Resin molded article, method for producing resin molded article, and mold

Abstract

This resin molded article is divided into a first resin molded member forming an exterior design surface, and a second resin molded member that is provided on the back side of the first resin molded member and that has protrusions and / or recesses formed on the back-side surface thereof. The first resin molded member is formed to have a uniform thickness. The back-side surface of the first resin molded member and the front-side surface of the second resin molded member are fused together.

Description

Resin molded product, manufacturing method of resin molded product and mold

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

[0002] In recent years, high-brightness metallic-finish molded products made by injection molding metallic-finish resins containing lustrous materials such as aluminum flakes and pearl powder have been adopted for the exterior design surfaces of home appliances and other products. However, when a molded product with a lustrous surface on the front side and a convex rib on the back side for reinforcement, fitting, etc. is molded from metallic-finish resin, the convex rib changes the flow direction of the resin, causing color defects due to the irregular orientation of the lustrous material on the exterior design surface. Furthermore, even when molding with resins other than metallic-finish resin, it can cause appearance defects such as sink marks and weld lines due to uneven resin flow.

[0003] In order to suppress color defects caused by such irregular orientation of the luster material, Patent Document 1 discloses that the base of the convex rib portion is thinned to suppress the flow of molten resin injected from the gate into the convex rib portion, thereby uniformly orienting the luster material on the exterior design surface in a certain direction and suppressing color defects on the surface of the molded product.

[0004] Patent No. 6334319

[0005] However, the above method requires a mold slide structure to thin the base of the convex rib portion, and the number of mold slide structures increases depending on the number of convex rib portions, which results in a complex mold structure and increased mold costs.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to suppress the occurrence of molding defects such as color defects, weld lines, and sink marks caused by the irregular orientation of the lustrous material on the surface of a molded product when molding a molded product whose plate thickness changes due to convex rib portions, concave recesses, etc. provided on the back side of the exterior design surface.

[0007] In order to achieve the above object, the resin molded product of the present disclosure is divided into a first resin molded member that constitutes the exterior design surface, and a second resin molded member that is provided on the back side of the first resin molded member and has at least one of a convex portion and a concave portion formed on the back side surface, the first resin molded member being configured to have a uniform thickness, and the back side surface of the first resin molded member and the front side surface of the second resin molded member being melt-bonded.

[0008] According to the present disclosure, the molded product is divided into a first resin molded member and a second resin molded member, the first resin molded member is configured to have an even thickness, and the back surface of the first resin molded member and the front surface of the second resin molded member are joined together, thereby suppressing the occurrence of molding defects such as color defects, weld lines, and sink marks due to irregular orientation of the lustrous material on the molded product surface.

[0009] 1A and 1B are perspective views of a molded product according to an embodiment of the present disclosure, where (A) is a perspective view of the exterior design surface of the molded product, and (B) is a perspective view of the back side of the exterior design surface of the molded product; 1C are cross-sectional views of a molded product according to an embodiment of the present disclosure; 1D are exploded perspective views showing the configuration of a molded product according to an embodiment of the present disclosure, where (A) is an exploded perspective view seen from the exterior design surface side, and (B) is an exploded perspective view seen from the back side of the exterior design surface; 1E are views showing the gate position during cover molding; 1F are views showing the state of the mold during base molding according to embodiment 1; 1G are views showing the state of the mold during cover molding according to embodiment 1; 1H are views showing the state of the mold during cover molding according to embodiment 2; 1I are views showing the state of the mold during base molding according to embodiment 2;

[0010] Hereinafter, a molded article and a method for manufacturing a molded article according to an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals.

