Method for recycling used PET film, pellets, and sliding parts of image forming devices

Abstract

To further expand the uses of used PET film with ceramics attached to the surface by recycling the film at low cost. [Solution] The method for recycling used PET film with ceramics attached to its surface includes a re-pelletizing process (step S2) in which the used PET film with ceramics still attached to its surface is re-pelletized to produce pellets, and a molding process (step S3) in which the pellets produced in the re-pelletizing process are used to mold a resin molded product.

Description

[Technical Field]

[0001] The present invention relates to a recycling method for used PET film, pellets, and sliding parts of an image forming apparatus, and more particularly to a recycling method for used PET film having ceramics attached to its surface, pellets, and sliding parts of an image forming apparatus. [Background technology]

[0002] In recent years, there has been a demand for the reuse of materials as a measure to conserve environmental resources. For example, PET film is used as a carrier film in the intermediate process of manufacturing multilayer electronic components such as multilayer ceramic capacitors, and there is a demand for the reuse of used PET film as well. For example, Patent Document 1 discloses a method for recycling used PET film, in which foreign matter adhering to the surface of the PET film is washed with a cleaning solution containing an organic solvent, and the cleaning solution adhering to the surface of the PET film is removed, thereby converting the used PET film into new PET film for recycling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-291690 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the method for recycling used PET film disclosed in Patent Document 1 is limited to recycling used PET film into new PET film, and the applications in which used PET film can be reused are limited.

[0005] The present invention has been made in view of the above circumstances, and aims to further expand the uses of used PET film having ceramics attached to its surface by recycling it at low cost. [Means for solving the problem]

[0006] A method for recycling used PET film according to one aspect of the present invention is a method for recycling used PET film having ceramics attached to its surface, and includes a re-pelleting step of re-pelletizing the used PET film to produce pellets, and a molding step of molding a resin molded product using the pellets produced in the re-pelleting step. [Effects of the Invention]

[0007] According to the present invention, by re-pelletizing used PET film to form pellets, the reuse of used PET film can be expanded beyond its use as new PET film to include resin molded products, and the number of steps required to produce pellets from used PET film with ceramics attached to its surface is reduced, thereby further expanding the range of uses for which used PET film with ceramics attached to its surface can be reused at low cost. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an outline of a manufacturing process for a multilayer ceramic capacitor, illustrating that ceramics are attached to the surface of a used PET film used in a method for recycling a used PET film according to a first embodiment of the present invention. [Figure 2] 1A to 1C are diagrams illustrating steps in a method for recycling used PET films according to a first embodiment. [Figure 3] 3 is a diagram showing an outline of products etc. in the process of the method for recycling used PET film shown in FIG. 2. [Figure 4] 4A to 4C are diagrams showing steps of a method for recycling used PET films according to a second embodiment of the present invention. [Figure 5] 5 is a diagram showing an outline of products etc. in the process of the method of recycling used PET film shown in FIG. 4. [Figure 6]5 is an explanatory diagram for explaining a mechanism for removing ceramics adhered to the surface from a used PET film in the ceramic removal step of FIG. 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment Hereinafter, a method for recycling used PET films according to a first embodiment of the present invention will be described with reference to the drawings.

[0010] First, we will explain about used PET film with ceramics attached to its surface.

[0011] PET film is used in the intermediate process of manufacturing multilayer electronic components such as multilayer ceramic capacitors. When PET film is used in the intermediate process of manufacturing multilayer electronic components, ceramics adhere to the surface of the PET film. When the multilayer electronic components are removed from the PET film in the intermediate process, the used PET film with the ceramics remaining on its surface becomes eligible for recycling.

[0012] The PET film is, for example, long and contains at least PET (polyethylene terephthalate) and silicone resin, with a PET content of, for example, 98% and a silicone resin content of 2% or less. The used PET film is a PET film that has been used in the manufacture of laminated electronic components, and the ceramics described above remain and adhere to the surface of the used PET film.

[0013] Next, the adhesion of ceramics to the surface of a PET film will be described with reference to Fig. 1. Fig. 1 is a diagram showing an outline of the manufacturing process of a multilayer ceramic capacitor, to explain the adhesion of ceramics to the surface of a PET film used in a method for recycling used PET film.

[0014] The PET film 1 is, for example, long and includes at least PET and a silicone resin, and has a base film and a release layer formed on one side of the base film. The base film contains PET, and the release layer contains a silicone resin. By including the silicone resin in the release layer, the release layer can be made to have excellent release properties, and the amount of ceramic residue remaining on the surface of the release layer after removing the ceramic green sheet described below can be reduced.

