Apparatus and method for removing coatings

Abstract

To provide a coating removal device that can efficiently and uniformly remove a coating from a substrate film having a coating. [Solution] The removal device of the present invention is a device for removing a coating from a coated film having a coating on one side of a base film via a layer mainly composed of a water-soluble resin. The removal device comprises a pressing member used by pressing it against the side of the coated film opposite to the coating in order to form cracks in the coating; a driving device for moving the coated film relative to the pressing member in the longitudinal direction of the coated film; a first water supply mechanism provided downstream of the pressing member in the transport direction, with the direction in which the coated film moves relative to the pressing member as the transport direction, and for applying a cleaning solution mainly composed of water to the coating; and a removal member provided downstream of the first water supply mechanism in the transport direction, and used by contacting the surface of the coating of the coated film in order to remove the coating.

Description

Technical Field

[0001] The present invention relates to a removal device and a removal method capable of efficiently and uniformly removing a coating on the surface of a thermoplastic resin film.

Background Art

[0002] While plastics are used in various fields, they are regarded as causes of marine pollution such as microplastics, and it is urgent to reduce the environmental burden caused by plastics.

[0003] In recent years, with the evolution of the Internet of Things (IoT), the number of electronic devices such as CPUs installed in computers and smartphones has increased. Along with this, the number of multilayer ceramic capacitors (MLCCs) required to drive these electronic devices has also increased rapidly. A general manufacturing method for this MLCC is to use a release film with a release layer formed on a plastic base film as a carrier sheet, and to form a ceramic green sheet layer on the release film, and a process of removing the ceramic green sheet layer to obtain a ceramic green sheet. In this process, the release film from which the ceramic sheet has been removed is discarded as waste.

[0004] That is, the increase in waste of release films accompanying the rapid increase in the number of MLCCs in recent years has become an environmental problem, and efforts towards the reuse of plastic base films have been actively carried out. Since the components of the release layer contained in the release film generally have a different composition from the components constituting the base film from the viewpoint of release properties, when a release film with a release layer is remelted as it is to form a recycled film, the components of the release layer exist as foreign substances, and stable film formation cannot be achieved.

[0005] Patent Document 1 discloses a roll-to-roll continuous cleaning method for removing release components from a release film, which uses a release film in which a water-soluble resin layer is formed between a base film and a release layer, and after immersing it in a hot water bath for more than 2 seconds, the release layer is removed by rubbing the surface of the release film with a brush roll. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-363140 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the coating removal method disclosed in Patent Document 1 has a problem in that, because the water-soluble resin layer dissolves into the hot water bath, the resin concentration in the hot water increases as the treatment time progresses, making it impossible to maintain the initial removal capacity. Even if a method is adopted to increase the amount of water supplied to suppress the increase in resin concentration, the amount of wastewater also increases along with the amount of water supplied, which not only significantly increases the cleaning cost but also increases the environmental burden. Furthermore, in order to maintain a high removal capacity even when the coating is thick, it is necessary to extend the time the coating is immersed in the water bath, which increases the volume of the water bath and further increases the amount of water used, thus worsening the environmental burden.

[0008] Therefore, the present invention provides a coating removal apparatus and a coating removal method that can efficiently and reliably remove a coating from a coated film having a layer mainly composed of a water-soluble resin between a base film and the coating. [Means for solving the problem]

[0009] [1] The present invention, which solves the above problems, is a device for removing a coating from a coated film having a coating on one side of a base film via a layer mainly composed of a water-soluble resin, A pressing member used to press against the opposite side of the coating of the coated film in order to form cracks in the coating, A drive device for moving the coated film relative to the pressing member in the longitudinal direction of the coated film, The direction in which the coated film moves relative to the pressing member is defined as the transport direction, and a first water supply mechanism is provided downstream of the pressing member in the transport direction, which applies a cleaning solution mainly composed of water to the coating. The system includes a removal member provided downstream of the first water supply mechanism in the transport direction, which is used to remove the coating by contacting the surface of the coating on the coated film.

[0010] The coating removal device of the present invention is preferably in any of the following embodiments [2] to [8]. [2] The coating removal device of [1], comprising a first tension-applying mechanism adjusted to apply tension T1 in the range of 10 to 1000 N / m in at least one longitudinal direction of the coated film before and after the pressing member. [3] The coating removal device according to [1] or [2], wherein the pressing member is positioned such that, when viewed from the width direction of the coated film, the angle formed by the coated film sandwiching the pressing member is in the range of 20 to 160°. [4] A coating removal device according to any of the above [1] to [3], which is provided upstream of the pressing member in the transport direction and includes a second water supply mechanism for applying a cleaning solution mainly composed of water to the coating. [5] A coating removal device according to any of [1] to [4] above, wherein the first water supply mechanism is a mechanism for immersing the coated film in an alkaline cleaning solution. [6] A coating removal device according to any of [1] to [5] above, wherein the first water supply mechanism is a mechanism for spraying steam at 70 to 120°C onto the coating. [7] A film removing device according to any one of [1] to [6] above, comprising a second tension applying mechanism adjusted to apply a tension T2 in the range of 10 to 1000 N / m in at least one direction in the longitudinal direction of the film with a coating before and after the removing member. [8] The film removing device according to [7] above, wherein the tension T1 and the tension T2 satisfy T1 < T2.

