Method for separating coating film from coated film and device for separating coating film

Abstract

A method for coating-film separation from a film having a coating film including a water-soluble resin is provided by which the coating film can be separated from the surface of the coated film at a high speed by dissolving the water-soluble resin using a solvent in a short time. This method is for separating a coating film from a coated film comprising a base film having a coating film on at least one surface thereof, and comprises making scratches, incisions, or holes in the coating film from the surface of the coated film where the coating film is present or making scratches, incisions, or holes which reach to the coating film, from the surface of the coated film where the coating film is absent, subsequently bringing a liquid detergent into contact with the coating film, and then separating the coating film containing the liquid detergent from the coated film.

Description

Method and apparatus for peeling coating from coated film

[0001] The present invention relates to a coating peeling method and coating peeling device that can efficiently remove a coating from the surface of a thermoplastic resin film.

[0002] While plastics are used in a variety of fields, they are also considered to be a cause of marine pollution, such as microplastics, making it urgent to reduce the environmental impact of plastics. Furthermore, with the recent advancement of the Internet of Things (IoT), the number of electronic devices, such as CPUs, installed in computers and smartphones has increased, and the number of multilayer ceramic capacitors (MLCCs) required to drive these electronic devices has also increased dramatically. A typical method for manufacturing MLCCs involves using a release film, which has a release layer formed on a plastic substrate film, as a carrier sheet, forming a ceramic green sheet layer on the release film, and peeling off the ceramic green sheet layer to obtain a ceramic green sheet.

[0003] In this process, the release film from which the ceramic green sheet layer has been peeled off is discarded as waste. In other words, the increase in release film waste due to the recent rapid increase in the number of MLCCs has become an environmental problem, and efforts to reuse plastic substrate films have been intensified. To reuse discarded release films, recycled films can be obtained by collecting, crushing, and turning them into resin chips, then remelting and forming films. However, from the perspective of releasability, the components of the release layer contained in the release film generally have a different composition from the components constituting the substrate film. Therefore, if a release film with a release layer is crushed, turned into resin chips, and then remelted and formed into a film, the components of the release layer will be present as foreign matter, making it difficult to stably form a film.

[0004] Furthermore, even if a film can be produced, the resulting film inevitably suffers from quality degradation due to the presence of the release layer as a foreign substance, such as coloration of the film and changes in surface composition, making it impossible to regenerate a film of the same quality as the original substrate film. Therefore, in order to recycle the release film as a recycled film, it is necessary to remove the components of the release layer contained in the release film to a trace amount of residue that does not affect the quality of the recycled film. Then, after recovering / pulverizing / obtaining high-purity resin chips, it is desirable to recycle them as recycled film over a long period of time at low cost.

[0005] However, to achieve this, it is necessary to spend a huge amount of time on the process of removing the release layer, which inevitably increases the cost of the recycled film.

[0006] Patent Document 1 discloses a method for removing release components from a release film, in which a release film having a water-soluble resin layer formed between a base film and a release layer is used, and the release film is immersed in a hot liquid bath for 2 seconds or more, and then the surface of the release film is rubbed with a brush roll to peel off the release layer.

[0007] Japanese Patent Application Laid-Open No. 2004-363140

[0008] Increasing the processing speed is very effective in achieving low costs. In the method disclosed in Patent Document 1, increasing the processing speed shortens the contact time in the hot liquid bath, and it is expected that it will be less than 2 seconds. If the contact time is less than 2 seconds, the water-soluble resin layer will not dissolve in time, making it impossible to remove the release component. Furthermore, the water-soluble resin layer itself will remain on the film and become foreign matter, making it impossible to obtain high-purity resin chips. In order to achieve contact for more than 2 seconds in the hot liquid bath while increasing the processing speed, it is necessary to increase the size of the hot liquid bath and increase the path length, which requires a hot liquid bath of an unrealistic size. Furthermore, increasing the size of the hot liquid bath increases the amount of waste liquid in which the water-soluble resin layer is dissolved, resulting in not only a significant increase in processing costs but also a significant increase in environmental impact.

[0009] Therefore, the present invention provides a method for peeling a coating from a coated film, and an apparatus for peeling a coating, which allows the coating to be peeled off quickly by scratching the surface of the coated film after use and then dissolving the water-soluble resin in a short period of time using a cleaning liquid.

[0010] [1] The coating peeling method of the present invention, which solves the above-mentioned problems, is a method for peeling a coating from a coated film having a coating on at least one side of a substrate film, comprising scratching, notching, or forming a hole in the coating from the side of the coated film with the coating, or scratching, notching, or forming a hole from the side of the coated film without the coating so that the scratch reaches the coating, then contacting the coating with a cleaning solution, and then peeling the coating containing the cleaning solution from the coated film. [2] In the coating peeling method of [1] above, it is preferable that the scratch is made while the coated film is being transported so that the angle (acute angle) between the longitudinal direction of the scratch and the transport direction is 60 degrees or less, or the notch is made so that the angle (acute angle) between the longitudinal direction of the notch and the transport direction is 60 degrees or less. [3] In the coating peeling method of [1] or [2] above, it is preferable that the coating contains a water-soluble resin. [4] In the coating peeling method of any of [1] to [3] above, it is preferable that the coating contains a curable silicone resin. [5] In the coating peeling method of any of [1] to [4] above, it is preferable that the cleaning liquid is water. [6] The coating peeling device of the present invention that solves the above problems is a device for peeling a coating from a coated film having a coating on at least one side of a substrate film, and includes: a coating damaging mechanism that scratches, cuts, or forms a hole in the coating from the coated side of the coated film, or that scratches, cuts, or forms a hole from the non-coated side of the coated film that reaches the coating; a cleaning liquid applying mechanism that applies a cleaning liquid to the coating of the scratched, cut, or holed coated film; and a peeling mechanism that peels the coating containing the cleaning liquid from the coated film. [7] The coating peeling device of [6] above is preferably equipped with a transport mechanism for transporting the coated film, and the coating damage mechanism makes the scratch so that the angle (acute angle) between the longitudinal direction of the scratch and the transport direction is 60 degrees or less, or makes the notch so that the angle (acute angle) between the longitudinal direction of the notch and the transport direction is 60 degrees or less.[8] The coating peeling device of [6] or [7] above may include an unwinding device for unwinding the coated film wound in a roll, and a winding device for winding up the base film from which the coating has been peeled off.

