Methods for reusing resin molded products

Abstract

This invention provides a method for reusing resin molded articles that can improve productivity while maintaining high accuracy in separating functional layers. [Solution] The method for reusing a resin molded body includes the step of separating at least a portion of the functional layer 302 from the resin molded body 30 by melting the resin molded body 30 having a functional layer 302 on its surface and passing it through screen mesh laminates 206, 209 provided in the BCSC 13, wherein the screen mesh laminates 206, 209 have two layers of screen mesh 221, 222, and at least one layer of screen mesh 221 has a plain weave, with a vertical wire diameter of 0.15 mm or less and a vertical mesh count of 50 or more, and / or a horizontal wire diameter of 0.10 mm or less and a horizontal mesh count of 250 or more.

Description

Technical Field

[0001] The present invention relates to a method for recycling resin molded articles.

Background Art

[0002] In the case of automotive parts, which were conventionally generally made of metal, in order to achieve weight reduction by replacing metal with resin and to impart scratch resistance and design properties, the use of resin molded articles provided with functional layers such as coating films and paint films on the surface has been expanding. At the same time, against the backdrop of the growing interest in circular economy in recent years, the need for technologies that utilize pre-consumer materials and post-consumer materials of resin molded articles is also increasing. However, if a resin molded article having such a functional layer is recycled without separating the functional layer, the mechanical properties of a newly produced resin molded article obtained by recycling may deteriorate. Further, even if high separation accuracy of the functional layer can be achieved by going through the process of separating the functional layer, the productivity of this process may be low.

[0003] As a method for separating a functional layer from a resin molded article, Patent Document 1 discloses a method for efficiently separating a coating film, which is a functional layer, from an automotive bumper made of resin and coated, characterized by comprising a pressing step of pressing the automotive bumper with a roll and a blasting step of subjecting the pressed product obtained in the pressing step to a blasting treatment. Further, Patent Document 2 discloses a surface treatment method of performing blasting by injecting an abrasive onto the surface of a thermoplastic resin molded article. Patent Document 3 discloses a method for removing a coating film by putting a resin material to be treated with a coating film into a vibration compressor to miniaturize and separate the coating film, and then extruding the resin material to be treated from an extruder and passing it through a screen mesh.

[0004] However, in the method described in Patent Document 1, shear heat generation can occur when pressure shear force is applied to the resin molded body during the pressing process using a roll. In this case, for example, if the functional layer on the surface is made of a material that softens easily, there was a concern that the functional layer would adhere to the roll, significantly reducing productivity. Furthermore, Patent Document 1 does not describe a method for reusing the resin molded body after the functional layer has been separated. On the other hand, Patent Document 2 describes a surface processing method for thermoplastic resin molded bodies by blasting, but does not describe a method for reusing the resin molded body after processing. Furthermore, Patent Document 3 describes that the screen mesh is composed of at least three layers and that it is compatible with any type of screen changer already on the market. However, with a screen mesh of this configuration, the pressure loss becomes large, so there was a concern that even if a screen changer capable of backwashing to clear clogging of the screen mesh was used, it would not function effectively in order to improve productivity while maintaining the accuracy of coating separation. In other words, if the pressure loss is large, the effect of clearing clogging of the screen mesh is small, and there was a concern that the difference in resin pressure before and after backwashing would not be large enough. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-187466 [Patent Document 2] Japanese Patent Application Publication No. 8-323858 [Patent Document 3] Japanese Patent Application Publication No. 7-227843 [Overview of the project]

[0006] (Problems that the invention aims to solve) In view of the above circumstances, the problem that the present invention aims to solve is a method for reusing a resin molded article, which includes a separation step of separating at least a portion of the functional layer from a resin molded article having a functional layer on its surface, and which can improve productivity while maintaining high separation accuracy of the functional layer in the separation step, and provides a resin molded article manufactured using the material obtained through the separation step that has excellent mechanical properties. The "separation accuracy of the functional layer" is an index indicated by the amount (content) of the functional layer contained in the resin molded article after the separation step. The "separation accuracy of the functional layer" is higher (preferred) as the content of the functional layer in the resin molded article after the separation step decreases. [Means for solving the problem]

[0007] The inventors of this invention have diligently studied and conducted research to solve the above problems, and as a result have arrived at the present invention. That is, the present invention is A method for reusing a resin molded body, comprising a separation step of melting a resin molded body having a base material containing a resin material and a functional layer provided on the surface of the base material, and passing the molten resin molded body through a screen mesh laminate provided in a backwash type continuous screen changer to remove at least a portion of the functional layer from the molten resin molded body, The aforementioned screen mesh laminate has a two-layer structure consisting of a first screen mesh and a second screen mesh stacked in the thickness direction. The first screen mesh is either plain weave with a vertical wire diameter of 0.09 mm or more and 0.15 mm or less, and a vertical mesh count of 50 or more and 80 or less, or plain weave with a horizontal wire diameter of 0.05 mm or more and 0.10 mm or less, and a horizontal mesh count of 250 or more and 500 or less, or plain weave with a vertical wire diameter of 0.09 mm or more and 0.15 mm or less, a vertical mesh count of 50 or more and 80 or less, a horizontal wire diameter of 0.05 mm or more and 0.10 mm or less, and a horizontal mesh count of 250 or more and 500 or less.

[0008] According to the present invention, in the process of separating at least a portion of the functional layer from a resin molded article having a functional layer on its surface, it is possible to improve productivity while maintaining high accuracy in separating the functional layer, and to provide a method for reusing resin molded articles that have excellent mechanical properties when another resin molded article (a new resin molded article) is made using the material obtained through the separation process. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view of a resin molded body. [Figure 2] Figure 2 is a schematic diagram of the equipment. [Figure 3] Figure 3 is a schematic diagram showing the configuration of a backwash type screen changer. [Figure 4A] Figure 4A is a schematic diagram showing the configuration of the first screen mesh laminate and the second screen mesh laminate. [Figure 4B] Figure 4B is an enlarged view of section IVB in Figure 4A. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below. However, the present invention is not limited to the embodiments shown below. In the following description, the method for reusing resin molded articles according to the embodiments of the present invention may be simply referred to as "reuse method".

[0011] Figure 1 is a schematic cross-sectional view showing the structure of the resin molded body 30 that is the target of the recycling method. As shown in Figure 1, the resin molded body 30 to be recycled has a base material 301 and a functional layer 302 provided on the surface of the base material 301. Details of the base material 301 and the functional layer 302 will be described later.

[0012] The reuse method includes a separation step. The separation step includes separating at least a portion of the functional layer 302 from the molten resin molded body 30 (molten material) by using a backwashing type continuous screen changer 13 equipped with screen mesh laminates 206, 209 having two layers. In this embodiment, extrusion is shown as the reuse method including the separation step.

[0013] <Equipment> Figure 2 is a schematic diagram showing the configuration of equipment 10 capable of performing a reuse method (extrusion). As shown in Figure 2, this equipment 10 includes a feeder 11, an extruder 12, a backwash continuous screen changer 13, a die 14, a water tank 15, and a pelletizer 16. Hereinafter, the "backwash continuous screen changer" may be abbreviated as "BCSC".

[0014] The feeder 11 is a device configured to store the resin molded bodies 30 that are subject to the reuse method, and to supply the stored resin molded bodies 30 to the extruder 12. The feeder 11 has a tank for storing the material and a conveying mechanism for transporting the material. Examples of conveying mechanisms include screw type and belt type conveying mechanisms. The capacity of the feeder 11 is expressed in terms of the supply volume. The supply volume is the weight of the resin molded bodies 30 (i.e., material) supplied from the feeder 11 per hour, and the unit is kg / hour. The resin molded bodies 30 supplied from the feeder 11 to the extruder 12 may have undergone a subdivision process described later, from the viewpoint of storage efficiency in the tank and ease of transport.

[0015] The extruder 12 is configured to supply the resin molded body 30 to the BCSC 13 in a molten state. The extruder 12 includes a cylinder 111 and a screw 112.

[0016] The cylinder 111 includes a feed port 113 for introducing the resin molded body 30 supplied from the feeder 11 and a heater (not shown), and is configured to apply heat to the resin molded body 30 supplied from the feeder 11. The cylinder 111 can melt the resin molded body 30 supplied in a solid state by heating with the heater or by frictional heat between the resin molded body 30 and the inner surface of the cylinder 111. The number of cylinders 111 provided in the extruder 12 is not limited, and for example, the extruder 12 may include a plurality of cylinders 111 connected to each other. Further, the cylinder 111 may be provided with a vent port or the like for degassing.

[0017] The screw 112 is disposed inside the cylinder 111 and is configured to rotate by the driving force of the driving force source 114. The screw 112 melts the resin molded body 30 and subdivides the functional layer 302 by shear force, and feeds (advances) the resin molded body 30 in a molten state toward the BCSC 13. The extruder 12 may be configured to include one screw 112 (a configuration in which the extruder 12 is single-screw), or may be configured to include a pair of two screws 112 (a configuration in which the extruder 12 is twin-screw). In the case of twin-screw, the two screws 112 may be configured to rotate in the same direction, or the two screws 112 may be configured to rotate in different directions from each other. The screw 112 can be configured by combining a feed segment having a great effect of advancing the resin molded body 30 in a molten state, a kneading segment having a great effect of kneading the resin molded body 30 in a molten state, etc., according to the purpose.