[0011] [9] The film removing method of the present invention for solving the above problems is a method of removing the coating from the film with a coating using the film removing device according to any one of [1] to [8] above.

[0012]

[10] In the film removing method of the present invention, it is preferable that the coating contains an energy ray-curable resin as a main component.

[0013] Before the removing member contacts, it is a "base material film with a coating", that is, a "film with a coating", and after the removing member contacts, it is a "base material film from which the coating has been removed". However, in order to avoid complicated explanations, in the present application, in some cases, it may be described as a "film with a coating" both before and after the removing member contacts.

Effects of the Invention

[0014] According to the film removing device and the film removing method of the present invention, the coating can be efficiently and reliably removed from a film with a coating having a layer mainly composed of a water-soluble resin between the base material film and the coating.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic view of the removing device of the first embodiment of the present invention. [Figure 2] It is a schematic view of the film removing device of the second embodiment of the present invention. [Figure 3] It is a schematic view of the film removing device of the third embodiment of the present invention.

Modes for Carrying Out the Invention

[0016] As a result of earnestly studying a method for efficiently and reliably removing a coating from the surface of a coated film having a coating on one side of a base film, the inventors of the present invention have found the following coating removal device and coating removal method.

[0017] [Target Coated Film] The coating removal device for removing a coating from the coated film of the present invention is a device for cleaning the coating and removing it from the coated film, targeting a coated film having a coating on one side of a base film.

[0018] The coated film targeted by the present invention has a coating on one side of a base film through a layer mainly composed of a water-soluble resin.

[0019] Examples of the water-soluble resin include water-soluble polyester resins, polyester urethane resins, acrylic resins, polyacrylamide resins, ethylene ionomer resins, polyvinyl alcohol resins, polyvinyl pyrrolidone resins, ethylene-vinyl alcohol resins, carboxymethyl cellulose, cyclodextrin, polysaccharides, starch, and the like.

[0020] Examples of the coating include films having desired functions, such as peelability, scratch resistance, self-healing property, reflectivity, semi-transparency, antireflection property, antiglare property, fingerprint resistance, lubricity, antistatic property, antifogging property, writing feel improvement property, anti-Newton ring property, coloring property, light diffusion property, specific wavelength cut property, design property, etc., and are not particularly limited. Among them, a film having particularly a peelability function is preferable when utilized for MLCC applications.

[0021] A releaseable film can be formed using a release agent. Examples of release agents include silicone-based, fluorine-based, alkyd-based, melamine-based, oxazoline-based, unsaturated polyester-based, epoxy-based, urethane-based, acrylic-based, polyolefin-based, and wax-based release agents. These resins may be used individually or in combination of two or more types.

[0022] From the viewpoint of inducing cracking, the coating is preferably made of a resin that is harder than the substrate. For example, when the substrate is a polyethylene terephthalate resin film, the coating can be made of, for example, a thermosetting silicone resin compound, a thermosetting acrylic resin compound, an energy-ray curable silicone resin compound that is cured by irradiation with energy rays such as UV light, an energy-ray curable acrylic resin compound, or other crosslinked compounds such as melamine-based, oxazoline-based, unsaturated polyester-based, or epoxy-based compounds. Among these, it is preferable to use an energy-ray curable resin as the main component because it is easy to adjust the hardness. In particular, an energy-ray curable acrylic resin compound is more preferable because it is easy to adjust the hardness of the coating by adjusting the degree of crosslinking, or to adjust the peeling performance as a release agent by partially introducing a siloxane-containing skeleton, since various polyfunctional acrylates and hydroxyl group-containing acrylates can be used as monomers. An energy-ray curable acrylic resin compound can be blended with a photopolymerization initiator to accelerate curing.

[0023] [Applicator for removing coatings from coated films] The coating removal device of the present invention comprises a pressing member used by pressing it against the side of the coated film opposite to the coating in order to form cracks in the coating of the coated film, and a driving device for moving the coated film relative to the pressing member in the longitudinal direction of the coated film.

[0024] Furthermore, the coating removal device of the present invention comprises a first water supply mechanism provided downstream of the pressing member in the transport direction, with the direction in which the coated film moves relative to the pressing member being the transport direction, and which applies a cleaning solution mainly composed of water to the coating; and a removal member provided downstream of the first water supply mechanism in the transport direction, which is used by contacting the surface of the coating on the coated film in order to remove the coating.

[0025] A preferred embodiment of the coating removal device of the present invention will be described below with reference to the drawings. The following description illustrates an embodiment of the present invention and is not limited thereto; various modifications are possible without departing from the spirit of the invention.

[0026] [Coating removal device according to the first embodiment] Figure 1 is a schematic diagram of a coating removal device 101 according to a first embodiment of the present invention. As shown in Figure 1, the coating removal device 101 comprises an unwinding device 4 for unwinding a coated film 1 and a winding device 5 for winding up the base film 3 after the coating has been peeled off. Between the unwinding device 4 and the winding device 5 are a pressing member 6 used to press the coated film 1 against the side 1a where the coating is not formed (the side opposite to the side where the coating is formed) to form cracks in the coating, a first water supply mechanism 7 for applying a water-based cleaning solution to the cracked coating of the coated film 2, and a removal member 8 used to contact the surface of the coating of the coated film 2 in order to remove the coating from the coated film 2 to which the cleaning solution has been applied.

