Coating layer removal method

Abstract

To provide a method for removing a coating layer, which can more easily remove the coating layer from a laminated film. [Solution] A method for removing a coating layer, comprising, in this order: a preparation step of preparing a laminated film (e.g., roll 50C) having a base film and a coating layer; an ultrasonic treatment step of irradiating the laminated film with ultrasonic waves via water W1; a removal step of removing the coating layer from the laminated film by treating the laminated film with treated water or water vapor; and a recovery step of recovering the base film, wherein the coating layer includes a hydrophilic and water-insoluble intermediate layer and a release agent layer, and the intermediate layer is disposed between the base film and the release agent layer.

Description

[Technical Field]

[0001] The present invention relates to a method for removing a coating layer. [Background technology]

[0002] In recent years, from the perspective of protecting global resources and the environment, there has been an increasing movement in various fields to build a recycling-oriented society through efforts such as reducing waste generation, reusing, and recycling. For example, Patent Document 1 discloses a release sheet that is a laminate having a substrate, an intermediate layer, and a release agent layer in this order on at least one surface side of the substrate, wherein the intermediate layer is a layer formed from a composition for forming an intermediate layer that contains a silane-based compound (A) that exhibits polycondensation properties through hydrolysis and an acrylate compound (B). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-148709 Summary of the Invention [Problem to be solved by the invention]

[0004] In the release sheet described in Patent Document 1, the substrate is separated from the release sheet by contacting the hydrophilic intermediate layer (containing a silane compound (A) and an acrylate compound (B)) with water. However, depending on the type of release sheet, the substrate may not be separated from the release sheet unless an operation such as stirring the release sheet in a water tank is performed. Furthermore, separating the substrate by leaving the release sheet in a water tank may take time. There is a need for a technology that allows for easier removal of a coating layer from a release sheet without adding any complicated means. Here, a release sheet in which multiple layers (e.g., an intermediate layer and a release agent layer) are laminated on a substrate, such as the release sheet described in Patent Document 1, is sometimes called a laminated film.

[0005] An object of the present invention is to provide a method for removing a coating layer that can more easily remove the coating layer from a laminated film. [Means for solving the problem]

[0006] [1] A preparation step of preparing a laminated film having a substrate film and a coating layer; an ultrasonic treatment step of irradiating the laminated film with ultrasonic waves through water; a removing step of removing the coating layer from the laminate film by treating the laminate film with treated water or water vapor; a recovery step of recovering the base film, the coating layer includes a hydrophilic and water-insoluble intermediate layer and a release agent layer; The intermediate layer is disposed between the base film and the release agent layer. How to remove the coating layer. [2] The laminated film in the ultrasonic treatment step is in a sheet, roll, or folded form; The method for removing a coating layer according to [1] above. [3] When the laminated film is in a roll or folded form, The method further includes a cutting step of cutting the laminated film into sheets between the ultrasonic treatment step and the removing step. The method for removing a coating layer according to [2] above. [4] The ultrasonic treatment step is carried out while the laminated film is immersed in water. The method for removing a coating layer according to any one of [1] to [3] above. [5] The removing step is a step of placing the laminated film and the treated water in a pressure vessel, heating the treated water while immersing the laminated film in the treated water, and pressurizing the pressure in the pressure vessel to a pressure higher than 1 atmosphere. The method for removing a coating layer according to any one of [1] to [4] above. [6] The removing step is a step of placing the laminated film in a treatment container and exposing the laminated film to water vapor in the treatment container. The method for removing a coating layer according to any one of [1] to [4] above. [7] The laminated film prepared in the preparing step is a laminated film with a ceramic green sheet, a ceramic green sheet is attached to the coating layer on the opposite side to the substrate film; The method for removing a coating layer according to any one of [1] to [6] above. [Effects of the Invention]

[0007] According to one aspect of the present invention, a method for removing a coating layer can be provided that allows for easier removal of a coating layer from a laminated film. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view of a laminated film used in the removal method according to the present embodiment. [Figure 2A] FIG. 3 is a diagram showing an example of a roll used in the removal method according to the embodiment. [Figure 2B] 10A and 10B are diagrams showing an example of a folded laminate used in the removal method according to the present embodiment. [Figure 2C] 1A and 1B are diagrams showing an example of a stack of sheets used in a removal method according to an embodiment of the present invention; [Figure 3A] FIG. 2 is a diagram showing an example of an ultrasonic treatment device used in the ultrasonic treatment step according to the present embodiment. [Figure 3B] FIG. 3B is a top view of FIG. 3A. [Figure 4] 5A to 5C are diagrams illustrating a cutting step according to the embodiment. [Figure 5] 5A to 5C are diagrams for explaining a removal step according to the embodiment. [Figure 6] 5A to 5C are diagrams for explaining a removal step according to the embodiment. [Figure 7] FIG. 4 is a diagram for explaining a recovery process according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] (Method for removing the coating layer) The coating layer removal method according to the present embodiment (hereinafter also referred to as the removal method according to the present embodiment) comprises, in this order, a preparation step of preparing a laminated film having a substrate film and a coating layer, an ultrasonic treatment step of irradiating the laminated film with ultrasonic waves via water, a removal step of removing the coating layer from the laminated film by treating the laminated film with treated water or water vapor, and a recovery step of recovering the substrate film. The coating layer includes a hydrophilic and water-insoluble intermediate layer and a release agent layer, and the intermediate layer is disposed between the substrate film and the release agent layer.

[0010] The present inventors have discovered that in a laminated film in which an intermediate layer and a release agent layer (coating layer) are laminated in this order on a base film, by performing a simple process (ultrasonic treatment process) of irradiating the laminated film with ultrasonic waves via water, and then treating the laminated film with treated water or water vapor, the coating layer will naturally separate, i.e., the coating layer will naturally peel off from the base film. The reasons for this are thought to be as follows. Generally, when ultrasonic waves are irradiated into a liquid, positive and negative pressures are alternately applied to the gas components (oxygen, nitrogen, carbon dioxide, etc.) contained in the water. This repeated compression and expansion causes the generation and disappearance of tiny bubbles that are difficult to see with the naked eye, resulting in the following (1) and (2). (1) The liquid near the object is pushed toward the object by the generated bubbles. (2) When bubbles that have formed near the object disappear, a flow of liquid is generated that tries to enter the space where the bubbles were present. It is believed that the phenomena (1) and (2) above impact the cross section of the edge of the laminated film (film edge), forming "peeling triggers" (triggering the coating layer to separate) in various places along the edge. The term "triggering of peeling" refers to the occurrence of peeling at the edge of the laminated film, resulting in the formation of a small gap between the base film and the intermediate layer at that edge. For example, when a laminate film is in roll form, the above phenomena (1) and (2) also occur at the edge in the TD direction of the roll (the direction perpendicular to the flow direction during production), and water penetrates into the interface between the base film and the intermediate layer, forming a "peeling trigger." When a laminate film with a "peeling trigger" formed is contacted with treated water or steam in the subsequent removal process, the treated water or steam penetrates into the small gap that has formed at the edge of the laminate film. The treated water or steam further widens the small gap and continuously weakens the adhesion of the coating layer from the edge to the center of the laminate film, promoting peeling of the coating layer. This is thought to result in spontaneous peeling of the coating layer. As described above, in the removal method according to this embodiment, first, a "peeling trigger" is formed in the laminated film in the ultrasonic treatment step, and then, in the subsequent removal step, the coating layer is peeled from the laminated film using the "peeling trigger" as the starting point. Therefore, it is significant to perform the ultrasonic treatment step and the removal step in this order.

[0011] According to the removal method of this embodiment, even for laminated films for which the coating layer could not be peeled off without operations such as stirring in a water tank in conventional removal processes, natural peeling of the coating layer can be caused by performing the removal process after the ultrasonic treatment process, and as a result, the coating layer can be easily removed from the laminated film. Therefore, it can be said that the ultrasonic treatment process of this embodiment is a means for promoting improved separation of the coating layer. In the removal method according to this embodiment, even if an ultrasonic treatment step is performed after the removal step, natural peeling of the coating layer is unlikely to occur, whereas natural peeling of the coating layer occurs when the removal step is performed after the ultrasonic treatment step. The removal method according to this embodiment has a preparation step, an ultrasonic treatment step, a removal step, and a recovery step in this order, thereby achieving the effect of this embodiment (easier removal of the coating layer).