[0018] Note that the "resin molded body 30 in a molten state (resin molded body 30 in a molten state)" is a resin molded body 30 in which at least a part of the base material 301 and the components to be reused are in a molten state so as to have fluidity, and may contain solid matter inside. For example, when the main component of the base material 301 is a polycarbonate resin to be reused, as long as the polycarbonate resin is in a molten state, it can be called the "resin molded body 30 in a molten state" even if other components including the functional layer 302 are not melted. In this case, for example, the functional layer 302 becomes solid matter refined by the shearing force of the screw 112. Also, the "resin molded body 30 in a molten state" is preferably at least a part or all of the functional layer 302, and the components to be separated are not in a molten state. For example, when the main component of the functional layer 302 is a pigment and the pigment is to be separated, it is preferable that the pigment is not melted. Note that the components other than the components to be separated in the functional layer 302 may or may not be in a molten state. Similarly, among the base material 301, the components other than the components to be reused may or may not be in a molten state.

[0019] In addition, a breaker plate, which is a perforated plate, may be provided near the tip of the screw 112 of the extruder 12 for the purpose of generating a back pressure flow and enhancing the kneading effect. In this case, the screen mesh laminates 206 and 209 can also be held on the breaker plate.

[0020] The BCSC 13 is configured to allow the resin molded body 30 in a molten state (resin molded body 30 in a molten state in which the molten base material 301 and the functional layer 302 as a solid object are mixed) fed from the extruder 12 to pass through. And the BCSC 13 is configured to remove at least a part of the functional layer 302, which is a solid object, from the passing resin molded body 30 in a molten state. Note that the configuration and operation of the BCSC 13 will be described later.

[0021] The die 14 is a mold that shapes the molten resin molded body 30 (the resin molded body 30 after at least a portion of the functional layer 302 has been removed) flowing out of the BCSC 13 into, for example, strands. The water tank 15 is a container for cooling and solidifying the molten resin molded body 30 flowing out of the BCSC 13. The pelletizer 16 is a device that cuts the resin (hereinafter sometimes referred to as "separated resin material") shaped by the die 14 and solidified in the water tank 15 into pellet shapes. The configurations of the die 14, water tank 15, and pelletizer 16 are not particularly limited, and conventionally known configurations can be applied.

[0022] Figure 3 is a schematic diagram showing the general configuration of BCSC13. As shown in Figure 3, BCSC13 comprises a first channel 201, a first channel valve 202, a second channel 203, a third channel 204, a second channel valve 205, a first screen mesh laminate 206, a fourth channel 207, a third channel valve 208, a second screen mesh laminate 209, a fifth channel 210, a sixth channel 211, and a fourth channel valve 212. The first channel 201, the second channel 203, the third channel 204, the fourth channel 207, the fifth channel 210, and the sixth channel 211 are all channels configured to allow the flow of a molten resin molded body 30.

[0023] The first flow path 201 is a flow path that connects the cylinder 111 of the extruder 12 to the second flow path 203 or the third flow path 204 via the first flow path valve 202. The first flow path 201 is configured to supply the molten resin molded body 30 extruded (supplied) from the extruder 12 to the first flow path valve 202. The first flow path valve 202 is a valve configured to switch between a first state in which the first flow path 201 and the second flow path 203 are in communication, and a second state in which the first flow path 201 and the third flow path 204 are in communication. The second flow path 203 is a flow path that connects the first flow path valve 202 and the first screen mesh laminate 206. The second flow path 203 is configured to supply the molten resin molded body 30 that has flowed into the BCSC 13 to the first screen mesh laminate 206. The second flow valve 205 is configured to discharge the molten resin molded body 30 that flows back from the first screen mesh laminate 206 during the backwash operation described later to the outside of the BCSC 13. The second flow valve 205 is configured to be switchable between a first state in which the first screen mesh laminate 206 is connected to the outside and the molten resin molded body 30 is discharged to the outside, and a second state in which the first screen mesh laminate 206 is not connected to the outside and the molten resin molded body 30 is not discharged to the outside.

[0024] The third channel 204 is a channel that connects the first channel valve 202 and the second screen mesh laminate 209. The third channel 204 is configured to supply the molten resin molded body 30 that has flowed into the BCSC 13 to the second screen mesh laminate 209. The third channel valve 208 is configured to discharge the molten resin molded body 30 that flows back from the second screen mesh laminate 209 during backwashing to the outside of the BCSC 13. The third channel valve 208 is a valve configured to switch between a first state in which the second screen mesh laminate 209 is connected to the outside and the molten resin molded body 30 is discharged to the outside, and a second state in which the second screen mesh laminate 209 is not connected to the outside and the molten resin molded body 30 is not discharged to the outside.

[0025] The first screen mesh laminate 206 and the second screen mesh laminate 209 are both structures in which two screen meshes (first screen mesh 221 and second screen mesh 222) are laminated in the thickness direction. A screen mesh is a woven fabric in which vertical and horizontal lines are woven in a mesh-like pattern at approximately constant intervals. For this reason, objects smaller than the gaps in the screen mesh (including liquids and viscous substances) can pass through the screen mesh, but solid objects larger than the gaps in the mesh cannot pass through the screen mesh.

[0026] Figure 4A is a schematic diagram showing the configuration of the first screen mesh laminate 206 and the second screen mesh laminate 209. Figure 4B is an enlarged view of section IVB of Figure 4A. The first screen mesh laminate 206 and the second screen mesh laminate 209 have the same configuration. In this embodiment, the first screen mesh laminate 206 and the second screen mesh laminate 209 have a substantially cylindrical shape. The first screen mesh 221 is located on the outer circumference of the cylindrical shape, and the second screen mesh 222 is located on the inner circumference of the cylindrical shape, and they are laminated together in the thickness direction (radial direction of the cylinder).

[0027] The molten resin molded body 30 supplied through the second channel 203 passes through the first screen mesh laminate 206 from the outer circumference to the inner circumference. Similarly, the molten resin molded body 30 supplied through the third channel 204 passes through the second screen mesh laminate 209 from the outer circumference to the inner circumference. In these cases, the first screen mesh 221 is located upstream of the flow of the molten resin molded body 30, and the second screen mesh 222 is located downstream of the flow of the molten resin molded body 30.

[0028] As a configuration for holding the first screen mesh laminate 206 and the second screen mesh laminate 209 in a cylindrical shape, for example, as shown in Figures 4A and 4B, a configuration using a cylindrical support member 223 can be applied. Specifically, this support member 223 comprises a substantially cylindrical outer cylinder 224 made of perforated metal, and an inner cylinder 225 also made of perforated metal and housed coaxially with the outer cylinder 224 on its inner circumference. Note that in Figure 4A, a portion of the outer cylinder 224 is removed for illustration. The first screen mesh laminate 206 and the second screen mesh laminate 209 are then housed between the outer cylinder 224 and the inner cylinder 225 of the support member 223 (or, more accurately, sandwiched between the outer cylinder 224 and the inner cylinder 225).

[0029] The first screen mesh 221 and the second screen mesh 222 are both woven fabrics in which vertical and horizontal lines, which are substantially perpendicular to each other when viewed in the thickness direction, are woven in a mesh-like pattern at predetermined intervals. Examples of weaving methods include plain weave, twill weave, plain weave, and twill weave. Of these, plain weave and / or plain weave are preferred from the viewpoint of compressive strength and availability. Examples of materials for the screen mesh include stainless steel, iron, and galvanized iron. Of these, stainless steel is preferred from the viewpoint of corrosion resistance and availability.

[0030] When the screen mesh is a flat woven type, the upper limit of the vertical wire diameter of the first screen mesh 221 and the second screen mesh 222 is preferably 0.15 mm and more preferably 0.13 mm, from the viewpoint of ensuring the screen mesh conforms to the cylindrical support member. The lower limit of the vertical wire diameter of the first screen mesh 221 and the second screen mesh 222 is preferably 0.09 mm and more preferably 0.11 mm, from the viewpoint of ensuring the pressure resistance strength of the screen mesh. The upper limit of the horizontal wire diameter of the first screen mesh 221 and the second screen mesh 222 is preferably 0.10 mm and more preferably 0.08 mm, from the viewpoint of ensuring the screen mesh conforms to the cylindrical support member. The lower limit of the horizontal wire diameter of the first screen mesh 221 and the second screen mesh 222 is preferably 0.05 mm and more preferably 0.07 mm, from the viewpoint of ensuring the pressure resistance strength of the screen mesh. The lower limit of the number of vertical meshes of the first screen mesh 221 and the second screen mesh 222 is preferably 50 and more preferably 60. The upper limit of the vertical mesh count for the first screen mesh 221 and the second screen mesh 222 is preferably 80, and more preferably 70. The lower limit of the horizontal mesh count for the first screen mesh 221 and the second screen mesh 222 is preferably 250, and more preferably 350. The upper limit of the horizontal mesh count for the first screen mesh 221 and the second screen mesh 222 is preferably 500, and more preferably 450. Note that the vertical mesh count is the number of vertical lines per inch, and the horizontal mesh count is the number of horizontal lines per inch.

[0031] Furthermore, if the first screen mesh 221 and the second screen mesh 222 are plain weave, the upper limits of the vertical and horizontal wire diameters of the first screen mesh 221 and the second screen mesh 222 are preferably 0.23 mm, respectively. The lower limits of the vertical and horizontal wire diameters of the first screen mesh 221 and the second screen mesh 222 are preferably 0.13 mm, respectively. The upper limits of the vertical and horizontal mesh counts of the first screen mesh 221 and the second screen mesh 222 are preferably 80, respectively. The lower limits of the vertical and horizontal mesh counts of the first screen mesh 221 and the second screen mesh 222 are preferably 50, respectively.