[0027] The coated film 1 shown in Figure 1 has a coating formed on one side of the film, and the pressing member 6 is placed opposite to side 1a, which is the side opposite to side 1b where the coating is formed. It is not a problem if a different coating other than the coating to be removed by the coating removal device of the present invention is formed on side 1a.

[0028] The coated film 1 unwound from the unwinding device 4 is transported by a transport mechanism consisting of drive devices 9a and 9b, and cracks are formed in the coating by the pressing member 6 before the cleaning solution is applied by the first water supply mechanism 7.

[0029] The pressing member 6 can preferably be a scraper or the corner of a metal plate. It is preferable to keep the pressing member 6 in direct contact with the surface 1a where the coating is not formed, so that the coated film 1 is bent or curved by the pressing member 6, and while maintaining this state, the coated film 1 is moved relative to the pressing member 6 in its longitudinal direction, thereby forming cracks in the coating of the coated film 1. When the coated film 1 in the bent or curved state is observed from the width direction, it is preferable that the angle formed by the coated film 1 with the pressing member 6 in between is in the range of 20 to 160°. An angle of 20° or more is preferable because it is possible to secure space to set the pressing member 6 while the coated film 1 is being pressed by the pressing member 6. An angle of 160° or less is preferable because it is possible to maintain a strong force pressing the pressing member against the coated film 1. As a result, a stronger stress can be applied to the coating of the coated film 1, making it possible to form cracks in the coating more efficiently. The narrower the contact area of ​​the pressing member 6 with the coated film 1, the more locally and strongly stress can be applied to the coating of the coated film, which is preferable. The angle is more preferably in the range of 50 to 130°.

[0030] Furthermore, it is preferable to have a first tension-applying mechanism adjusted to apply tension in the range of 10 to 1000 N / m in at least one longitudinal direction of the coated film 1 before and after the pressing member 6. In this first embodiment, the drive units 9a and 9b also serve as the first tension-applying mechanism. Alternatively, the drive units 9a and 9b may not serve as the first tension-applying mechanism, and the first tension-applying mechanism may be provided between the drive units 9a and 9b. By setting the tension applied by the first tension-applying mechanism to 10 N / m or more, the coated film 1 can be transported stably without slackening, and large fluctuations in tension or meandering during transport can be suppressed, which can lead to unstable crack formation in the coating. On the other hand, by setting the tension to 1000 N / m or less, the coated film 1 is not pulled excessively strongly in one direction, which can suppress the occurrence of multiple corrugated iron wrinkles in the width direction that extend in the longitudinal direction of the film. If multiple creases occur in the width direction of the corrugated iron, some of these creases will become folded creases at the points where they come into contact with the pressing member, resulting in insufficient crack formation in the coating at those folded crease points. This can be prevented. The tension applied by the first tension-applying mechanism is more preferably in the range of 100 to 800 N / m.

[0031] Furthermore, the method of pressing the pressing member 6 against the surface 1a where no coating has been formed is effective in efficiently forming cracks in the coating. In addition, since it does not require making cuts that penetrate the base material of the coated film, making holes, or creating large scratches, tears and wrinkles are less likely to occur when transporting the coated film, thus improving transportability.

[0032] The coated film 2, in which cracks have formed on the coating, is transported by a transport mechanism consisting of drive units 9b and 9c, and after a cleaning solution is applied by the first water supply mechanism 7, the coating is removed by the removal member 8.

[0033] The first water application mechanism 7 pumps a cleaning solution mainly composed of water from a tank (not shown) using a pump 11, and continuously applies the cleaning solution to the coating of the coated film 2. The application mechanism can be any type that can apply the cleaning solution, such as a spray system, a nozzle system, or a bar coating system. The cleaning solution may be applied in droplet form using a spray nozzle, for example, or a high-pressure or high-temperature cleaning solution may be applied using a high-pressure washer or steam generator. The amount of cleaning solution applied is preferably adjusted appropriately according to the properties and thickness of the coating to be removed, and should be properly controlled by the method of applying the cleaning solution. For example, the amount of cleaning solution may be controlled by pumping it with a metering pump, a flow meter may be installed in the flow path through which the cleaning solution is pumped, or the cleaning solution applied to the surface of the coating may be collected and its mass measured. To enhance the cleaning effect, a mechanism that sprays steam at 70-120°C is particularly preferred for the cleaning solution application mechanism.

[0034] The removal member 8 is exemplified by, but is not limited to, a scraper, cloth, metal plate, or rotating brush roll. Any form is acceptable as long as it can directly contact the coating of the coated film 2 and physically remove the coating. It is preferable to keep the removal member 8 in direct contact with the surface of the coated film 2 having the coating, by pressing the removal member 8 against it. The coating can be removed from the coated film 2 by bending or curving the coated film 2 with the removal member 8 and maintaining this bent or curved state while moving the coated film 2 relative to the removal member 8 in its longitudinal direction. When the coated film 2 is bent or curved as described above, it is preferable that the angle formed by the coated film 1 with the removal member 8 in between is in the range of 20 to 150° when viewed from the width direction. This allows the removal member 8 to be pressed firmly against the surface of the coating of the coated film 2, making it possible to remove the coating efficiently and uniformly. Therefore, the narrower the contact area of ​​the removal member 8 with the coated film 2, the more strongly the removal member 8 can be pressed locally against the surface of the coated film 2, which is preferable. Among the removal members exemplified above, scrapers and the corners of metal plates are preferably used. The angle is more preferably in the range of 50 to 130°.