[0012] In the removal method according to this embodiment, the water used in the ultrasonic treatment step and the treated water used in the removal step will be described later.

[0013] (Laminated film) FIG. 1 is a cross-sectional view of a laminated film used in the removal method according to this embodiment. The laminated film 50 has a base film 51 and a coating layer 52. The coating layer 52 includes an intermediate layer 521 and a release agent layer 522, and the intermediate layer 521 is disposed between the base film 51 and the release agent layer 522. 1, a indicates the surface of intermediate layer 521 facing the base film, b indicates the surface of intermediate layer 521 facing the release agent layer, d indicates the surface of the release agent layer, c indicates the surface of release agent layer 522 facing the intermediate layer, and e indicates the surface of the base film. In the laminated film according to this embodiment, the base film and the intermediate layer are preferably in direct contact with each other. In the case of Fig. 1, the base film 51 and the intermediate layer 521 are in direct contact with each other, and the intermediate layer 521 and the release agent layer 522 are in direct contact with each other.

[0014] The laminated film 50 may be a laminated film used in the production of a ceramic green sheet after the ceramic green sheet has been peeled off. Residues of the ceramic green sheet may be attached to the laminated film. The ceramic green sheet is preferably used in the production of a multilayer ceramic capacitor (MLCC). The laminated film 50 is a laminated film with a ceramic green sheet, and a ceramic green sheet may be attached to the surface of the coating layer 52 opposite to the substrate film 51 (symbol d in FIG. 1). Fig. 2A is a diagram of a roll in which a laminated film 50G with a ceramic green sheet is wound around a shaft core 1G. Fig. 2A shows a state in which the laminated film 50G with a ceramic green sheet is unwound from the roll. 2A, residue 920 of the ceramic green sheet is attached to the surface of coating layer 52. After the ceramic green sheet is peeled off, recesses 910 are formed, and coating layer 52 is exposed from recesses 910.

[0015] In the laminated film used in the removal method according to this embodiment, the intermediate layer is hydrophilic and water-insoluble. When the intermediate layer is hydrophilic, the coating layer can be more easily removed from the laminated film. The reason for this will be explained with reference to FIG. The intermediate layer 521 in the laminate film 50 is adhered to the base film 51 mainly by hydrogen bonding and the anchor effect (FIG. 1). If the intermediate layer 521 is hydrophilic, then in the removal step, the laminate film is immersed in treatment water or exposed to water vapor, which makes it easier for the treatment water or water vapor to penetrate into the interface between the base film 51 and the intermediate layer 521 from the end of the laminate film 50 in the planar direction, and it is thought that this weakens the hydrogen bonding and anchor effect between the intermediate layer 521 and the base film 51. In the removal method according to this embodiment, "peeling triggers" are formed in various places at the edges of the laminated film during the ultrasonic treatment process prior to the removal process, and therefore, it is believed that the coating layer 52 (intermediate layer 521 and release agent layer 522) will naturally peel off during the removal process (treatment using treated water or water vapor).

[0016] Furthermore, since the intermediate layer is water-insoluble, the components of the intermediate layer 521 are prevented from eluting into water during the ultrasonic treatment step. Similarly, in the subsequent removal step, the components of the intermediate layer 521 are prevented from eluting into the treated water. Therefore, since the intermediate layer 521 is water-insoluble, contamination of the water or treated water can be prevented, and the water or treated water can be easily reused after use.

[0017] In this specification, whether an intermediate layer is "hydrophilic" or not is determined to be hydrophilic when the contact angle of water on the surface of the intermediate layer facing the substrate film is 55 degrees or less. In the case of the laminated film 50 shown in FIG. 1, when the water contact angle of the surface of the intermediate layer 521 on the base film side (symbol a in FIG. 1) is 55 degrees or less, the intermediate layer 521 is hydrophilic. Furthermore, from the viewpoint of promoting the separability of the base film, the contact angle is preferably 50 degrees or less, more preferably 45 degrees or less. The contact angle is a value obtained by measuring the water contact angle of the surface of the intermediate layer that was in contact with the base film (the peeled surface) after separating the base film from the laminate film, i.e., after contacting the intermediate layer with water and peeling the interface between the intermediate layer and the base film. Purified water is used as the water that is brought into contact with the intermediate layer when measuring the water contact angle.

[0018] Specifically, the intermediate layer is separated from the substrate film and the water contact angle of the surface of the intermediate layer facing the substrate film is measured by the following method: The obtained value is the water contact angle of the surface of the intermediate layer facing the substrate film. A 50 mm wide adhesive tape (manufactured by Nitto Denko Corporation, product name "Polyester Adhesive Tape No. 31B") is attached to the surface of the release agent layer of the laminated film, and then cut to a size of 50 mm x 50 mm to prepare a test piece. 2 L of purified water was placed in a 5 L pressure vessel, and the purified water was boiled to 100°C using a heater. The test specimen (cut into a size of 50 mm x 50 mm) was then immersed in the boiling water (purified water) at 100°C. The lid of the pressure vessel was then closed, and heating was resumed so that the pressure inside the vessel was reduced to 2 atmospheres. Boiling (fuming) was confirmed to confirm that the pressure inside the pressure vessel had reached 2 atmospheres, and after 15 minutes had passed (maintained) in this state, the pressure inside the pressure vessel was returned to normal pressure. After that, it is confirmed that the test piece is separated into a laminate in which the release agent layer and the intermediate layer are integrally supported on the adhesive tape and the base film in the pressure vessel, and the adhesive tape supporting the release agent layer and the intermediate layer is removed from the purified water and dried at room temperature for 24 hours. Thereafter, the water contact angle is measured for the surface of the intermediate layer supported on the adhesive tape (the surface of the intermediate layer that was in contact with the surface of the base film).

[0019] The water contact angle may be a value measured by the following method. The test piece (cut into a size of 50 mm x 50 mm) is prepared. Next, a 500 mL glass beaker was filled with 300 mL of purified water, and the entire test piece was immersed in purified water heated to 90°C and left for 3 hours. After that, it was confirmed that the test piece had separated into a laminate in which the release agent layer and intermediate layer were integrally supported on the adhesive tape and the substrate film. The adhesive tape bearing the release agent layer and intermediate layer was then removed from the heated purified water and dried at room temperature for 24 hours. The water contact angle was then measured for the surface of the intermediate layer supported on the adhesive tape (the surface of the intermediate layer that had been in contact with the substrate film surface). The contact angle was measured using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product name "DM-701") by the sessile drop method in accordance with JIS R3257:1999. Distilled water was used for the droplet.

[0020] In this specification, whether an intermediate layer is "water-insoluble" or not is determined when the difference between the water contact angle of the release agent layer surface (symbol d in Figure 1) and the water contact angle of the intermediate layer's surface on the substrate film side (symbol a in Figure 1), measured using the following method, is 30 degrees or more. The difference in contact angles is preferably 40 degrees or more, and more preferably 50 degrees or more. If this difference is small, it means that the components constituting the intermediate layer have dissolved in water and the release agent layer is partially exposed. The water contact angle of the release agent layer surface is not particularly limited, but is usually at least 80 degrees, preferably at least 85 degrees, and more preferably at least 90 degrees. The upper limit of the water contact angle of the release agent layer surface is usually 150 degrees, preferably 140 degrees, and more preferably 130 degrees. The water contact angle of the release agent layer surface is measured using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product name "DM-701") by the sessile drop method in accordance with JIS R3257: 1999. Distilled water is used as the droplet.

[0021] Each step of the removal method according to this embodiment will be described.

[0022] <Preparation process> The preparation step is a step of preparing a laminated film having a substrate film and a coating layer. The laminated film prepared in the preparation step is preferably in the form of a sheet, a roll, or a folded state.