[0032] In this embodiment, it is preferable that at least one of the first screen mesh 221 and the second screen mesh 222 has a configuration shown in any one of the following (A), (B), or (C). (A) The weaving method is plain weave, the warp wire diameter is 0.09 mm or more and 0.15 mm or less, and the number of warp meshes is 50 or more and 80 or less. (B) The weaving method is plain tatami weave, the horizontal wire diameter is 0.05 mm or more and 0.10 mm or less, and the number of horizontal meshes is 250 or more and 500 or less. (C) The weaving method is flat weave, the vertical wire diameter is 0.09 mm or more and 0.15 mm or less, the number of vertical meshes is 50 or more and 80 or less, the horizontal wire diameter is 0.05 mm or more and 0.10 mm or less, and the number of horizontal meshes is 250 or more and 500 or less.

[0033] However, the mesh size (gap) of the first screen mesh 221 is the same as or smaller than the mesh size of the second screen mesh 222. The mesh size (gap) can also be defined as "the size of a solid object that can pass through." Furthermore, regarding the relationship between the vertical wire diameter and the number of vertical meshes, a configuration can be applied in which "when the vertical wire diameter is set to a predetermined value, the number of meshes is selected (from a defined range) so that the vertical wire diameter can achieve that predetermined value." Alternatively, a configuration may be applied in which "when the number of vertical meshes is set to a predetermined value, the vertical wire diameter is selected (from a defined range) so that the number of vertical meshes can achieve that predetermined value." The same applies to the relationship between the horizontal wire diameter and the number of horizontal meshes.

[0034] Furthermore, of the first screen mesh 221 and the second screen mesh 222, it is more preferable that the first screen mesh 221 has one of the configurations (A), (B), or (C) above. And if the first screen mesh 221 has one of the configurations (A), (B), or (C) above, it is preferable that the second screen mesh 222 has one of the configurations shown in (D), (E), or (F) below. (D) The weave is plain weave, the warp wire diameter is 0.13 mm or more and 0.23 mm or less, and the number of warp meshes is 50 or more and 80 or less. (E) The weave is plain weave, the horizontal wire diameter is 0.13 mm or more and 0.23 mm or less, and the number of horizontal meshes is 50 or more and 80 or less. (F) The weave is plain weave, the warp wire diameter is 0.13 mm or more and 0.23 mm or less, the number of warp meshes is 50 or more and 80 or less, the weft wire diameter is 0.13 mm or more and 0.23 mm or less, and the number of weft meshes is 50 or more and 80 or less.

[0035] The fourth channel 207 is a channel that connects the inner circumferential space of the first screen mesh laminate 206 to the fourth channel valve 212. The fifth channel 210 is a channel that connects the inner circumferential space of the second screen mesh laminate 209 to the fourth channel valve 212. The sixth channel 211 is a channel that connects the fourth channel valve 212 to the outside of the BCSC 13. The sixth channel 211 is configured to discharge the molten resin molded body 30 that has passed through the first screen mesh laminate 206 or the second screen mesh laminate 209 to the outside of the BCSC 13. The fourth channel valve 212 is a valve configured to switch the communication state between the fourth channel 207, the fifth channel 210, and the sixth channel 211. Specifically, the fourth channel valve 212 is configured to be selectively switchable between a first state, a second state, and a third state. The first state is when the fourth channel 207 and the sixth channel 211 are connected, and the fifth channel 210 is not connected to any other channel. The second state is when the fifth channel 210 and the sixth channel 211 are connected, and the fourth channel 207 is not connected to any other channel. The third state is when the fourth channel 207, the fifth channel 210, and the sixth channel 211 are all connected to each other.

[0036] <Separation process> The separation process using the above-described equipment 10 includes the steps of: melting the resin molded body 30 with the extruder 12 and feeding it to the BCSC 13; removing at least a portion of the functional layer 302 from the molten resin molded body 30 fed from the extruder 12 in the BCSC 13; and forming the resin discharged from the BCSC 13 (the resin after at least a portion of the functional layer 302 has been removed) into a predetermined shape with the pelletizer 16.

[0037] The operation of BCSC13 in the separation process is as follows. BCSC13 includes a normal operation without backwashing and a backwashing operation with backwashing. In the normal operation, the first flow valve 202 is set to the first state, the second flow valve 205 is set to the second state, and the fourth flow valve 212 is set to the first state. Alternatively, the first flow valve 202 is set to the second state, the third flow valve 208 is set to the second state, and the fourth flow valve 212 is set to the second state. When the first flow valve 202 is set to the first state, the second flow valve 205 is set to the second state, and the fourth flow valve 212 is set to the first state, the molten resin molded body 30 supplied from the extruder 12 passes sequentially through the first flow channel 201, the first flow valve 202, the second flow channel 203, the first screen mesh laminate 206, the fourth flow channel 207, the fourth flow valve 212, and the sixth flow channel 211, and is discharged to the outside of BCSC13. Then, as the molten resin molded body 30 passes through the first screen mesh laminate 206 from the outer circumference to the inner circumference, at least a portion of the solid material (specifically, the functional layer 302) contained in the molten resin molded body 30 is removed from the molten resin molded body 30. Furthermore, when the first flow valve 202 is set to the second state, the third flow valve 208 is set to the second state, and the fourth flow valve 212 is set to the second state, the molten resin molded body 30 supplied from the extruder 12 passes sequentially through the first flow channel 201, the first flow valve 202, the third flow channel 204, the second screen mesh laminate 209, the fifth flow channel 210, the fourth flow valve 212, and the sixth flow channel 211, and is discharged to the outside of the BCSC 13. Then, as the molten resin molded body 30 passes through the second screen mesh laminate 209 from the outer circumference to the inner circumference, at least a portion of the solid material (functional layer 302) contained in the molten resin molded body 30 is removed from the molten resin molded body 30. The direction of flow of the molten resin molded body 30 during normal operation (the direction in which the molten resin molded body 30 passes through the first screen mesh laminate 206 and the second screen mesh laminate 209 from the outer circumference to the inner circumference) is an example of the first direction of the present invention.

[0038] Thus, as the molten resin molded body 30 passes through the first screen mesh laminate 206 or the second screen mesh laminate 209 from the outer circumference to the inner circumference, at least a portion of the functional layer 302, which is a solid object contained in the molten resin molded body 30, cannot pass through the first screen mesh 221 located on the outer circumference side of the cylindrical shape (upstream side of the flow of the molten resin molded body 30). Therefore, the solid object contained in the molten resin molded body 30 is removed. The first screen mesh 221 is located upstream of the second screen mesh 222, and the line spacing (mesh gap) of the first screen mesh 221 is the same as or smaller than the line spacing of the second screen mesh 222. For this reason, the force that the first screen mesh 221 receives from the molten resin molded body 30 (a force that pushes it towards the inner circumference of the cylindrical shape) is the same as or greater than the force that the second screen mesh 222 receives from the molten resin molded body 30. In particular, this force increases when the first screen mesh 221 becomes clogged with solid objects. In this embodiment, the first screen mesh 221 is supported by the second screen mesh 222, thereby preventing or suppressing deformation and damage caused by forces from the molten resin molded body 30.

[0039] On the other hand, since the spacing of the lines in the second screen mesh 222 is larger than that of the first screen mesh 221, the force it receives from the molten resin molded body 30 is smaller than that of the first screen mesh 221. Also, since solid objects that have passed through the first screen mesh 221 can pass through the second screen mesh 222, clogging does not occur (or is unlikely to occur) in the second screen mesh 222. Therefore, an increase in the force that the second screen mesh 222 receives from the molten resin molded body 30 due to clogging is prevented or suppressed. Thus, the second screen mesh 222 can support the first screen mesh 221 while preventing or suppressing deformation caused by the force received from the molten resin molded body 30.

[0040] If the first screen mesh 221 of the first screen mesh laminate 206 or the second screen mesh laminate 209 becomes clogged with the functional layer 302, the BCSC 13 backwash operation is performed. The backwash operation is the operation of passing the molten resin molded body 30, from which at least a portion of the functional layer 302 has been separated, through the first screen mesh laminate 206 or the second screen mesh laminate 209 from the inner circumference side. This backwash operation flushes out the functional layer 302, which is a solid object filtered into the first screen mesh laminate 206 or the second screen mesh laminate 209. In other words, it clears the clogging of the first screen mesh laminate 206 or the second screen mesh laminate 209. The effect of clearing the clogging can be evaluated by the pressure difference of the molten resin molded body 30 before and after backwashing. Specifically, the pressure difference of the molten resin molded body 30 before and after backwashing is preferably 1 MPa or more, and more preferably 2 MPa or more.

[0041] The backwashing operation for cleaning the first screen mesh laminate 206 is performed while the operation to remove solid material from the molten resin molded body 30 using the second screen mesh laminate 209 is being carried out. Specifically, the first flow valve 202 is set to the second state, the second flow valve 205 is set to the first state, the third flow valve 208 is set to the second state, and the fourth flow valve 212 is set to the third state. As a result, a portion of the molten resin molded body 30 that has passed through the second screen mesh laminate 209 from the outer circumference to the inner circumference is discharged to the outside of the BCSC 13 via the fourth flow valve 212 and the sixth flow channel 211. The remaining portion flows into the inner circumference of the first screen mesh laminate 206 via the fourth flow valve 212 and the fourth flow channel 207, and passes through the first screen mesh laminate 206 from the inner circumference to the outer circumference. The molten resin molded body 30 that has passed through the first screen mesh laminate 206 from the inner circumference to the outer circumference is discharged to the outside of the BCSC 13 through the second flow channel valve 205, along with the solid material accumulated on the outer circumference side of the first screen mesh 221 of the first screen mesh laminate 206.