[0035] Furthermore, it is preferable to have a second tension-applying mechanism adjusted to apply tension in the range of 10 to 1000 N / m in at least one longitudinal direction of the coated film 2 before and after the removal member 8. In this first embodiment, the drive units 9b and 9c also serve as the first tension-applying mechanism. Alternatively, the drive units 9b and 9c may not serve as the second tension-applying mechanism, and a second tension-applying mechanism may be provided between the drive units 9b and 9c. By setting the tension applied by the second tension-applying mechanism to 10 N / m or more, the coated film 2 can be transported stably without slackening, and large fluctuations in tension or meandering during transport can be suppressed, which can lead to unstable removal of the coating. On the other hand, by setting the tension to 1000 N / m or less, the coated film 2 is not pulled excessively strongly in one direction, which can suppress the occurrence of multiple corrugated iron wrinkles in the width direction that extend in the longitudinal direction of the film. If multiple creases form in the width direction of the corrugated iron, some of these creases will become folds where they come into contact with the pressing member, resulting in insufficient removal of the coating in those folds. This can be prevented. The tension applied by the second tension-applying mechanism is more preferably in the range of 100 to 800 N / m.

[0036] Preferably, the discharge head and removal member 8 of the first water supply mechanism 7 are enclosed in the booth 10. Being enclosed not only prevents the supplied cleaning solution from splashing into the surroundings, but also provides a heat retention effect when supplying high-temperature cleaning solution, thereby enhancing the cleaning effect.

[0037] The film with a coating is conveyed by the driving devices 9a, 9b, and 9c and will move in the conveying direction a. Also, the driving devices 9a, 9b, and 9c preferably have a configuration that can perform tension cutting in order to stably convey the film with a coating. When performing tension cutting with a suction roll, a part of the coating of the film with a coating 1 may be sucked, which may cause trouble. Therefore, a configuration in which a metal driving roll and a rubber roll are nipped is more preferably used. Each driving roll of the driving devices 9a, 9b, and 9c can be individually set with a rotation speed and control its rotation speed, so that for the films with a coating 1 and 2 between the driving devices 9a and 9b, or between the driving devices 9b and 9c, it is preferable that the tension applied in the longitudinal direction of the films with a coating 1 and 2 can be controlled. It is not limited to this as long as it has a mechanism for controlling the tension applied in the longitudinal direction of the films with a coating 1 and 2 to the films with a coating 1 and 2.

[0038] Let the tension applied in at least one direction in the longitudinal direction of the film with a coating 1 before and after the pressing member 6, that is, the tension applied by the first tension applying mechanism between the driving devices 9a and 9b, be T1, and also let the tension applied in at least one direction in the longitudinal direction of the film with a coating 2 before and after the removing member 8, that is, the tension applied by the second tension applying mechanism between the driving devices 9b and 9c, be T2. It is preferable that T1 and T2 are adjusted so as to satisfy T1 < T2. By setting T1 < T2, the effect of expanding the gap of the crack formed in the coating works, and the cleaning liquid applied to the crack promotes the effect of penetrating or dissolving the layer mainly composed of the water-soluble resin under the crack, which is preferable.

[0039] Also, although not shown in the figure, a structure may be added after the removing member 8 to inject a clean cleaning liquid free of impurities such as foreign substances for rinsing and drying with an air nozzle.

[0040] Furthermore, if the coated film has coatings at regular intervals along the longitudinal direction of the base film, the system may include a mechanism to remove the coatings by transporting the coated film for a certain length, then stopping or changing the transport speed, and moving a removal member relative to the areas of the coated film that have coatings. After the coatings are removed, the transport can be restarted or the transport speed can be returned to its original level, allowing for highly efficient and uniform coating removal. It is also preferable to include a mechanism to stop or change the transport speed during the coating removal process to inspect the base film after the coating has been removed and confirm whether any coatings remain. Any inspection mechanism is acceptable as long as it can detect the presence of remaining coatings.

[0041] Furthermore, if the coated film of the present invention is a film that has been used as a release film for the process, there may be residual material on the surface of the coating. Therefore, it is preferable to provide a device between the unwinding device 4 and the drive device 9a to expose the surface of the coated film. The device for exposing the surface of the coating may be a contact type or a non-contact type, and can be appropriately selected depending on the residual state of the material to be released. Examples of the material to be released are appropriately selected depending on the characteristics of the coating, but include inorganic materials such as metals provided by vapor deposition, adhesives made of organic materials such as acrylics provided by coating, and ceramic green sheets mainly composed of barium titanate.

[0042] [Second embodiment of coating removal device] Figure 2 is a schematic diagram of a coating removal device 201 according to a second embodiment of the present invention. In the second embodiment, as shown in Figure 2, a cleaning tank is provided as the first water supply mechanism 7 provided in the first embodiment. The first water supply mechanism 7 shown in Figure 2 consists of a liquid tank 7b for storing cleaning liquid 7a and a pump 11 for supplying the cleaning liquid 7a from a tank (not shown). By transporting the coated film 2 while immersing it in the cleaning liquid 7a in the liquid tank 7b, the cleaning liquid 7a is continuously supplied to the coated film 2. In this case, it is preferable that the cleaning liquid 7a is an alkaline aqueous solution, as this promotes the effect of penetrating the cleaning liquid into or dissolving the water-soluble resin layer located beneath the cracks in the coated film 2. Furthermore, it is also preferable that the liquid tank 7b is equipped with a mechanism for heating the cleaning liquid, as this promotes the effect of penetrating the cleaning liquid into or dissolving the water-soluble resin layer.