[0023] (roll laminated film) The roll-shaped laminate film is, for example, a roll (hereinafter, sometimes simply referred to as a roll) in which a single long laminate film is wound around a shaft core. The dimensions of the roll are, for example, a width (dimension perpendicular to the winding direction) of 100 mm or more and 1000 mm or less, and preferably 200 mm or more and 600 mm or less. The winding diameter of the roll (the diameter of the roll including the core) is, for example, 100 mm or more and 1500 mm or less, and preferably 150 mm or more and 1000 mm or less. The laminate film constituting the roll is preferably wound up so that the first surface of the coating layer opposite the substrate film (in the case of Figure 1, the release agent layer surface (symbol d)) and the second surface of the substrate film opposite the coating layer (in the case of Figure 1, the substrate film surface (symbol e)) face each other directly or indirectly. "Directly facing" means that the first surface of the coating layer and the second surface of the base film face each other without any other material interposed therebetween, while "indirectly facing" means that the first surface of the coating layer and the second surface of the base film face each other with some other material (e.g., a ceramic green sheet) interposed therebetween (see FIG. 2A).

[0024] (folded laminated film) The folded laminate film is, for example, a laminate in which one sheet-like laminate film is folded by any folding method (hereinafter, may be referred to as a folded laminate). The folding method is not particularly limited, but examples include a method of folding in a zigzag pattern so that the sides of the folded-over portions are aligned (overlapping at the top and bottom) when the folded-over stack is viewed in a plane (see Figure 2B), and a method of folding in a zigzag pattern so that the sides of the folded-over portions do not overlap at the top and bottom. FIG. 2B is a diagram showing an example of a folded stack 50A.

[0025] For example, when a laminate film unwound from a normal roll is folded to form a folded laminate, the size (width, length, and thickness (height)) of the folded laminate is preferably within the following ranges: By folding the laminate film, the folded laminate can be formed into a rectangular parallelepiped block, which makes it easier to load and transport than a roll-shaped laminate. The width of the folded laminate depends on the width of the roll before being unwound, but is usually 100 mm or more and 1000 mm or less, and preferably 200 mm or more and 600 mm or less. The length of the folded laminate is preferably 100 mm or more and 1000 mm or less, more preferably 200 mm or more and 600 mm or less. The thickness (height) of the folded laminate is preferably 100 mm or more and 1000 mm or less, more preferably 200 mm or more and 600 mm or less.

[0026] (sheet-type laminated film) Any number of sheets of laminated film are prepared. The shape of the sheet-like laminated film is not particularly limited, and examples thereof include a rectangular shape, a polygonal shape, etc. The sheet-like laminated film may also have an irregular shape. When the sheet-shaped laminated film is rectangular, the dimensions of the laminated film are, for example, 100 mm or more and 1000 mm or less on one side, and preferably 200 mm or more and 600 mm or less.

[0027] The sheet-like laminated film may be prepared as a stack (hereinafter, sometimes referred to as a sheet stack) in which multiple sheets are stacked in the thickness direction, as shown in Fig. 2C. Fig. 2C is a diagram showing an example of a sheet stack 50B. The method of stacking multiple laminate films is not particularly limited, and the laminate films may be stacked in the same direction, or the laminate films may be stacked so that the base films and coating layers face each other between each laminate film. The laminate films may be stacked in any direction. "Stacking in the same direction" means stacking the laminate films so that the base films and coating layers face each other between each laminate film. The thickness (height) of the stack of sheets is preferably 100 mm or more and 1000 mm or less, more preferably 200 mm or more and 600 mm or less.

[0028] Hereinafter, the term "laminated film" will collectively refer to sheet-shaped, roll-shaped, and folded laminated films.

[0029] <Ultrasonic treatment process> In the removal method according to this embodiment, the ultrasonic treatment step is a step of irradiating the laminated film with ultrasonic waves via water. In the ultrasonic treatment step, ultrasonic waves are irradiated through water to the laminated film prepared in the preparation step, and therefore, the laminated film in the ultrasonic treatment step is preferably in the form of a sheet, a roll, or a folded state. The ultrasonic treatment step is preferably carried out with the laminated film immersed in water, but may also be carried out with only a portion of the laminated film immersed in water. For example, when the laminated film is in the form of a roll, the ultrasonic treatment process may be performed by alternately (i) immersing only the area near the top surface of the roll of the laminated film in water and ultrasonically treating it, and (ii) immersing only the area near the bottom surface of the roll in water and ultrasonically treating it. In the ultrasonic treatment step, the oscillation frequency when irradiating ultrasonic waves is preferably 10 kHz or more and 300 kHz or less, more preferably 20 kHz or more and 200 kHz or less. In the ultrasonic treatment step, the ultrasonic power density is preferably 0.1 W / cm 2 More than 2.0W / cm 2 Less than or equal to 0.3 W / cm, more preferably 0.3 W / cm 2 More than 1.5W / cm2 The following is the result. The ultrasonic power density is calculated by dividing the ultrasonic power set in the ultrasonic oscillator by the area of ​​the vibration plate. In the ultrasonic treatment step, the ultrasonic irradiation time is preferably 1 minute or more and 60 minutes or less, more preferably 3 minutes or more and 30 minutes or less.

[0030] The water used in the ultrasonic treatment step can be water of the same quality as the "normal water" described below in the "Water to be used as treatment water" section. The water used in the ultrasonic treatment step is preferably not pure water or purified water, as this makes it easier for cavitation to occur. This is because pure water and purified water do not contain dissolved gases, and therefore do not generate cavitation when irradiated with ultrasonic waves. Furthermore, water saturated with dissolved gases is also not preferred for use in the ultrasonic treatment process, because the diameter of the cavitation bubbles generated by the ultrasonic waves tends to be too large, which may prevent the impact from reaching the laminated film being treated. The temperature of the water used in the ultrasonic treatment step is preferably 60°C or less from the viewpoint of efficiently generating cavitation and from the viewpoint of the heat resistance of parts such as the ultrasonic vibrator. The lower limit of the water temperature is preferably 10°C or more from the viewpoint of facilitating the generation of cavitation. The temperature of the water used in the ultrasonic treatment step is preferably lower than the temperature of the treated water used in the removal step.

[0031] <Cutting process> In the removal method according to this embodiment, when the laminated film is in a roll or folded form, it is preferable to further include a cutting step of cutting the laminated film into sheets between the ultrasonic treatment step and the removal step. The cutting means for cutting the laminated film into sheets is not particularly limited, and examples thereof include a cutting machine equipped with a cutter, etc. Examples of cutters include a cutter blade, a water jet cutter, a laser cutter, and an ultrasonic cutter. The laminated film unwound from the roll or folded stack is cut into strips, for example, by passing it between a pair of nip rolls and a pair of cutter blades. The size of the cut laminated film is selected arbitrarily depending on the size of the pressure vessel. For example, when the cut laminate film has a rectangular shape, the dimension of one side of the laminate film is preferably 15 cm or less, more preferably 10 cm or less, and even more preferably 5 cm or less. The lower limit of the dimension of one side of the laminate film is preferably 5 mm or more.

[0032] <Removal process> In the removal method according to this embodiment, the removal step is a step of removing the coating layer from the laminate film by treating the laminate film with treated water or water vapor. The removal step is carried out after the ultrasonic treatment step, and by treating the laminated film with treated water or water vapor, the coating layer (intermediate layer and release agent layer) is naturally peeled off from the substrate film.

[0033] The laminated film when the removing step is carried out is preferably in the form of a single laminated film or a laminate of single films. Specifically, when the ultrasonic treatment step is performed on a rolled or folded laminate film, the rolled or folded laminate film is cut in the cutting step described above after the ultrasonic treatment step. Therefore, the laminate film is in the form of a sheet of laminate film when the removal step is performed. The sheet-like laminated film may be randomly housed in a pressure vessel or the like, or may be housed in a holding vessel, or may be fixed (held) using a jig. Examples of the holding vessel include a vessel having a plurality of holes.

[0034] Hereinafter, the removal step in which the laminated film is treated with treated water may be referred to as a removal step according to embodiment 1, and the removal step in which the laminated film is treated with water vapor may be referred to as a removal step according to embodiment 2.