[0011] (Embodiment 1) Fig. 1 is a perspective view showing a molded product 1 molded by a molded product manufacturing method according to an embodiment of the present disclosure, showing a handle part for a refrigerator as an example. Fig. 1(a) is a perspective view of the molded product 1 as seen from the side of the exterior design surface 2, which is the front side, and Fig. 1(b) is a perspective view of the molded product 1 as seen from the back side of the exterior design surface 2. The molded product 1 is a high-brightness metallic-look resin molded product obtained by injection molding a metallic-look resin containing a lustrous material such as aluminum flakes or pearl powder, and the exterior design surface 2 has a metallic appearance. A convex rib portion 3 is provided on the back side of the exterior design surface 2 for purposes such as reinforcement and fitting.

[0012] Fig. 2 is a cross-sectional view of the molded product 1. Fig. 3 is an exploded perspective view showing the configuration of the molded product 1, with Fig. 3(a) being an exploded perspective view seen from the exterior design surface 2 side, and Fig. 3(b) being an exploded perspective view seen from the back side of the exterior design surface 2. The molded product 1 includes a cover 4, which is a molded product including the exterior design surface 2, and a base 5, which is a molded product including a convex rib portion 3, and the two molded products are joined to form the molded product 1, which is a single member. Note that the molded product 1 is an example of a resin molded product of the present disclosure, the cover 4 is an example of a first resin molded member of the present disclosure, and the base 5 is an example of a second resin molded member of the present disclosure.

[0013] The front side of the cover 4 is the exterior design surface 2, and the back side is the cover joining surface 7 that joins with the base 5. The exterior design surface 2 and the cover joining surface 7 have a nearly flat shape with fewer convex ribs and concave recesses to suppress irregular resin flow during resin filling, thereby minimizing changes in the plate thickness of the cover 4. Generally, when a molded product has convex ribs or concave recesses, the flow of molten resin becomes uneven during resin filling, resulting in weld lines and sink marks due to differences in the thickness and shape of the molded product. In particular, metallic resins containing luster pigments are prone to color defects due to poor orientation of the luster pigment caused by resin flow. Furthermore, resins containing glass fibers in addition to the luster pigment to improve the resin's rigidity are prone to reduced rigidity due to poor orientation of the glass fibers. For these reasons, the exterior design surface 2 and the cover joining surface 7 of the cover 4 have a shape with fewer convex ribs and concave recesses. It is preferable that the cover 4 has a uniform thickness, but "uniform" here means that the variation is less than 20%. Furthermore, the thickness of the cover 4 is set to 0.6 mm or greater, taking into account the fluidity of the resin. If the thickness of the cover 4 is set to less than 0.6 mm, depending on the color tone or transparency of the metallic resin containing the lustrous material, the shape, color tone defects, and molding defects of the underlying base 5 may be visible through the cover 4, raising concerns that the shape, color tone defects, and molding defects of the base 5 may not be concealed. By setting the thickness of the cover 4 to 0.6 mm or greater, the shape, color tone defects, and molding defects of the base 5 are not visible through the cover 4, and the fluidity of the resin during resin filling is also ensured. More preferably, the thickness of the cover 4 is set to greater than 1.0 mm or 2.0 mm, for example.

[0014] 4 shows the position of the gate through which the metallic resin is injected when molding the cover 4. Gate 8 through which the metallic resin is injected when molding the cover 4 is provided in only one location, in the center of the longitudinal side of the cover 4. If gates were provided in multiple locations, the flow of the metallic resin would become too diverse, resulting in color defects due to the orientation of the lustrous material and molding defects due to weld lines.

[0015] Returning to FIG. 3 , the base 5 has a base joining surface 6 on its front side, which joins with the cover joining surface 7 of the cover 4 through laminate molding. The base joining surface 6 has a flat, even shape to prevent color defects caused by irregular orientation of the luster material when the cover 4 is laminate molded in secondary molding. The back surface of the base 5 is provided with a shape that varies the thickness of the base 5, such as a convex rib portion 3 for reinforcement or fitting purposes and a concave recess. Since the base 5 is laminate molded with the cover 4, appearance is not a concern; the thickness is sufficient as long as it is completely filled with the metallic resin and does not cause problems in terms of shape and strength. Similarly, the position and number of gates through which the resin is injected are sufficient as long as it is completely filled with the metallic resin and does not cause problems in terms of shape and strength. In particular, multiple gates allow for diverse flow of the metallic resin.