[0011] By using the method and apparatus for peeling a coating from a coated film of the present invention, the water-soluble resin can be dissolved from the surface of the coated film using a cleaning liquid in a short period of time, and the coating can be peeled off at high speed.

[0012] 1. A schematic diagram of a stripping apparatus 101 according to a first embodiment of the present invention. 2. A schematic diagram of a stripping apparatus 201 according to a second embodiment of the present invention. 3. A schematic diagram of a stripping apparatus 301 according to a third embodiment of the present invention. 4. A schematic diagram of a stripping apparatus 401 according to a fourth embodiment of the present invention. 5. A schematic diagram of a stripping apparatus 501 according to a fifth embodiment of the present invention. 6. A schematic diagram of a stripping apparatus 601 according to a sixth embodiment of the present invention. 7. A schematic diagram of a stripping apparatus 701 according to a seventh embodiment of the present invention. 8. A schematic diagram of a stripping apparatus 801 according to an eighth embodiment of the present invention. 9. A schematic diagram of a coating damage mechanism 6 according to FIG. 11. 10. A schematic diagram of a stripping apparatus 901 according to a ninth embodiment of the present invention. 11. A schematic diagram of a coating damage mechanism 6 according to FIG. 13. 12. A schematic diagram of a stripping apparatus 111 according to a tenth embodiment of the present invention. 13. A schematic diagram of a coating damage mechanism 6 according to FIG. 15.

[0013] The present inventors have conducted extensive research into a method for rapidly removing a coating by using a cleaning agent to dissolve the resin in the coating in a short period of time, and as a result have discovered the following method and apparatus for removing a coating from a coated film.

[0014] [Target Coated Films] The coating peeling method of the present invention targets a coated film having a coating on the surface of a substrate film, and involves cleaning the coating to peel and remove it from the substrate film. The coating may be present on one or both sides of the substrate film, and is not particularly limited. The coating of the target coated film may be of any composition, but a coating containing a water-soluble resin is preferred, taking into consideration factors such as environmental impact. More preferred water-soluble resins are those containing at least one of water-soluble polyester resins, polyester urethane resins, acrylic resins, ethylene ionomer resins, polyvinyl alcohol resins, polyvinylpyrrolidone resins, ethylene-vinyl alcohol resins, and starch as a main component.

[0015] The coating containing a water-soluble resin may be a single layer containing a water-soluble resin, a laminate of two or more layers containing a water-soluble resin, or a laminate of a layer containing a water-soluble resin and a layer not containing a water-soluble resin.

[0016] Furthermore, as a coated film, a coated release film containing a release component in addition to a water-soluble resin as part of the coating is particularly preferred, as it can efficiently exhibit the effect of coating release. The release component here refers to a component that increases the contact angle of the coating surface with water, i.e., reduces the surface energy of the coating. Examples of the release component include curable silicone resins such as thermosetting silicone resin compounds having a dimethylsiloxane main skeleton, and UV-curable silicone resin compounds that are prepared by blending a photopolymerization initiator with an organopolysiloxane containing an acryloyl group or a methacryloyl group and curing the resin by irradiating it with UV light, as well as compounds having long-chain alkyl groups and compounds having fluorine. The coating may be a mixture of a water-soluble resin and a release component, or may be a laminate of a layer containing a water-soluble resin and a layer containing a release component. In the case of a laminated coating, it is preferable to form a layer containing a water-soluble resin directly on the substrate film, and then a layer containing a release component on the outermost surface. It is particularly preferable to use a thermosetting silicone resin compound having a main skeleton of dimethylsiloxane, which has high water permeability, as the release component.

[0017] [Method for Peeling a Coating from a Coated Film] The method for peeling a coating from a coated film of the present invention (hereinafter referred to as the coating peeling method) involves scratching, notching, or forming a hole in the coating from the coated side of the coated film, or scratching, notching, or forming a hole from the uncoated side of the coated film that reaches the coating, then contacting the coating with a cleaning solution, and then peeling the coating containing the cleaning solution from the coated film. That is, this method is characterized by damaging the coating by scratching, notching, or forming a hole in the coating before contacting it with the cleaning solution, allowing the cleaning solution to efficiently penetrate the coating and dissolve the coating in a short period of time.

[0018] Here, "scratching" means physically rubbing the coating to roughen the surface of the coating and form irregularities, "making cuts" means making cuts in the coating by bringing a sharp object into contact with the coating, and "forming holes" means forming round holes, polygonal holes, etc. in the coating.

[0019] The dissolution of the water-soluble resin progresses as the cleaning solution penetrates through the coating surface. Damaging the coating increases the contact area with the cleaning solution, and the presence of irregularities, cuts, or holes in the coating makes it easier for the cleaning solution to penetrate deeper into the thickness of the coating, allowing the water-soluble resin to be dissolved in a short time. In the case where the coating of the target coated film is a laminated layer consisting of a layer containing a water-soluble resin directly above the substrate film and a layer containing a release component on the outermost surface, scratching, cutting, or forming a hole through the outermost layer allows the cleaning solution to be efficiently guided to the underlying layer containing the water-soluble resin.