[0035] (Removal step according to embodiment 1 (when treating laminated film with treated water)) The removing step according to the first embodiment is preferably a step of removing the coating layer from the laminate film by immersing at least a portion of the laminate film (preferably the entire laminate film) in treated water. The removing step according to the first embodiment is preferably a step of submerging the substrate film in treatment water and floating the coating layer on the treatment water. The treated water used in the removal step according to the first embodiment may be water or an alkaline aqueous solution.

[0036] (treated water) First, a case where water is used as treated water will be described. The water used as treatment water refers to the liquid water in which the laminated film is immersed in the removal step. The water used as treatment water refers to "normal water," i.e., it is preferably industrial water, and may be purified water, distilled water, or water saturated with dissolved gases. It may also be water recycled from wastewater used in various industrial production processes, or water recycled from wastewater used in the implementation of this embodiment. When wastewater is reused, it may be recycled wastewater as appropriate. From the viewpoint of improving work efficiency, the water used as the treated water may contain additives that impart functionality as appropriate, but it is preferable that it does not contain additives. Examples of additives include surfactants and water-soluble organic solvents. When the water used as the treated water contains additives, the concentration of the active ingredient of the additive in the treated water is preferably 0.2 mass% or less, more preferably 0.1 mass% or less, relative to the total amount of the treated water. Furthermore, it is preferable that the water used as the treated water is not water to which additives have been intentionally added. Furthermore, since there is a possibility that wastewater can be recycled simply, the water used as treated water may contain basic and acidic substances as additives. In this case, however, it is preferable that the pH of the treated water be 5.8 or higher and 8.6 or lower, so as to comply with the uniform effluent standards (other items) based on the Water Pollution Control Act.

[0037] When the treated water is used as hot water, the temperature of the treated water is preferably 80°C or higher and 100°C or lower, and more preferably 90°C or higher and 100°C or lower. In the removal step, after the water temperature reaches a target temperature, the laminate film is kept in the treatment water at this temperature for a predetermined time. In this specification, the time the laminate film is kept in the treatment water from the time the target temperature is reached is defined as the treatment time of the laminate film. The processing time for the laminated film is preferably 5 minutes or more, more preferably 30 minutes or more, and is preferably 120 minutes or less, more preferably 60 minutes or less.

[0038] The water used for treatment may be superheated water, which is liquid water heated under pressure to above 100°C. When the treated water is used in the form of superheated water, the removal step according to aspect 1 is preferably a step of placing the laminated film and the treated water in a pressure vessel, heating the treated water while immersing the laminated film in the treated water, and pressurizing the pressure in the pressure vessel to a pressure higher than 1 atmosphere. The water stored in the pressure vessel can be water of the same quality as the "normal water" described above in the "water used as treated water." Therefore, in the removal process, superheated water used as treated water can be obtained by heating "normal water" under pressure. In the removal step, the air pressure inside the pressure vessel and the temperature of the heated water (superheated water) are determined by Boyle's law, and are preferably within the following ranges. The pressure inside the pressure vessel is preferably 1.2 atmospheres or more, more preferably 1.4 atmospheres or more, from the viewpoint of facilitating infiltration of superheated water into the interface between the base film and the release agent layer. The pressure inside the pressure vessel is preferably 9.9 atmospheres or less, more preferably 4.7 atmospheres or less, from the viewpoint of suppressing melting of the resin component contained in the laminated film. The pressure inside the pressure vessel is adjusted by a pressure regulating valve or the like. The temperature of the superheated water is preferably 105°C or higher, more preferably 110°C or higher, from the viewpoint of facilitating penetration of the superheated water into the interface between the base film and the release agent layer, and is preferably 180°C or lower, more preferably 150°C or lower, from the viewpoint of suppressing melting of the resin component contained in the release film. In the removal step, the time for which the laminate film is held in the superheated water after the water temperature reaches the target temperature (the treatment time of the laminate film) is, for example, preferably 5 minutes or more, more preferably 10 minutes or more, and the treatment time of the laminate film in the superheated water is preferably 40 minutes or less, more preferably 30 minutes or less.

[0039] An alkaline aqueous solution may be used as the treatment water. When an alkaline aqueous solution is used as the treatment water, the removing step according to the first embodiment is a step of removing the coating layer from the laminate film by immersing at least a part of the laminate film (preferably the entire laminate film) in the alkaline aqueous solution as the treatment water. Examples of the alkaline aqueous solution include one or more aqueous solutions selected from a sodium hypochlorite aqueous solution, a sodium hydroxide aqueous solution, and a potassium hydroxide aqueous solution. The alkaline aqueous solution is preferably a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, and more preferably a potassium hydroxide aqueous solution. The alkaline aqueous solution may further contain an auxiliary. Examples of the auxiliary include surfactants, water-soluble inorganic compounds, water-soluble organic compounds, and water-soluble solvents. Specific examples of the auxiliary include nonionic surfactants, water-soluble inorganic salts, water-soluble organic salts, water-soluble polymers, polysaccharides, alcohols, glycols, and water-soluble organic solvents. Examples of glycols include ethylene glycol, diethylene glycol, and propylene glycol. Examples of water-soluble organic solvents include dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and ethylene glycol ethers (various cellosolves). The auxiliary may be used alone or in combination.

[0040] The temperature of the alkaline aqueous solution is preferably 5° C. or higher, more preferably 20° C. or higher. The temperature of the alkaline aqueous solution is preferably 100° C. or lower, more preferably 80° C. or lower.

[0041] In the removal step, the concentration of the alkaline aqueous solution when the laminated film is immersed in the alkaline aqueous solution is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 3.0% by mass or more. The concentration of the alkaline aqueous solution is preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, even more preferably 47% by mass or less, and even more preferably 45% by mass or less. When the alkaline aqueous solution contains an auxiliary, the concentration of the alkaline aqueous solution refers to the total concentration of the alkaline components in the alkaline aqueous solution.

[0042] In the removal step, the laminated film is immersed in the alkaline aqueous solution for preferably 5 minutes or more, more preferably 30 minutes or more, and preferably 120 minutes or less, more preferably 60 minutes or less. In the removal step, the temperature or concentration of the alkaline aqueous solution can be kept mild by prolonging the immersion time of the laminated film. After the removal step is carried out, the alkaline aqueous solution used as the treated water is neutralized so that it can be disposed of.

[0043] (Removal step according to embodiment 2 (when treating laminated film with water vapor)) The removing step according to the second embodiment is preferably a step of placing the laminated film in a treatment container and exposing the laminated film to water vapor in the treatment container. The step of exposing to water vapor is carried out without immersing the laminated film in liquid water. The water vapor used in the removal step according to the second embodiment is obtained by evaporating water for generating water vapor (hereinafter, sometimes referred to as "water for water vapor source"). As the water for water vapor source, water of the same quality as the "normal water" described above in the "water to be used as treated water" can be used. Examples of methods for exposing a laminate film to water vapor include a method in which water vapor is supplied into a treatment vessel while the laminate film is housed in the treatment vessel, and a method in which the laminate film and water for a water vapor source are housed in the treatment vessel and then the water for a water vapor source is heated, etc. Alternatively, the method for exposing a laminate film to water vapor may be a method in which the laminate film is placed in a treatment vessel filled with water vapor.

[0044] In the step of exposing the laminated film to water vapor, from the viewpoint of facilitating penetration of water vapor into the interface between the base film and the intermediate layer and from the viewpoint of suppressing melting of the resin component contained in the laminated film, the air pressure and temperature inside the treatment container in the step of exposing the laminated film to water vapor are preferably within the following ranges. In the step of exposing to water vapor, the pressure inside the treatment vessel is preferably 1.2 atmospheres or more, more preferably 1.4 atmospheres or more, and is preferably 9.9 atmospheres or less, more preferably 4.7 atmospheres or less. In the step of exposing to water vapor, the temperature inside the treatment vessel is preferably 105° C. or higher, more preferably 110° C. or higher. The temperature inside the treatment vessel is preferably 180° C. or lower, more preferably 150° C. or lower.

[0045] In the step of exposing the laminated film to water vapor, the time for exposing the laminated film to water vapor is, for example, 5 minutes or more and 40 minutes or less, and preferably 10 minutes or more and 30 minutes or less.