[0042] The backwashing operation for cleaning the second screen mesh laminate 209 is performed while the operation to remove solid material from the molten resin molded body 30 using the first screen mesh laminate 206 is being carried out. Specifically, the first flow valve 202 is set to the first state, the second flow valve 205 is set to the second state, the third flow valve 208 is set to the first state, and the fourth flow valve 212 is set to the third state. As a result, a portion of the molten resin molded body 30 that has passed through the first screen mesh laminate 206 from the outer circumference to the inner circumference is discharged to the outside of the BCSC 13 through the fourth flow valve 212 and the sixth flow channel 211. The remaining portion flows into the inner circumference of the second screen mesh laminate 209 through the fourth flow valve 212 and the fifth flow channel 210, and passes through the second screen mesh laminate 209 from the inner circumference to the outer circumference. The molten resin molded body 30, having passed through the second screen mesh laminate 209 from the inner circumference to the outer circumference, is discharged to the outside of the BCSC 13 through the third flow channel valve 208, along with the solid material accumulated on the outer circumference side of the first screen mesh 221 of the second screen mesh laminate 209. The direction of flow of the molten resin molded body 30 during the backwash operation (the direction in which the molten resin molded body 30 passes through the first screen mesh laminate 206 and the second screen mesh laminate 209 from the inner circumference to the outer circumference) is an example of the second direction of the present invention.

[0043] Thus, the BCSC13 can continuously perform the separation of at least a portion of the functional layer 302 from the incoming molten resin molded body 30 using one of the two sets of screen mesh laminates 206,209, and the backwashing operation to clear clogging of the other set of screen mesh laminates 206,209 caused by the functional layer 302, without stopping the inflow of the molten resin molded body 30 from the extruder 12. In other words, the BCSC13 has two sets of screen mesh laminates 206,209 so that it can perform backwashing of the other set of screen mesh laminates 206,209 while separating at least a portion of the functional layer 302 with one set of screen mesh laminates 206,209.

[0044] In the above description, examples are shown where the first screen mesh laminate 206 and the second screen mesh laminate 209 are cylindrical in shape, but their shapes are not limited to cylindrical. For example, the first screen mesh laminate 206 and the second screen mesh laminate 209 may have a substantially flat plate shape. In this case, both the first screen mesh laminate 206 and the second screen mesh laminate 209 comprise two flat screen meshes (first screen mesh 221 and second screen mesh 222), with the two screen meshes 221 and 222 laminated in the thickness direction. The first screen mesh laminate 206 and the second screen mesh laminate 209 are arranged such that the first screen mesh 221 is located upstream of the flow of the molten resin molded body 30 during normal operation, and the second screen mesh 222 is located downstream. The direction of the flow of the molten resin molded body 30 during normal operation (the direction through which the first screen mesh laminate 206 and the second screen mesh laminate 209 pass) is the first direction of the present invention.

[0045] In other words, the first direction is the stacking direction of the first screen mesh 221 and the second screen mesh 222, and is the direction from the first screen mesh 221 toward the second screen mesh 222. On the other hand, the second direction is the opposite direction to the first direction, that is, the stacking direction of the first screen mesh 221 and the second screen mesh 222, and is the direction from the second screen mesh 222 toward the first screen mesh 221. As a configuration for holding the first screen mesh laminate 206 and the second screen mesh laminate 209 in a flat plate shape, a configuration can be applied that uses a support member equipped with two flat plate-shaped perforated metals spaced apart in the thickness direction and arranged substantially parallel to each other. In this case, the first screen mesh laminate 206 and the second screen mesh laminate 209 are sandwiched between the two perforated metals, respectively.

[0046] The separation process may include, in addition to the separation of at least a portion of the functional layer 302 by BCSC13, a step of separating at least a portion of the functional layer 302 from the resin molded body 30 before the resin molded body 30 is melted by the extruder 12. For example, a step of separating at least a portion of the functional layer 302 by rubbing the surfaces of the resin molded body 30 together using a plastic pellet surface treatment machine can be applied (hereinafter also referred to as "surface treatment"). In this case, by passing the resin molded body 30 through a cylindrical screen using feed rollers and milling rollers, the surfaces of the resin molded body 30 rub against each other, and at least a portion of the functional layer 302 can be separated from the resin molded body 30 as dust. From the viewpoint of storage efficiency in the tank, ease of transport, and separation efficiency by friction, it is preferable that the material supplied from the feed rollers has undergone the subdivision process described later. Including such a process in the separation process can further improve the separation accuracy of the functional layer.

[0047] <Segmentation process> In addition to the separation step, the reuse method may include a subdivision step in which the resin molded body 30 is subdivided before the separation step. For example, the resin molded body 30 may be cut with scissors or nippers, crushed with a cutter mill, shredder, hammer crusher, etc., pulverized by lowering the temperature to the point where the resin undergoes brittle fracture, blasted by spraying blasting material, sliced ​​with a knife, slit with a shear blade or gang blade, etc.

[0048] <Subsequent steps> Furthermore, the recycling method may include a step of manufacturing raw materials for a new resin molded product (another resin molded product) using the separated resin material or the separated resin material after a fragmentation process (fragmented separated resin material), and a step of manufacturing a new resin molded product using the manufactured raw materials. Alternatively, the recycling method may include a step of directly manufacturing a new resin molded product using the separated resin material or the fragmented separated resin material, instead of the two steps mentioned above.

[0049] Applicable processes for manufacturing new resin molded products include: a process of manufacturing a new resin molded product, such as a molded object (three-dimensional object), by injecting pellets produced from the separated resin material into a mold using an injection molding machine, etc., as at least part of the raw material; a process of manufacturing a new resin molded product, such as a film, sheet, or molded object, by shaping pellets produced from the separated resin material using a hot press, etc., as at least part of the raw material; a process of forming a new resin molded product, such as a film or sheet, by melting pellets produced from the separated resin material using an extrusion molding machine and passing them through a mold, etc., as at least part of the raw material; and a process of forming a new resin molded product, such as a film or sheet, by dissolving pellets produced from the separated resin material in a solvent, casting the mixture, and then removing the solvent.

[0050] Examples of new resin molded articles produced by the recycling method according to this embodiment include exterior and interior parts for automobiles. Examples of exterior parts for automobiles include outside door handles, sunroof panels, pillar garnishes, and door sash moldings. Examples of interior parts for automobiles include inside door handles.

[0051] According to the reuse method of this embodiment, at least a portion of the functional layer 302 can be separated from the resin molded body 30, which has a functional layer 302 on its surface, during the separation process. Furthermore, according to this embodiment, by using a BCSC13 assembled with screen mesh laminates 206, 209 having two layers of screen mesh 221, 222, productivity can be improved while maintaining high separation accuracy of the functional layer 302. That is, by having one of the first screen mesh 221 and the second screen mesh 222 constituting the screen mesh laminates 206, 209 have the configuration shown in any of (A), (B), or (C), the separation accuracy of the functional layer 302 can be improved. As a result, the mechanical properties of another resin molded body (a new resin molded body) made using the material obtained through the separation process are excellent.

[0052] Furthermore, if the screen mesh laminates 206 and 209 have a two-layer structure, the cleaning effect during backwashing can be enhanced, thereby preventing or suppressing a decrease in productivity caused by clogging of the screen mesh laminates 206 and 209. Specifically, if the screen mesh laminates 206 and 209 have a two-layer structure, pressure loss due to the screen mesh laminates 206 and 209 can be suppressed, thereby preventing or suppressing a decrease in the effectiveness of clearing clogging of the first screen mesh 221 during backwashing. As a result, productivity can be improved. In addition, since the amount of functional layer 302 that remains unremoved can be reduced, the mechanical properties of the new resin molded article manufactured using the resin material obtained in the separation process as a raw material can be improved.

[0053] Furthermore, if the first screen mesh 221 has the configuration shown in any of (A), (B), or (C), and the second screen mesh 222 has the configuration shown in any of (D), (E), or (F), the resistance when the molten resin molded body 30 passes through the second screen mesh 222 will be smaller than the resistance when it passes through the first screen mesh 221. Therefore, when the molten resin molded body 30 passes through the screen mesh laminates 206, 209, the force that the second screen mesh 222 receives from the molten resin molded body 30 can be made smaller than the force that the first screen mesh 221 receives from the molten resin molded body 30. Thus, by supporting the first screen mesh 221 with the second screen mesh 222, damage to the first screen mesh 221 can be prevented, while damage to the second screen mesh 222 can be prevented or suppressed.

[0054] <Resin molded parts to be reused> Next, the resin molded body 30 that is the target of the recycling method will be described. The target of the recycling method is a resin molded body 30 having a resin content of 60% by mass or more of the total (preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more), and having a base material 301 and a functional layer 302 formed on the surface of the base material 301. Such resin molded bodies 30 include molded bodies formed by injection molding, press molding, vacuum molding, pressure molding, etc., and films and sheets formed by extrusion molding, cast molding, etc.

[0055] In addition, components other than resin in the resin molded body 30 include the functional layer 302 if it is not made of resin, as well as additives (such as reinforcing agents and fillers) added to the functional layer 302 or the base material 301, as described later. If the resin molded body 30 after the separation process contains (remains) components other than resin, a new raw material for a resin molded body can be manufactured from the resin molded body 30 containing the components other than resin.

[0056] (Functional layer) According to the reuse method of this embodiment, what is removed from the resin molded body 30 is a solid object contained in the molten resin molded body 30, and more specifically, a solid object that does not melt even when the base material 301 melts in the extruder 12. For this reason, the functional layer 302 contains at least a portion of a substance that does not melt even when the base material 301 melts.