[0020] At the same time, by making scratches, notches, or holes that reach the layer containing the water-soluble resin, the contact area with the cleaning liquid increases, and the presence of unevenness, notches, or holes in the layer containing the water-soluble resin makes it easier for the cleaning liquid to reach deeper positions in the thickness direction of the coating, so the water-soluble resin can be dissolved in a short time. Furthermore, the scratches, notches, or holes may reach the base film, in which case the contact area with the cleaning liquid in the thickness direction of the layer containing the water-soluble resin can be further increased.

[0021] Furthermore, if a thermosetting silicone resin compound having a main skeleton of dimethylchloroethane, which has high permeability to cleaning liquids, is used as the release component in a coating having a layer containing a release component laminated on the outermost surface, the cleaning liquid will easily permeate from the coating surface and reach the layer containing the water-soluble resin. In addition, the formation of scratches, cuts, and holes will promote penetration, making it possible to dissolve the water-soluble resin in the underlying layer in an even shorter time.

[0022] On the other hand, depending on the physical properties and compositions of the base film and each layer, and the state of the interface, when the scratch, notch, or hole is formed, a part of the layer containing the water-soluble resin may be buried in the base film, preventing the cleaning solution from reaching the fine details. In such cases, it is preferable to form the scratch, notch, or hole so as to penetrate through the base film, which allows the originally buried part to be pushed out to the back side of the base film, thereby preventing it from being buried.

[0023] Furthermore, when a coating is present on only one side of the substrate film, scratches, slits, or holes may be formed from the side without the coating to the coating. By forming scratches or the like from the side without the coating, a force acts on the layer containing the water-soluble resin in a direction that pushes it out of the substrate film, thereby preventing it from being buried in the substrate film. In this case, the cleaning solution can be expected to penetrate from the coated side and also from the back side of the substrate film through the scratches, slits, or holes on the substrate film side, thereby further promoting the dissolution of the water-soluble resin.

[0024] Furthermore, when scratching the coated film, it is preferable to scratch the film while transporting it so that the angle (acute angle) between the longitudinal direction of the scratch and the transport direction is 60° or less. Alternatively, when making a notch, it is preferable to make the notch so that the angle (acute angle) between the longitudinal direction of the notch and the transport direction is 60° or less. In particular, when a scratch or notch is made from a surface with a coating that reaches a part of the base film, and the transport tension of the film is large and the angle between the longitudinal direction of the scratch or notch and the transport direction is 90°, the tension acts directly at a right angle to the scratch or notch, which may lead to elongation or breakage of the base film. Therefore, by making the angle between the longitudinal direction of the scratch or notch and the transport direction less than 90°, the force acting at a right angle to the scratch or notch can be reduced. It is preferable to make the angle between the longitudinal direction of the scratch and the transport direction 60° or less, which makes the film less likely to elongate or break.

[0025] The higher the temperature of the cleaning solution applied to the coating, the faster the dissolution rate of the water-soluble resin, so the temperature of the cleaning solution applied to the coated film is preferably 40° C. or higher. On the other hand, in order to suppress dimensional changes in the substrate film due to heat, the temperature of the cleaning solution is preferably 150° C. or lower. Therefore, the temperature of the cleaning solution is preferably adjusted in accordance with the configuration of the device to be used so that the temperature of the cleaning solution and the temperature of the film at the point where the cleaning solution is applied are each in the range of 40° C. to 150° C.

[0026] The cleaning solution can be applied to the coating by immersing the coated film in the cleaning solution stored in a liquid tank. Alternatively, the required amount of cleaning solution can be sprayed onto the coated film without using a liquid tank, or, if the cleaning solution is water, steam can be sprayed onto the coated film. Furthermore, as long as the cleaning solution can be applied to the coating, it can be sprayed onto either one or both sides of the coated film.

[0027] Subsequently, the coating having the layer containing the water-soluble resin that has been sufficiently dissolved by the application of the cleaning solution can be easily peeled off by peeling means, which may be any method such as bringing a rotating brush into contact with the coating, scraping off the coating by continuously contacting a member having ridges with the coating, or blowing off the coating with an air nozzle.

[0028] By using the above method, the water-soluble resin can be dissolved in a short time, and the coating can be peeled off at high speed without increasing the size of the liquid tank or the amount of waste liquid.

[0029] [Apparatus for Peeling a Coating from a Coated Film] A preferred embodiment of the apparatus for peeling a coating from a coated film (hereinafter referred to as the coating peeling apparatus) of the present invention will be described with reference to the drawings. Note that the following description is an example of an embodiment of the present invention, and is not limited thereto, and various modifications are possible within the scope of the present invention.

[0030] Figure 1 is a schematic diagram of a coating peeling apparatus 101 according to a first embodiment of the present invention. As shown in Figure 1, the coating peeling apparatus 101 includes an unwinding device 4 that unwinds a coated film 2 and a winding device 5 that winds up the substrate film 3 after the coating has been peeled off. Between the unwinding device 4 and the winding device 5, there are provided a coating damaging mechanism 6 that scratches the coating of the coated film 2 from the surface 2a on which the coating is formed, a cleaning liquid applying mechanism 10 that applies cleaning liquid 7 to the scratched coating of the coated film 2, and a peeling mechanism 11 that peels off the coating containing the cleaning liquid 7 from the coated film 2 on which the cleaning liquid 7 has been applied.

[0031] 1 has a coating formed on one side of the film, and a coating damage mechanism 6 is provided opposite the surface 2a on which the coating is formed. If the coating film 2 has coatings formed on both sides, the coating damage mechanism 6 may be provided opposite each coating surface.