[0015] As shown in Fig. 1(A), a slurry containing a dielectric ceramic powder, a binder, an organic solvent, etc. is applied in sheet form to the surface of a release layer constituting a PET film 1 by a doctor blade method or the like, and the organic solvent component is dried and removed to form a ceramic green sheet 2. The binder material is, for example, polyvinyl butyral (PVB) resin, etc. The organic solvent material is, for example, ethanol, toluene, etc.

[0016] 1(B), electrode patterns 3A to 3F are formed by screen-printing an electrode paste containing, for example, nickel on the surface of the ceramic green sheet 2. In FIG. 1, for the sake of simplicity, each of the electrode patterns 3A to 3F is represented by a square (□).

[0017] The ceramic green sheet 2 on which the electrode patterns 3A to 3F are formed is cut into rectangles, and the cut rectangular portions are peeled off from the PET film 1 to produce parts 4A to 4F of the multilayer ceramic capacitor (for one layer) as shown in Figure 1(C).

[0018] Furthermore, when the cut rectangular portion is peeled off from the PET film 1, a remnant 5 of the ceramic green sheet 2 remains on the used PET film 100, as shown in Figure 1(C). In this way, a used PET film 100 with ceramics attached to its surface is produced.

[0019] A predetermined number of parts for one layer of the multilayer ceramic capacitor are laminated. For example, as shown in Fig. 1(D), three parts 4A to 4C for one layer of the multilayer ceramic capacitor are laminated as the predetermined number, and an electrode pattern is formed on the outer surface of the laminated body to manufacture the multilayer ceramic capacitor 6.

[0020] The above-mentioned used PET film with ceramics attached to its surface is one example, and in this embodiment, any used PET film with ceramics attached to its surface is eligible for recycling, regardless of how the ceramics became attached to the surface of the used PET film.

[0021] Next, the steps of the method for recycling used PET film having ceramics attached to its surface will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a diagram showing the steps of the method for recycling used PET film according to the first embodiment. Fig. 3 is a diagram showing an outline of the products and the like in the steps of the method for recycling used PET film shown in Fig. 2.

[0022] First, a used PET film having ceramics attached to its surface is prepared (preparation of used PET film: step S1). The used PET film contains at least PET and silicone resin. The used PET film 100 prepared in the preparation of used PET film in step S1 has ceramics 102 attached to a surface 101 of the used PET film 100, as shown in FIG. 3(A). Note that FIG. 3(A) shows the PET film 100 in a rolled state.

[0023] The used PET film 100 prepared in the used PET film preparation step S1 is re-pelletized to produce pellets (re-pelletization step: step S2). In the re-pelletization step of the first embodiment, the used PET film 100 is re-pelletized while ceramics are still attached to the surface of the used PET film 100. In the re-pelletization step, for example, the used PET film 100 with ceramics still attached to the surface is crushed in a known crusher (having a known structure and performing a known operation) to a size that can be fed into a known extruder (having a known structure and performing a known operation). The crushed material is then fed into a known extruder, where it is thermally melted to produce pellets of a size that is easy to process. The re-pelletization step of the first embodiment is characterized in that the used PET film 100 with ceramics attached to its surface is used as the raw material, and known techniques can be used for the re-pelletization. In the re-pelletization step of step S2, pellets 110 shown in FIG. 3(B) are produced.

[0024] The pellets produced in the re-pelletizing process are used to mold a resin molded product (molding process: step S3). Methods for molding resin molded products include, for example, known injection molding and known blow molding. Injection molding, sometimes called injection molding, is a molding method in which, for example, heated and molten resin is injected and filled into a set of concave and convex molds at high temperature and pressure, and then cooled and solidified. Blow molding, sometimes called hollow molding, is a molding method in which, for example, heated and molten resin is extruded into a pipe shape (called a parison), the parison is sandwiched between a pair of concave and concave molds, compressed air is blown into the molten parison to inflate it and make it adhere to the inside of the mold, and then cooled and solidified. Resin molded products can also be molded as follows. Heated and melted resin is injected and filled into a mold at high temperature and pressure, then cooled and solidified to create a preform (injection molding). The heated and melted preform is then sandwiched between molds, and compressed air or the like is blown into the molten preform to inflate it and attach it to the inside of the mold. The preform is then cooled and solidified (blow molding), resulting in a resin molded product. For example, the toner container bottle 120, the exterior of which is shown in FIG. 3C, is manufactured in the molding process of step S3, which involves injection molding and subsequent blow molding. The toner container bottle 120 is a resin molded product that requires slidability, including gears and other components that require slidability. The toner container bottle 120 is a sliding component of an image forming device. The toner container bottle 120 is an example of a sliding component of an image forming device, and the resin molded product molded in the molding process of step S3 may be, for example, a sliding component of an image forming device other than the toner container bottle 120. The resin molded product molded in the molding process of step S3 may be, for example, a sliding part of a product other than an image forming device, or a part other than a sliding part of an image forming device or a product other than an image forming device, or may be a product.

