Molded articles and methods for manufacturing molded articles

Abstract

This invention provides a technology that can suppress the entry of molten resin between the mold and the decorative sheet during decorative molding. [Solution] The molded product 100 comprises a decorative sheet 10 and a resin part 20. The resin part 20 is manufactured by injection molding with the decorative sheet 10 inserted into a mold. The resin part 20 is plate-shaped with a surface 21 and a back surface 22. The decorative sheet 10 covers a portion of the surface 21 of the resin part 20. The back surface 22 of the resin part 20 has a gate mark 23 and a raised portion 24. The gate mark 23 is located in a region of the resin part 20 that does not overlap with the decorative sheet 10 in the thickness direction. The raised portion 24 is located in a region that overlaps in the thickness direction with the edge portion 11 of the decorative sheet 10 on the gate mark 23 side. During injection molding, molten resin flows along the raised portion 24. This prevents molten resin from entering between the mold and the decorative sheet 10.

Description

Technical Field

[0001] The present disclosure relates to a molded article and a method for manufacturing the molded article.

Background Art

[0002] Conventionally, a decorative molding technique is known in which injection molding is performed with a decorative sheet inserted in a mold, thereby decorating the surface of a molded article with the decorative sheet. A conventional decorative molding technique is described in, for example, Patent Document 1. In Patent Document 1, a decorative sheet is arranged on a part of the molding surface of a mold. Thereby, a molded article is produced in which a part of the surface of the molding resin is covered with the decorative sheet, and the other part of the surface of the molding resin is exposed from the decorative sheet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a decorative sheet is arranged on a part of the molding surface of a mold as in Patent Document 1, part of the molten resin flowing along the molding surface of the mold may enter between the mold and the decorative sheet. As a result, the surface of the decorative sheet of the manufactured molded article is partially covered with the resin, and the aesthetic appearance of the molded article is impaired.

[0005] Accordingly, an object of the present disclosure is to provide a technique capable of suppressing entry of molten resin between a mold and a decorative sheet in decorative molding.

Means for Solving the Problems

[0006] This disclosure relates to a molded article comprising one or more decorative sheets and a resin part manufactured by injection molding with the one or more decorative sheets inserted in a mold, wherein the resin part is plate-shaped having a front surface and a back surface, the decorative sheet covers a portion of the front surface, and the back surface has a gate mark located in a region that does not overlap with a first decorative sheet included in the one or more decorative sheets in the thickness direction of the resin part, and a raised portion located in a region that overlaps with the gate mark side edge of the first decorative sheet in the thickness direction.

[0007] In a cross-section including the gate mark and the raised portion, the raised portion has a first inclined surface located on the gate mark side and a second inclined surface located on the opposite side of the gate mark. When considering a circle centered on the surface of the resin portion at a position closer to the gate mark than the edge of the first decorative sheet on the gate mark side, it is desirable that the circle in contact with the first inclined surface is larger than the circle in contact with the hypothetical back surface when the thickness of the resin portion is designed to be constant.

[0008] In a cross-section including the gate mark and the raised portion, the raised portion has a first inclined surface located on the gate mark side and a second inclined surface located on the opposite side of the gate mark. When considering a circle centered on the position where the edge portion of the first decorative sheet on the gate mark side is located on the surface of the resin portion, it is desirable that the second inclined surface is in contact with a circle larger than the circle tangent to the hypothetical back surface when the thickness of the resin portion is designed to be constant.

[0009] In a cross-section including the gate mark and the raised portion, the raised portion has a first inclined surface located on the gate mark side and a second inclined surface located on the opposite side of the gate mark, and it is desirable that the angle of the first inclined surface with respect to a hypothetical back surface when the thickness of the resin portion is designed to be constant is greater than the angle of the second inclined surface with respect to the hypothetical back surface.

[0010] The one or more decorative sheets include the first decorative sheet and a second decorative sheet separate from the first decorative sheet, and the gate marks may be located in a region that overlaps with the second decorative sheet in the thickness direction.

[0011] The back surface of the resin portion may have a plurality of gate marks, and the raised portion may be located in a region that overlaps in the thickness direction with the edge of the decorative sheet on the gate mark closest to the decorative sheet among the plurality of gate marks.