[0057] Examples of functional layers 302 formed on the surface of the base material 301 of the resin molded body 30 include layers that provide scratch resistance, aesthetic appeal, self-healing properties, reflectivity, scattering properties, anti-reflective properties, anti-scattering properties, anti-glare properties, stain resistance, fingerprint resistance, conductivity, antistatic properties, ultraviolet absorption, ultraviolet reflection, infrared absorption, infrared reflection, dichroic properties, half-mirror properties, water repellency, anti-fogging properties, antibacterial properties, antiviral properties, and anti-blocking properties.

[0058] Methods for forming the functional layer 302 on the surface of the base material 301 of the resin molded body 30 include painting, coating, printing, transfer, lamination, insert / in-mold molding, wet plating, dry plating, etching, and vapor deposition.

[0059] The functional layer 302 may contain a curable resin to improve scratch resistance, shape retention, etc. Examples of such curable resins include thermosetting, ultraviolet curing, or ionizing radiation curing resins, such as urethane resins, unsaturated polyester resins, acrylic resins, acrylic urethane resins, silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, diallyl phthalate resins, urea resins, alkyd resins, guanamine resins, vinyl ester resins, and fluororesins.

[0060] The functional layer 302 may contain a curing agent along with the curable resin to improve the curing reaction efficiency. Examples of curing agents include isocyanates, organic sulfonates, radical polymerization initiators, and cationic polymerization initiators. Examples of radical polymerization initiators include organic peroxides, azo compounds, benzoin compounds, benzophenone compounds, acetophenone compounds, phosphine oxide compounds, titanocene compounds, oxime ester compounds, acridone compounds, acridine compounds, and thioxanthone compounds. Examples of cationic polymerization initiators include sulfonium salts, iodonium salts, ammonium salts, phosphonium salts, diazonium salts, and iron-arene complexes.

[0061] The functional layer 302 may contain additives to improve aesthetics, rigidity, durability, etc. Examples of additives include fillers, interface control agents, colorants, refractive index adjusters, antioxidants, UV absorbers, light stabilizers, flame retardants, antistatic agents, antibacterial agents, antiviral agents, and antiblocking agents.

[0062] Examples of fillers include silica, alumina, zirconia, titanium oxide, zinc oxide, cerium oxide, aluminum oxide, magnesium oxide, zirconium oxide, tin oxide, indium-doped tin oxide, antimond-doped tin oxide, calcium carbonate, magnesium carbonate, barium sulfate, barium titanate, aluminum hydroxide, silicon nitride, aluminum nitride, calcium zirconate, wollastonite, mica, talc, kaolin, carbon, clay, boehmite, zeolite, and diatomaceous earth.

[0063] Examples of interface control agents include silane coupling agents, which are silane compounds having at least two different reactive groups of organic residues having hydrolyzable groups (e.g., methoxy group, ethoxy, 2-methoxyethoxy group, halogen group, etc.) and reactive functional groups at their terminals (e.g., amino group, epoxy group, vinyl group, styryl group, methacrylic group, acrylic group, isocyanate group, isocyanurate group, mercapto group, ureido group, acid anhydride group, etc.).

[0064] Examples of colorants include inorganic pigments, organic pigments, polycyclic pigments, azo pigments, lake pigments, fluorescent pigments, natural dyes, and fluorescent dyes. Examples of refractive index modifiers include titanium dioxide, zirconium oxide, zinc oxide, aluminum oxide, silica, magnesium fluoride, and sodium hexanefluoroaluminate. Examples of antioxidants include phenolic compounds, amine compounds, phosphorus compounds, and sulfur compounds. Examples of ultraviolet absorbers include benzotriazole compounds, benzoate compounds, benzophenone compounds, triazine compounds, oxalic acid anilide compounds, and malonic acid ester compounds.

[0065] Examples of light stabilizers include hindered amine compounds. Examples of flame retardants include antimony trioxide, phosphorus compounds, halogen compounds, guanidine compounds, melamine compounds, silicone compounds, hydroxides, etc. Examples of antistatic agents include glycerin fatty acid esters, nonionic surfactants, anionic surfactants, cationic surfactants, polythiophene compounds, polypyrrole compounds, polyaniline compounds, antimond-doped tin oxide, zinc oxide, titanium dioxide, carbon black, carbon nanotubes, etc.

[0066] Examples of antibacterial agents include silver compounds, copper compounds, zinc compounds, titanium dioxide, and tungsten oxide. Examples of antiviral agents include silver compounds, copper compounds, zinc compounds, titanium dioxide, and tungsten oxide. Examples of antiblocking agents include fatty acid esters, higher alcohols, glycerin esters, sorbitan esters, polyhydric alcohols, fatty acids, oily waxes, low molecular weight polyolefins, monoamides, bisamides, acrylic microparticles, styrene microparticles, silica, talc, zeolite, and diatomaceous earth.

[0067] When the method for forming the functional layer 302 is wet plating, dry plating, etc., examples of elements included in the functional layer 302 (elements that form the functional layer 302) include chromium, tin, gold, platinum, silver, copper, nickel, zinc, rhodium, indium, magnesium, zirconium, aluminum, cerium, hafnium, lanthanum, niobium, silicon, tantalum, titanium, tungsten, yttrium, germanium, and the like.

[0068] When the method for forming the functional layer 302 is coating, examples of methods for forming the functional layer 302 include spray coating, die coating, gravure coating, flexo coating, comma coating, kiss coating, knife coating, bar coating, spin coating, roll coating, lip coating, dip coating, extrusion coating, etc.

[0069] If the method for forming the functional layer 302 is painting, examples of methods for forming the functional layer 302 include brush painting, spatula painting, roller brush painting, air spray painting, airless spray painting, hot airless spray painting, hot spray painting, dipping painting, electrostatic painting, electrodeposition painting, powder coating, curtain flow coater painting, roller coater painting, etc.

[0070] If the functional layer 302 is formed by printing, examples of methods for forming the functional layer 302 include gravure printing, flexographic printing, screen printing, offset printing, inkjet printing, and pad printing. If the functional layer 302 is formed by transfer, examples of methods include thermal transfer and hydrographic transfer. If the functional layer 302 is formed by lamination, examples of methods for forming the functional layer 302 include dry lamination, thermal lamination, and extrusion lamination.

[0071] When the functional layer 302 is formed by insert / in-mold molding, examples of methods for forming the functional layer 302 include film insert molding and film in-mold molding.

[0072] When the functional layer 302 is formed by wet plating, examples of methods for forming the functional layer 302 include electroplating, electroless plating, and displacement plating. When the functional layer 302 is formed by vapor deposition, examples of methods for forming the functional layer 302 include vacuum deposition, sputtering, ion plating, laser ablation, molecular beam epitaxy, thermochemical vapor deposition, plasma chemical vapor deposition, organometallic chemical vapor deposition, photochemical vapor deposition, and hot-dip plating. When the functional layer 302 is formed by etching, examples of methods for forming the functional layer 302 include chemical etching and electrolytic etching.

[0073] (base material) The base material 301 (the resin forming the portion excluding the functional layer 302) of the resin molded body 30 may be, for example, polyethylene (PE), polypropylene (PP), cyclic polyolefin (COP), polyvinyl chloride (PVC), polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS), acrylonitrile butadiene styrene (ABS) resin, acrylonitrile styrene (AS) resin, acrylonitrile styrene acrylic acid ester (ASA) resin, polyamide (PA), polyacetal (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene Applicable materials include naphthalate (PEN), polyphenylsulfone (PPSU), polysulfone (PSU), polyarylate (PAR), polyetherimide (PEI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyphenylene ether (PPE), polyimide (PI), polyethersulfone (PES), polyamideimide (PAI), polybenzimidazole (PBI), liquid crystal polymer (LCP), polylactic acid (PLA), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDC), thermoplastic elastomers, etc. From the viewpoint of impact resistance, durability, and moldability, it is preferable that the base material 301 is a material containing polycarbonate.

[0074] The base material 301 may also contain additives to improve its design, rigidity, durability, etc. Examples of additives include reinforcing agents, fillers, colorants, nucleating agents, refractive index modifiers, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, antistatic agents, antibacterial agents, antiviral agents, and antiblocking agents.

[0075] Examples of reinforcing agents include glass fibers, carbon fibers, aramid fibers, cellulose fibers, carbon nanofibers, carbon nanotubes, cellulose nanofibers, wollastonite, mica, talc, kaolin, carbon, clay, glass flakes, and glass beads. From the viewpoint of reinforcing effect, the inclusion of wollastonite is preferable.

[0076] Examples of fillers include silica, alumina, zirconia, titanium dioxide, zinc oxide, cerium oxide, aluminum oxide, magnesium oxide, zirconium oxide, tin oxide, indium-doped tin oxide, antimond-doped tin oxide, calcium carbonate, magnesium carbonate, barium sulfate, barium titanate, aluminum hydroxide, silicon nitride, aluminum nitride, calcium zirconate, mica, talc, kaolin, carbon, clay, boehmite, zeolite, and diatomaceous earth. Examples of colorants include inorganic pigments, organic pigments, polycyclic pigments, azo pigments, lake pigments, fluorescent pigments, natural dyes, and fluorescent dyes. Examples of nucleating agents include sorbitol compounds, nonitol compounds, xylitol compounds, carboxylate metal salts, phosphate ester metal salts, rosin metal salts, and triaminobenzene derivatives.

