Method for manufacturing resin molded body and mold device

Abstract

A method for manufacturing a resin molded body, comprising: a step of preparing a mold device including a first mold provided with an injection hole, a second mold forming, between the first mold and the second mold, a cavity communicating with the injection hole, a first release film disposed so as to close the injection hole, and a second release film disposed between the first release film and the second mold; a step of injecting a molding material containing a resin through the injection hole, breaking the first release film by means of the molding material, and injecting the molding material between the first release film and the second release film; and a step of curing the molding material.

Description

Method for manufacturing resin molded body and mold device

[0001] The present disclosure relates to a method for manufacturing a resin molded body and a mold device.

[0002] Patent Document 1 describes a method for manufacturing a resin molded product using an upper mold and a lower mold. In the method described in Patent Document 1, a release film provided with through holes is disposed before the step of clamping the upper mold and the lower mold. The diameter of the through holes provided in the release film is the same as or slightly larger than the opening diameters of the resin injection port and the discharge port.

[0003] Japanese Patent Application Laid-Open No. 2023-60989

[0004] When manufacturing a resin molded body using a mold device, using a release film can make it easier to remove the resin molded body from the mold device, but there is room for improvement in the method for manufacturing the resin molded body and the mold device.

[0005] A method for manufacturing a resin molded body according to an embodiment of the present disclosure includes a first mold provided with an injection hole, a second mold that forms a cavity connected to the injection hole between the first mold, a first release film disposed so as to block the injection hole, and a second release film disposed between the first release film and the second mold. The method includes preparing a mold device having these components, injecting a molding material containing resin from the injection hole, breaking the first release film with the molding material, and injecting the molding material between the first release film and the second release film, and curing the molding material.

[0006] A mold device according to an embodiment of the present disclosure includes a first mold provided with an injection hole, a second mold that forms a cavity connected to the injection hole between the first mold, a first release film disposed so as to block the injection hole, and a second release film disposed between the first release film and the second mold.

[0007] According to the above-described method for manufacturing a resin molded body and the mold device, the releasability of the resin molded body obtained by curing the molding material can be improved.

[0008] Figure 1 is a flowchart illustrating the method for manufacturing a resin molded article according to the embodiment. Figure 2 is a schematic cross-sectional view showing a mold apparatus according to the embodiment. Figure 3 is a schematic cross-sectional view showing a mold apparatus according to the embodiment. Figure 4 is a schematic cross-sectional view illustrating one step of the method for manufacturing a resin molded article according to the embodiment. Figure 5 is a schematic cross-sectional view illustrating one step of the method for manufacturing a resin molded article according to the embodiment. Figure 6A is a schematic plan view showing a resin molded article. Figure 6B is a schematic cross-sectional view along the line VIB-VIB in Figure 6A. Figure 6C is a schematic plan view showing another example of a resin molded article. Figure 7 is a schematic partial enlargement view illustrating a modified example. Figure 8 is a schematic partial enlargement view illustrating a modified example. Figure 9 is a schematic partial enlargement view illustrating a modified example. Figure 10 is a schematic partial enlargement view illustrating a modified example. Figure 11 is a schematic partial enlargement view illustrating a modified example. Figure 12 is a schematic perspective view showing a retaining component.

[0009] The embodiments of the present invention will be described in detail below. The embodiments shown below are examples for realizing the technical concept of the present invention and do not limit the present invention to these. The drawings used to describe the embodiments are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between parts, etc., are not necessarily the same as those of reality. Even when representing the same part, the dimensions and ratios may be represented differently in the drawings.

[0010] The manufacturing method and mold apparatus for the resin molded article of the embodiment will be explained using Figures 1 to 6C. Figure 1 is a flowchart of the manufacturing method for the resin molded article of the embodiment. Figures 2 and 3 are schematic cross-sectional views showing the mold apparatus of the embodiment. Figures 4 and 5 are schematic cross-sectional views illustrating one step of the manufacturing method for the resin molded article of the embodiment. Figure 6A is a schematic plan view showing a resin molded article. Figure 6B is a schematic cross-sectional view along the line VIB-VIB in Figure 6A. Figure 6C is a schematic plan view showing another example of a resin molded article.

