of the polyester film with an active energy ray. In this irradiation step, the surface of the functional layer of the laminated polyester film is irradiated with active energy rays using an irradiation device.
The irradiation device is provided with, for example, a moving device for moving the film by a belt conveyor or the like, or a film unwinding device and a film winding device. By moving with the driving force and line speed of each of these devices, the laminated polyester film is conveyed to a predetermined irradiation position, and the active energy ray is irradiated to the functional layer surface of the laminated polyester film with an irradiation lamp or the like at the irradiation position. .

This functional layer removing method can improve the removal rate of the functional layer by including the irradiation step (A). The mechanism by which the removal rate of the functional layer can be improved by the irradiation step (A) is not clear, but is presumed as follows.
When the surface of the functional layer of the laminated polyester film is irradiated with active energy rays, the energy causes the main chains and side chains of the surface molecules of the functional layer, that is, the chemical bonds to break. Then, in the washing step (B) described later, it is presumed that the specific detergent becomes easier to permeate, and it becomes possible to effectively remove the functional layer from the laminated polyester film. In particular, a functional layer with a high cross-linking density (for example, a layer containing the aforementioned urethane acrylate) is difficult for the cleaning agent described below to permeate, so cutting chemical bonds in the functional layer by the irradiation step (A) is effective. target.

As the active energy ray, one having a high energy capable of breaking chemical bonds in the functional layer, such as γ-rays, X-rays, ultraviolet rays, electron beams, etc., can be used. Among them, those having a short wavelength are preferable, and vacuum ultraviolet rays, which are ultraviolet rays having a wavelength of 200 nm or less, are more preferable. Short-wave energy, particularly energy emitted from vacuum ultraviolet rays, is preferred because it has a very high level of photon energy that breaks most molecular bonds (chemical bonds).
Among vacuum ultraviolet rays, excimer light having a half width of 50 nm or less is more preferable from the viewpoint of ease of breaking chemical bonds. Examples of excimer light include argon excimer light (126 nm), krypton excimer light (146 nm), xenon excimer light (172 nm), and argon/fluorine excimer light (193 nm).
Active energy rays may be used singly or in combination of two or more. For example, after irradiating vacuum ultraviolet rays, which are ultraviolet rays with a wavelength of 200 nm or less, ultraviolet rays other than vacuum ultraviolet rays, or active energy rays such as gamma rays, X-rays, and electron beams may be irradiated. Examples of ultraviolet rays other than vacuum ultraviolet rays include ultraviolet rays with a wavelength of 200 nm or more emitted from high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, UV-LED lamps, and the like. Examples of electron beams include gamma rays, X-rays, and electron beams emitted from an EB irradiator or the like.

In the irradiation step (A), it is preferable to carry out the irradiation in an oxygen-poor environment such as a nitrogen atmosphere as the atmosphere during the irradiation with the active energy ray. The oxygen concentration in the atmosphere is preferably 10% or less, more preferably 5% or less, still more preferably 3% or less, and particularly preferably 1% or less.

The integrated amount of light irradiated with the active energy ray can be appropriately selected depending on the composition and film thickness of the functional layer, and is not particularly limited, but is preferably 1 to 10000 mJ/cm ² , more preferably 100 to 8000 mJ/cm ² . , more preferably 1000 to 6000 mJ/cm ² .
The reaching illuminance can also be selected as appropriate and is not particularly limited, but is preferably 1 to 500 mW/cm ² , more preferably 2 to 300 mW/cm ² , still more preferably 3 to 100 mW/cm ² .
If the integrated amount of light and the reaching illuminance are in the range, chemical bonds in the functional layer can be sufficiently broken, leading to an improvement in removal rate of the functional layer.

The number of times the irradiation step is performed (hereinafter, also referred to as “the number of passes”) may be one or more times.

<Washing step (B)>
In addition to the irradiation step (A), this functional layer removing method includes a washing step (B) of washing the laminated polyester film with a washing agent containing the alkalizing agent (a). By having such a washing step (B), the functional layer can be easily removed from the laminated polyester film.

The washing step (B) is preferably performed after the irradiation step (A). By providing the washing step (B) after the irradiation step (A), as described above, it is presumed that the washing agent can easily penetrate and the functional layer can be effectively removed from the laminated polyester film. .