[0077] Examples of refractive index modifiers include titanium dioxide, zirconium oxide, zinc oxide, aluminum oxide, silica, magnesium fluoride, and sodium hexanefluoroaluminate. Examples of antioxidants include phenolic compounds, amine compounds, phosphorus compounds, and sulfur compounds. Examples of ultraviolet absorbers include benzotriazole compounds, benzoate compounds, benzophenone compounds, triazine compounds, oxalic acid anilide compounds, and malonic acid ester compounds. Examples of light stabilizers include hindered amine compounds. Examples of flame retardants include antimony trioxide, phosphorus compounds, halogen compounds, guanidine compounds, melamine compounds, silicone compounds, and hydroxides.

[0078] Examples of antistatic agents include glycerin fatty acid esters, nonionic surfactants, anionic surfactants, cationic surfactants, polythiophene compounds, polypyrrole compounds, polyaniline compounds, antimony dope tin oxide, zinc oxide, titanium dioxide, carbon black, and carbon nanotubes. Examples of antibacterial agents include silver compounds, copper compounds, zinc compounds, titanium dioxide, and tungsten oxide. Examples of antiviral agents include silver compounds, copper compounds, zinc compounds, titanium dioxide, and tungsten oxide. Examples of antiblocking agents include fatty acid esters, higher alcohols, glycerin esters, sorbitan esters, polyhydric alcohols, fatty acids, oily waxes, low molecular weight polyolefins, monoamides, bisamides, acrylic microparticles, styrene microparticles, silica, talc, zeolite, and diatomaceous earth.

[0079] <Examples> The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to these examples. The inventors prepared test pieces according to the examples of the present invention (new resin molded articles) and test pieces according to the comparative examples (resin molded articles) from a resin molded article 30 having a base material 301 and a functional layer 302 provided on the surface of the base material 301, and evaluated the characteristics of each. In the following examples and comparative examples, the functional layer 302 of the resin molded article 30 (in other words, the functional layer 302 to be separated) is a paint layer.

[0080] (Resin molded body (1)) The resin molded body (1) is a resin molded body that serves as the material for the test pieces of the examples and comparative examples of the present invention. The resin molded body (1) uses an outside door handle (product name: HANDLE, FR DOOR OUTSIDE, 185 mm in length, 45 mm in width, 55 mm in height) whose surface functional layer is a paint layer (0.04 mm thick, white). The base material 301 (the part of the outside door handle excluding the paint layer) is made of a polycarbonate (PC) / polybutylene terephthalate (PBT) alloy containing 10% by mass of wollastonite.

[0081] <Segmentation process> Prior to the separation process, the resin molded body (1) was subdivided (pulverized) in a subdivision process. A pulverizer (model number: DAS-28, manufactured by Daiko Seiki Co., Ltd.) was used for the subdivision process.

[0082] <Separation process> For the surface treatment process in the separation stage, a plastic pellet surface treatment machine (model number: PBA25A, manufactured by Satake Corporation) was used. The screen holes of this machine are circular with a diameter of 2 mm. The roller rotation speed is 638 rpm.

[0083] The equipment and extrusion conditions used in the separation process are as follows:

[0084] • Feeder: Loss-in-weight type 2-axis screw feeder (Model number: KF-M3500 (control module) / CE-W-1 (feeder), manufactured by Kubota Corporation) The feed rate from this feeder was set to 16 kg / hour.

[0085] • Extruder: Twin-screw extruder (Model number: PCM30, manufactured by Ikegai Co., Ltd.) This extruder has an L / D ratio of 42 and 12 cylinders. The feed port is located above the upstreammost cylinder. The open vent port is located on the sixth cylinder from the upstream side. The screw system is twin-screw. The screws rotate in the same direction. For the screw segment configuration, the tenth cylinder from the upstream side is used as the kneading segment, and the other cylinders are used as feed segments. The screw rotation speed is 85 rpm. The breaker plate is located at the downstream end of the downstreammost cylinder. Furthermore, as described later, the operation of the BCSC was switched based on the resin pressure (internal pressure) inside the cylinder. The resin pressure is measured directly above the breaker plate.

[0086] • BCSC: Backwash type continuous screen changer (Model number: FDC30, manufactured by GPC Tsuchiya Co., Ltd.) The BSCS13 is attached to the breaker plate removal section of the extruder 12 via a flange. Two sets of screen mesh laminates (first screen mesh laminate 206 and second screen mesh laminate 209) are assembled to the BCSC13. Both sets of screen mesh laminates 206 and 209 have a roughly cylindrical shape. Each set of screen mesh laminates 206 and 209 is installed sandwiched between a porous outer cylinder and an inner cylinder. The filtration area of ​​each set of screen mesh laminates 206 and 209 is 30 cm². 2 That is the case.

[0087] The die 14 has four holes with a diameter of 3 mm, and is configured to allow the molten resin molded body 30 to flow out through these holes, thereby shaping the molten resin molded body 30 into strands. The water tank 15 has dimensions of 2000 mm in length, 300 mm in width, and 150 mm in depth. A drum cutter type pelletizer (product number: PS50, manufactured by Ikegai Co., Ltd.) was used as the pelletizer 16.

[0088] The subdivided resin molded body (1) was supplied into the cylinder 111 of the extruder 12 using the feeder 11. The subdivided resin molded body (1) was transported through the cylinder 111 by the rotation of the screw 112 and melted. The molten resin molded body 30 then flowed out of the extruder 12 and into the BCSC 13 connected to the extruder 12. The molten resin molded body 30 that flowed into the BCSC 13 passed through the first screen mesh laminate 206 or the second screen mesh laminate 209 before flowing out of the BCSC 13. The molten resin molded body 30 (separated resin material) that flowed out of the BCSC 13 passed through the die 14 connected to the BCSC 13, and as it flowed out of the die 14, it became four strands, which were cooled and solidified in the water tank 15. The solidified separated resin material was cut into pellet shapes by the pelletizer 16. Through this process, resin molded pellets (3 mm in diameter, 4 mm in length) made from the separated resin material are obtained.

[0089] The BCSC13 comprises two sets of screen mesh laminates (first screen mesh laminate 206 and second screen mesh laminate 209). The BCSC13 then performs the following operations in the order of (1) to (5). This allows the separation of the functional layer 302 to continue even if one of the screen mesh laminates 206, 209 becomes clogged, without stopping the supply of material from the feeder 11 or the operation of the extruder 12. In other words, the separation process can be continued.

[0090] (1) By setting the first flow valve 202 to the first state, the molten resin molded body (1) is allowed to flow into the first screen mesh laminate 206 only from the upstream side. Then, by setting the second flow valve 205 to the second state and the fourth flow valve 212 to the first state, the molten resin molded body (1) with at least a portion of the functional layer 302 separated is allowed to flow out of the BCSC13 from the sixth flow channel 211. (2) When the resin pressure reaches 10 MPa, the first flow valve 202 is switched to the second state, allowing the molten resin molded body (1) to flow into the second screen mesh laminate 209 only from the upstream side. Then, by setting the second flow valve 205 to the first state, the third flow valve 208 to the second state, and the fourth flow valve 212 to the third state, the molten resin molded body (1) with at least a portion of the functional layer 302 separated is discharged to the outside of the BCSC13 from the sixth flow channel 211, and the molten resin molded body (1) with at least a portion of the functional layer 302 separated is also allowed to flow into the first screen mesh laminate 206 for backwashing, and the backwash discharge containing a portion of the functional layer 302 is discharged to the outside of the BCSC13 from the second flow valve 205. (3) When the resin pressure reaches 12 MPa, the first flow valve 202 is switched to the first state, allowing the molten resin molded body 30 to flow into the first screen mesh laminate 206 only from the upstream side. Then, the second flow valve 205 is set to the second state, the third flow valve 208 is set to the first state, and the fourth flow valve 212 is set to the third state, causing the molten resin molded body (1) with at least a portion of the functional layer 302 separated to flow out of the BCSC13 from the sixth flow channel 211, and the molten resin molded body (1) with at least a portion of the functional layer 302 separated to flow into the second screen mesh laminate 209 for backwashing, and the backwash discharge containing a portion of the functional layer 302 is discharged out of the BCSC13 from the third flow valve 208. (4) When the resin pressure reaches 14 MPa, the first flow valve 202 is switched to the second state, allowing the molten resin molded body (1) to flow into the second screen mesh laminate 209 only from the upstream side. Then, by setting the second flow valve 205 to the first state, the third flow valve 208 to the second state, and the fourth flow valve 212 to the third state, the molten resin molded body (1) with at least a portion of the functional layer 302 separated is discharged to the outside of the BCSC13 from the sixth flow channel 211, and the molten resin molded body (1) with at least a portion of the functional layer 302 separated is also allowed to flow into the first screen mesh laminate 206 for backwashing, and the backwash discharge containing a portion of the functional layer 302 is discharged to the outside of the BCSC13 from the second flow valve 205. (5) The operation will be terminated when the resin pressure reaches 16 MPa.

[0091] Then, the separation process was carried out on the resin molded body (1) under different conditions.

[0092] (Preparation of test specimens of resin molded body (2)) Subsequently, a resin molded body (2) was manufactured using the separated resin material obtained from the resin molded body (1) as part of the material. That is, resin molded body (2) is a resin molded body molded using the pellets of the resin molded body (1) that have undergone the separation process as part of the raw material. Specifically, the pellets of the resin molded body (1) that have undergone the separation process and virgin pellets of polycarbonate (PC) / polybutylene terephthalate (PBT) alloy containing 10% by mass of wollastonite were weighed and placed in a tumbler, and the tumbler was rotated to mix them uniformly and create a mixture. The percentage of the weight of the pellets of the resin molded body (1) that have undergone the separation process in this mixture was defined as the recycling rate. Using this mixture as the raw material, an ISO 527-2-1A test specimen of the resin molded body (2) was manufactured using an injection molding machine (model number: SE180-DU, manufactured by Sumitomo Heavy Industries, Ltd.). Injection molding was performed under the following conditions: cylinder temperature 270°C, mold temperature 78°C, screw rotation speed 150 rpm, back pressure 5 MPa, injection pressure 250 MPa, injection time 2.5 seconds, holding pressure 100 MPa, holding time 11 seconds, and cooling time 20 seconds.