[0046] <Recovery process> In the removal method according to the present embodiment, the recovery step is a step of recovering the base film. The recovery means is not particularly limited, but examples thereof include at least one of a tray or container having a mesh structure (e.g., a colander), a filter, an outlet of a container, and a pump. The substrate film has the property of easily sinking in the treatment water, while the coating layer has the property of easily floating in the treatment water, and therefore, it is preferable to carry out the recovery step by utilizing these properties. For example, as shown in Figure 5, after the removal process is performed, in the container (pressure container 60A in Figure 5), the base film 51D sinks to the bottom of the container, and the coating layer 52D floats on the upper side of the container. Also, for example, FIG. 7 shows a state in which the substrate film 51D and the coating layer 52D after the removal step have been transferred to a collection container 100 (for example, a water tank). The collection container 100 shown in Fig. 7 includes an upper discharge pipe 18 and a lower discharge pipe 19. The upper discharge pipe 18 is connected to an upper discharge port 18A and has an upper discharge valve 21. The lower discharge pipe 19 is connected to a lower discharge port 19A and has a lower discharge valve 22. The upper discharge valve 21 and the lower discharge valve 22 allow the upper discharge pipe 18 and the lower discharge pipe 19 to be opened and closed, respectively. By using the collection container 100 as shown in FIG. 7, the base film 51D can be easily collected from the lower discharge port 19A. The removal step may also be carried out using a pressure vessel having a base film discharge port at the bottom that is airtight and can be opened or closed. In this case, after the removal step, the base film submerged in the treated water can be easily recovered from the base film discharge port. Water droplets are removed from the recovered substrate film by a known method.

[0047] The method for recovering the coating layer is not particularly limited, and for example, the coating layer may be recovered directly from the pressure vessel after the air pressure inside the pressure vessel is returned to normal pressure, or the contents inside the pressure vessel may be transferred to a recovery vessel 100 equipped with drainage outlets at the top and bottom, as shown in Figure 7, and water may be poured into the pressure vessel, allowing the coating layer 52D in the upper layer portion to be recovered from an upper discharge outlet 18A. The coating layer 52D (residue of the coating layer) tends to float in the treated water, and therefore can be easily recovered using a tray or container with a mesh structure.

[0048] (Example 1) The removal method according to Example 1 is carried out as follows. A roll of laminated film is prepared by winding the laminated film around a shaft core 3G (preparation step, see FIG. 3A). Hereinafter, the roll of laminated film may be referred to as roll 50C. In Specific Example 1, an ultrasonic treatment step is performed on a roll 50C using an ultrasonic treatment device 80 shown in Fig. 3A, and a removal step is performed using a pressure vessel 60A and treated water shown in Fig. 5. The removal step according to Specific Example 1 is an example of the removal step according to Aspect 1. FIG. 3A is a schematic diagram of an ultrasonic processing device 80, and FIG. 3B is a top view of FIG. 3A. The ultrasonic treatment device 80 includes a water tank 81, a vibration plate 82 having an ultrasonic vibrator therein, a treatment object placement table 84 provided above the vibration plate 82, and an ultrasonic oscillator 40 connected to the vibration plate 82. Tap water W1 is stored in the water tank 81. 3B, the workpiece placement table 84 is made up of multiple rod-shaped members 84A spaced apart at regular intervals. The spacing between the rod-shaped members 84A is set to be smaller than the diameter D1 of the roll 50C. The roll 50C is held between the two rod-shaped members 84A above the vibration plate 82, preventing the roll 50C from coming into contact with the vibration plate 82 and interfering with its vibration. A gap is also formed between the roll 50C and the vibration plate 82, which generates cavitation in the gap and applies an impact to the entire roll 50C. The ultrasonic oscillator 40 supplies high frequency power to the diaphragm 82 to drive the diaphragm 82. The ultrasonic processing device 80 generates cavities in the tap water W1 by the ultrasonic vibrations from the diaphragm 82. The distance D2 from the upper surface of the vibrating plate 82 to the lower surface of the roll 50C depends on the diameter D1 of the roll 50C, but is usually 10 mm or more and 500 mm or less. The distance D3 from the upper surface of the vibrating plate 82 to the water surface is usually 110 mm or more and 2000 mm or less. In the case of FIG. 3A, a rubber band 55 is wrapped around the end of the roll 50C to prevent the end of the roll 50C from becoming unwound.

[0049] After the roll 50C is placed on the treatment object placing table 84, tap water W1 is placed in the water tank 81, and the roll 50C is immersed in the tap water W1. The roll 50C may be placed on the treatment object placing table 84 with the tap water W1 placed in the water tank 81. While the roll 50C is immersed in tap water W1, ultrasonic waves are irradiated onto the roll 50C under predetermined conditions (ultrasonic treatment step).

[0050] After the ultrasonic treatment step, roll 50C is removed from water tank 81. Rubber band 55 is removed from roll 50C, and the laminated film is unwound by known means (not shown), and the laminated film is cut into sheets of laminated film using a cutter (not shown) (see FIG. 4). Hereinafter, the cut laminate film sheets, and the base film and coating layer constituting the laminate film sheets may be referred to as laminate film 50D, base film 51D, and coating layer 52D, respectively.

[0051] Next, the coating layer 52D is removed from the laminated film 50D by treating the laminated film 50D with superheated water using a pressure vessel 60A shown in FIG. FIG. 5 shows a state in which the laminated film 50D is housed in a pressure vessel 60A together with water TW1 as treated water. The pressure vessel 60A comprises a pressure vessel body 62A and a pressure lid 61A. A rim 601A is formed around the outer periphery of the pressure lid 61A. A pressure control unit 70 is disposed on top of the pressure lid 61A. The pressure control unit 70 controls the air pressure inside the pressure vessel 60A to a first air pressure higher than 1 atmosphere. The pressure control unit 70 can be, for example, a pressure control valve (e.g., a safety valve), a pressure control valve (e.g., a relief valve), or a pressure regulating valve (e.g., a weight-type or spring-type) used in a normal pressure cooker. 5, the pressure control unit 70 includes a relief valve 71 and a pressure sensor 72. The relief valve 71 adjusts the air pressure inside the pressure vessel 60A to a predetermined pressure by controlling the opening area of ​​a steam exhaust port 71A formed in the pressure lid 61A. The opening area of ​​the steam exhaust port 71A is controlled by a computer control unit in accordance with the air pressure value acquired by the pressure sensor 72. The control of the air pressure inside the pressure vessel 60A is not limited to this. A heater 68 for heating the water TW1 to be treated is disposed in the lower part of the pressure vessel main body 62A. As the heater 68, a known heater such as an IH heater can be used. The removal step according to Example 1 is carried out after the ultrasonic treatment step, so that the coating layer 52D is naturally peeled and separated from the base film 51D. After the removal step, the substrate film 51D sinks to the bottom of the pressure vessel 60A, and the coating layer 52D floats on the water TW1. The base film 51D may be recovered directly from the pressure vessel 60A after the air pressure inside the pressure vessel 60A is returned to normal pressure, or the contents inside the pressure vessel 60A may be transferred to a recovery vessel 100 shown in Figure 7, and the base film 51D may be recovered from the lower discharge port 19A (recovery process).

[0052] (Example 2) The removal method according to Example 2 is carried out as follows. The removal method according to Example 2 is the same as the removal method according to Example 1, except that the laminated film is treated with water vapor in Example 1. The removal step according to Example 2 is an example of the removal step according to Aspect 2. Ultrasonic waves are applied to the roll 50C (ultrasonic treatment step) in the same manner as in Example 1. Thereafter, the laminate film is unwound by known means (not shown) and cut into sheets of laminate film 50D (cutting step). FIG. 6 shows a state in which the laminated film 50D is housed in a pressure vessel 60A together with water TW2 (water for a steam source) as treatment water. A mounting table 66 having a height higher than the depth of the water TW2 is installed in the pressure vessel 60A, and a laminated film 50D is stored in a basket 67 on the mounting table 66. The removal process is carried out as follows. The water TW2 in the pressure vessel 60A is heated by the heater 68, and the pressure inside the pressure vessel 60A is increased to a pressure higher than 1 atmosphere, thereby generating water vapor inside the pressure vessel 60A. The generated water vapor fills the pressure vessel 60A, and the laminated film is exposed to the water vapor (removal process). The laminated film placed on the mounting table 66 is exposed to water vapor (not shown) without being immersed in water TW2. The removal step according to Example 2 is carried out after the ultrasonic treatment step, so that the coating layer 52D is naturally peeled and separated from the base film 51D within the basket 67. Thereafter, the pressure inside the pressure vessel 60A is returned to normal pressure, and the base film 51D and coating layer 52D separated inside the basket 67 are then released into, for example, water W2 in a collection vessel 100 shown in FIG. 7. The base film 51D can be collected from the lower discharge port 19A (collection step). The coating layer 52D can be collected from the upper discharge port 18A.