[0032] The cleaning liquid application mechanism 10 comprises a liquid tank 8 for storing the cleaning liquid 7 and a pump 9 for delivering the cleaning liquid 7 from a tank (not shown), and by transporting the coated film 2 while immersed in the cleaning liquid 7 in the liquid tank 8, the cleaning liquid 7 is continuously applied to the coated film 2. The cleaning liquid application mechanism 10 may be any device, such as a spray or a nozzle, as long as it is capable of applying the cleaning liquid 7 to the coating.

[0033] The coated film 2 unwound from the unwinding device 4 is transported by a transport mechanism consisting of drive devices 12a and 12b, and before the cleaning liquid 7 is applied by the cleaning liquid application mechanism 10, scratches are made in the coating by the coating damage mechanism 6.

[0034] The coating damage mechanism 6 is composed of a brush roll. Using a brush roll that can efficiently scratch the coating can scrape the coating surface, creating scratches and also potentially removing the coating. The brush roll can continuously scratch the coating by conveying the coated film 2 without rotating. To create more scratches, the brush roll needs to be rotated. A higher rotation speed is preferable because it increases the opportunities for the brush bristles to come into contact with the coating, resulting in greater scratches. Rotating the brush roll is also preferable because it allows the coating chips generated by coating damage to be discharged rather than remaining in one place. While Figure 1 shows the brush roll rotating in the opposite direction to the conveyance direction of the coated film 2, the brush roll rotation direction may be either the same direction or the opposite direction relative to the conveyance direction of the coated film 2, and is not particularly limited as long as it scratches the coating.

[0035] The material of the bristles of the brush roll may be appropriately selected from resin, metal, animal hair, plant fiber, etc., and is not particularly limited as long as it can make scratches in the coating, but if a material harder than the coating is selected, scratches can be easily made. The bristles are preferably thin and dense, which allows more scratches to be made.

[0036] Alternatively, a roller or the like having an uneven surface formed on a cylinder can be used as the coating damage mechanism 6, and the coating can be scratched by rubbing it. In this case, it is preferable to use a roller or a round bar with a knurled surface or one with an uneven surface formed by etching or engraving.

[0037] The peeling mechanism 11 is composed of a brush roll similar to that used in the coating damage mechanism 6. The peeling mechanism 11 has a mechanism for rotating a brush roll made of metal or resin in the same direction as the conveyance direction or in the opposite direction, and directly contacts the coating surface of the coated film 2 to peel off the cleaning solution and coating. The peeling mechanism 11 may be provided with a metal plate with a sharp tip that directly contacts the coated film 2, a resin plate, or a thin metal plate that bends when pressed against the coated film 2 like a blade. Alternatively, the coating may be peeled off by pressing a rag or fabric against the coated film 2 to wipe it off, or by blowing it off with an air nozzle.

[0038] Furthermore, although not shown, a structure may be added after the peeling mechanism 11 to spray clean cleaning liquid that is free from impurities such as foreign matter for rinsing, and then dry it with an air nozzle.

[0039] FIG. 2 is a schematic diagram of a coating peeling device 201 according to a second embodiment of the present invention. As shown in FIG. 2 , the second embodiment includes a backup roll 61 positioned opposite the brush roll of the coating damage mechanism 6 provided in the first embodiment, sandwiching the coated film 2 between them. When the conveying tension of the coated film 2 is low or when the brush roll rotates at high speed, a force is applied to push the coated film 2 toward the opposite side of the brush roll, causing the coated film 2 to float up at short intervals, which can result in insufficient contact force between the brush roll and the coated film 2 and a reduction in the number and depth of scratches. Therefore, providing the backup roll 61 to prevent the coated film 2 from floating up is preferable, as it ensures that the brush roll can contact the coated film 2 reliably. In this case, by using a brush roll bristles made of a material harder than the substrate film 3, scratches can be made through the coating, including a portion of the substrate film, thereby more reliably inflicting scratches across the entire thickness of the coating.

[0040] Figure 3 is a schematic diagram of a coating peeling apparatus 301 according to a third embodiment of the present invention. Figure 4 is a schematic top view of the coating damage mechanism 6A shown in Figure 3. In the third embodiment, as shown in Figures 3 and 4, instead of the brush roll provided in the first embodiment, the coating damage mechanism 6A is provided with multiple cutters 62 in the width direction, which make incisions 63 in the coating. Note that in Figure 4, the coating damage mechanism 6A is observed through the coated film 2, and the coating damage mechanism 6A and the incisions 63 are not actually visible, so the cutters 62 and the incisions 63 are shown with dashed lines.

[0041] Generally, the thickness of the coating is thin relative to the thickness of the substrate film. Therefore, simply by lightly placing the cutter 62 against the surface 2a on which the coating is formed, it is possible to make incisions 63 in the coating without penetrating the substrate film. Furthermore, by adjusting the amount of pressure of the cutter 62 against the coating and the conveying tension of the coated film 2, it is possible to make incisions that reach not only the coating but also part of the substrate film. The number of incisions 63 is determined by the number of cutters 62 and their arrangement pitch, and can be adjusted appropriately to obtain the desired incisions 63. The cutter 62 may be a rotating circular blade, or may be made of a sharp-tipped member. The cutter 62 may be made of any material, such as metal, ceramic, or resin, as long as it has a sharp tip.

[0042] Figure 5 is a schematic diagram of a coating peeling apparatus 401 according to a fourth embodiment of the present invention. Figure 6 is a schematic top view of the coating damage mechanism 6B shown in Figure 5. In the fourth embodiment, as shown in Figures 5 and 6, the pressure of the cutter 62 of the coating damage mechanism 6A provided in the third embodiment is increased to cut a slit that penetrates the substrate film and cuts the entire thickness of the coating. In the coating peeling apparatus 401, when the coated film 2 is immersed in the cleaning liquid 7 stored in the liquid tank 8 of the cleaning liquid application mechanism 10, the cleaning liquid 7 is applied through the slits 63 in the substrate film to the surface 2a on which the coating is formed and the surface 2b on which the coating is not formed, thereby efficiently dissolving the water-soluble resin.