(Alkalizing agent)
The alkalinizing agent (a) constituting the detergent used in the present invention (hereinafter also referred to as "this detergent") makes the detergent alkaline and can also be called an alkaline agent. The alkalizing agent may be an inorganic alkalizing agent or an organic alkalizing agent.
The inorganic alkalinizing agent is preferable because it is suitable for combination with the compound (b) having at least one hydroxyl group and the compatibilizing agent (c), which will be described later.

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 type can be used alone, or two or more types can be used in combination. When two or more of them are used in combination, it is preferable to use potassium hydroxide and sodium hydroxide in combination from the viewpoint of effect and handleability.

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, and triisopropanolamine.
The organic alkalinizing agent may contain a compound having at least one hydroxyl group. If the acidity constant (pKa) of the compound is 30 or more, a compound having at least one hydroxyl group (described later) ( Treat as alkalizing agent (a) instead of b).

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.

The content of the alkalinizing agent (a) in the entire detergent is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and even more preferably 3 to 10% by mass. . Within the above range, a sufficient effect as a cleaning agent can be obtained.

(Compound with at least one hydroxyl group)
The detergent used in the present invention preferably contains a compound (b) having at least one hydroxyl group in addition to the above component (a).
Although the mechanism by which the functional layer can be effectively removed by using the above-mentioned components (a) and (b) together is not clear, it is presumed as follows.
It is presumed that the reaction described below proceeds at the interface between the polyester film and/or the functional layer, which is the substrate, and the functional layer can be efficiently peeled off from the laminated polyester film.

When a functional layer that undergoes hydrolysis, such as a laminated polyester film having an acrylic adhesive layer or an acrylic hard coat layer, is washed, the functional layer and/or the alkoxide generated from the hydroxyl group of compound (b) having at least one hydroxyl group is washed. Alternatively, a transesterification reaction occurs at the ester bond portion of the polyester film to obtain a low-molecular-weight compound. Then, the hydroxyl group ionized from the alkalinizing agent (a) nucleophilically attacks the ester bond of the low-molecular-weight compound, thereby proceeding a saponification reaction and obtaining a carboxylate (ionization). It is presumed that this causes the functional layer to elute.

Even when a laminated polyester film having a functional layer that is not subject to hydrolysis, such as a silicone release layer, is washed, the reaction mechanism described above causes the ester exchange reaction of the polyester film surface to cause a low molecular weight, saponification, and elution. The functional layer laminated on the film can be peeled off and removed.
Therefore, it is considered that the combination of the (a) component and the (b) component enabled the efficient peeling of the functional layer from the laminated polyester film.

Examples of the compound (b) having at least one hydroxyl group include alcohols and phenols.

Alcohols include monovalent alcohols such as hexafluoro-2-propanol, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, benzyl alcohol, 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; and polyhydric alcohols such as glycerin.

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

These compounds (b) having at least one hydroxyl group may be used singly or in combination of two or more.
Among these, alcohols are preferable from the viewpoint of maintaining the detergency without impairing the alkalinity of the detergent.

From the viewpoint of detergency, the acidity constant (pKa) of the alcohol described above as the compound (b) having at least one hydroxyl group is preferably in the range of 8.0 or more and 20.0 or less, preferably 8.0. 18.0 or less is more preferable, 9.0 or more and 16.0 or less is more preferable, 9.3 or more and 15.6 or less is particularly preferable, and 14.0 or more and 15.4 or less is most preferable.
If the acidity constant (pKa) of the alcohol is within the above range, the alkoxide is generated without impairing the alkalinity of the cleaning agent, thereby improving the cleaning ability of the cleaning agent.

The acidity constants (pKa) of some alcohols are shown below. 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).

Among the above alcohols, at least one selected from the group consisting of hexafluoro-2-propanol, methyl alcohol, ethyl alcohol, propyl alcohol and benzyl alcohol is more preferable from the viewpoint of detergency. Among these, use of benzyl alcohol is more preferable from the viewpoint of low volatility and usable temperature range. These alcohols easily ionize protons to form alkoxides and have high detergency.