[0016] When manufacturing the molded article 1 having the above configuration, the cover 4 is laminated by secondary molding onto the primarily molded base 5 using a DSI (Die Slide Injection Molding) molding method. That is, the base 5 and the cover 4 are both molded by injection molding, not by film insert molding, and after the base 5 is molded by injection molding, the cover 4 is injection molded in the same mold. Next, the procedure for manufacturing the molded article 1 by laminate molding using the DSI molding method will be described.

[0017] 5 and 6 show cross-sectional views of a mold 10 for molding the molded product 1. FIG. 5 shows the state of the mold 10 when molding the base 5, and FIG. 6 shows the state of the mold 10 when molding the cover 4. The mold 10 includes a fixed mold 11 and slide molds 12A and 12B. The slide molds 12A and 12B are slidable molds and are slid by a drive mechanism (not shown). The fixed mold 11 has an uneven portion formed in the shape of a portion of the base 5 for molding the base 5. The slide mold 12A has a recess formed in the shape of a portion of the base 5 for molding the base 5, and the slide mold 12B has a recess formed in the shape of a portion of the cover 4 for molding the cover 4. The slide mold 12A is an example of a second slide mold of the present disclosure, and the slide mold 12B is an example of a second slide mold of the present disclosure.

[0018] When molding the molded product 1, first, the slide mold 12A is slid to position the fixed mold 11 and the slide mold 12A as shown in FIG. 5 . In this state, a base molding cavity 13, which is a space for molding the base 5, is formed by the uneven portion provided on the fixed mold 11 and the recessed portion provided on the slide mold 12A, which is shaped like a part of the base 5. The slide mold 12A is formed with a runner 14 that guides molten resin injected from an injection device (not shown). The runner 14 is connected to a gate formed near the base molding cavity 13. The slide mold 12A is clamped against the fixed mold 11. After clamping is completed, the base 5 is injection-molded by injecting metallic resin from the injection device through the runner 14 into the base molding cavity 13 as a primary molding process.

[0019] Once the base 5 has been molded by primary molding, the drive mechanism is driven to slide the slide mold 12A into the slide mold 12B. A recess formed in the shape of part of the cover 4 for molding the cover 4 is formed in the slide mold 12B, adjacent to the recess formed in the shape of part of the base 5. By driving the drive mechanism to slide the slide mold 12B into the slide mold 12B and replacing it, the slide mold 12B is moved to a position where the recess formed in the shape of part of the cover 4 faces the concave-convex portion provided in the fixed mold 11. Figure 6 shows a state where the recess formed in the shape of part of the cover 4 of the slide mold 12B has moved to a position where it faces the concave-convex portion provided in the fixed mold 11.

[0020] The base 5 is formed by primary molding on the uneven portion of the fixed mold 11. In this state, a cover molding cavity 15, which is a space for molding the cover 4, is formed by the base joint surface of the base 5 formed on the uneven portion of the fixed mold 11 and a recess formed in the slide mold 12B that is shaped like part of the cover 4. A runner 16 is formed in the slide mold 12B to guide molten resin injected from an injection device. The runner 16 is connected to a gate formed near the cover molding cavity 15. The slide mold 12B is clamped in contact with the fixed mold 11. After clamping is completed, a metallic resin is injected from the injection device through the runner 16 into the cover molding cavity 15, thereby laminating and molding the cover 4 on the base joint surface of the base 5. The cover 4 is laminated onto the base 5 in a heat-welded state using the molten resin used in the secondary molding. As a result, the interface between the cover 4 and the base 5 is melted and bonded, so that the cover 4 and the base 5 are firmly bonded together to form a single member.