[0043] If the cleaning liquid application mechanism 10 is a sprayer or the like, the spraying may be performed only from the side 2a on which the coating is formed, or preferably, by spraying from both sides of the coated film 2, the water-soluble resin can be efficiently dissolved, just as in the case of immersion in the cleaning liquid 7 stored in the liquid tank 8.

[0044] Furthermore, when the coating is formed on both sides of the film and the cleaning liquid 7 is applied by spraying using a spray or the like, the cleaning liquid will reach the coating through the slits in the base film, so the water-soluble resin can be dissolved even if the cleaning liquid is applied from either side, but it is more preferable to apply the cleaning liquid from both sides to efficiently dissolve the water-soluble resin.

[0045] FIG. 7 is a schematic diagram of a coating peeling apparatus 501 according to a fifth embodiment of the present invention. In the fifth embodiment, instead of the brush roll used in the first embodiment, a roller 64 with sharp protrusions on its cylindrical surface is used as the coating damage mechanism 6C. This roller 64 contacts the coating and forms holes in the coating. By rotating the roller 64 at the same peripheral speed as the conveying speed of the coated film 2, holes of substantially the same shape as the protrusions formed on the surface can be formed. When the roller 64 is not rotated, a cut similar to that of the cutter used in the third embodiment can be made. Furthermore, by rotating the roller 64 at a peripheral speed different from the conveying speed or in the opposite direction to the conveying direction, holes extending in the conveying direction can be formed depending on the difference in peripheral speed. The shape of the holes is not particularly limited, and any shape, such as a round hole, an elongated hole, or a polygonal hole, can be used.

[0046] The sharp protrusions on the roller 64 can be realized, for example, by embedding needle-shaped members such as pin holders on the cylindrical surface, or by forming sharp protrusions on the cylindrical surface by laser engraving or machining. Generally, the thickness of the coating is thin compared to the thickness of the substrate film, so it is possible to form holes in the coating without penetrating the substrate film by simply lightly pressing the roller 64 against the coating surface. It is also possible to form holes that reach not only the coating but also part of the substrate film by significantly adjusting the amount of pressure the roller 64 places on the coating and the conveying tension of the coated film 2.

[0047] The number of holes is determined by the number of protrusions and their arrangement pitch, and can be adjusted appropriately to obtain the desired number of holes. The material of the protrusions can be metal, ceramic, resin, etc., and is not particularly limited as long as it can at least form holes in the coating.

[0048] 8 is a schematic diagram of a coating peeling apparatus 601 according to a sixth embodiment of the present invention. In the sixth embodiment, a coating damaging mechanism 6D is provided by a roller 64 having sharp protrusions on its cylindrical surface, as shown in FIG. 7 in the fifth embodiment, and the pressing force of the roller 64 is increased to form holes penetrating the substrate film, thereby forming holes throughout the entire thickness of the coating.

[0049] FIG. 9 is a schematic diagram of a coating peeling device 701 according to a seventh embodiment of the present invention. FIG. 10 is a schematic top view of the coating damage mechanism 6E shown in FIG. In the seventh embodiment, the cutter 62 provided in the third embodiment is provided on the non-coated surface 2b of the coating damage mechanism 6E, which penetrates the substrate film and cuts the coating. Depending on the physical properties and composition of the substrate film and the coating, and the state of the interface between the substrate film and the coating, when a scratch is made, part of the coating may become embedded in the substrate film, preventing the cleaning solution 7 from reaching every detail. In this case, it is preferable to make a scratch from the non-coated surface 2b of the coated substrate film 2, as this pushes the coating away from the substrate film, thereby eliminating the risk of the coating becoming embedded in the substrate film.

[0050] Fig. 11 is a schematic diagram of a coating peeling apparatus 801 according to an eighth embodiment of the present invention. Fig. 12 is a schematic top view of the coating damaging mechanism 6F shown in Fig. 11. In the eighth embodiment, the coating damaging mechanism 6F is a roller 64 having sharp protrusions on its cylindrical surface, as in the sixth embodiment, which is provided on the surface 2b on which the coating is not formed, and penetrates the substrate film to form holes 67 in the coating. This provides the same functions and effects as those of the seventh embodiment.

[0051] Figure 13 is a schematic diagram of a coating peeling apparatus 901 according to a ninth embodiment of the present invention. Figure 14 is a schematic top view of the coating damaging mechanism 6G shown in Figure 13. The coating damaging mechanism 6G of the ninth embodiment includes a pinholder-shaped member 65 provided with a plurality of sharp protrusions or cutters, and a means for moving the member 65 (not shown). The coating damaging mechanism 6G is provided on the side of the surface 2a on which the coating is formed, and uses the moving means to move the member 65 in the width direction of the coated film 2, thereby forming a notch 62 in the coating or in a portion of the coating and the substrate film in the thickness direction.

[0052] By repeatedly moving the member 65 back and forth while the coated film 2 is being transported, the slit 62 can be made obliquely relative to the transport direction. In this case, the angle (acute angle) θ between the longitudinal direction of the slit 62 and the transport direction is preferably 60 degrees or less. Tension is applied to the film during transport. If the angle θ exceeds 60 degrees, a force obtained by multiplying the applied tension by sin θ, i.e., a force of 87% or more of the tension, acts perpendicular to the slit 62. Applying a large tension may result in stretching or breakage of the base film. In particular, if the slit 62 extends partially through the thickness of the base film, the film is more likely to stretch or break. Therefore, the angle θ is preferably 60 degrees or less.