[0025] According to the first embodiment described above, used PET film is re-pelletized to produce pellets, and the pellets are used to mold a resin molded product, thereby expanding the scope of reuse of used PET film with ceramics attached to the surface to various resin molded products other than PET film.

[0026] In addition, because the used PET film is re-pelletized with the ceramics still attached to its surface, the number of steps required to produce pellets from the used PET film with the ceramics attached to its surface is reduced. This allows pellets to be produced at low cost from the used PET film with the ceramics attached to its surface, thereby reducing the production costs of resin molded products made from the pellets.

[0027] Furthermore, since the pellets used in the molding process of step S3 contain silicon resin, ceramics, and the like in addition to PET, resin molded products molded using these pellets become cloudy. When coloring a cloudy resin molded product, the amount of coloring material used can be reduced compared to when coloring a transparent resin molded product, which allows for reduced costs associated with coloring when coloring a resin molded product is required.

[0028] Second Embodiment A second embodiment of the method for recycling used PET film according to the present invention will be described below with reference to the drawings. The first embodiment of the method for recycling used PET film involves re-pelletizing the used PET film with ceramics still attached to its surface, whereas the second embodiment of the method for recycling used PET film involves removing the ceramics from the surface and then re-pelletizing the used PET film.

[0029] In the second embodiment, similar to the first embodiment, a used PET film with ceramics attached to its surface is the target for recycling. The PET film is, for example, long and contains at least PET and silicone resin, with a PET content of, for example, 98% and a silicone resin content of 2% or less. The used PET film has been used in the manufacture of laminated electronic components, and ceramics remain attached to the surface of the used PET film.

[0030] Next, the steps of the method for recycling used PET film having ceramics attached to its surface will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a diagram showing the steps of the method for recycling used PET film according to a second embodiment. Fig. 5 is a diagram showing an outline of the products etc. in the steps of the method for recycling used PET film shown in Fig. 4.

[0031] First, a used PET film having ceramics attached to its surface is prepared (preparation of used PET film: step S11). The used PET film contains at least PET and silicone resin. The used PET film 100 prepared in the preparation of used PET film in step S11 has ceramics 102 attached to a surface 101 of the used PET film 100, as shown in FIG. 5(A).

[0032] The ceramics adhering to the surface of the used PET film are mechanically removed from the used PET film (ceramics removal step: step S12). For example, in the ceramics removal step of step S12, as shown in Fig. 6, the used PET film 100 is unwound by rollers 150, 155, and the used PET film is rewound by rollers 150, 155 while a blade 200 is in contact with the surface 101 of the used PET film 100 to which the ceramics 102 are adhered. During the rewinding of the used PET film 100, the blade 200 contacts the ceramics 102 adhering to the surface 101 of the used PET film 100, thereby peeling and removing the ceramics 102 from the surface 101 of the used PET film 100. Note that the mechanism for mechanically removing the ceramics adhering to the surface of the used PET film from the surface of the used PET film is not particularly limited. By the ceramic removal process of step S12, the used PET film 100 having the ceramics 102 attached to the surface 101, the appearance of which is shown in Figure 5(A), becomes the used PET film 100 having the ceramics 102 attached to the surface 101 removed, the appearance of which is shown in Figure 5(B).

[0033] In the ceramic removal process (step S12), the silicon resin contained in the used PET film is left behind, and the ceramics attached to the surface are mechanically removed.

[0034] The used PET film after the ceramics adhering to the surface have been mechanically removed in the ceramic removal step (step S12) is re-pelletized to produce pellets (re-pelletization step: step S13). The re-pelletization step of the second embodiment is characterized in that the used PET film after the ceramics adhering to the surface have been removed is used as the material, and a known method can be used for the re-pelletization. In the re-pelletization step of step S13, pellets 110 shown in FIG. 5(C) are produced.

[0035] As described above, in the first embodiment, the pellets are produced by repelletizing used PET film with ceramics still attached to its surface, whereas in the second embodiment, the pellets are produced by repelletizing used PET film after the ceramics attached to its surface have been removed.

[0036] A resin molded product is molded using the pellets produced in the re-pelletizing process (molding process: step S14). The molding method for the resin molded product is the same as in the first embodiment. For example, the toner container bottle 120, the appearance of which is shown in FIG. 5(D), is manufactured in the molding process of step S14, which involves injection molding and blow molding after the injection molding. The toner container bottle 120 is a resin molded product that requires slidability and includes parts (e.g., gears) that require slidability. The toner container bottle 120 is a sliding part of an image forming device. The toner container bottle 120 is an example of a sliding part of an image forming device, and the resin molded product molded in the molding process of step S14 may be, for example, a sliding part of an image forming device other than the toner container bottle 120. Note that the resin molded product molded in the molding process of step S14 may be, for example, a sliding part of a product other than an image forming device, or a part other than a sliding part of an image forming device or a product other than an image forming device, or may be a product.