[0021] When the cover 4 is laminated onto the base 5 by secondary molding, the mold 10 is moved and opened, and the laminated molded product 1 is removed from the mold 10. In this way, the molded product 1 is completed.

[0022] According to this embodiment, even when molding a molded product 1 having a convex rib portion 3 made of a metallic resin for reinforcement or fitting purposes, the molded product is divided into a cover 4 that forms the exterior design and a base 5 having the convex rib portion 3 for reinforcement or fitting purposes. By laminating the cover 4 and base 5, a high-brightness metallic molded product can be obtained, suppressing molding defects such as color defects, weld lines, and sink marks due to the orientation of the luster material on the exterior design surface of the cover 4. Furthermore, during secondary molding, the cover joining surface 7 of the cover 4 and the base joining surface 6 of the base 5 are thermally welded together, resulting in a stronger bond between the two parts than would be possible if the two parts were joined by fitting using nails, and eliminating the "squeak" and "squeak noise" that would occur between the two molded products. Furthermore, because the interface between the cover 4 and the base 5 is melted and joined, there is no need to apply a separate adhesive to the interface for bonding. Furthermore, by molding the base 5 in primary molding, there is no need to worry about color defects and molding defects due to the orientation of the luster material, which would result in poor appearance, during molding of the base 5. Therefore, it is possible to reduce injection time, pressure holding time, cooling time, etc. during molding, which leads to cost reduction by shortening the molding cycle.

[0023] In this embodiment, the slide mold 12A for molding the base 5 and the slide mold 12B for molding the cover 4 are alternately replaced with each other for each molding due to the slide structure. At this time, the mold temperatures of the slide mold 12A for the base 5, which does not form the design, and the slide mold 12B for the cover 4, which forms the design, can be set arbitrarily. By increasing the mold temperature of the slide mold 12B higher than that of the slide mold 12A, the mold transferability of the surface of the cover 4, which forms the design, can be improved and gloss can be imparted. For example, the mold temperature of the slide mold 12B for the cover 4, which forms the design, can be increased by 1 to 50°C compared to the typical mold temperature of 30 to 60°C for ABS (Acrylonitrile Butadiene Styrene) resin. This increases the gloss of the design surface of the cover 4 of the molded product 1 and also produces a highly luminous metallic molded product.

[0024] In this embodiment, the same resin material is used to mold the cover 4 and the base 5, but different resin materials may be used to mold them. For example, due to laminate molding, the surface of the cover 4, which forms the exterior design, is visible to the user, but the base 5 is not. Therefore, an unused metallic resin containing a lustrous material is used as the resin material to mold the cover 4. In contrast, since the base 5 is not visible to the user, an inexpensive resin not containing a lustrous material or an environmentally friendly resin such as a recycled resin or biomass plastic is used as the resin material to mold the base 5. This makes it possible to mold using a combination of multiple types of resin materials.

[0025] Specifically, using a two-color molding machine equipped with two injection cylinders that melt and inject resin, in the primary molding, the base 5 is molded from an inexpensive resin that does not contain lustrous materials, or an environmentally friendly resin such as recycled resin or biomass plastic. In the secondary molding, the cover 4 is laminated onto the base 5 using unused metallic resin that contains lustrous materials. This not only reduces manufacturing costs by reducing the amount of unused metallic resin used and using inexpensive resin, but also contributes to the environment by reducing waste resin and utilizing recycled resin.

[0026] In the first embodiment, the base 5 is laminated by being molded as a primary mold and the cover 4 is laminated by being molded as a secondary mold, but in the present embodiment, the molding order is reversed, and the cover 4 is laminated by being molded as a primary mold and the base 5 is laminated by being molded as a secondary mold. Even in this case, a high-brightness metallic molded product can be obtained in which molding defects such as color imperfections due to the orientation of the lustrous material, weld lines, or sink marks are suppressed in the appearance design surface of the cover 4.