[0053] Figure 15 is a schematic diagram of a coating peeling apparatus 111 according to a tenth embodiment of the present invention. Figure 16 is a schematic top view of the coating damage mechanism 6 shown in Figure 15. In the tenth embodiment, instead of the sharp protrusions or pinholder-shaped member 65 with multiple cutters used in the ninth embodiment, the coating damage mechanism 6H uses a strip-shaped brush 66 to rub against the coating and create scratches 68. In the coating peeling apparatus 111, the brush 66 is repeatedly moved back and forth while the coated film 2 is being transported, thereby creating scratches 68 oblique to the transport direction. In this case, as in the tenth embodiment, the angle θ between the longitudinal direction of the scratch 68 and the transport direction (acute angle) is preferably 60 degrees or less.

[0054] The coating damage mechanisms 6 to 6H shown in the first to tenth embodiments may be provided in multiple locations along the film feed direction. Providing multiple coating damage mechanisms 6 to 6H makes it possible to create more scratches, cuts, and holes, which can lead to faster coating peeling. This is also effective when the water-soluble resin is difficult to dissolve due to factors such as the composition or thickness of the coating.

[0055] As described above, by using the coating peeling method and coating peeling device of the present invention, the water-soluble resin can be dissolved from the surface of the coated film in a short time using a cleaning solution, and the coating can be peeled off at high speed. As a result, high-purity resin chips free of foreign matter can be obtained at low cost without significantly increasing the environmental load.

[0056] The present invention will be described below with reference to examples, but the present invention is not necessarily limited to these examples.

[0057] <Coated Film> The following three types of coated films were prepared.

[0058] <Coated film a> A 0.1 μm thick polyvinyl alcohol resin coating was formed on a 30 μm thick, 100 mm wide base film made of polyethylene terephthalate as a layer containing a water-soluble resin. Further, a 0.1 μm thick curable silicone resin coating was formed on top of the base film as a layer containing a release component, with reference to the coating material described in JP 2015-189226 A. Materials used: Thermosetting silicone, manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KS-847T": 100 parts by mass; Platinum catalyst, manufactured by Shin-Etsu Chemical Co., Ltd., trade name "CAT-PL-50T": 3 parts by mass. The coating material was prepared by dissolving the above thermosetting silicone and platinum catalyst in a mixture of toluene and MEK as a solvent (toluene: MEK mass ratio 1:1) so that the solids content was 1.8% by mass. Next, a coating material was applied onto the polyvinyl alcohol resin coating using a bar coater, and dried in an oven at 90° C. for 20 seconds to form a coating of a release component, thereby obtaining a coated film a.

[0059] <Coated Form b> A 0.1 μm thick polyvinyl alcohol resin coating was formed on a 30 μm thick, 100 mm wide polyethylene terephthalate substrate film as a layer containing a water-soluble resin. Furthermore, a 0.1 μm thick resin coating containing a compound having a long-chain alkyl group was formed on top of that as a layer containing a release component, as follows, with reference to the coating material described in JP 2019-137005 A. Materials used: Long-chain alkyl group-containing compound, manufactured by Lion Specialty Chemicals, trade name "Peiroil" 1050: 10 parts by mass in solids; Crosslinking agent, manufactured by Sumitomo Chemical Co., Ltd., trade name "Sumimar" M-55: 2.5 parts by mass in solids; Acid catalyst, manufactured by Teica Corporation, trade name "TAYCACURE" AC-700: 1.3 parts by mass in solids; Solvent, toluene 400 parts by mass, MEK 130 parts by mass. The coating material was prepared by dissolving the above-mentioned long-chain alkyl group-containing compound, crosslinking agent, and acid catalyst in a solvent. Next, the coating material was applied onto the coating of the polyvinyl alcohol resin using a gravure coater, pre-dried at 100 ° C., and then heated and dried at 160 ° C. to form a coating of the release component, and a coated film b was obtained.

[0060] <Coated film c> A 0.1 μm thick polyvinyl alcohol resin coating was formed on a 30 μm thick, 100 mm wide polyethylene terephthalate substrate film as a water-soluble resin layer. Furthermore, a 0.1 μm thick curable silicone resin coating was formed on the polyvinyl alcohol resin coating as a release component layer, as described below, with reference to the coating material described in WO 2013 / 145864. Materials used: Active energy ray curable component, dipentaerythritol hexaacrylate, manufactured by Shin-Nakamura Kogyo Co., Ltd., product surface "A-DPH" solid content 100% by mass: 99.0 parts by mass; Silicone component, polyether-modified acryloyl group-containing polydimethylsiloxane, manufactured by BYK-Chemie, trade name "BYK-3500" solid content 100% by mass: 1.0 part by mass; Photopolymerization initiator 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, manufactured by BASF, trade name "IRGACURE 907": 5.0 parts by mass. The coating material was prepared by diluting the above dipentaerythritol hexaacrylate, polyether-modified acryloyl group-containing polydimethylsiloxane, and photopolymerization initiator with a mixed liquid of isopropyl alcohol and methyl ethyl ketone (mixing mass ratio 3:1), and this was used as a release agent solution (solid content 20% by mass). This release agent solution was applied to the polyvinyl alcohol resin coating using a bar coater so that the thickness after curing would be 0.97 μm, and the coating was dried at 80° C. for 1 minute. Thereafter, ultraviolet light was irradiated (integrated light amount: 250 mJ / cm ２ ) and the release agent composition was cured to form a coating of the release component, thereby obtaining a coated film c.