[0053] [Modification of the embodiment] The present invention is not limited to the above-described embodiment, and may include modifications and improvements within the scope of achieving the object of the present invention.

[0054] For example, in the removal step according to specific example 1, instead of the pressure vessel 60A, a normal water tank may be used, and the laminate film may be immersed in treatment water (water or alkaline aqueous solution) for a predetermined time. In the removal step according to this embodiment, the coating layer 52D is naturally peeled off from the base film 51D without performing operations such as stirring. Therefore, the removal step according to specific example 1 may be a step of leaving the laminate film in treatment water for a predetermined time. Furthermore, in the removal step according to specific example 2, instead of generating steam within pressure vessel 60A, steam generated externally (e.g., from a boiler) may be introduced into pressure vessel 60A, thereby exposing the laminated film to steam.

[0055] The structure of the laminated film used in the above embodiment and modified examples will be described.

[0056] [Laminated film] The laminated film used in the above embodiment has a substrate film and a coating layer. The laminated film used in the above embodiment may be referred to as a release film. The coating layer includes an intermediate layer and a release agent layer. The intermediate layer is disposed between the substrate film and the release agent layer. The intermediate layer may be a single layer or a multilayer consisting of two or more intermediate layers of the same or different types. The release agent layer may be a single layer or a multilayer consisting of two or more release agent layers of the same or different types. From the viewpoint of facilitating removal of the coating layer from the laminate film and recovery of the remaining substrate film, the laminate film preferably has a configuration in which the substrate film and the intermediate layer are directly laminated together. Here, "direct lamination" refers to a configuration in which, for example, the substrate film and the intermediate layer are in direct contact with each other without any other layer between them. In one embodiment of the laminated film, the base film, the intermediate layer, and the release agent layer may be laminated directly in this order, i.e., the base film, the intermediate layer, and the release agent layer may be in direct contact with each other without any other layers between them.

[0057] <Base film> The substrate film is a resin film formed from the resin component to be recovered. Examples of the resin film include polyester films such as polyethylene terephthalate film, polybutylene terephthalate, and polyethylene naphthalate; polyolefin films such as polyethylene film and polypropylene film; polyimide film; polyamide film; polycarbonate film; polyacetate film; ethylene-vinyl acetate copolymer (EVA) film; ethylene-(meth)acrylic acid copolymer film; ethylene-(meth)acrylic acid ester copolymer film; cycloolefin polymer film; polyurethane film; polyphenylene sulfide film; cellophane; and the like. The density of the substrate film is preferably greater than the density of water at 40°C, and is 1.0 g / cm 3 This makes it easier for the base film to sink in the treatment water, making it easier to recover the base film. Among the substrate films, polyester films are preferred because they have a density greater than that of water at 40°C and are excellent in heat resistance and strength. As polyester films, polyester films containing polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate as the main component are preferred from the viewpoint of easy recovery and recycling of the resin. In this specification, the term "main component" or "principal component" means that the proportion of the main component to the total mass of the material is 50% by mass or more. The resin film may also contain known fillers, colorants, antistatic agents, antioxidants, organic lubricants, catalysts, etc. The resin film may be transparent or may be colored as desired. At least one surface of the substrate film may be subjected to a surface treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, or etching such as oxidation, as needed.

[0058] The thickness of the substrate film is not particularly limited, but from the viewpoint of strength, rigidity, etc., it is preferably 10 μm or more and 500 μm or less, more preferably 15 μm or more and 300 μm or less, and even more preferably 20 μm or more and 200 μm or less.

[0059] <Release agent layer> The release agent layer is preferably a layer formed from a release agent composition. The release agent composition used to form the release agent layer is not particularly limited as long as it has releasability, and examples thereof include release agent compositions containing as a main component a silicone compound, a fluorine compound, a long-chain alkyl group-containing compound, or a thermoplastic resin material such as an olefin resin or a diene resin. It is also preferable to use a release agent composition containing as a main component an energy ray-curable or thermosetting resin. These release agent compositions may be used alone or in combination of two or more.

[0060] In the release agent composition containing a silicone compound as a main component, the silicone compound may be a silicone compound having an organopolysiloxane as a basic skeleton. Examples of the silicone compound include heat-curable silicone compounds such as addition reaction type and condensation reaction type; and energy beam-curable silicone compounds such as ultraviolet-curable and electron beam-curable types.

[0061] In the release agent composition containing a fluorine compound as a main component, examples of the fluorine compound include fluorine silicone compounds, fluorine boron compounds, and poly(perfluoroalkylene ether) chain-containing compounds.

[0062] In the release agent composition containing a long-chain alkyl group-containing compound as a main component, examples of the long-chain alkyl group-containing compound include polyvinyl carbamate obtained by reacting a polyvinyl alcohol polymer with a long-chain alkyl isocyanate, alkyl urea derivatives obtained by reacting a polyethyleneimine with a long-chain alkyl isocyanate, and copolymers of long-chain alkyl (meth)acrylates. Furthermore, a long-chain alkyl-modified alkyd resin may be used, which is an alkyd resin obtained by the condensation reaction of a polyhydric alcohol and a polybasic acid and which uses a long-chain fatty acid as a modifier.

[0063] A preferred example of a release agent composition containing an energy ray-curable resin as a primary component is one containing an energy ray-curable compound having a reactive functional group selected from a (meth)acryloyl group, an alkenyl group, and a maleimide group, and a polyorganosiloxane. In a release agent layer formed from this release agent composition, an energy ray-curable compound and a polyorganosiloxane having different molecular structures, polarities, and molecular weights are used. Therefore, before curing, components derived from the polyorganosiloxane are segregated near the outer surface of the release agent layer, and then cured by energy rays, solidifying the segregation. This improves the releasability of the release agent layer. A release agent composition containing an energy ray-curable resin as a primary component may further contain a photopolymerization initiator.

[0064] Examples of release agent compositions containing a thermosetting resin as a primary component include release agent compositions containing a melamine resin as a primary component and release agent compositions containing an epoxy resin as a primary component. Release agent compositions containing a melamine resin as a primary component include compositions containing a melamine resin as a primary component, an acid catalyst for thermally curing the melamine resin, and a polyorganosiloxane that imparts release properties to the release agent layer. Furthermore, release agent compositions containing an epoxy resin as a primary component include compositions containing an epoxy resin as a primary component, an acid or basic thermosetting catalyst for thermally curing the epoxy resin, and a polyorganosiloxane that imparts release properties to the release agent layer. Before curing, components derived from the polyorganosiloxane segregate near the outer surface of the release agent layer, and then cure to solidify the segregation. This improves the release properties of the release agent layer.

[0065] The release agent layer may contain other additives in addition to the resin component, such as an antioxidant, a light stabilizer, a flame retardant, a conductive agent, an antistatic agent, and a plasticizer.

[0066] The thickness of the release agent layer can be selected appropriately and is not particularly limited, but is, for example, preferably 0.02 μm or more and 5 μm or less, more preferably 0.03 μm or more and 2 μm or less, and even more preferably 0.05 μm or more and 1.5 μm or less.

[0067] <Middle class> The intermediate layer is preferably a layer made of a silane-based compound that is hydrophilic and water-insoluble and exhibits polycondensability upon hydrolysis, from the viewpoint of easier removal of the coating layer from the surface of the intermediate layer facing the substrate film.