[0027] 5 and 6 , in the first embodiment, fixed mold 11 is formed with a concave portion having a shape of a portion of base 5 for molding base 5, slide mold 12A is formed with a recess having a shape of a portion of base 5 for molding base 5, and slide mold 12B is formed with a recess having a shape of a portion of cover 4 for molding cover 4. In contrast, in the present embodiment, mold 20 includes fixed mold 21 and slide molds 22A and 22B, and fixed mold 21 is formed with a recess having a shape of a portion of cover 4 for molding cover 4, slide mold 22A is formed with a recess having a shape of a portion of cover 4 for molding cover 4, and slide mold 22B is formed with a concave portion having a shape of a portion of base 5 for molding base 5. Note that slide mold 22A is an example of a first slide mold of the present disclosure, and slide mold 22B is an example of a second slide mold of the present disclosure.

[0028] When molding the molded product 1, first, the slide mold 22A is slid to position the fixed mold 21 and the slide mold 22A as shown in FIG. 7 . In this state, a recess formed in the fixed mold 21 and a recess formed in the slide mold 22A are shaped like a portion of the cover 4, forming a cover molding cavity 23, which is a space for molding the cover 4. The slide mold 22A is formed with a runner 24 that guides molten resin injected from an injection device (not shown). The runner 24 is connected to a gate formed near the cover molding cavity 23. Then, in the primary molding process, the cover 4 is injection-molded by injecting metallic resin from the injection device through the runner 24 into the cover molding cavity 23.

[0029] Once the cover 4 has been formed by primary molding, the drive mechanism is driven to slide the slide mold 22A into the slide mold 22B. The slide mold 22B has an uneven portion shaped like a part of the base 5 for molding the base 5, adjacent to a recess shaped like a part of the cover 4. By driving the drive mechanism to slide the slide mold 22B into the slide mold 22B and replacing it, the slide mold 22B is moved to a position where the uneven portion shaped like a part of the base 5 faces the recess provided in the fixed mold 21. Figure 8 shows a state in which the uneven portion shaped like a part of the base 5 of the slide mold 22B has moved to a position where it faces the recess provided in the fixed mold 21.

[0030] A primarily molded cover 4 is formed in the recess of the fixed mold 21. In this state, a base molding cavity 25, which is a space for molding the base 5, is formed by the cover joining surface of the cover 4 formed on the recess provided in the fixed mold 21 and the uneven portion shaped like a part of the base 5 provided in the slide mold 22B. A runner 26 is formed in the slide mold 22B to guide molten resin injected from an injection device. The runner 26 is connected to a gate formed near the base molding cavity 25. Then, in the secondary molding process, metallic resin is injected from the injection device through the runner 26 into the base molding cavity 25, thereby laminating and molding the base 5 on the cover joining surface of the cover 4. The base 5 is laminated onto the cover 4 in a heat-welded state by the molten resin of the secondary molding.

[0031] When the base 5 is laminated to the cover 4 by secondary molding, the mold 20 is moved and opened, and the laminated molded product 1 is removed from the mold 20. This completes the molded product 1. In this embodiment, as in the first embodiment, the cover 4 and the base 5 may be molded using different resin materials.

[0032] (Embodiment 3) In the above-described embodiment, for a configuration in which a convex rib portion 3 for reinforcement, fitting, etc. is provided on the back side of a molded product 1, the molded product is divided into a cover 4 that is a molded product including an appearance design surface 2 and a base 5 that is a molded product including the convex rib portion 3, and the two molded products are laminated to form the molded product 1. In contrast, even in cases in which the thickness of the molded product 1 varies partially due to a concave shape, the occurrence of molding defects such as color defects, weld lines, or sink marks due to the orientation of the lustrous material on the appearance design surface 2 of the molded product can be similarly suppressed by using a divided molded product configuration and laminate molding.