[0061] <Peeling Evaluation Method> (1) Peelability of Coating Peelability was evaluated using a commercially available dyne pen (surface energy: 30, 70 mN / m) by the following method. When a drawing was made on the surface of a sample with the dyne pen at room temperature (23°C) and the state was maintained for 4 seconds or more, it was determined that the surface energy of the sample surface was higher than that of the dyne pen. If the release component coating of coated films a to c remained on the surface, the surface energies of these films were all less than 30 mN / m, and therefore the reagent was repelled by the sample surface with any of the dyne pens, making it impossible for the drawing to be maintained. On the other hand, if the release component coating was peeled off and the polyvinyl alcohol resin was exposed, the surface energy was 70 mN / m or more, and therefore any of the dyne pens could maintain the drawing. When both the release component coating and the water-soluble polyvinyl alcohol resin coating are peeled off and the polyethylene terephthalate is exposed, the surface energy is 43.8 mN / m, so that a 30 mN / m dyne pen drawing is maintained but a 70 mN / m dyne pen drawing is not maintained. Using the above evaluation method, it was determined whether or not the coating of the coated film was peeled off.

[0062] (2) Quality of Recycled Resin Chips (i) Melt Film Formability After peeling the coating from the coated film, the substrate film is recovered. The recovered substrate film is crushed in a crusher and granulated in a granulator to produce recycled resin chips. The recycled resin chips are dried at 180°C for 2 hours, then fed into an extruder and melt-extruded at 280°C, and molded into a sheet on a casting drum cooled to 25°C. It is confirmed whether a polyethylene terephthalate film can be produced without any problems.

[0063] (ii) Intrinsic Viscosity The intrinsic viscosity IV(R) of the sheet obtained in (i) above is measured. The intrinsic viscosity IV(R) is measured by dissolving a polyethylene terephthalate film in 100 ml of orthochlorophenol (solution concentration C = 1.2 g / dl), and measuring the viscosity of the solution at 25°C using an Ostwald viscometer. The viscosity of the solvent is also measured in the same manner. Using the obtained solution viscosity and solvent viscosity, [η] (dl / g) is calculated according to the following formula (a), and the obtained value is taken as the intrinsic viscosity. (a) ηsp / C = [η] + K[η] ２・C (where ηsp = (solution viscosity (dl / g) / solvent viscosity (dl / g)) - 1, and K is the Huggins constant (assumed to be 0.343).) Next, before producing the coated film, the intrinsic viscosity IV(I) of a sampled base film before forming the coating is measured in the same manner. Since a deterioration in the quality of resin chips caused by the inclusion of foreign matter or the like is expressed as the difference between IV(R) and IV(I), ΔIV is calculated using the following formula (b), and the obtained value is used to make the following judgment: (b) ΔIV = IV(R) - IV(I) - Difference in intrinsic viscosity is 0.05 or less: The quality of the recycled resin chip is within an acceptable range. - Difference in intrinsic viscosity is more than 0.05 but less than 0.2: The quality of the recycled resin chip is slightly inferior, but within a practical range. - Difference in intrinsic viscosity is more than 0.2: The quality of the recycled resin chip is not suitable for practical use.

[0064] Example 1: A coated film 2 (a film a) was used, which had a coating formed on one side of a substrate film. The film was set in the unwinding device 4 of the peeling device 101 shown in Figure 1. The coating damage mechanism 6 used a brush roll, which rotated at 500 rpm in the reverse direction relative to the film transport direction, contacting and scraping the coating surface to create scratches. The brush roll bristles were made of nylon resin and had a wire diameter of 0.15 mm. Warm water at 60°C was used as the cleaning liquid 7. The cleaning liquid application mechanism 10 contained cleaning liquid 7 in a liquid tank 8. The coated film 2 was introduced into the liquid tank 8, and the polyvinyl alcohol resin coating was dissolved while the film was immersed and transported in the cleaning liquid 7. The length of time the coated film 2 was immersed in the cleaning liquid 7 was 0.5 m. The film transport tension was 60 N, and the transport speed was 50 m / min. Therefore, the time the coated film 2 was in contact with the cleaning liquid 7 was 0.6 seconds. The peeling mechanism 11 used a metal brush roll, which rotated at 500 rpm in the reverse direction of the film transport direction and contacted the coating surface to peel off the coating. The film was wound up using the winding device 5, and the substrate film 3 from which the coating had been peeled was collected. The peeling state of the coating was confirmed using a dyne pen. It was confirmed that both the curable silicone resin and water-soluble polyvinyl alcohol resin coatings, which were the release components, had been peeled off. The substrate film 3 was then recovered, crushed in a crusher, and made into resin chips using a granulator. The film was then placed in an extruder, melt-extruded at 280°C, and formed into a sheet on a cast drum cooled to 25°C to produce a polyethylene terephthalate film. No bubbles or gels were observed in the molten polymer, and no abnormalities such as pressure increases occurred, resulting in a polyethylene terephthalate film. The difference in intrinsic viscosity was 0.03, which was confirmed to be within the acceptable range for the quality of recycled resin chips.

[0065] Example 2: A coated film 2 (a film a) was used, in which a coating was formed on one side of a substrate film. It was set in the unwinding device 4 of the peeling device 901 shown in FIG. 13 . The coating damage mechanism 6G used a member 65, consisting of multiple 1 mm diameter stainless steel wires arranged at 3 mm intervals as sharp protrusions. The member 65 was placed along the coating surface and reciprocated in the film width direction at a speed of 50 m / min to create incisions 62 in the coating. As a result, the angle (acute angle) between the longitudinal direction of the incision 62 and the conveying direction was 45 degrees. It was also visually confirmed that the incision 62 reached a portion of the substrate film. The coating was peeled off under the same conditions as in Example 1. The substrate film 3 was wound up by the winding device 5, and the peeled coating was sampled. The peeling state of the coating was confirmed using a dyne pen. It was confirmed that both the release component curable silicone resin and water-soluble polyvinyl alcohol resin coatings were peeled off. After recovering the base film 3, a polyethylene terephthalate film was produced using the recycled resin chips in the same manner as in Example 1. No bubbles or gels were observed in the molten polymer, and no abnormalities such as pressure increase occurred. A polyethylene terephthalate film was obtained. The difference in intrinsic viscosity was 0.05, which was confirmed to be within the acceptable range for the quality of the recycled resin chips.