[0068] The silane compound preferably contains, as a main component, at least one selected from tetrafunctional silane compounds represented by the following general formula (a) and oligomers thereof. Si(OR) p (X) 4-p (a) [In general formula (a), R represents an alkyl group, and X represents a halogen atom. When a plurality of Rs are present, the plurality of Rs may be the same or different. When a plurality of Xs are present, the plurality of Xs may be the same or different. p represents an integer of 0 or more and 4 or less.] The alkyl group preferably has 1 or more and 4 or less carbon atoms. The silane compounds represented by the general formula (a) may be used alone or in combination of two or more.

[0069] The silane compound represented by the general formula (a) preferably includes a silane compound in which p is 4 in the general formula (a). The silane compound in which p is 4 in the general formula (a) (i.e., a tetrafunctional silane compound) is preferably a tetraalkoxysilane. Specific examples of more preferred tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. Among these, from the viewpoints of availability and reactivity in the hydrolysis reaction, at least one of tetramethoxysilane and tetraethoxysilane, or a mixture of tetramethoxysilane and tetraethoxysilane, is preferred.

[0070] Commercially available products can also be used as the hydrolysis polycondensate of the silane compound, and suitable examples of such commercially available products include "Colcoat (registered trademark) N-103X," "Colcoat (registered trademark) PX," "Methyl silicate 51" which is an average tetramer oligomer of tetramethoxysilane, "Methyl silicate 53A" which is an average heptamer oligomer of tetramethoxysilane, "Ethyl silicate 40" which is an average pentamer oligomer of tetraethoxysilane, "Ethyl silicate 48" which is an average decamer oligomer of tetraethoxysilane, and "EMS-485" which is a mixture of an average decamer oligomer of tetramethoxysilane and an average decamer oligomer of tetraethoxysilane (all manufactured by Colcoat Co., Ltd.).

[0071] The laminate film used in each embodiment is preferably a laminate film after use for a specific purpose. The laminate film when used for a specific purpose (in practical use) may have a configuration in which a water-insoluble resin component is blended in the intermediate layer together with the silane compound to improve adhesion between the substrate film and the coating layer (intermediate layer and release agent layer) during use, within a range that does not impair the effects of this embodiment. The intermediate layer may be configured by applying and curing a composition blended with a water-insoluble resin component. Examples of the water-insoluble resin component include energy ray curable resins, epoxy resins, and melamine resins. It is preferable that the water-insoluble resin component maintains its water-insolubility even after being cured.

[0072] The "water-insoluble resin component" is preferably an energy ray curable resin, for example, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tri(meth)acrylate, and polyfunctional (meth)acrylates such as pentaerythritol tetra(meth)acrylate. When the intermediate layer contains a hydrophilic, water-insoluble resin (preferably the silane-based compound), the content of the hydrophilic, water-insoluble resin is preferably 30% by mass to 90% by mass, more preferably 40% by mass to 80% by mass, based on the total mass of the intermediate layer. The upper limit of the content of the hydrophilic, water-insoluble resin in the intermediate layer is 100% by mass. When the intermediate layer contains a hydrophilic, water-insoluble resin (preferably the silane compound) and a "water-insoluble resin component," the content of the hydrophilic, water-insoluble resin is preferably 30% by mass to 90% by mass, and more preferably 40% by mass to 80% by mass, based on the total mass of the intermediate layer. The content of the "water-insoluble resin component" is preferably 10% by mass to 70% by mass, and more preferably 20% by mass to 60% by mass, based on the total mass of the intermediate layer. The upper limit of the total content of the hydrophilic, water-insoluble resin and the "water-insoluble resin component" in the intermediate layer is 100% by mass.

[0073] When the intermediate layer contains an energy ray-curable resin, the intermediate layer preferably further contains a photopolymerization initiator, such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, or 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone. When the intermediate layer contains a photopolymerization initiator, the content of the photopolymerization initiator is preferably 20 parts by mass or less, and more preferably 10% by mass or less, based on 100 parts by mass of the "water-insoluble resin component."

[0074] The thickness of the intermediate layer is preferably 0.01 μm or more and 1 μm or less, more preferably 0.03 μm or more and 0.5 μm or less, and even more preferably 0.05 μm or more and 0.3 μm or less, from the viewpoint of facilitating water penetration when the intermediate layer comes into contact with water.

[0075] The laminated film used in each embodiment of the present invention has a hydrophilic, water-insoluble intermediate layer, so that the removed coating layer residue has a configuration in which the surface of the release agent layer and the surface of the hydrophilic intermediate layer are present. When the residue with this configuration is immersed in cleaning water, the release agent layer surface faces the air due to surface tension, and the intermediate layer surface faces the water, resulting in stability. In other words, the residue with this configuration is more likely to exist at the water-air interface than in water. Here, because the coating layer residue is an extremely thin film, even if it has a slightly high density, the buoyancy due to surface tension is greater, and it is thought that the water-insoluble intermediate layer allows it to continue floating on the surface of the water.

[0076] The laminate film used in each embodiment is generally used for the purpose of protecting the surfaces of other functional sheets or various parts used for specific purposes during the manufacture, transportation, storage, etc. of these functional sheets or parts. In fact, after fulfilling its role of protecting these parts, it is often peeled off from the surface and discarded. Therefore, by using the laminate film, the coating layer and the base film can be easily separated from the laminate film, which is an application that greatly contributes from the viewpoints of resource conservation and environmental protection.

[0077] The present invention is not limited to the above-described embodiment, and may include modifications and improvements within the scope of achieving the object of the present invention. [Example]

[0078] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0079] (Preparation of laminated film) A biaxially stretched polyethylene terephthalate film (thickness: 31 μm) was prepared as the substrate film.

[0080] (Preparation of composition for forming intermediate layer) A hydrolysis polycondensation product of alkoxysilane (manufactured by Colcoat Co., Ltd., product name "Colcoat (registered trademark) N-103X") and a polyfunctional acrylate, dipentaerythritol hexaacrylate (manufactured by Toagosei Co., Ltd., product name "Aronix M-400"), were mixed in a solids ratio (mass ratio) of 65:35 to obtain a mixture. A photopolymerization initiator (manufactured by IGM Resins BV, product name "Omnirad 907") and 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one (solids content 100% by mass) were added to the mixture. Finally, methyl ethyl ketone (MEK) and isopropyl alcohol were mixed in a volume ratio of 3:7 to obtain a composition for forming an intermediate layer with a solids content of 1.0% by mass. The mixing ratio of the photopolymerization initiator, 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one to the mixture is as follows: Photopolymerization initiator: 10% by mass relative to Aronix M-400 (solid content 100% by mass) 2-Methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-ol Aronix M-400 (solid content 100% by mass) at a ratio of 10% by mass (forming the middle layer)

[0081] Next, the composition for forming an intermediate layer was applied onto the substrate film using a bar coater, and the substrate was passed through a drying oven at 130°C for 1 minute, and then irradiated with ultraviolet light (integrated light amount: 250 mJ / cm 2 ) to obtain a film with an intermediate layer (thickness: 0.04 μm).

[0082] (Preparation of Release Agent Layer-Forming Composition) A release agent composition with a solids concentration of 20% by mass was prepared by diluting 94 parts by mass of the polyfunctional acrylate dipentaerythritol hexaacrylate (100% solids by mass), 1 part by mass of an acrylic-modified polydimethylsiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "X-22-164A", 100% solids by mass), and 5 parts by mass of a photopolymerization initiator (manufactured by IGM Resins BV, product name "Omnirad® 907" (2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 100% solids by mass) with a mixed solvent of isopropyl alcohol and methyl ethyl ketone. The mixing ratio of the mixed solvent of isopropyl alcohol and methyl ethyl ketone was 3:1 (by mass). Dipentaerythritol hexaacrylate corresponds to the water-insoluble resin component.