[0011] The method for manufacturing the resin molded body 100 of the embodiment comprises the steps of: step S101 of preparing a mold apparatus 10; step S102 of injecting a molding material; and step S103 of curing. In step S101, a mold apparatus 10 is prepared, which includes a first mold 11, a second mold 12, a first release film 13, and a second release film 14. The first mold 11 is provided with an injection hole 15. The second mold 12 forms a cavity 16 between itself and the first mold 11 that is connected to the injection hole 15. The first release film 13 is positioned to block the injection hole 15. The second release film 14 is positioned between the first release film 13 and the second mold 12. In step S102, a molding material 20 containing resin is injected through the injection hole 15, the molding material 20 breaks the first release film 13, and the molding material 20 is injected between the first release film 13 and the second release film 14. In step S103, the molding material 20 is cured. This makes it possible to obtain a resin molded body 100 in which the molding material 20 has been cured.

[0012] If injection holes are provided in the first release film 13 beforehand, if the positions of the holes in the first release film 13 and the injection holes 15 are misaligned, the surface of the first mold 11 will be exposed from the first release film 13. To avoid this, precise alignment is required. According to the manufacturing method of this embodiment, the first release film 13 is broken by the molding material 20 in step S102, so such precise alignment is unnecessary. The molding material 20 that has broken through the first release film 13 is then injected between the first release film 13 and the second release film 14. Therefore, according to the manufacturing method of this embodiment, the release properties of the resin molded body 100 obtained by curing the molding material 20 can be improved. This makes it possible to improve the yield rate of the resulting resin molded body 100.

[0013] (Process for preparing the mold device) In process S101, the mold device 10 is prepared.

[0014] (Mold apparatus) Figure 2 is a schematic diagram showing the mold apparatus 10 in the open state. In Figure 2, the first mold 11 and the second mold 12 are separated. Figure 3 is a schematic diagram showing the mold apparatus 10 in the clamped state. In Figure 3, the first release film 13 and the second release film 14 are sandwiched between the first mold 11 and the second mold 12.

[0015] The mold device 10 includes a first mold 11, a second mold 12, a first release film 13, and a second release film 14. The first mold 11 is provided with an injection hole 15. The second mold 12 forms a cavity 16 between itself and the first mold 11 that connects to the injection hole 15. The first release film 13 is positioned to cover the injection hole 15. The second release film 14 is positioned between the first release film 13 and the second mold 12. By using the mold device 10, the release properties of the resin molded body 100 can be improved. This makes it possible to improve the yield rate of the resin molded body 100. The mold device 10 can be used for injection molding. The manufacturing method of the resin molded body 100 in this embodiment may be a manufacturing method using injection molding.

[0016] When the mold apparatus 10 is clamped, the space enclosed by the first mold 11 and the second mold 12 becomes the cavity 16. In Figure 3, a connecting portion 17 is formed between the first mold 11 and the second mold 12, connecting the injection hole 15 and the cavity 16. By providing the connecting portion 17, the possibility of the first release film 13 reaching the cavity 16 when injecting the molding material 20 can be reduced. As shown in Figure 3, the second release film 14 may be in a state where it is adsorbed to the second mold 12. The first release film 13 may be in a state where it is adsorbed to the first mold 11.

[0017] The first mold 11 includes a metal material. The first mold 11 is provided with an injection hole 15. The first mold 11 may be composed of multiple parts. The first mold 11 may be provided with a suction hole for adsorbing the first release film 13. The first mold 11 may have ejector pins.

[0018] The second mold 12 includes a metal material. The second mold 12 may be composed of multiple parts. The second mold 12 may be provided with suction holes for adsorbing the second release film 14. As shown in Figures 2 and 3, the second mold 12 may have ejector pins 18.