The above-mentioned suitable alcohols may be used together, or the above-mentioned suitable alcohols may be used together with a dihydric alcohol or a polyhydric alcohol.

In the detergent, the content of the compound (b) having at least one hydroxyl group is preferably 10-99% by mass, more preferably 20-98% by mass, and even more preferably 30-97% by mass. Within the above range, the amount of the alkalinizing agent (a) is appropriate, so that when the polyester film is recovered, contamination with foreign matter due to precipitation of the alkalinizing agent component is suppressed. Therefore, the quality of recycled polyester products including recycled polyester film can be maintained.
In addition to the components (a) and (b), in the cleaning agent, when the component (c), which will be described later, is used in combination, or when the cleaning agent is an aqueous cleaning agent, the (b) component in the cleaning agent is preferably 10 to 90% by mass, more preferably 20 to 75% by mass, still more preferably 30 to 65% by mass, and particularly preferably 35 to 50% by mass. Within the above range, in addition to the alkalinizing agent (a), the amount of the compatibilizing agent (c), which will be described later, can also be appropriately adjusted. Moreover, in the case of water-based, it is also possible to contain a certain amount or more of water.

(Compatibilizer)
The detergent used in the present invention preferably further contains a compatibilizer (c).
The compatibilizer (c), when used in combination with the above components (a) and (b), has the function of helping the functional layer to dissolve out of the laminated polyester film, and at the same time, the above components (a) and (b). , and other optionally added additives.
Further, by containing the compatibilizer (c), the compatibility between the components (a) and (b) is improved even when the cleaning agent contains water as one component.

The compatibilizer (c) is not particularly limited, and any of anionic compatibilizers, cationic compatibilizers, nonionic compatibilizers and amphoteric compatibilizers can be used.
Since the compatibilizer includes a compound corresponding to the alkalinizing agent (a), the compatibilizer (c) is different from the components (a) and (b).

Examples of anionic compatibilizers include alkylsulfonic acids, alkylbenzenesulfonic acids, aromatic sulfonic acids such as alkylnaphthalenesulfonic acids, alkylcarboxylic acids, aromatic carboxylic acids, α-olefinsulfonic acids, dialkylsulfosuccinic acids, α-sulfonated fatty acid, N-methyl-N-oleyl taurine, petroleum sulfonic acid, alkyl sulfuric acid, sulfated fat, polyoxyethylene alkyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphoric acid, polyoxyethylene alkyl ether phosphoric acid, Polyoxyethylene alkylphenyl ether phosphate, naphthalenesulfonic acid formaldehyde condensate, salts thereof, and the like.

Cationic compatibilizers 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.

Examples of nonionic compatibilizers include polyoxyalkylene ethers such as polyoxyethylene alkyl ethers and polyoxyethylene-polyoxypropylene alkyl ethers; 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, monomethylamine, dimethylamine, trimethylamine , monoethanolamine, diethanolamine, triethanolamine, morpholine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 1-amino-2-propanol, triisopropanolamine, polyoxyethylenealkylamine, triethanolamine fatty acid Examples include organic amine compounds such as partial esters and trialkylamine oxides.

Amphoteric compatibilizers 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.

As the compatibilizing agent (c), a compound corresponding to the compound (b) having at least one hydroxyl group may be included. is treated as a compatibilizer (c).
Examples of alkanolamine compounds (hydroxyl-containing amines) include monoethanolamine, diethanolamine and triethanolamine. Alkanolamide compounds include monoethanolamide, diethanolamide and triethanolamide.
Examples of hydroxy compounds having 12 or more carbon atoms include polyoxyethylene alkyl ether-based, thioether-based, polyoxyalkylene glycol-based, acetylene glycol-based, ester-based and glycoside-based hydroxy compounds having 12 or more carbon atoms.

Among the compatibilizers (c) that can be contained in the cleaning agent, it is preferable to use at least one selected from the group consisting of aromatic sulfonates and hydroxyl-containing amine compounds from the viewpoint of compatibility and handleability. Specific compounds include alkanolamines such as sodium benzenesulfonate, sodium toluenesulfonate, sodium 2,4-dimethylbenzenesulfonate, sodium 2-naphthalenesulfonate, monoethanolamine, diethanolamine and triethanolamine. . Among these, use of the aromatic sulfonate having a high boiling point is more preferable from the viewpoint of raising the upper limit of heating of the cleaning agent.
Here, as described above, it is assumed that a compound different from the alkalinizing agent (a) is used.