[0083] (Formation of release agent layer) The obtained release agent composition was applied onto the intermediate layer formed on the substrate film using a bar coater and dried at 80°C for 1 minute to obtain a coating layer. Next, the coating layer was irradiated with ultraviolet light (integrated light amount: 250 mJ / cm 2 ) to form a release agent layer (thickness: 1 μm), and a laminated film (substrate film / intermediate layer / release agent layer) was obtained in which the substrate film, intermediate layer, and release agent layer were laminated in this order. The layer consisting of the intermediate layer and the release agent layer (intermediate layer / release agent layer) constitutes a coating layer. In the obtained laminated film (substrate film / intermediate layer / release agent layer), the water contact angle of the surface of the intermediate layer facing the substrate film was 42 degrees. The water contact angle of the surface of the release agent layer was 93 degrees. From these results, the difference in water contact angle between the surface of the release agent layer and the surface of the intermediate layer facing the substrate film was calculated to be 51 degrees.

[0084] [Example 1] The coating layer was removed from the resulting laminated film by the following method. The laminated film was cut into a width of 50 mm and a length of 100 m, and wound around a core at a winding tension of 60 N to prepare a roll (preparation step). The resulting roll width was 50 mm and the roll diameter was 110 mm. In addition, the end of the roll was secured with a 50 mm square adhesive tape to prevent the end of the roll from unwinding.

[0085] (Ultrasonic treatment process) The roll obtained in Example 1 was irradiated with ultrasonic waves using an ultrasonic treatment device 80 shown in FIG. 3A. First, tap water W1 was placed in a water tank 81. Next, the roll was placed on a treatment object setting table 84 and immersed in tap water W1. In this state, ultrasonic waves were irradiated onto the roll. The conditions for ultrasonic irradiation were as follows: (Ultrasonic irradiation conditions) Type of water: Tap water Water temperature: 25℃ Oscillation frequency: 40kHz Ultrasonic irradiation time: 10 minutes Power density: 0.70 (W / cm 2 ) Distance D2 from the top surface of the vibration plate 82 installed in the water tank 81 to the bottom of the roll: 80 mm Distance D3 from the top of the vibration plate 82 installed in the water tank 81 to the water surface: 200 mm

[0086] (Cutting process and removal process) After the ultrasonic treatment step, 3 m of the laminated film was unwound from the roll, and a 50 mm square piece of film was cut out from the unwound point, which was used as a sample for evaluation (cutting step). Using a pressure vessel having the same configuration as the pressure vessel 60A shown in FIG. 5, the evaluation sample was treated with treated water in the following manner. The pressure vessel used in this example was a cylindrical stainless steel pressure vessel with a capacity of 5 L. First, 2 L of water to be treated was placed in the pressure vessel body, and the water was boiled to 100°C using an induction heating (IH) heater (heater 68 in Figure 5). The evaluation sample was then immersed in the boiling water at 100°C, the pressure lid was closed, the relief valve was set to 2 atmospheres, and heating was resumed. After confirming boiling (fuming), the pressure inside the pressure vessel reached 2 atmospheres, and the temperature of the superheated water was confirmed to be 120°C. After 15 minutes had passed (maintained) in this state, the pressure inside the pressure vessel was returned to normal pressure (removal process).

[0087] [Examples 2 to 5] The coating layer removal method in Examples 2 to 5 was carried out in the same manner as in Example 1, except that the ultrasonic irradiation conditions (water temperature and oscillation frequency) in Example 1 were changed to the conditions shown in Table 1.

[0088] [Comparative Example 1] The coating layer of Comparative Example 1 was removed in the same manner as in Example 1, except that the ultrasonic treatment step was not performed.

[0089] Comparative Example 2 In the method for removing the coating layer in Comparative Example 2, a cutting step, a removing step, and an ultrasonic treatment step were carried out in this order. (cutting process) A laminated film was produced in the same manner as in Example 1. A 50 mm square film piece was cut out from the resulting laminated film, and this was used as a sample for comparative evaluation. (Removal process) The removal step was carried out in the same manner as in Example 1, except that the comparative evaluation sample was used instead of the evaluation sample in Example 1. After the removal step, the comparative evaluation sample was removed from the pressure vessel with tweezers. (Ultrasonic treatment process) Using the same ultrasonic treatment device 80 as in Example 1, ultrasonic waves were irradiated onto the comparative evaluation sample in the following manner. The comparative evaluation sample was placed in a basket (16 cm long, 16 cm wide, and 2 cm high) with multiple 20 mm square holes. This basket was placed on a workpiece placement table 84 in a water tank 81 containing tap water W1. In this state, ultrasonic waves were irradiated to the comparative evaluation sample under the same conditions as in Example 1.

[0090] [evaluation] (Base film separation test) After the removal process, a sample (50 mm square) for evaluation was taken from the pressure vessel with tweezers, and the separation of the base film was visually confirmed. Note that the sample for evaluation was simply taken with tweezers, and no operations such as stirring the sample in water were performed. In the case of Comparative Example 2, after the ultrasonic treatment step, a comparative evaluation sample (50 mm square) was taken from the basket with tweezers, and the separation property of the base film was visually confirmed. As with the evaluation sample, the comparative evaluation sample was not subjected to operations such as stirring in water. In the separation test, the case where the release agent layer / intermediate layer was completely peeled off from the substrate film was rated A, and the case where it was not completely peeled off was rated F.

[0091] Table 1 shows the ultrasonic irradiation conditions and the results of the separation test for each example.

[0092] [Table 1]

[0093] According to the coating layer removal methods of Examples 1 to 5, by carrying out an ultrasonic treatment process, the coating layer (release agent layer / intermediate layer) was completely peeled off from the substrate film in the subsequent removal process without performing operations such as stirring the laminated film in water. On the other hand, in Comparative Example 1, in which the ultrasonic treatment step was not performed, and Comparative Example 2, in which the ultrasonic treatment step was performed after the removal step, the coating layer (release agent layer / intermediate layer) was not completely peeled off from the substrate film. [Explanation of symbols]

[0094] 18...upper discharge pipe, 18A...upper discharge port, 19...lower discharge pipe, 19A...lower discharge port, 21...upper discharge valve, 22...lower discharge valve, 40...ultrasonic oscillator, 50, 50D, 50G...laminated film, 50A...folded laminate, 50B...sheet laminate, 50C...roll, 51, 51D...base film, 52, 52D...coating layer, 55...rubber band, 60A...pressure vessel, 61A...pressure lid, 62A...pressure vessel body, 66...mounting table, 67...basket, 68 heater..., 70...pressure control unit, 71...relief valve, 72...pressure sensor, 80...ultrasonic processing device, 81...water tank, 82...vibration plate, 84...treatment object mounting table, 100...collection container, 521...intermediate layer, 522...release agent layer.

Claims

1. A preparation step for preparing a laminated film having a base film and a coating layer, An ultrasonic treatment step in which ultrasonic waves are irradiated onto the laminated film via water, A removal step of removing the coating layer from the laminated film by treating the laminated film with treated water or steam, The process includes, in this order, a recovery step for recovering the aforementioned base film, The coating layer comprises a hydrophilic and water-insoluble intermediate layer and a release agent layer. The intermediate layer is disposed between the base film and the release agent layer. How to remove the coating layer.

2. The laminated film in the ultrasonic treatment process is in the form of a single sheet, a roll, or a folded sheet. A method for removing a coating layer according to claim 1.

3. If the laminated film is in the form of a roll or folded, The process further includes a cutting step of cutting the laminated film into single sheets between the ultrasonic treatment step and the removal step. The method for removing the coating layer according to claim 2.

4. The ultrasonic treatment process is carried out with the laminated film immersed in water. A method for removing a coating layer according to claim 1 or claim 2.

5. The removal step involves placing the laminated film and the treated water in a pressure vessel, immersing the laminated film in the treated water, heating the treated water, and pressurizing the pressure inside the pressure vessel to a pressure higher than 1 atmosphere. A method for removing a coating layer according to claim 1 or claim 2.

6. The removal step is to place the laminated film in a processing container and expose the laminated film to water vapor inside the processing container. A method for removing a coating layer according to claim 1 or claim 2.

7. The laminated film prepared in the above preparation step is a laminated film with a ceramic green sheet, A ceramic green sheet is attached to the side of the coating layer opposite to the substrate film. A method for removing a coating layer according to claim 1 or claim 2.

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