[0012] Furthermore, this disclosure relates to a method for manufacturing a molded product, comprising the steps of a) inserting a decorative sheet into a cavity in a mold, and d) filling the cavity with molten resin and curing it to form a plate-shaped resin portion having a front surface and a back surface, and fixing the decorative sheet to a portion of the surface of the resin portion, wherein the mold comprises a first mold for forming the front surface of the resin portion and a second mold for forming the back surface of the resin portion, and the second mold has a gate located in the thickness direction of the resin portion in a region that does not overlap with the first decorative sheet included in the one or more decorative sheets, and a recessed portion located in a region that overlaps with the gate-side edge of the first decorative sheet in the thickness direction. [Effects of the Invention]

[0013] According to this disclosure, during injection molding, molten resin flows along the recessed portion (protruding portion after molding) of the mold. This prevents molten resin from entering the space between the mold and the first decorative sheet. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view of a molded product. [Figure 2] This is a perspective view of a molded product. [Figure 3] This is a cross-sectional view of the molded product. [Figure 4] This is a flowchart showing the manufacturing procedure for molded products. [Figure 5] This diagram shows the heating process during the shaping of the decorative sheet. [Figure 6] This is a diagram showing the state of forming during shaping of a decorative sheet. [Figure 7] This is a diagram showing the state of trimming after shaping of a decorative sheet. [Figure 8] This is a diagram showing the state of inserting a decorative sheet into a mold. [Figure 9] This is a diagram showing the state of mold clamping of the mold. [Figure 10] This is a diagram showing the state of filling the molten resin into the mold. [Figure 11] This is a diagram showing the state of releasing the molded product from the mold. [Figure 12] This is a diagram partially showing the flow of molten resin during injection molding. [Figure 13] This is a partial cross-sectional view of a molded product manufactured by injection molding. [Figure 14] This is a partial cross-sectional view of a molded product showing variations in the shape of raised portions. [Figure 15] This is a partial cross-sectional view of a molded product showing variations in the shape of raised portions. [Figure 16] This is a diagram showing the state of injection molding when two decorative sheets are provided. [Mode for Carrying Out the Invention]

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that in each drawing of the present disclosure, the dimensions of each part may be depicted in an exaggerated manner for ease of understanding.

[0016] <1. Configuration of Molded Product> Figure 1 and Figure 2 are perspective views of a molded product 100 according to an embodiment. Figure 3 is a cross-sectional view of the molded product 100. This molded product 100 is a resin product partially decorated with a decorative sheet 10. The molded product 100 is used, for example, as an exterior panel of an automobile. However, the molded product 100 may also be used for automobile interiors or applications other than automobiles.

[0017] As shown in Figures 1 to 3, the molded product 100 has a decorative sheet 10 and a resin part 20. The decorative sheet 10 in this embodiment is an example of the "first decorative sheet" in the present invention. When manufacturing the molded product 100, the decorative sheet 10 is inserted into the mold, and molten resin is injected into the mold. The resin part 20 is then molded by curing the resin in the mold. The decorative sheet 10 is fixed to the surface of the resin when the resin hardens in the mold. The detailed manufacturing procedure of the molded product 100 will be described later.

[0018] As shown in Figures 1 to 3, the resin part 20 of this embodiment is a bent thin plate. The resin part 20 has a surface 21 and a back surface 22. The decorative sheet 10 covers a portion of the surface 21 of the resin part 20. That is, the surface 21 of the resin part 20 has a portion covered by the decorative sheet 10 and a portion exposed from the decorative sheet 10. By making the portion covered by the decorative sheet 10 and the portion exposed from the decorative sheet 10 into a single molded product 100 rather than separate molded products, the number of molded parts can be reduced. In addition, the number of injection molding steps in the manufacturing process can be reduced.

[0019] The decorative sheet 10 is composed of multiple layers, including a backer layer, a design layer, and a top layer. The backer layer is a resin base film. The backer layer plays a role in maintaining the shape of the decorative sheet 10. The design layer is a layer of ink for adding decorations such as patterns and colors to the molded product 100. The top layer is a transparent film that covers the surface of the design layer. The patterns and colors of the design layer are visible from the outside through the top layer.

[0020] Furthermore, the surface of the top layer may have fine irregularities to create a matte texture. Also, the layer structure of the decorative sheet 10 is not limited to the example described above.