[0043] The coating removal device 201 of the second embodiment of the present invention includes a removal member 8 used to remove the coating from a coated film 2 to which a cleaning solution has been applied, by contacting the surface of the coating on the coated film 2. Examples of removal members include scrapers, cloth, metal plates, and rotating brush rolls, but in Figure 2, a rotating brush roll is provided.

[0044] The material of the brush roll bristles can be appropriately selected from resin, metal, animal hair, plant fibers, etc., and is not particularly limited. However, selecting a material that is harder than the coating or selecting a brush with densely arranged bristles can improve the efficiency of coating removal.

[0045] Although not shown in the diagram, a structure may be added after the removal member 8 to spray a clean cleaning solution free of foreign matter and other impurities for rinsing, and then dry it with an air nozzle.

[0046] [Cover removal device according to the third embodiment] Figure 3 is a schematic diagram of a coating removal device 301 according to a third embodiment of the present invention. As shown in Figure 3, the third embodiment is provided with a second water supply mechanism 12 that applies a cleaning solution mainly composed of water to the coated film 1, located upstream in the transport direction from the pressing member 6 of the first embodiment.

[0047] The second water application mechanism 12 pumps a cleaning solution mainly composed of water from a tank (not shown) using a pump 13, and continuously applies the cleaning solution to the coating of the coated film 1. The application mechanism can be any type that can apply the cleaning solution, such as a spray system, a nozzle system, or a bar coating system. The cleaning solution may be applied in droplet form using a spray nozzle, for example, or a high-pressure or high-temperature cleaning solution may be applied using a high-pressure washer or steam generator. The amount of cleaning solution applied is preferably adjusted appropriately according to the properties and thickness of the coating to be removed, and should be properly controlled by the method of applying the cleaning solution. For example, the amount of cleaning solution may be controlled by pumping it with a metering pump, a flow meter may be installed in the flow path through which the cleaning solution is pumped, or the cleaning solution applied to the surface of the coating may be collected and its mass measured. The cleaning solution application mechanism is particularly preferably a mechanism that sprays steam at 70 to 120°C to promote crack formation in the coating at the pressing member 6 located downstream.

[0048] [Method for removing the coating from a coated film] The present invention provides a method for removing a coating from a coated film (hereinafter referred to as the "coating removal method"), which involves removing the coating and the water-soluble resin-based layer from a coated film having a coating on one side of a base film via a layer mainly composed of a water-soluble resin. The method involves forming cracks in the coating of the coated film, then bringing a cleaning solution into contact with the water-soluble resin-based layer between the coating and the base film, and then peeling the coating and the water-soluble resin-based layer from the base film of the coated film. In other words, the method is characterized by forming cracks in the coating before bringing the cleaning solution into contact with the water-soluble resin-based layer between the coating and the base film, thereby efficiently penetrating the water-soluble resin-based layer between the coating and the base film and reducing the adhesion between the coating and the base film in a short time.

[0049] Here, "forming cracks" refers to creating partial fractures in the film that occur when the film can no longer follow the deformation caused by applying physical stress acting in the direction of the film surface. It is preferable that the cracks are formed in a way that penetrates the film in the direction of its thickness. Furthermore, it is preferable that there are multiple cracks, and that their frequency is high, when observed from directly above the film surface, as this promotes the removal of the film. Also, it is preferable that the length of a single crack in the direction of the film surface is long when observed from directly above the film surface, as this promotes the removal of the film.

[0050] As described above, the coating removal method of the present invention is preferable if the coating has an energy ray curable resin as its main component, because this allows for more efficient crack formation and further accelerates the removal of the coating.

[0051] Furthermore, as mentioned above, it is preferable to apply a water-based cleaning solution to the coating of the coated film before pressing the pressing member against the coated film to form cracks, as this allows for more efficient crack formation.

[0052] In the coating removal method of the present invention, if a mechanism for applying a cleaning solution to the coating is provided, any solvent capable of dissolving water-soluble resins will be effective as the cleaning solution. However, to reduce environmental impact, it is preferable to use a solvent mainly composed of water. Alternatively, by adding a surfactant or the like to a water-based solvent, the wettability between the cleaning solution and the coating surface can be improved, making it easier for the cleaning solution to spread throughout the entire coating.

[0053] As described above, the coating removal apparatus and method of the present invention can be used to efficiently and uniformly remove the coating from the surface of a coated film. Furthermore, the coating removal apparatus and method of the present invention do not significantly increase the environmental burden, and high-purity resin chips free of foreign matter can be obtained at low cost, thus enabling the stable production of recycled films. [Examples]

[0054] The present invention will be described below with reference to examples, but the present invention is not necessarily limited thereto.

[0055] [Coated film] Three types of coated films were prepared, as shown below.

[0056] [Coated film a] A 30 μm thick, 450 mm wide base film made of polyethylene terephthalate was coated with a 0.1 μm thick film of polyvinyl alcohol resin, which is a water-soluble resin, on one side.