[0093] (Paint content) In this example and comparative example, the paint content of the resin molded body (2) was evaluated as an indicator of the separation accuracy of the functional layer. Specifically, for the test pieces of Examples 1-5 and Comparative Examples 1-7 that were prepared, the surface of the test piece was acquired as image data using an image measuring machine (product number: QV-X404PIL-C, manufactured by Mitutoyo Corporation), and then the paint content was measured by calculating the area of ​​paint unevenly distributed on the surface of the test piece using image analysis software (product number: Image-Pro, Hakuto Co., Ltd.). That is, the paint content is "((paint area) / (area of ​​the shooting range of the test piece surface)) × 100 (%)". Then, the paint content of Examples 1-5 and Comparative Examples 2-7 was calculated with the paint content of Comparative Example 1 set to 1. A lower paint content indicates higher separation accuracy of the functional layer. From the viewpoint of the design of the resin molded body (2), a paint content of 0.5 or less was considered to indicate good functional layer separation accuracy, and a paint content greater than 0.5 was considered to indicate poor accuracy.

[0094] (Time until the resin pressure reaches 16 MPa) When BCSC13 is operating normally, the functional layer 302 accumulates on the outer periphery of the first screen mesh 221 of the first screen mesh laminate 206 and the second screen mesh laminate 209 (in other words, clogging occurs), and the amount of molten resin molded body (1) passing through the first screen mesh laminate 206 and the second screen mesh laminate 209 per unit time decreases. Therefore, in order to maintain productivity, a backwash operation must be performed when the functional layer 302 accumulates on the outer periphery of the first screen mesh 221 of the first screen mesh laminate 206 and the second screen mesh laminate 209. In this disclosure, clogging is considered to have occurred in the first screen mesh laminate 206 and the second screen mesh laminate 209 when the resin pressure on the outer periphery of the first screen mesh laminate 206 and the second screen mesh laminate 209 exceeds 16 MPa. Furthermore, the longer the time it takes from the backwashing operation until the resin pressure on the outer periphery of the first screen mesh laminate 206 and the second screen mesh laminate 209 reaches 16 MPa or higher, the higher the productivity can be considered. From a productivity standpoint, a time of 3 minutes or more was judged as good, and a time of less than 3 minutes was judged as poor.

[0095] (Difference in resin pressure before and after backwashing) If the pressure loss due to the first screen mesh laminate 206 or the second screen mesh laminate 209 increases, the effect of the backwashing operation in clearing clogging of the first screen mesh 221 decreases, resulting in reduced productivity. In this disclosure, the difference in resin pressure before and after the backwashing operation (the difference between the resin pressure immediately before the backwashing operation and the resin pressure immediately after the backwashing operation) is used as an indicator of the effect of the backwashing operation in clearing clogging. A higher difference in resin pressure before and after backwashing indicates a higher effect in clearing clogging of the first screen mesh 221. From the viewpoint of the effectiveness of backwashing, if the difference in resin pressure before and after the backwashing operation is 2 MPa or more, it is judged that the pressure loss of the screen mesh laminates 206 and 209 is small and the effect of the backwashing operation in clearing clogging of the first screen mesh 221 is high (good), and if it is less than 2 MPa, it is judged that the effect is low (poor).

[0096] (Tensile test) In this disclosure, tensile fracture strain was evaluated as one of the indicators showing the mechanical properties of the resin molded articles (2) manufactured by the recycling method. Specifically, tensile tests were performed on the test pieces of Examples 1 to 5 and Comparative Examples 1 to 7 using a tensile testing machine (model number: AG-X PLUS 10kN, manufactured by Shimadzu Corporation), and the tensile fracture strain was measured. The tests were conducted under the conditions of a temperature of 23°C, a chuck distance of 115 mm, and a tensile speed of 50 mm / sec. From the viewpoint of the ductility of the resin molded articles (2), a tensile fracture strain of 15% or more was considered good, and a strain of less than 15% was considered poor.

[0097] (Impact test) In this disclosure, Charpy impact strength was evaluated as another indicator of the mechanical properties of the resin molded articles (2) manufactured by the reuse method. Specifically, notches were made (outer diameter: 75 mm, angle: 45°, tip radius: 0.25 mm) using a notching tool (product number: A-3, manufactured by Toyo Seiki Seisakusho Co., Ltd.) on the test pieces of Examples 1 to 5 and Comparative Examples 1 to 7, and then impact tests were performed using a Charpy impact testing machine (product number: DG UB, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The tests were conducted under ISO 179-1 conditions, at a temperature of 23°C and a lifting angle of -150°. In this disclosure, the Charpy impact strength of the resin molded articles (2) was determined to be 12 kJ / m² based on the toughness of the resin molded articles (2). 2 The above is considered satisfactory, 12 kJ / m³ 2 Anything below this level was considered defective.

[0098] [Table 1]

[0099] (Example 1) The two sets of BCSC screen mesh laminates (first screen mesh laminate and second screen mesh laminate) used in the extrusion process have the following configurations. The first screen mesh has a plain weave, a vertical wire diameter of 0.12 mm, 60 vertical meshes, a horizontal wire diameter of 0.07 mm, 400 horizontal meshes, and is made of stainless steel. The second screen mesh has a plain weave, a vertical wire diameter of 0.14 mm, 80 vertical meshes, a horizontal wire diameter of 0.14 mm, 80 horizontal meshes, and is made of stainless steel. The recycling rate of the resin molded product (2) was set at 30%.

[0100] (Example 2) The conditions are the same as in Example 1, except that the recycling rate of the resin molded body (2) is 15%.

[0101] (Example 3) Before the extrusion of the subdivided resin molded body 30, a surface treatment process was performed by passing it through a plastic pellet surface treatment machine four times. Otherwise, the conditions were the same as in Example 1.

[0102] (Example 4) Before extrusion of the subdivided resin molded body 30, a surface treatment process was performed by passing it once through a plastic pellet surface treatment machine. Otherwise, the conditions were the same as in Example 1.

[0103] (Example 5) The first screen mesh of the two screen mesh laminates has a vertical wire diameter of 0.14 mm and 50 vertical meshes, a horizontal wire diameter of 0.09 mm and 300 horizontal meshes. Except for the first screen mesh, the conditions are the same as in Example 1.

[0104] (Comparative Example 1) This is an example where a screen mesh laminate is not used in the extrusion process. Otherwise, the conditions are the same as in Example 1.

[0105] (Comparative Example 2) This is an example of using a single screen mesh in the extrusion process, without using a screen mesh laminate. The single screen mesh used is the same as the first screen mesh of the screen mesh laminate in Example 1. Otherwise, the conditions are the same as in Example 1.

[0106] (Comparative Example 3) This is an example using a screen mesh laminate comprising a third screen mesh laminated in contact with a second screen mesh (i.e., having a three-layer laminated structure). The second screen mesh is woven in a plain weave pattern, with a vertical wire diameter of 0.12 mm and 60 vertical meshes, a horizontal wire diameter of 0.07 mm and 400 horizontal meshes. The third screen mesh is woven in a plain weave pattern, with a vertical wire diameter of 0.14 mm and 80 vertical meshes, a horizontal wire diameter of 0.14 mm and 80 horizontal meshes, and is made of stainless steel. All other conditions are the same as in Example 1.

[0107] (Comparative Example 4) This example uses a screen mesh laminate with a first screen mesh having a vertical wire diameter of 0.18 mm, 30 vertical meshes, a horizontal wire diameter of 0.14 mm, and 200 horizontal meshes. All other conditions are the same as in Example 1.

[0108] (Comparative Example 5) This example uses a screen mesh laminate in which the first screen mesh is plain weave, the vertical wire diameter is 0.03 mm, the number of vertical meshes is 250, the horizontal wire diameter is 0.03 mm, the number of horizontal meshes is 250, and the material is stainless steel. Otherwise, the conditions are the same as in Example 1.

[0109] (Comparative Example 6) This example uses an extruder with a single screen mesh laminate held in a breaker plate, without using BCSC. Otherwise, the conditions are the same as in Example 1. In this case, the screen mesh laminate is planar, and the filtration area of ​​the screen mesh laminate is 25 cm². 2 That is the case.

[0110] (Comparative Example 7) This is an example using a screen mesh laminate that includes a third screen mesh laminated in contact with a second screen mesh (i.e., having a three-layer laminated structure). The second screen mesh is woven in a plain weave pattern, with a vertical wire diameter of 0.12 mm, 60 vertical meshes, a horizontal wire diameter of 0.07 mm, 400 horizontal meshes, and is made of stainless steel. The third screen mesh is woven in a plain weave pattern, with a vertical wire diameter of 0.14 mm, 80 vertical meshes, a horizontal wire diameter of 0.14 mm, 80 horizontal meshes, and is also made of stainless steel. Similar to Comparative Example 6, an extruder was used in which one set of screen mesh laminates was held on a breaker plate, without using BCSC. Other than these, the conditions were the same as in Example 1. The shape of the screen mesh laminate is planar, and the filtration area of ​​the screen mesh laminate is 25 cm². 2 That is the case.