[0037] According to the second embodiment described above, used PET film is re-pelletized to produce pellets, and the pellets are used to mold a resin molded product, thereby expanding the scope of reuse of used PET film with ceramics attached to the surface to various resin molded products other than PET film.

[0038] Furthermore, the process for producing pellets from used PET film having ceramics attached to its surface is configured to include a ceramics removal process (step S12) in which the ceramics attached to the surface are mechanically removed from the used PET film, and a re-pelleting process (step S13) in which the used PET film after the ceramics attached to its surface have been removed is re-pelletized to produce pellets. This allows pellets to be produced at low cost from used PET film having ceramics attached to its surface, thereby reducing the production costs of resin molded products formed using the pellets.

[0039] Furthermore, by carrying out a ceramics removal process to remove ceramics adhering to the surface of used PET film from the used PET film before the re-pelleting process, the content of components other than PET in the pellets can be reduced. This slows the hardening rate of PET etc. compared to when pellets made from used PET film with ceramics adhering to the surface are used, and it is possible to provide pellets suitable for blow molding, which is performed when producing resin molded products.

[0040] Furthermore, the removal of ceramics from the surface of used PET film can be easily achieved by mechanically removing the ceramics from the surface. For example, when the ceramics attached to the surface of used PET film are chemically removed using an organic solvent, a purification process using the organic solvent is required to prevent the organic solvent from adversely affecting the environment, which is a significant workload. In contrast, when the ceramics attached to the surface of used PET film are mechanically removed from the surface of used PET film, no special work is required other than the removal of the ceramics, so the workload is reduced.

[0041] In addition, in the ceramic removal process, the silicone resin contained in the used PET film is left behind, and the ceramics attached to the surface are mechanically removed. As a result, the silicone resin contained in the used PET film is also contained in the resin molded product, making this a method of recycling used PET film suitable for resin molded products that require good releasability or good sliding properties (such as gears).

[0042] Furthermore, since the pellets used in the molding process of step S14 contain silicone resins other than PET, resin molded products molded using these pellets become cloudy. When coloring a cloudy resin molded product, the amount of colorant used can be reduced compared to when coloring a transparent resin molded product, which reduces the cost of coloring when coloring a resin molded product is required.

[0043] The present invention is not limited to the configurations of the above-described embodiments or modified examples, and various modifications are possible. Furthermore, the configuration and steps shown in the first embodiment using Figures 1 to 3 and the configuration and steps shown in the second embodiment using Figures 4 to 6 are merely one embodiment of the present invention, and are not intended to limit the present invention to these configurations and steps. [Explanation of symbols]

[0044] S1 Preparing used PET film S2 Re-pelleting process S3 Molding process S11 Preparation of used PET film S12 Ceramics removal process S13 Re-pelleting process S14 Molding process

Claims

1. A method for recycling used PET film having ceramics attached to its surface, comprising the steps of: a re-pelleting step of re-pelletizing the used PET film to produce pellets; a molding step of molding a resin molded product using the pellets produced in the re-pelletizing step; A method for recycling used PET film.

2. 2. The method for recycling used PET film according to claim 1, wherein in the re-pelleting step, the used PET film is re-pelletized with the ceramics still attached to the surface.

3. The method for recycling used PET film comprises: a ceramics removal step of mechanically removing the ceramics adhering to the surface of the used PET film from the used PET film before the re-pelleting step; Furthermore, 2. The method for recycling used PET film according to claim 1, wherein the re-pelleting step involves re-pelletizing the used PET film after the ceramics adhering to the surface have been mechanically removed in the ceramics removal step.

4. The used PET film contains at least PET and a silicone resin, 4. The method for recycling used PET film according to claim 3, wherein in the ceramic removing step, the ceramic adhering to the surface is mechanically removed while leaving the silicone resin.

5. 5. The method for recycling used PET film according to claim 4, wherein the resin molded product is required to have slidability.

6. A pellet manufactured using a used PET film having ceramics attached to its surface, Pellets produced by repelletizing the used PET film.

7. The pellet according to claim 6, which is produced by repelletizing the used PET film with the ceramic still attached to the surface.

8. The pellet according to claim 6, which is produced by repelletizing the used PET film after the ceramics adhering to the surface have been mechanically removed.

9. A sliding part of an image forming device manufactured using a used PET film having ceramics attached to its surface, The used PET film contains at least PET and a silicone resin, and the sliding part of the image forming device is molded using pellets produced by re-pelletizing the used PET film after the ceramics adhering to the surface have been mechanically removed, leaving the silicone resin.

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