[0057] Furthermore, a coating made of UV-curable acrylic resin with a thickness of 1 μm was formed on top of that, with reference to the coating material described in Japanese Patent Publication No. 2015-195291, as follows. Materials used: Hexamethylene diisocyanate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1. • Dimethylorganopolysiloxane, manufactured by Chisso Corporation, product name "Cylaprene FM-DA11" • A mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate, manufactured by Toagosei Co., Ltd., product name "M-400". · 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]-phenyl}2-methylpropan-1-one, manufactured by BASF, product name "IRGACURE127".

[0058] In a reactor equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 100 parts by mass of hexamethylene diisocyanate (based on solid content; the same applies hereafter), 300 parts by mass of dimethyl organopolysiloxane, and 400 parts by mass of methyl ethyl ketone were charged. The mixture was heated to 85°C and maintained at that temperature for 7 hours to allow the reaction to proceed and obtain the reaction product.

[0059] Next, in another reactor equipped similarly to the one described above, 286 parts by mass of a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate, 12 parts by mass of the solid content of the reaction product obtained above, and 286 parts by mass of methyl ethyl ketone were charged. The temperature was raised to 85°C and maintained for 7 hours to allow the reaction to proceed. The disappearance of the isocyanate group was confirmed by IR measurement, and an energy-ray curable component was obtained.

[0060] 100 parts by mass of the energy ray curable component obtained above and 5 parts by mass of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one as a photopolymerization initiator were diluted to a solid content concentration of 20% by mass with a mixed solvent of isopropyl alcohol and methyl ethyl ketone (mass ratio 3:1).

[0061] The diluted coating material was applied using a gravure coater to the polyvinyl alcohol resin on a polyethylene terephthalate substrate film that had the polyvinyl alcohol resin coating formed on it, so that the cured thickness would be 1 μm, and dried at 80°C for 1 minute. Then, ultraviolet light was irradiated (cumulative light intensity: 250 mJ / cm2) to cure the energy ray curable component and form a coating, obtaining coated film a.

[0062] [Coated film b] A 30 μm thick, 450 mm wide base film made of polyethylene terephthalate was coated with a 0.1 μm thick film of polyvinyl alcohol resin, which is a water-soluble resin, on one side.

[0063] Furthermore, a coating made of thermosetting silicone resin with a thickness of 1 μm was formed on top of that, with reference to the coating material described in Japanese Patent Publication No. 2015-189226, as follows. Materials used: • Thermosetting silicone, manufactured by Shin-Etsu Chemical Co., Ltd., product name "KS-847T" Platinum catalyst, manufactured by Shin-Etsu Chemical Co., Ltd., product name "CAT-PL-50T".

[0064] A coating material containing thermosetting components was obtained by dissolving 100 parts by mass of thermosetting silicone and 5 parts by mass of platinum catalyst in a mixture of toluene and MEK (toluene:MEK mass ratio is 1:1) so that the solid content was 3.0% by mass.

[0065] Next, the coating material containing the thermosetting component obtained above was applied by gravure coater onto the polyvinyl alcohol resin of the polyethylene terephthalate substrate film on which the polyvinyl alcohol resin coating had been formed, so that the thickness after curing would be 1 μm. The coating was then dried at 100°C for 1 minute to form a film, and a coated film b was obtained.

[0066] [Coated film c] A coated film c was obtained in the same manner as the coated film a described above, with a coating formed on one side of polyethylene terephthalate, except that a coating made of UV-curable acrylic resin with a thickness of 1 μm was directly formed on one side of a base film made of polyethylene terephthalate with a thickness of 30 μm and a width of 450 mm, without forming a water-soluble resin on the other side.

[0067] [Removal Evaluation Method] (1) Removability of the coating The removal capability was evaluated using a commercially available DynePen (surface energy: 30 mN / m) and measured by the following method. Under room temperature conditions of 23°C, if the DynePen drew on the sample surface and the state was maintained for 4 seconds or more, it was determined that the surface energy of the sample surface was higher than the surface energy of the DynePen. If the coating components of the coated film remained on the surface, their surface energy would be less than 30 mN / m, so the DynePen would repel the reagent from the sample surface and would not be able to maintain the drawing. On the other hand, if the coating was removed and the water-soluble resin layer or the polyethylene terephthalate substrate was exposed, the surface energy would exceed 30 mN / m, and the DynePen would maintain the drawing. Based on the above evaluation method, it was determined whether or not the coating of the coated film had been removed.

[0068] (2) Uniformity of coating removal In evaluating the removeability of the coating described above, a 450 mm wide substrate was divided into 18 sections at 25 mm intervals in the width direction. Drawing was performed using a dye pen at the center of each of the 18 sections, and the removeability of the coating was evaluated. The uniformity of coating removal was determined according to the following criteria. [Judgment criteria] Excellent uniformity: The coating was removed in all 18 sections. Poor uniformity: The coating remains in at least one of the 18 sections. The uniformity of the above-mentioned coating removal was evaluated for each example and comparative example by changing the substrate transport speed to 25 m / min, 50 m / min, and 100 m / min. Since the uniformity of removal is easily affected by the transport speed, if good uniformity is achieved at all speeds, it can be determined that the removal device or method has excellent uniformity of removal.

[0069] [Example 1] A coated film a was set in the unwinding device 4 of the coating removal device 101 shown in Figure 1. The pressing member 6 was a stainless steel plate with a tip diameter of 20 μm, and was positioned so that the angle between the pressing member and the coated film when viewed from the width direction was 90°. The first tension-applying mechanism, which is combined into the drive devices 9a and 9b, applied a tension of 500 N / m to the coated film in front of and behind the pressing member 6.