[0033] (Embodiment 4) In the above-described embodiment, the molded product 1 is divided into two molded products, the cover 4 and the base 5, and the two molded products are laminate-molded to form the molded product 1. Alternatively, the cover 4, which forms the exterior design surface 2, may be a single molded product, while the base 5 may be divided into multiple molded products. The cover 4, which forms the exterior design surface 2, is formed as a single molded product because it is necessary to prevent molding defects such as color defects, weld lines, or sink marks due to the orientation of the lustrous material in the exterior design surface 2 of the molded product. On the other hand, since the base 5 is laminate-molded with the cover 4, it is possible to divide the base 5 into multiple molded products without having to consider appearance. For example, molds may be provided for each molded product obtained by dividing the base 5 into multiple parts, and the molds for each molded product obtained by dividing the base 5 into multiple parts mounted on a slide mold may be moved relative to the primarily molded cover 4 to sequentially laminate-molde the molded product 1. The divisional structure of the base 5, which is not a design element, can be changed as appropriate in terms of the division locations and number of divisions, and the resin material can be changed for each divisional structure.

[0034] 4, the gate 8 through which resin is injected when molding the cover 4 is located on the long side of the cover 4. However, if there are no problems with the flowability, moldability, quality, etc. of the resin, the gate 8 may be located on the short side of the cover 4. Note that the position and shape of the gate 8 are not limited to those described above and can be changed as appropriate.

[0035] Sixth Embodiment In the above-described embodiment, a molded article 1 having a convex rib portion 3 for the purpose of reinforcement or fitting has been described using a metallic resin. However, this is not limited to metallic resins, and resins that do not contain a luster material may also be used. Similarly to the above-described embodiment, the molded article 1 may be divided into two molded articles, a cover 4 and a base 5, and the two molded articles may be laminated to form the molded article 1. The base 5 may also be further divided into multiple molded articles. This makes it possible to obtain a molded article with a sophisticated, high-quality exterior design that is free of molding defects such as weld lines and sink marks.

[0036] Seventh Embodiment In the above-described embodiment, the molded article 1 is formed by layered molding utilizing the DSI molding method. However, the molded article 1 may be divided into two types of molded articles, the cover 4 and the base 5, which are molded, and then the molded cover 4 and base 5 may be joined by ultrasonic welding, heat welding, or the like to manufacture the molded article 1. Even if the divided cover 4 and base 5 are joined in a later process, a molded article with a sophisticated and high-quality exterior design surface can be obtained, as in the above-described embodiment.

[0037] The present disclosure allows various embodiments and modifications without departing from the broad spirit and scope of the present disclosure. Furthermore, the above-described embodiments are intended to explain the present disclosure and do not limit the scope of the present disclosure. In other words, the scope of the present disclosure is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of equivalent disclosures are considered to be within the scope of the present disclosure.

[0038] This application is based on Japanese Patent Application No. 2023-157437 filed on September 22, 2023. The entire specification, claims, and drawings of Japanese Patent Application No. 2023-157437 are incorporated herein by reference.

[0039] Various aspects of the present disclosure are summarized below as appendices.