[0019] By providing the first release film 13, the resin molded body 100 obtained by curing the molding material 20 can be more easily peeled off the mold device 10 compared to the case where the first mold 11 and the molding material 20 are in direct contact. The first release film 13 is, for example, a film made of resin.

[0020] The first release film 13 is positioned to block the injection hole 15. The first release film 13 is positioned to block the path from the injection hole 15 to the cavity 16. Preferably, the first release film 13 covers at least the entire surface of the first mold 11 that forms the cavity 16. This improves the release properties of the resin molded body 100 from the mold device 10. In addition, preferably, the first release film 13 also covers the entire surface of the first mold 11 that forms the connecting portion 17. This further improves the release properties of the resin molded body 100 from the mold device 10. The first release film 13 may also cover all of the surface of the first mold 11 that faces the second mold 12.

[0021] Furthermore, the portion of the surface of the first mold 11 that forms the cavity 16 and the connecting portion 17 is the portion that defines the cavity 16 and the connecting portion 17. Even though the molding material 20 is in direct contact with the first release film 13, the first release film 13 stretches along the first mold 11 when the molding material 20 is injected, so it can be said that the first mold 11 defines the cavity 16 and the connecting portion 17.

[0022] By providing the second release film 14, the resin molded body 100 obtained by curing the molding material 20 can be more easily peeled off the mold device 10 compared to the case where the second mold 12 and the molding material 20 are in direct contact. The second release film 14 is, for example, a film made of resin.

[0023] The second release film 14 is positioned between the first release film 13 and the second mold 12. Preferably, the second release film 14 covers all of the surface of the second mold 12, at least the portion that forms the cavity 16. This improves the release properties of the resin molded body 100 from the mold device 10. In addition, preferably, the second release film 14 also covers all of the surface of the second mold 12, including the portion that forms the connecting portion 17. This further improves the release properties of the resin molded body 100 from the mold device 10. Note that the portion of the surface of the second mold 12 that forms the cavity 16 and the connecting portion 17 is the portion that defines the cavity 16 and the connecting portion 17. The second release film 14 may also cover all of the surface of the second mold 12 that faces the first mold 11.

[0024] The first release film 13 and the second release film 14 preferably have a tensile elongation at 180°C of 400% or more, and more preferably 600% or more. This makes it easier to stretch the first release film 13 and the second release film 14 along the surfaces of the first mold 11 and the second mold 12. The tensile elongation at 180°C of the first release film 13 and the second release film 14 can be measured in accordance with JIS K 7127. The tensile elongation at 180°C of the first release film 13 and the second release film 14 may be 3000% or less, and may also be 1500% or less. The tensile elongation at 180°C of the first release film 13 and the second release film 14 may also be 1000% or less.

[0025] The tensile elongation at 180°C of the first release film 13 and the second release film 14 may be the same or different. The tensile elongation at 180°C of the first release film 13 may be lower than that of the second release film 14. This makes the first release film 13 easier to tear in step S102. To make the first release film 13 easier to tear in step S102, the first release film 13 may be provided with a tearing notch, such as a cut. If a tearing notch is provided, it is preferable that the size of the tearing notch be smaller than the size of the opening of the injection hole 15 covered by the first release film 13 so that precise alignment is not required. The first release film 13 does not need to be provided with a tearing notch, such as a cut.

[0026] At least one of the first release film 13 and the second release film 14 may have a surface roughness Rz of 50 μm or more. This allows for an increase in the bonding area when the resulting resin molded body 100 is fixed to another member using an adhesive, and an improvement in adhesion can be expected. At least one of the first release film 13 and the second release film 14 may have a surface roughness Rz of 25 μm or less. This allows for an improvement in slipperiness when the resulting resin molded body 100 is inserted into a hole provided in another member.