[0070] The first water supply mechanism 7 used a steam generator (BOILER.V manufactured by Nippon Denetsu Co., Ltd.) and a discharge head (φ10 opening nozzle) to discharge steam at a discharge temperature of 100°C.

[0071] The removal member 8 is a stainless steel plate with a tip diameter of 20 μm, and is positioned so that the angle between the coated film sandwiching the removal member is 90° when viewed from the width direction. The second tension-applying mechanism, which is combined into the drive units 9b and 9c, applies a tension of 500 N / m to the coated film before and after the removal member 8.

[0072] The base film 3, from which the coating was removed by winding with the winding device 5, was collected and the uniformity of the coating removal was checked with a dye pen. As shown in Table 1, at a transport speed of 100 m / min, some of the coating remained in a portion of the film in the width direction, indicating poor uniformity of removal. However, at transport speeds of 25 m / min and 50 m / min, it was confirmed that the coating was removed uniformly.

[0073] [Example 2] The coated film a was placed in the unwinding device 4 of the coating removal device 301 shown in Figure 3. The second water supply mechanism 12 used a steam generator (BOILER.V manufactured by Nippon Denetsu Co., Ltd.) and a discharge head (φ10 opening nozzle) to discharge steam at a discharge temperature of 100°C.

[0074] The pressing member 6 was arranged using a stainless steel plate with a tip diameter of 20 μm such that the angle formed by the film-coated film sandwiching the pressing member was 90° in the observation view from the width direction. With the first tension applying mechanism also serving as the driving devices 9a and 9b, a tension of 500 N / m was applied to the film-coated films before and after the pressing member 6, respectively.

[0075] For the first water applying mechanism 7, a steam generator (BOILER.V manufactured by Nippon Densetsu Co., Ltd.) and a discharge head (φ10 opening nozzle) were used to discharge steam at a discharge temperature of 100°C.

[0076] The removing member 8 was arranged using a stainless steel plate with a tip diameter of 20 μm such that the angle formed by the film-coated film sandwiching the removing member was 90° in the observation view from the width direction. With the second tension applying mechanism also serving as the driving devices 9b and 9c, a tension of 500 N / m was applied to the film-coated films before and after the removing member 8, respectively.

[0077] Winding was performed with the winding device 5, and the base film 3 from which the film had been removed was collected. When the uniformity of film removal was confirmed with a dye pen, it was confirmed that the film could be uniformly removed at all conveyance speeds as shown in Table 1. As a result of water being applied by the second water applying mechanism 12, the formation of cracks in the film by the pressing member 6 was promoted, and it is considered that the film removability was improved compared to Example 1.

[0078] [Example 3] Film removal was carried out in the same manner as in Example 1, except that the tension T1 applied by the first tension applying mechanism was changed to 300 N / m. When the uniformity of film removal was confirmed, it was confirmed that the film could be uniformly removed at all conveyance speeds as shown in Table 1. Since the relationship between T1 and T2 satisfied T1 < T2, the effect of expanding the gap of the cracks formed in the film worked, and the effect of promoting the penetration of the cleaning liquid applied to the cracks into the layer mainly composed of the water-soluble resin under the cracks or dissolving the layer was promoted. As a result, it is considered that the film removability was improved compared to Example 1.

[0079] [Example 4] The coated film a was set in the unwinding device 4 of the coating removal device 201 shown in Figure 2. The pressing member 6 was a stainless steel plate with a tip diameter of 20 μm, and was positioned so that the angle between the pressing member and the coated film when viewed from the width direction was 90°. The first tension-applying mechanism, which is combined into the drive devices 9a and 9b, applied a tension of 500 N / m to the coated film in front of and behind the pressing member 6.

[0080] In the first water supply mechanism 7, a 3 wt% sodium hydroxide aqueous solution was used as the washing solution 7a, and the liquid tank 7b was designed to heat and maintain the washing solution 7a at 60°C.

[0081] The removal member 8 used a brush roll and was brought into contact with the film surface by rotating it in the opposite direction to the film transport direction at 100 rpm. The bristles of the brush roll were made of nylon resin and had a wire diameter of 0.15 mm. A second tension-applying mechanism, which was combined by the drive units 9b and 9c, applied a tension of 500 N / m to the coated film before and after the removal member 8.

[0082] The base film 3, from which the coating was removed by winding with the winding device 5, was collected and the uniformity of coating removal was checked with a dye pen. As shown in Table 1, at conveying speeds of 100 m / min and 50 m / min, some portions of the coating remained in the film width direction, indicating poor uniformity of removal. However, at a conveying speed of 25 m / min, it was confirmed that the coating was removed uniformly. When a mechanism was used to immerse the coated film in an alkaline cleaning solution as the first water application mechanism, compared to a mechanism that sprays steam at 70-120°C onto the coated film, a longer time was required for the cleaning solution to penetrate into or dissolve the layer mainly composed of water-soluble resin beneath the cracks. As a result, it is thought that the coating removal performance was inferior compared to Example 1.