Specific examples of the combination of the alkalinizing agent (a) and the compatibilizing agent (c) include an anion as the compatibilizing agent (c) when an inorganic alkalinizing agent is used as the alkalinizing agent (a) At least one selected from the group consisting of system compatibilizers, cationic compatibilizers, nonionic compatibilizers, and amphoteric compatibilizers may be used. When an organic alkalinizing agent is used as the alkalinizing agent (a), the compatibilizing agent (c) may be an anionic compatibilizing agent, a cationic compatibilizing agent, or a nonionic phase other than an organic amine compound. At least one selected from the group consisting of solubilizers and amphoteric compatibilizers may be used.

In the present detergent, an inorganic alkalinizing agent is used as the alkalinizing agent (a), and at least one selected from the group consisting of aromatic sulfonates and hydroxyl group-containing amine compounds is used as the compatibilizing agent (c). It is preferred to use
Among them, a combination of at least one inorganic alkalinizing agent selected from the group consisting of sodium hydroxide and potassium hydroxide and an aromatic sulfonate such as sodium 2,4-dimethylbenzenesulfonate is preferred.
In addition, at least one inorganic alkalinizing agent selected from the group consisting of sodium hydroxide and potassium hydroxide, monoethanolamine, diethanolamine, triethanolamine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol , 1-amino-2-propanol, and triisopropanolamine, preferably a combination of at least one hydroxyl-containing amine compound selected from the group consisting of sodium hydroxide and potassium hydroxide. A combination of at least one inorganic alkalinizing agent and at least one hydroxyl group-containing amine compound selected from the group consisting of monoethanolamine and diethanolamine is more preferable.

Two or more of the above compatibilizers may be used in combination from the viewpoint of comprehensively compatibilizing various additives in the detergent.
The content of the compatibilizing agent (c) in the detergent is preferably in the range of 1 to 30% by mass. Sufficient detergency can be obtained within the above range. From the above viewpoints, the content of the (c) compatibilizing agent in the detergent is more preferably in the range of 5 to 25% by mass, more preferably in the range of 8 to 20% by mass, and further preferably in the range of 10 to 20% by mass. % range is even more preferred.

The cleaning agent used in the present invention is preferably an aqueous cleaning agent. The water-based detergent is obtained by dissolving and diluting the above components (a) to (c) 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.

The cleaning agent used in the present invention may contain various additives in addition to the above components (a) to (c). For example, antioxidants, rust inhibitors, pH adjusters, preservatives, viscosity adjusters, antifoaming agents, etc. can be added.

The washing step (B) in the functional layer removing method of the present invention is a step of removing the functional layer of the laminated polyester film using the washing agent. The washing step (B) includes, for example, an immersion method in which the laminated polyester film is immersed in a washing bath containing a detergent, a coating method in which a detergent in solution is applied to the laminated polyester film, and a detergent in solution or vaporized washing. A spraying method or the like can be used in which the agent is sprayed onto the laminated polyester film. Among these methods, the immersion method is preferable from the viewpoint of penetration of the cleaning agent into the laminated polyester film.

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 cleaning agent has a low viscosity and easily permeates each layer of the laminated polyester film, so that good cleaning properties can be obtained. From the above viewpoints, the temperature of the cleaning agent in the immersion method is preferably 40° C. or higher, more 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 the water-based detergent, which is a preferred embodiment of the present invention, the temperature is preferably 100°C or lower, more preferably 90°C or lower.
Note that the temperature of the cleaning agent during cleaning is the same as described above even in methods other than the immersion method.
In the washing 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.

It is preferable that the cleaning time (for example, the immersion time in the case of the immersion method) is appropriately adjusted as follows depending on the type of object to be cleaned.