[0040] (Appendix 1) A resin molded product divided into a first resin molded member constituting an exterior design surface, and a second resin molded member provided on the back side of the first resin molded member and having at least one of a convex portion and a concave portion formed on the back side surface, wherein the first resin molded member is formed to a uniform thickness, and the back side surface of the first resin molded member and the front side surface of the second resin molded member are fused and joined. (Appendix 2) The resin molded product according to Appendix 1, wherein the exterior design surface and the back side surface of the first resin molded member are free of irregularities. (Appendix 3) The resin molded product according to Appendix 1 or 2, wherein the first resin molded member is formed as a single member, and the second resin molded member is formed by dividing it into a plurality of members. (Appendix 4) The resin molded product according to any one of Appendixes 1 to 3, wherein the thickness of the first resin molded member is 0.6 mm or more. (Appendix 5) The resin molded product according to any one of Appendices 1 to 4, wherein the first resin molded member and the second resin molded member are joined by laminate molding. (Appendix 6) The resin molded product according to Appendices 5, wherein the first resin molded member and the second resin molded member are laminate molded by sliding and interchanging a first slide mold that molds the first resin molded member and a second slide mold that molds the second resin molded member. (Appendix 7) The resin molded product according to Appendices 6, wherein the first resin molded member and the second resin molded member are laminate molded by the first slide mold and the second slide mold that have different mold temperatures. (Appendix 8) The resin molded product according to Appendices 7, wherein the mold temperature of the first slide mold is 1 to 50°C higher than the mold temperature of the second slide mold. (Appendix 9) The resin molded product according to Appendices 8, wherein the mold temperature of the second slide mold is 30 to 60°C. (Appendix 10) The resin molded product according to any one of Appendices 1 to 4, wherein the first resin molded member and the second resin molded member are joined by ultrasonic welding or thermal welding. (Appendix 11) The resin molded product according to any one of Appendices 1 to 10, wherein the first resin molded member and the second resin molded member are molded from different resin materials.(Supplementary Note 12) The resin molded product according to Supplementary Note 11, wherein the first resin molded member is molded from a metallic resin, and the second resin molded member is molded from a recycled resin or a biomass plastic. (Supplementary Note 13) A method for manufacturing a resin molded product by injection molding, comprising: a step of primarily molding a first resin molded member having an appearance design surface and configured to a uniform thickness, and a step of secondary molding a second resin molded member on the first resin molded member, the second resin molded member having a surface on which at least one of a convex portion and a concave portion is formed, and joining a surface opposite to the surface on which at least one of the convex portion and the concave portion is formed to the first resin molded member by melting the interface between the first resin molded member and the second resin molded member. (Appendix 14) A method for manufacturing a resin molded product by injection molding, comprising the steps of: primary molding a second resin molded member having a surface on which at least one of a convex portion and a concave portion is formed; and secondary molding a first resin molded member having an appearance design surface and configured to be uniform in thickness onto the second resin molded member, and joining a surface opposite to the surface on which at least one of the convex portion and the concave portion is formed to the first resin molded member by melting the interface between the first resin molded member and the second resin molded member. (Appendix 15) A method for manufacturing a resin molded product according to Appendix 13 or 14, wherein a gate for injecting resin to mold the first resin molded member is provided at one location on a side wall of the first resin molded member, and resin is injected from the gate to mold the first resin molded member. (Appendix 16) The method for manufacturing a resin molded product according to any one of Appendices 13 to 15, wherein the first resin molded member and the second resin molded member are molded by sliding and interchanging a first slide mold that molds the first resin molded member and a second slide mold that molds the second resin molded member. (Appendix 17) The method for manufacturing a resin molded product according to Appendices 16, wherein the first resin molded member and the second resin molded member are molded by the first slide mold and the second slide mold that have different mold temperatures.(Appendix 18) A method for manufacturing a resin molded product according to Appendix 17, wherein the mold temperature of the first slide mold is set to be 1 to 50°C higher than the mold temperature of the second slide mold. (Appendix 19) A method for manufacturing a resin molded product according to Appendix 18, wherein the mold temperature of the second slide mold is 30 to 60°C. (Appendix 20) A mold for molding the resin molded product according to Appendix 7, comprising a slide structure in which the first slide mold and the second slide mold are alternately switched for each molding, and wherein the mold temperatures of the first slide mold and the second slide mold are set individually. (Appendix 21) A mold according to Appendix 20, wherein the mold temperature of the first slide mold is set to be 1 to 50°C higher than the mold temperature of the second slide mold. (Appendix 22) A mold according to Appendix 21, wherein the mold temperature of the second slide mold is 30 to 60°C.

[0041] The present disclosure can be widely applied to resin molded products in which the front surface is an exterior design surface and the back surface is provided with a convex rib portion for the purpose of reinforcement, fitting, etc.