[0027] The mold device 10 may have a heating element such as a heater. The mold device 10 may also have an orientation magnet. This allows a magnetic field to be applied to the molding material 20. An electromagnet or a permanent magnet can be used as the orientation magnet. When a permanent magnet is used as the orientation magnet, injection molding and magnetic field application are performed simultaneously. The magnitude of the orientation magnetic field can be, for example, 637 kA / m (8 kOe) or more, and 1511 kA / m (19 kOe) or less. The mold device 10 may also have a retaining part, which will be described later.

[0028] (Step of injecting molding material) In step S102, a molding material 20 containing resin is injected from the injection hole 15. As shown in Figure 4, the first release film 13 can be broken by injecting the molding material 20. The molding material 20 that has broken through the first release film 13 is injected between the first release film 13 and the second release film 14. The molding material 20 is pushed out from the injection hole 15 toward the cavity 16. The injection of the molding material 20 may be continued until the cavity 16 is completely filled with the molding material 20.

[0029] It is preferable that the first release film 13 tears in the region including the injection hole 15 and the connecting portion 17. As a result, the torn portion of the first release film 13 is included in the portion of the resin molded body 100 that hardens at the connecting portion 17, so by removing the portion hardened at the connecting portion 17 from the resin molded body 100, the torn portion of the first release film 13 can also be removed. The region including the injection hole 15 and the connecting portion 17 is the region from the entrance of the injection hole 15 to the exit of the connecting portion 17. Since the molding material 20 is extruded from the injection hole 15 toward the connecting portion 17, if the first release film 13 is located at the boundary between the injection hole 15 and the connecting portion 17 before the molding material 20 is injected, the first release film 13 tends to tear at the connecting portion 17. As in the modified example described later, if the first release film 13 is located inside the injection hole 15 before the molding material 20 is injected, the first release film 13 tends to tear at the injection hole 15.

[0030] The resin contained in the molding material 20 is either a thermoplastic resin or a thermosetting resin. Preferably, the resin contained in the molding material 20 is a thermosetting resin. If a thermoplastic resin is used, even if some of the thermoplastic resin remains in the mold device 10 after the resin molded body 100 is removed from the mold device 10, the remaining resin can be easily removed from the mold device 10 by heating. In the case of a thermosetting resin, it does not melt even when heated to the same degree as a thermoplastic resin, making it more difficult to remove the remaining resin from the mold device 10. By using the mold device 10 of this embodiment, the release properties of the resin molded body 100 can be improved, thereby reducing the possibility of residual resin generation. Using a thermosetting resin makes it easier to improve the heat resistance of the resulting resin molded body 100 compared to using a thermoplastic resin. The proportion of thermosetting resin in the total resin of the molding material 20 can exceed 80%, and may be 95% or more. The resin contained in the molding material 20 may consist solely of thermosetting resin.

[0031] Examples of thermosetting resins include epoxy resins, phenolic resins, urea resins, melamine resins, guanamine resins, unsaturated polyesters, vinyl ester resins, diallyl phthalate resins, polyurethane resins, silicone resins, polyimide resins, alkyd resins, furan resins, dicyclopentadiene resins, acrylic resins, and allyl carbonate resins. Epoxy resins are preferred as the thermosetting resin due to their mechanical properties and heat resistance. The thermosetting resin is preferably a liquid at room temperature or a solid that dissolves in a solvent to become liquid. The molding material 20 may contain a curing agent for curing the thermosetting resin.

[0032] The molding material 20 may contain magnetic powder. This allows a bonded magnet to be obtained as the resin molded body 100. The magnetic powder may be ferromagnetic. The resin molded body 100 may be a permanent magnet. When the molding material 20 contains magnetic powder, the residual resin is attracted to the first mold 11 and / or the second mold 12 by magnetic force, making it more difficult to remove the residual resin from the mold device 10 compared to when the molding material 20 does not contain magnetic powder. By using the mold device 10 of this embodiment, the release properties of the resin molded body 100 can be improved, thereby reducing the possibility of residual resin generation.