When a polyester film provided with an acrylic adhesive layer as a functional layer is to be washed, the washing time is preferably 1 second or more and 30 minutes or less. When the time is 1 second or longer, the cleaning agent sufficiently permeates into the laminated polyester film, and cleaning performance can be exhibited. On the other hand, when the time is 30 minutes or less, the polyester film does not dissolve excessively, and the amount of polyester obtained when recovered can be ensured.
From the above viewpoints, the washing time 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, the washing time is preferably 1 second or more and 30 minutes or less. When the time is 1 second or longer, the cleaning agent sufficiently permeates into the laminated polyester film, and cleaning performance can be exhibited. On the other hand, when the time is 30 minutes or less, the polyester film does not dissolve excessively, and the amount of polyester obtained when recovered can be ensured.
From the above viewpoints, the washing time is more preferably 15 seconds or more and 30 minutes or less, further 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 washed, the washing time is preferably 1 second or more and 30 minutes or less. When the time is 1 second or longer, the cleaning agent sufficiently permeates into the laminated polyester film, and cleaning performance can be exhibited. On the other hand, when the time is 30 minutes or less, the polyester film does not dissolve excessively, and the amount of polyester obtained when recovered can be ensured.
From the above viewpoints, the washing time is more preferably 15 seconds or more and 20 minutes or less, further preferably 30 seconds or more and 10 minutes or less, and particularly preferably 1 minute or more and 5 minutes or less. .

When the functional layer contains (meth)acrylate, which is one of the preferred embodiments described above, the washing time (immersion time) is preferably 1 second or more and 30 minutes or less. When the time is 1 second or more, the cleaning agent sufficiently penetrates into the laminated polyester film, and cleaning performance can be exhibited. On the other hand, when the time is 30 minutes or less, the polyester film does not dissolve excessively, and the amount of polyester obtained when recovered can be ensured.
From the above viewpoints, the washing time (immersion time) is more preferably 15 seconds or more and 20 minutes or less, further preferably 30 seconds or more and 10 minutes or less, and 1 minute or more and 5 minutes or less. is particularly preferred.

The washing step (B) is preferably a step of removing the functional layer by immersing it in a washing bath containing a detergent. As a specific aspect of the cleaning step (B), it is preferable to remove the functional layer in order from the irradiation step (A) and the cleaning step (B) by a roll-to-roll method.
According to the above aspect, the functional layer can be efficiently removed from the roll-shaped laminated polyester film which is a waste material, and the steps required for removing the functional layer can be minimized.

<Recovery process>
After removing the functional layer from the laminated polyester film using this functional layer removing method, there may be a recovery step of recovering the polyester film. Moreover, the functional layer removing method may have a rinsing step and a drying step, which will be described later, before the recovery step. Each step is continuously carried out by roll-to-roll, and it can be efficiently collected by winding up through an irradiation step, a washing step, and optionally a rinsing step and a drying step.
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 removing the functional layer and before the recovering step, a rinsing step for washing away the cleaning agent may be provided. This step is a step of washing away the cleaning agent adhering to the polyester film after removing the functional layer with a rinsing liquid. Water is preferable as the rinsing liquid, but the rinsing step can be omitted if the cleaning agent does not need to be washed away.

In the rinsing step, the functional layer separated from the polyester film may also be washed away together with the cleaning agent. The water and materials that made up the functional layer are then separated and the water can be reused in the rinsing step. In addition, it is also possible to reuse the material that constitutes the functional layer.

The rinsing step is preferably performed after the washing step, and since the washing step is preferably performed after the irradiation step as described above, it is preferable to perform the irradiation step, the washing step, and the rinsing step in this order.

<Drying process>
A drying step may follow the rinsing step. 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. In addition, when the rinsing process is omitted, the drying process is preferably performed after the washing process.