[0042] 1 Molded product, 2 Appearance design surface, 3 Convex rib portion, 4 Cover, 5 Base, 6 Base joining surface, 7 Cover joining surface, 8 Gate, 10, 20 Mold, 11, 21 Fixed mold, 12A, 12B, 22A, 22B Slide mold, 13, 25 Base molding cavity, 14, 16, 24, 26 Runner, 15, 23 Cover molding cavity.

Claims

1. A resin molded product divided into a first resin molded member that constitutes the exterior design surface, and a second resin molded member that is provided on the back side of the first resin molded member and has at least one of a convex portion and a concave portion formed on the back surface, the first resin molded member being configured with a uniform thickness, and the back surface of the first resin molded member and the front surface of the second resin molded member being fused and joined.

2. The resin molded product according to claim 1, wherein the exterior design surface and the back surface of the first resin molded member are free of irregularities.

3. The resin molded product according to claim 1 or 2, wherein the first resin molded member is composed of a single member, and the second resin molded member is divided into a plurality of members.

4. The resin molded product according to any one of claims 1 to 3, wherein the thickness of the first resin molded member is 0.6 mm or more.

5. The resin molded product according to any one of claims 1 to 4, wherein the first resin molded member and the second resin molded member are joined by lamination molding.

6. The resin molded product according to any one of claims 1 to 4, wherein the first resin molded member and the second resin molded member are joined by ultrasonic welding or thermal welding.

7. The resin molded product according to any one of claims 1 to 6, wherein the first resin molded member and the second resin molded member are molded from different resin materials.

8. The resin molded product according to claim 7, wherein the first resin molded member is molded from a metallic resin, and the second resin molded member is molded from a recycled resin or a biomass plastic.

9. A method for manufacturing a resin molded product by injection molding, comprising the steps of: primarily molding a first resin molded member having an exterior design surface and being configured to be of uniform thickness; secondary molding a second resin molded member having a surface on which at least one of a convex portion and a concave portion is formed onto the first resin molded member, and melting the interface between the first resin molded member and the second resin molded member to join the surface opposite to the surface on which at least one of the convex portion and the concave portion is formed to the first resin molded member.

10. A method for manufacturing a resin molded product by injection molding, comprising the steps of: primarily molding a second resin molded member having a surface on which at least one of a convex portion and a concave portion is formed; secondary molding a first resin molded member having an appearance design surface and configured to be of uniform thickness onto the second resin molded member, and joining the surface opposite to the surface on which at least one of the convex portions and the concave portion is formed to the first resin molded member by melting the interface between the first resin molded member and the second resin molded member.

11. A method for manufacturing a resin molded product as described in claim 9 or 10, wherein a gate for injecting resin to mold the first resin molded part is provided in one location on a side wall of the first resin molded part, and the first resin molded part is molded by injecting resin from the gate.

12. A method for manufacturing a resin molded product described in any one of claims 9 to 11, wherein the first resin molded member and the second resin molded member are molded by sliding and interchanging a first slide mold that molds the first resin molded member and a second slide mold that molds the second resin molded member.

13. The method for manufacturing a resin molded product according to claim 12, wherein the first resin molded member and the second resin molded member are molded by the first slide mold and the second slide mold having different mold temperatures.

14. The method for producing a resin molded product according to claim 13, wherein the mold temperature of the first slide mold is set to be 1 to 50° C. higher than the mold temperature of the second slide mold.

15. The method for manufacturing a resin molded product according to claim 14, wherein the mold temperature of the second slide mold is 30 to 60°C.

16. A mold for molding the resin molded product according to claim 5, comprising a slide structure in which a first slide mold for molding the first resin molded member and a second slide mold for molding the second resin molded member are alternately replaced for each molding, and the mold temperatures of the first slide mold and the second slide mold are set individually.

17. The mold according to claim 16, wherein the mold temperature of the first slide mold is set 1 to 50° C. higher than the mold temperature of the second slide mold.

18. The mold according to claim 17, wherein the mold temperature of the second slide mold is 30 to 60°C.

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