[0033] Examples of magnetic powders include rare earth magnetic powders such as SmFeN-based, NdFeB-based, and SmCo-based powders. The magnetic powder may be SmFeN-based magnetic powder. In this case, the resin molded body 100 has a resin and SmFeN-based magnetic powder. SmFeN-based magnetic powders have the general formula Sm ｘ Fe １００－ｘ－ｙ N ｙ Examples include nitrides composed of rare earth metal Sm, iron Fe, and nitrogen N, represented by [formula]. Preferably, x is 8.1 atomic% or more and 10 atomic% or less, y is 13.5 atomic% or more and 13.9 atomic% or less, and the remainder is mainly Fe. The magnetic powder is Th ２ Zn １７ The magnetic powder may be an SmFeN-based magnetic powder having a crystalline structure of a certain type. The magnetic powder may be an anisotropic SmFeN-based magnetic powder. The SmFeN-based magnetic powder can be manufactured, for example, by the method disclosed in Japanese Patent Application Publication No. 11-189811. The magnetic powder may have an SmFeN-based core and a coating containing P and O. The magnetic powder may be surface-treated with a silane coupling agent or the like.

[0034] The filling rate of magnetic powder in the resin molded body 100 is preferably 50% by volume or more, and more preferably 60% by volume or more. This makes it possible to improve the residual magnetic flux density of the resin molded body 100 when the resin molded body 100 is a magnet.

[0035] When obtaining a resin molded body 100 as a magnet with oriented magnetic powder, an orientation magnetic field is applied to the molding material 20 in step S102 and / or step S103. The application of the orientation magnetic field is started at least before the molding material 20 has completely solidified. By applying a magnetic field to the molding material 20, the easy magnetization axes of the magnetic powder contained in the molding material 20 can be aligned. Since the mold device 10 has an orientation magnet, the mold device 10 can apply a magnetic field to the molding material 20.

[0036] (Curing process) In step S103, the molding material 20 is cured. By curing the molding material 20, a resin molded body 100 can be obtained. If the molding material 20 contains a thermosetting resin, it can be cured by heating. Heat can be transferred to the molding material 20 by heating the first mold 11 and the second mold 12 with a heating element such as a heater. Curing may be started after the injection of the molding material 20 is completed, or it may be started during the injection process.

[0037] (Step to remove the resin molded body) After the curing step S103, the cured resin molded body 100 is removed from the first mold 11 and the second mold 12. As shown in Figure 5, the resin molded body 100 may be removed from the second mold 12 by pressing it with an ejector pin 18. The pressing with the ejector pin 18 may be done while separating the second release film 14 from the second mold 12. As a result, as shown in Figure 5, the second release film 14 partially separates from the resin molded body 100. The entire second release film 14 may also separate from the resin molded body 100. If the first mold 11 has an ejector pin, the resin molded body 100 may be pressed using the ejector pin of the first mold 11.

[0038] Figures 6A and 6B show an example of the resin molded body 100. After removing the resin molded body 100 from the first mold 11 and the second mold 12, a portion of the resin molded body 100 may be removed. An example of the resin molded body 100 in this case is shown in Figure 6C. If there is a connecting portion 17, it is preferable to remove the portion of the resin molded body 100 that is molded at the connecting portion 17. This is because a portion of the first release film 13 may remain in this portion.

[0039] If the resin molded body 100 is a magnet, a magnetization step may be performed after the step of removing the resin molded body 100 from the first mold 11 and the second mold 12. In the magnetization step, a magnetic field for magnetization is applied to the resin molded body 100. Examples of magnetization methods include a pulsed magnetic field generation method or a static magnetic field generation method. The magnitude of the magnetic field for magnetization in the magnetization step can be, for example, 1990 kA / m (25 kOe) or more, and 4777 kA / m (60 kOe) or less. The magnetic field for magnetization in the magnetization step can be greater than the magnetic field for orientation described above.