<Recycled polyester product and its manufacturing method>
The polyester film obtained by this method for removing the functional layer can be reused as a polyester raw material for the production of so-called recycled polyester products. In one aspect of the present invention, a method for producing a recycled polyester product includes a recovery step of recovering the polyester film from which the functional layer has been removed by the above-described method for removing the functional layer, and a recycled polyester product using the recovered polyester film as a raw material. and a manufacturing process for manufacturing the

Specifically, the recovered polyester film can be pelletized and stored as pellet-like polyester (polyester product). Also, the recovered polyester film can be incorporated into at least a part of the raw material and formed into various polyester products such as a polyester film by melt extrusion or the like. The subject of the present invention is also a recycled polyester product containing, as a raw material, at least a part of the polyester film from which the functional layer has been removed by the method for removing the functional layer.
From the viewpoint of ease of production, the recovered polyester film 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 polyester film.
Recycled polyester can also be used by blending with conventionally produced polyester. Moreover, it is also possible to make a multilayer film using recycled polyester and polyester produced by a conventional method.
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 removal device for laminated polyester film>
The functional layer removing apparatus for a laminated polyester film according to the present invention (hereinafter also referred to as "this functional layer removing apparatus") irradiates a laminated polyester film having a functional layer on at least one surface of the polyester film with an active energy ray. and a cleaning device that includes a cleaning agent containing an alkalinizing agent (a) and cleans the laminated polyester film with the cleaning agent.
The functional layer removing apparatus will be described below with reference to FIG. Note that the apparatus shown in FIG. 1 is an example schematically shown for describing the embodiment, and is not limited to the configuration shown in FIG. For example, the configuration of FIG. 1 shows a so-called roll-to-roll system in which a roll-shaped laminated polyester film is unwound and further wound up with a roll, but other systems may be used. .

(Irradiation device)
The functional layer removing device 10 has an irradiation device 11 . An unwinding device 12 is installed in front of the irradiation device 11 , and the laminated polyester film F is unwound from the device 12 . After that, as described above, a moving device (not shown) for moving the laminated polyester film by, for example, a belt conveyor, etc., or an unwinding device 12 and a winding device 17 are provided. The laminated polyester film may be transported to a predetermined irradiation position by moving the target laminated polyester film.
The unwinding device 12 unwinds the roll-shaped laminated polyester film F into a sheet and supplies it to the irradiation device 11 . The irradiation device 11 has an irradiation lamp 11A at a predetermined irradiation position. The irradiation lamp 11A may be arranged at a position where the functional layer of the laminated polyester film F can be irradiated with active energy rays. Although one irradiation lamp 11A is shown in FIG. 1, one or more irradiation lamps 11A may be arranged.

Irradiation of the active energy ray by the irradiation device 11 may be carried out by, for example, irradiating the laminated polyester film on the belt conveyor with the irradiation lamp 11A while moving the laminated polyester film on the belt conveyor.
Alternatively, the laminated polyester film may be irradiated with active energy rays using an irradiation lamp in a roll-to-roll system provided with an unwinding device and a winding device.

The functional layer removing device 10 further includes a cleaning device 13 .

(Washing equipment)
The cleaning device 13 is equipped with a cleaning agent containing the compound described above, and is a device for cleaning the laminated polyester film F with the cleaning agent. Typically, as shown in FIG. 1, a washing tank filled with the above-described detergent is used as the washing tank, and the laminated polyester film F, which is a waste material, is introduced into the washing tank and immersed in the washing tank for washing.
As the cleaning device, a coating device for applying a cleaning agent in a solution state, a cleaning agent in a solution state or in a vaporized state, or a spraying device for forming a mist of the cleaning agent and spraying the mist may be used.

The cleaning agent is as described above, and the cleaning agent is preferably a water-based cleaning agent. It is preferable to use a water-based cleaning agent because it enables rinsing with water in a rinsing device 14, which will be described later.

Further, the functional layer removing apparatus 10 is preferably provided with a rinsing apparatus 14 as described in detail below.

(Rinse device)
The rinsing device 14 is a device for washing away the cleaning agent adhering to the polyester film after the functional layer has been removed by the irradiation device 11 and the cleaning device 13 . Specifically, a spraying device for spraying a rinse liquid, an immersion device for immersing in a rinse liquid shown in FIG. 1, and the like can be used. As described above, when a water-based cleaning agent is used as the cleaning agent, water can be used in the rinsing step, which is highly safe and does not require an explosion-proof device, which is preferable in terms of cost.
Further, the functional layer removing apparatus 10 may include a separating device (not shown) that separates the rinse liquid used in the rinsing device 14 into the material constituting the functional layer and water. The separator may be of any type, and may be a device that separates by filtering with a filter, a solid-liquid separator such as a centrifugal separator, an oil-water separator, or a device that vaporizes and separates water such as a distiller. Also, the separation device may be used singly, or two or more separation devices may be used in combination. The functional layer removing device can reuse the water used as the rinsing liquid and the material forming the functional layer by including the separating device.