[0083] [Example 5] Except for changing the coated film set in the unwinding device 4 to coated film b, the coating removal was carried out in the same manner as in Example 3. When the uniformity of coating removal was checked, as shown in Table 1, at a transport speed of 100 m / min, the coating remained in some sections in the film width direction, indicating poor uniformity of removal. However, at transport speeds of 25 m / min and 50 m / min, it was confirmed that the coating was removed uniformly. It is thought that because the coating of film b does not mainly consist of energy ray curable resin, the hardness of the film is low, and crack formation in the coating is less likely to occur, resulting in inferior coating removal performance compared to Example 3.

[0084] [Example 6] The coating was removed in the same manner as in Example 1, except that the tension applied by the first tension-applying mechanism was changed to 10 N / m. When the uniformity of the coating removal was checked, as shown in Table 1, the coating remained in some sections in the film width direction at conveying speeds of 100 m / min and 50 m / min, indicating poor uniformity of removal. However, at a conveying speed of 25 m / min, it was confirmed that the coating was removed uniformly. It is thought that the low tension applied by the first tension-applying mechanism caused large tension fluctuations and meandering during conveying, resulting in unstable crack formation of the coating and thus inferior coating removal performance compared to Example 1.

[0085] [Example 7] The coating was removed in the same manner as in Example 1, except that the arrangement of the pressing member was changed so that the angle between the pressing member and the coated film was 170°. When the uniformity of the coating removal was checked, as shown in Table 1, the coating remained in some sections in the width direction of the film at conveying speeds of 100 m / min and 50 m / min, indicating poor uniformity of removal. However, at a conveying speed of 25 m / min, it was confirmed that the coating was removed uniformly. It is thought that the angle between the pressing member and the coated film was too large, which weakened the force pressing the pressing member against the coated film, resulting in unstable crack formation in the coating, and consequently, the coating removal performance was inferior compared to Example 1.

[0086] [Comparative Example 1] The coating was removed in the same manner as in Example 3, except that the pressing member was removed and not used. When the uniformity of the coating removal was checked, as shown in Table 1, the coating remained in some sections in the film width direction at all transport speeds, indicating poor uniformity of removal. It is thought that the removal efficiency of the coating was significantly poor because crack formation in the coating did not occur due to the absence of the pressing member.

[0087] [Comparative Example 2] The coating removal was carried out in the same manner as in Example 3, except that the coated film set in the unwinding device 4 was changed to coated film c. When the uniformity of coating removal was checked, as shown in Table 1, the coating remained in some sections in the film width direction at all transport speeds, indicating poor uniformity of removal. It is thought that because film c does not have a layer mainly composed of water-soluble resin, the adhesion between the substrate and the coating was not reduced by the cleaning solution, resulting in significantly poor coating removal.

[0088] [Table 1] [Industrial applicability]

[0089] The present invention makes it possible to efficiently and uniformly remove the coating from a substrate film having a coating, and to provide a resource with few impurities that is suitable for reuse. [Explanation of Symbols]

[0090] 1. Coated film 2. Film with a cracked coating 3. Substrate film after the coating has been removed. 4 Unwinding device 5 Winding device 6 Pressing member 7. First water supply mechanism 8. Removal Members 9a, 9b, 9c drive unit 10 booths 12. Second water supply mechanism a. Film transport direction

Claims

1. An apparatus for removing a coating from a coated film having a coating on one side of a base film via a layer mainly composed of a water-soluble resin, A pressing member used by pressing it against the side of the coated film opposite to the coating in order to form cracks in the coating, A drive device for moving the coated film relative to the pressing member in the longitudinal direction of the coated film, The direction in which the coated film moves relative to the pressing member is defined as the transport direction, and a first water supply mechanism is provided downstream of the pressing member in the transport direction, and applies a cleaning solution mainly composed of water to the coating. A removal member is provided downstream in the transport direction from the first water supply mechanism and is used to remove the coating by contacting the surface of the coating on the coated film, A coating removal device equipped with the following features.

2. The coating removal device according to claim 1, further comprising a first tension-applying mechanism adjusted to apply tension T1 in the range of 10 to 1000 N / m in at least one longitudinal direction of the coated film before and after the pressing member.

3. The coating removal device according to claim 1, wherein the pressing member is positioned such that, when viewed from the width direction of the coated film, the angle formed by the coated film sandwiching the pressing member is in the range of 20 to 160°.

4. The coating removal device according to claim 1, further comprising a second water supply mechanism provided upstream of the pressing member in the transport direction for supplying a cleaning solution mainly composed of water to the coating.

5. The coating removal apparatus according to claim 1, wherein the first water supply mechanism is a mechanism for immersing the coated film in an alkaline cleaning solution.

6. The coating removal apparatus according to claim 1, wherein the first water supply mechanism is a mechanism for spraying steam at 70 to 120°C onto the coating.

7. The coating removal device according to claim 1, further comprising a second tension-applying mechanism adjusted to apply a tension T2 in the range of 10 to 1000 N / m in at least one longitudinal direction of the coated film before and after the removal member.

8. The coating removal device according to claim 2, further comprising a second tension-applying mechanism adjusted to apply a tension T2 in the range of 10 to 1000 N / m in at least one longitudinal direction of the coated film before and after the removal member, wherein the tensions T1 and T2 satisfy T1 < T2.

9. A method for removing a coating from a coated film using a coating removal apparatus according to any one of claims 1 to 8.

10. The method for removing a coating according to claim 9, wherein the coating mainly consists of an energy ray curable resin.

Images