[0040] (Modified Version) A modified version will be explained using Figures 7 to 12. Figures 7 to 11 are schematic enlarged sections illustrating the modified version. Figure 12 is a schematic perspective view showing the retaining part.

[0041] The modified mold device 10 has a retaining component 30. The retaining component 30 is positioned between the first release film 13 and the second release film 14. The retaining component 30 prevents the first release film 13 from separating from the first mold 11 when the molding material 20 tears through the first release film 13. The molding material 20 is injected through the injection hole 15. By having the retaining component 30 in the mold device 10, the possibility of the molding material 20 being injected between the first release film 13 and the first mold 11 can be reduced. This can further improve the release properties of the resin molded body 100. The retaining component 30 preventing the first release film 13 from separating from the first mold 11 means that the degree to which it separates from the first mold 11 is reduced compared to when the retaining component 30 is not provided.

[0042] As shown in FIG. 7, it is preferable that the first mold 11 has a stepped portion 40 provided at the outlet of the injection hole 15. Thereby, as shown in FIG. 8, the pressing component 30 can be disposed on the stepped portion 40. By disposing the pressing component 30 on the stepped portion 40, a part of the first release film 13 can be disposed in the injection hole 15. Also in FIG. 8, the first release film 13 is disposed so as to block the injection hole 15. The first release film 13 is sandwiched between the pressing component 30 and the first mold 11.

[0043] As shown in FIG. 9, it is preferable that the second mold 12 has a portion that suppresses the pressing component 30 from separating from the first mold 11 when the molding material 20 breaks the first release film 13. Thereby, in the mold-closed state, the movement of the pressing component 30 can be suppressed by the second mold 12, and in the mold-open state, the pressing component 30 can be easily attached and detached. In the mold-closed state shown in FIG. 9, at least a part of the pressing component 30 is sandwiched between the first mold 11 and the second mold 12.

[0044] As shown in FIG. 10, the shape and arrangement of the pressing component 30 can be such that the pressing component 30 does not deviate from the suppression of the second mold 12 when the molding material 20 is injected. The first release film 13 may be broken by the injection of the molding material 20, and a part of it may adhere to the pressing component 30. When the first release film 13 is sandwiched between the pressing component 30 and the molding material 20, the pressing component 30 can be easily removed from the cured resin molded body 100.

[0045] As shown in FIG. 11, the resin molded body 100 may be taken out of the mold device 10 in a state where the pressing component 30 is attached to the resin molded body 100. In this case, after taking out from the mold device 10, it is preferable to remove the portion including the pressing component 30 from the resin molded body 100.

[0046] As shown in Figure 12, the shape of the retaining part 30 is preferably annular. This makes it possible to suppress the movement of the retaining part 30 even if only a part of the retaining part 30 is sandwiched between the first mold 11 and the second mold 12 in the mold clamping state. The shape of the retaining part 30 may be annular. In this case, the stepped portion 40 may also be annular.