As shown in FIG. 1, the rinsing device 14 is preferably arranged after both the irradiation device 11 and the cleaning device 13 . Therefore, it is preferable to arrange the irradiation device 11, the cleaning device 13, and the rinse device 14 in this order from the front stage.
However, the rinse device 14 may be omitted.

(Drying device)
Preferably, the functional layer removing device 10 according to the present invention further comprises a drying device 15, which will be described in detail below.
The drying device 15 is for drying the polyester film F from which the functional layer has been removed and the detergent has been washed away by the rinsing device 14, and the drying conditions are as described above.
Examples of the drying device 15 include infrared heaters, ovens, hot air dryers, microwave heating dryers, and the like. The polyester film is collected through the drying process in the drying device.
The functional layer removing device 10 preferably has both the rinsing device 14 and the drying device 15 .
If the rinsing device 14 is omitted, the drying device 15 may be provided after the cleaning device 13 to dry the polyester film after cleaning with the cleaning agent.

<Recycling device>
The functional layer removing device described above is preferably used in a recycling device. In the present invention, the recycling device 16 includes the functional layer removing device 10 described above, a collecting device for collecting the polyester film from which the functional layer has been removed, and a manufacturing device for manufacturing recycled polyester products using the collected polyester film as a raw material. , provided. A device for collecting the polyester film is not particularly limited, but it is preferable that it is a winding device 17 for collecting the polyester film from which the functional layer has been removed in a roll form.
The recycling device 16 preferably has a pellet manufacturing device 18 as one of manufacturing devices for manufacturing recycled polyester products. The recovered polyester film is preferably pelletized in a pelletizing device 18 in order to facilitate handling. By pelletizing the polyester film, the handleability can be further improved.
Further, the recycling device 16 may be provided with a manufacturing device other than a pellet manufacturing device, such as an extruder, instead of the pellet manufacturing device 18, as one of manufacturing devices for manufacturing recycled polyester products. The recovered polyester film may be used as a polyester product in a form other than pellets as described above, and may be used as a recycled polyester product in the form of a film, for example. The recycling device 16 may include both a pellet manufacturing device and a manufacturing device other than the pellet manufacturing device. The pellets produced by the pellet production equipment may be made into various recycled polyester products by other production equipment.

<<explanation of words>>
In the present invention, the term "film" includes the "sheet", and the term "sheet" includes the "film".
In the present invention, when "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, "X or more and Y or less" and "preferably larger than X" or "preferably Y It also includes the meaning of "less than".
In addition, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably greater than X" unless otherwise specified, and is described as "Y or less" (Y is an arbitrary number). If not otherwise specified, it also includes the meaning of "preferably smaller than Y".

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) 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.

(2) Removal rate evaluation of functional layer: Trace total nitrogen analysis Using a trace total nitrogen analyzer (TN-2100H, manufactured by Nitto Seiko Analyticc Co., Ltd.), N contained in the laminated polyester film after the irradiation process or after the washing process Quantitative analysis of elements was performed. In this evaluation, the N element content of the laminated polyester film before treatment was set to 100%, and the functional layer of the laminated polyester film was not coated, and the N element content of the plain film was set to 0% to remove the functional layer. rate was calculated.

<Functional layer removing method>
(A) Irradiation step Using an irradiation device, an A4 (300 × 225 mm) size laminated polyester film was irradiated with excimer light according to the conditions in Table 1 below (illuminance on tube surface: 100 mW/cm ² , reaching illumination: 64 mW/cm ^{2 )} . , irradiation distance 2 mm, 5 irradiation lamps, nitrogen atmosphere (oxygen concentration 1% or less), temperature 25° C., humidity 50%). The irradiation apparatus used was a laboratory testing machine, and irradiation was performed while conveying at a conveying speed of 1 m/min.