[0066] Example 3: A coated film b, in which a coating was formed on one side of a substrate film, was used as the coated film 2. Peeling was performed using the peeling device 101 of Example 1 under the same conditions as in Example 1. The film was wound up using the winding device 5, and the substrate film 3 from which the coating had been peeled was sampled. The peeling state of the coating was confirmed using a dyne pen. It was confirmed that both the resin containing the compound having a long-chain alkyl group as a release component and the water-soluble polyvinyl alcohol resin coating had been peeled off. After recovering the substrate film 3, a polyethylene terephthalate film was produced using recycled resin chips in the same manner as in Example 1. No bubbles or gels were observed in the molten polymer, and no abnormalities such as pressure increases occurred. The difference in intrinsic viscosity was 0.04, which was confirmed to be within the acceptable range for the quality of recycled resin chips.

[0067] Example 4: A coated film c, in which a coating was formed on one side of a substrate film, was used as the coated film 2, and peeling was performed using the peeling device 101 of Example 1. The brush roll of the coating damage mechanism 6 rotated at 1,500 rpm in the reverse direction relative to the film transport direction, contacting and scraping the coating surface to create scratches. Other conditions were the same as in Example 1. The film was wound up using the winding device 5, and the substrate film 3 from which the coating had been peeled was sampled. The peeling state of the coating was confirmed using a dyne pen. It was confirmed that both the release component coatings, the curable silicone resin and the water-soluble polyvinyl alcohol resin coatings, had been peeled off. After recovering the substrate film 3, a polyethylene terephthalate film was produced using recycled resin chips in the same manner as in Example 1. No bubbles or gels were observed in the molten polymer, and no abnormalities such as pressure increases occurred. The difference in intrinsic viscosity was 0.05, which was confirmed to be within the acceptable range for recycled resin chip quality.

[0068] Comparative Example 1: A coated film a, in which a coating was formed on one side of a substrate film, was used as the coated film 2. Peeling was performed using the peeling device 101 shown in FIG. 1 , with the brush roll (coating damage mechanism 6) removed. The coating was peeled off under the same conditions as in Example 1. The substrate film 3 was wound up using the winding device 5, and the peeled substrate film 3 was sampled. The peeled state of the coating was confirmed with a dyne pen, confirming that a portion of the coating of the curable silicone resin and water-soluble polyvinyl alcohol resin, which are release components, remained. After recovering the substrate film 3, a polyethylene terephthalate film was produced using recycled resin chips in the same manner as in Example 1. Air bubbles were found to be present in the molten polymer. Furthermore, the difference in intrinsic viscosity of the produced polyethylene terephthalate film was 0.23, confirming that the recycled resin chips were of unsuitable quality for practical use.

[0069] The method and apparatus for peeling a coating from a coated film of the present invention are not limited to films having a coating containing a water-soluble resin on one side of a substrate film, but can also be applied to methods and apparatus for peeling a coating from recyclable resin films, paper films, and metal films having a coating containing an easily soluble resin layer.

[0070] 2 Coated film 2a Surface on which coating is formed 2b Surface on which coating is not formed 3 Base film 4 Unwinding device 5 Winding device 6, 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H Coating damage mechanism 7 Cleaning liquid 8 Liquid tank 9 Pump 10 Cleaning liquid application mechanism 11 Peeling mechanism 12a, 12b Driving device 61 Backup roll 62 Cutter 63 Notch 64 Roller 65 Member 66 Brush 67 Hole 68 Scratch 101, 201, 301, 401, 501, 601, 701, 801, 901, 111 Peeling device

Claims

1. A method for peeling a coating from a coated film having a coating on at least one side of a substrate film, comprising scratching, slitting or forming a hole in the coating from the coated side of the coated film, or scratching, slitting or forming a hole from the uncoated side of the coated film that reaches the coating, then contacting the coating with a cleaning fluid, and then peeling the coating containing the cleaning fluid from the coated film.

2. The method for peeling a coating from a coated film according to claim 1, wherein, while the coated film is being transported, the scratch is made so that the angle (acute angle) between the longitudinal direction of the scratch and the transport direction is 60 degrees or less, or the notch is made so that the angle (acute angle) between the longitudinal direction of the notch and the transport direction is 60 degrees or less.

3. The method for removing a coating from a coated film according to claim 1 or 2, wherein the coating contains a water-soluble resin.

4. The method for removing a coating from a coated film according to claim 1 or 2, wherein the coating comprises a curable silicone resin.

5. The method of stripping a coating from a coated film according to claim 3, wherein the cleaning liquid is water.

6. A peeling device for peeling a coating from a coated film having a coating on at least one surface of a base film, comprising: a coating damaging mechanism that scratches, cuts, or forms a hole in the coating from the side of the coated film that has the coating, or that scratches, cuts, or forms a hole from the side of the coated film that does not have the coating and reaches the coating; a cleaning liquid applying mechanism that applies a cleaning liquid to the coating of the scratched, cut, or holed coated film; and a peeling mechanism that peels the coating containing the cleaning liquid from the coated film.

7. An apparatus for peeling a coating from a coated film according to claim 6, further comprising a transport mechanism for transporting the coated film, wherein the coating damaging mechanism makes the scratch so that the angle (acute angle) between the longitudinal direction of the scratch and the transport direction is 60 degrees or less, or makes the notch so that the angle (acute angle) between the longitudinal direction of the notch and the transport direction is 60 degrees or less.

8. An apparatus for peeling a coating from a coated film according to claim 6 or 7, comprising: an unwinding device for unwinding the coated film wound in a roll; and a winding device for winding up the base film from which the coating has been peeled.