[0111] (evaluation) As shown in Table 1, in Examples 1 to 5, the paint content was 0.43 or less, there was no tearing of the screen mesh 221 and 222, the difference in resin pressure before and after the backwashing operation was 2 MPa or more, and the time required to reach a resin pressure of 16 MPa was 3 minutes or more. Thus, according to Examples 1 to 5, which are within the scope of this disclosure, it was confirmed that productivity can be improved while maintaining high separation accuracy of the functional layer 302. Furthermore, it was confirmed that the test specimen (resin molded body (2)) manufactured using at least a portion of the resin molded body (1) from which at least a portion of the functional layer 302 had been separated exhibited excellent mechanical properties (especially tensile fracture strain).

[0112] On the other hand, as is clear from Comparative Example 1, the separation accuracy of the functional layer is lower when a screen mesh is not used compared to when one is used.

[0113] As is clear from Comparative Example 2, when a screen mesh laminate with one layer was used, the screen mesh rupture occurred due to the low pressure resistance of the screen mesh laminate, resulting in a low separation accuracy of the functional layer. Furthermore, as is clear from Comparative Example 3, when a screen mesh laminate with three layers was used, the separation accuracy of the functional layer was high, but the productivity was low.

[0114] As is clear from Comparative Example 4, when the mesh count and wire diameter of the screen mesh in the screen mesh laminate fall outside the range of the present invention, it was confirmed that the separation accuracy of the functional layer is low. As is clear from Comparative Example 5, when a screen mesh with a plain woven weave is not used, the pressure resistance strength of the screen mesh is low, opening of the mesh occurs due to deformation, and it was confirmed that the separation accuracy of the functional layer is low.

[0115] As is clear from Comparative Examples 6 and 7, it was confirmed that when BCSC is not used, the separation accuracy of the functional layer is high, but the productivity is low.

[0116] Based on the above, it was confirmed that, according to the examples, productivity can be improved while maintaining high separation accuracy of the functional layer, and that another resin molded body (a new resin molded body) made using the material obtained through the separation process has excellent mechanical properties.

[0117] <Summary of Embodiments> (1) The method for reusing the resin molded article according to this embodiment is: A method for reusing a resin molded body, comprising a separation step of melting a resin molded body 30 having a base material 301 containing a resin material and a functional layer 302 provided on the surface of the base material 301, and passing the molten resin molded body 30 through a screen mesh laminate (first screen mesh laminate 206, second screen mesh laminate 209) provided in a backwash type continuous screen changer (BCSC13) to remove at least a portion of the functional layer 302 from the molten resin molded body 30, wherein The aforementioned screen mesh laminate (first screen mesh laminate 206, second screen mesh laminate 209) has a two-layer structure consisting of a first screen mesh 221 and a second screen mesh 222 that are stacked in the thickness direction. The first screen mesh 221 is either plain weave, with a vertical wire diameter of 0.09 mm or more and 0.15 mm or less, and a vertical mesh count of 50 or more and 80 or less; or plain weave, with a horizontal wire diameter of 0.05 mm or more and 0.10 mm or less, and a horizontal mesh count of 250 or more and 500 or less; or plain weave, with a vertical wire diameter of 0.09 mm or more and 0.15 mm or less, a vertical mesh count of 50 or more and 80 or less, a horizontal wire diameter of 0.05 mm or more and 0.10 mm or less, and a horizontal mesh count of 250 or more and 500 or less.

[0118] By providing the first screen mesh 221 as described above in the screen mesh laminate (first screen mesh laminate 206, second screen mesh laminate 209), the separation accuracy of the functional layer can be improved. As a result, the mechanical properties of another resin molded body (new resin molded body) made using the material obtained through the separation process are excellent. In addition, damage to the first screen mesh 221 can be prevented. Furthermore, if the screen mesh laminate (first screen mesh laminate 206, second screen mesh laminate 209) has a two-layer structure, the cleaning effect during backwashing can be enhanced, thereby preventing or suppressing a decrease in productivity caused by clogging of the screen mesh (first screen mesh 221, second screen mesh 222). Therefore, according to this embodiment, productivity can be improved while maintaining high separation accuracy of the functional layer 302.

[0119] (2) The backwash-type continuous screen changer (BCSC13) is configured to allow the molten resin molded body 30 to pass through the screen mesh laminate (first screen mesh laminate 206, second screen mesh laminate 209) in a direction that can be switched between a first direction and a second direction opposite to the first direction. During the backwash operation to clean the screen mesh laminate (first screen mesh laminate 206, second screen mesh laminate 209), the resin molded body 30 is configured to pass through the screen mesh laminate (first screen mesh laminate 206, second screen mesh laminate 209) in the second direction. The second screen mesh 222 is either plain weave, with a vertical wire diameter of 0.13 mm or more and 0.23 mm or less and a vertical mesh count of 50 or more and 80 or less, or plain weave, with a horizontal wire diameter of 0.13 mm or more and 0.23 mm or less and a horizontal mesh count of 50 or more and 80 or less, or plain weave, with a vertical wire diameter of 0.13 mm or more and 0.23 mm or less, a vertical mesh count of 50 or more and 80 or less, a horizontal wire diameter of 0.13 mm or more and 0.23 mm or less, and a horizontal mesh count of 50 or more and 80 or less. A configuration can be applied in which the second screen mesh 222 is stacked on the downstream side of the first screen mesh 221 in the first direction.

[0120] With this configuration, the resistance when the molten resin molded body 30 passes through the second screen mesh 222 is smaller than the resistance when it passes through the first screen mesh 221. Therefore, it is possible to improve the accuracy of the separation of the functional layer 302 while improving productivity (preventing or suppressing a decrease in productivity). In addition, when the molten resin molded body 30 passes through the screen mesh laminate (first screen mesh laminate 206, second screen mesh laminate 209), the force that the second screen mesh 222 receives from the molten resin molded body can be made smaller than the force that the first screen mesh 221 receives from the molten resin molded body 30. Therefore, by supporting the first screen mesh 221 with the second screen mesh 222, it is possible to prevent damage to the first screen mesh 221 while preventing or suppressing damage to the second screen mesh 222.

[0121] (3) The process includes manufacturing another resin molded body from a raw material containing the resin molded body 30 from which at least a portion of the functional layer 302 has been separated in the separation step, This configuration can be applied.

[0122] With this configuration, it is possible to manufacture resin molded articles with excellent mechanical properties.

[0123] (4) The separation step includes a step of separating at least a portion of the functional layer 302 from the base material 301 by rubbing the surfaces of the resin molded body 30 together before the resin molded body 30 is brought to a melting state.

[0124] With this configuration, the separation accuracy of the functional layer 302 can be further improved.

[0125] Although embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples. The present invention can be modified in various ways without departing from its spirit, and these modifications are also included within the technical scope of the present invention. [Explanation of Symbols]

[0126] 10... Equipment, 11... Extruder, 13... BCSC, 14... Die, 15... Water tank, 16... Pelletizer, 30... Resin molded body, 301... Substrate for resin molded body, 302... Functional layer for resin molded body

Claims

1. A method for reusing a resin molded body, comprising a separation step of melting a resin molded body having a base material containing a resin material and a functional layer provided on the surface of the base material, and passing the molten resin molded body through a screen mesh laminate provided in a backwash type continuous screen changer to remove at least a portion of the functional layer from the molten resin molded body, The aforementioned screen mesh laminate has a two-layer structure consisting of a first screen mesh and a second screen mesh stacked in the thickness direction. The first screen mesh is either plain weave, with a vertical wire diameter of 0.09 mm or more and 0.15 mm or less, and a vertical mesh count of 50 or more and 80 or less; or plain weave, with a horizontal wire diameter of 0.05 mm or more and 0.10 mm or less, and a horizontal mesh count of 250 or more and 500 or less; or plain weave, with a vertical wire diameter of 0.09 mm or more and 0.15 mm or less, a vertical mesh count of 50 or more and 80 or less, a horizontal wire diameter of 0.05 mm or more and 0.10 mm or less, and a horizontal mesh count of 250 or more and 500 or less. Methods for reusing resin molded products.

2. A method for reusing a resin molded article according to claim 1, The aforementioned backwashing continuous screen changer is configured to allow the direction in which the molten resin molded body passes through the screen mesh laminate to be switched between a first direction and a second direction opposite to the first direction, and is configured to set the direction in which the resin molded body passes through the screen mesh laminate to the second direction during the backwashing operation to clean the screen mesh laminate. The second screen mesh is either plain weave, with a vertical wire diameter of 0.13 mm or more and 0.23 mm or less and a vertical mesh count of 50 or more and 80 or less, or plain weave, with a horizontal wire diameter of 0.13 mm or more and 0.23 mm or less and a horizontal mesh count of 50 or more and 80 or less, or plain weave, with a vertical wire diameter of 0.13 mm or more and 0.23 mm or less, a vertical mesh count of 50 or more and 80 or less, a horizontal wire diameter of 0.13 mm or more and 0.23 mm or less, and a horizontal mesh count of 50 or more and 80 or less. The second screen mesh is stacked on the downstream side of the first screen mesh in the first direction. Methods for reusing resin molded products.

3. A method for reusing a resin molded article according to claim 1 or claim 2, The process includes a step of producing another resin molded body from a raw material containing the resin molded body from which at least a portion of the functional layer has been separated in the separation step, Methods for reusing resin molded products.

4. A method for reusing a resin molded article according to claim 1 or claim 2, The separation step includes a step of separating at least a portion of the functional layer from the substrate by rubbing the surfaces of the resin molded body together before melting the resin molded body. Methods for reusing resin molded products.

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