(B) Washing step The following detergent was placed in a 30 ml container, and a laminated polyester film having a size of 40 x 30 mm was immersed therein. The cleaning agent was immersed at 80° C. for 5 minutes.
(Washing soap)
(a) component: potassium hydroxide 5 parts by mass (b) component: benzyl alcohol 41 parts by mass (c) component: sodium 2,4-dimethylbenzenesulfonate 18 parts by mass Other components: water 36 parts by mass

<Laminated polyester film having a functional layer>
A laminated polyester film having the following functional layers was prepared as a sample.
Laminated polyester film: Laminated polyester film having a functional layer (hard coat layer, 1 μm) containing urethane acrylate as a main component on one side of a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, Diafoil, 31 μm)

[Example 1]
The irradiation step was carried out under the conditions shown in Table 1 using the above laminated polyester film.
Next, the above washing process was performed, and the functional layer removal rate after the washing process was calculated as described above. Table 1 shows the evaluation results.

[Comparative Example 1]
Using the above laminated polyester film, only the irradiation step was performed under the conditions shown in Table 1, and the functional layer removal rate after the irradiation step was calculated.

[Comparative Example 2]
Using the laminated polyester film, only the washing process was performed, and the functional layer removal rate after the washing process was calculated.

As shown in Table 1, by including the irradiation step and the washing step, the functional layer can be sufficiently removed from the laminated polyester film, and the removal rate of the functional layer can be improved. Since the functional layer can be removed from the laminated polyester film at a high removal rate in this manner, it is possible to recycle the polyester film without causing problems such as the generation of offensive odors, quality deterioration, and defective film formation.

10 Functional layer removal device 11 Irradiation device 11A Irradiation lamp 12 Unwinding device 13 Washing device 14 Rinsing device 15 Drying device 16 Recycling device 17 Winding device 18 Pellet manufacturing device F Laminated polyester film

Claims (13)

An irradiation step (A) of irradiating an active energy ray to a laminated polyester film having a functional layer on at least one surface of the polyester film;
a cleaning step (B) of cleaning the laminated polyester film with a cleaning agent containing an alkalizing agent (a);
A method for removing a functional layer of a laminated polyester film. 2. The method for removing a functional layer of a laminated polyester film according to claim 1, wherein said active energy ray is a vacuum ultraviolet ray. 3. The method for removing a functional layer of a laminated polyester film according to claim 2, wherein the vacuum ultraviolet rays are excimer rays. The method for removing a functional layer of a laminated polyester film according to any one of claims 1 to 3, wherein the irradiation step (A) is performed in a nitrogen atmosphere. The method for removing a functional layer of a laminated polyester film according to any one of claims 1 to 4, wherein the cleaning agent further contains a compound (b) having at least one hydroxyl group. The method for removing a functional layer of a laminated polyester film according to any one of claims 1 to 5, wherein the functional layer contains (meth)acrylate. The method for removing a functional layer of a laminated polyester film according to claim 6, wherein urethane acrylate is contained as the (meth)acrylate. The method for removing a functional layer of a laminated polyester film according to any one of claims 1 to 7, further comprising a rinsing step for washing off the cleaning agent adhering to the polyester film after removing the functional layer. A recycled polyester product containing, as a raw material, at least a part of the polyester film from which the functional layer has been removed by the method for removing the functional layer according to any one of claims 1 to 8. A recovery step of recovering the polyester film from which the functional layer has been removed by the method for removing the functional layer according to any one of claims 1 to 8;
A manufacturing process for manufacturing a recycled polyester product using the collected polyester film as a raw material;
A method of manufacturing a recycled polyester product, comprising: An irradiation device for irradiating an active energy ray to a laminated polyester film having a functional layer on at least one surface of the polyester film;
a cleaning device comprising a cleaning agent containing an alkalinizing agent (a) and cleaning the laminated polyester film with the cleaning agent;
A functional layer removing device for a laminated polyester film. 12. The functional layer removing apparatus for a laminated polyester film according to claim 11, further comprising a rinsing device for washing off the cleaning agent adhering to the polyester film from which the functional layer has been removed. The functional layer removing device according to claim 11 or 12;
a collecting device for collecting the polyester film from which the functional layer has been removed by the functional layer removing device;
A manufacturing device that manufactures recycled polyester products using the collected polyester film as a raw material,
a recycling device.

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