[0047] Embodiments may include the following configurations: (1) A method for manufacturing a resin molded article, comprising the steps of: preparing a mold apparatus having a first mold provided with an injection hole, a second mold forming a cavity connected to the injection hole between the first mold and the first mold, a first release film positioned to close the injection hole, and a second release film positioned between the first release film and the second mold; injecting a molding material containing resin from the injection hole, breaking the first release film with the molding material, and injecting the molding material between the first release film and the second release film; and curing the molding material. (2) The method for manufacturing a resin molded article according to claim 1, wherein the mold apparatus has a retaining component positioned between the first release film and the second release film to prevent the first release film from separating from the first mold when the molding material breaks the first release film. (3) The method for manufacturing a resin molded article according to item 2, wherein the first mold has a stepped portion at the outlet of the injection hole, and the retaining component is positioned on the stepped portion. (4) The method for manufacturing a resin molded article according to item 2 or 3, wherein the second mold has a portion that prevents the retaining component from separating from the first mold when the molding material breaks the first release film. (5) The method for manufacturing a resin molded article according to any one of items 1 to 4, wherein a connecting portion is formed between the first mold and the second mold, connecting the injection hole and the cavity, and the first release film breaks in the region including the injection hole and the connecting portion. (6) The method for manufacturing a resin molded article according to any one of items 1 to 5, wherein the first release film and the second release film have a tensile break elongation of 400% or more at 180°C. (Clause 7) The method for manufacturing a resin molded article according to any one of Clauses 1 to 6, wherein at least one of the first release film and the second release film has a surface roughness Rz of 50 μm or more. (Clause 8) The method for manufacturing a resin molded article according to any one of Clauses 1 to 7, wherein the resin contained in the molding material is a thermosetting resin. (Clause 9) The method for manufacturing a resin molded article according to any one of Clauses 1 to 8, wherein the molding material contains magnetic powder.(Item 10) A mold apparatus comprising: a first mold provided with an injection hole; a second mold forming a cavity connected to the injection hole between itself and the first mold; a first release film positioned to close the injection hole; and a second release film positioned between the first release film and the second mold. (Item 11) The mold apparatus according to item 10, further comprising a retaining component positioned between the first release film and the second release film to prevent the first release film from separating from the first mold when the molding material injected from the injection hole breaks the first release film.

[0048] 10 Mold apparatus 11 First mold 12 Second mold 13 First release film 14 Second release film 15 Injection hole 16 Cavity 17 Connecting part 18 Ejector pin 20 Molding material 30 Retaining part 40 Stepped part 100 Resin molded body

Claims

1. A method for manufacturing a resin molded article, comprising the steps of: preparing a mold apparatus having a first mold provided with an injection hole, a second mold forming a cavity connected to the injection hole between the first mold and the second mold, a first release film positioned to close the injection hole, and a second release film positioned between the first release film and the second mold; injecting a molding material containing resin through the injection hole, rupturing the first release film with the molding material, and injecting the molding material between the first release film and the second release film; and curing the molding material.

2. The method for manufacturing a resin molded article according to claim 1, wherein the mold apparatus has a retaining component disposed between the first release film and the second release film, which prevents the first release film from separating from the first mold when the molding material tears the first release film.

3. The method for manufacturing a resin molded article according to claim 2, wherein the first mold has a stepped portion at the outlet of the injection hole, and the retaining component is positioned on the stepped portion.

4. The method for manufacturing a resin molded article according to claim 2 or 3, wherein the second mold has a portion that prevents the retaining component from separating from the first mold when the molding material breaks the first release film.

5. A connecting portion is formed between the first mold and the second mold, connecting the injection hole and the cavity, and the first release film tears in the region including the injection hole and the connecting portion, the method for manufacturing a resin molded article according to any one of claims 1 to 4.

6. The method for manufacturing a resin molded article according to any one of claims 1 to 5, wherein the first release film and the second release film have a tensile elongation at 180°C of 400% or more.

7. A method for manufacturing a resin molded article according to any one of claims 1 to 6, wherein at least one of the first release film and the second release film has a surface roughness Rz of 50 μm or more.

8. The method for producing a resin molded article according to any one of claims 1 to 7, wherein the resin contained in the molding material is a thermosetting resin.

9. A method for producing a resin molded article according to any one of claims 1 to 8, wherein the molding material includes magnetic powder.

10. A mold apparatus comprising: a first mold provided with an injection hole; a second mold forming a cavity connected to the injection hole between itself and the first mold; a first release film positioned to close the injection hole; and a second release film positioned between the first release film and the second mold.

11. The mold apparatus according to claim 10, further comprising a retaining component positioned between the first release film and the second release film, which prevents the first release film from separating from the first mold when the molding material injected from the injection hole breaks the first release film.

Images