[0021] As shown in Figures 2 and 3, the resin part 20 has a gate mark 23. The gate mark 23 is the trace of a gate provided in the mold. During injection molding, molten resin is injected from this gate in the mold. The gate mark 23 is located on the back surface 22 of the resin part 20. Furthermore, the gate mark 23 is located in a region of the resin part 20 in the thickness direction that does not overlap with the decorative sheet 10.

[0022] Furthermore, as shown in Figures 2 and 3, the resin portion 20 has a raised portion 24. The raised portion 24 is a projection provided on the back surface 22 of the resin portion 20. The raised portion 24 is located in the region of the back surface 22 that overlaps in the thickness direction with the edge portion of the decorative sheet 10 on the gate mark 23 side. In the region other than the raised portion 24, the thickness of the resin portion 20 is approximately constant, but the thickness of the resin portion 20 at the location of the raised portion 24 is greater than the thickness of other parts of the resin portion 20.

[0023] <2. Manufacturing method of molded products> Next, a method for manufacturing the molded product 100 having the decorative sheet 10 described above will be explained. Figure 4 is a flowchart showing the manufacturing procedure for the molded product 100. Figures 5 to 11 show the process of manufacturing the molded product 100.

[0024] When manufacturing the molded product 100, first, a flat decorative sheet 10 is shaped into a three-dimensional shape (step S1). In step S1, first, as shown in Figure 5, the decorative sheet 10 is heated by a heater 90. This softens the decorative sheet 10. Next, as shown in Figure 6, the decorative sheet 10 is shaped into a predetermined shape by vacuum forming or pressure forming. After that, as shown in Figure 7, the unnecessary portion of the outer periphery of the shaped decorative sheet 10 is trimmed by a cutter 80.

[0025] Next, the shaped decorative sheet 10 is inserted into the mold 70 (step S2). As shown in Figure 8, the mold 70 has a first mold 71 and a second mold 72. The first mold 71 is a mold for molding the surface 21 of the resin part 20. The second mold 72 is a mold for molding the back surface 22 of the resin part 20. The decorative sheet 10 is placed in a portion of the concave surface 711 that forms the cavity 73 of the first mold 71. The concave surface 711 of the first mold 71 is provided with a plurality of suction holes, which are not shown. The decorative sheet 10 is adsorbed to the concave surface 711 by the negative pressure generated in the plurality of suction holes.

[0026] After the decorative sheet 10 is placed on the concave surface 711 of the first mold 71, the first mold 71 and the second mold 72 are clamped together as shown in Figure 9. This creates a cavity 73 between the first mold 71 and the second mold 72. The decorative sheet 10 is then inserted into the cavity 73 inside the mold 70.

[0027] In this state, as shown in Figure 10, molten resin is injected into the cavity 73 in the mold 70 (step S3). The second mold 72 has a gate 74 which serves as the supply port for the molten resin. The gate 74 is a hole provided on the molding surface of the second mold 72. In step S3, molten resin is injected from the gate 74 into the cavity 73. The cavity 73 is then filled with molten resin.

[0028] Subsequently, the molten resin filled in the cavity 73 is cured (step S4). This forms a resin part 20 having a shape corresponding to the cavity 73. At this time, the first mold 71 forms the surface 21 of the resin part 20. The second mold 72 forms the back surface 22 of the resin part 20. The decorative sheet 10 is fixed to the surface 21 of the resin part 20 when the resin hardens in the mold 70.

[0029] After the resin has hardened, the first mold 71 and the second mold 72 are opened as shown in Figure 11, and the molded product 100 is released from the mold 70 (step S5). This yields a molded product 100 with a decorative sheet 10 and a resin part 20.

[0030] <3. Preventing resin from penetrating the surface of the decorative sheet> Figure 12 is a diagram partially showing the flow of molten resin during injection molding. The gate 74 of the second mold 72 is located in a region that does not overlap with the decorative sheet 10 in the thickness direction of the resin part 20. Therefore, as shown in Figure 12, a flow of molten resin occurs from the gate 74 toward the decorative sheet 10 during injection molding. If a portion of this molten resin enters the space between the decorative sheet 10 and the first mold 71, the surface of the decorative sheet 10 will be partially covered with resin. This may impair the aesthetic appearance of the molded product 100.

[0031] Therefore, the mold 70 of this embodiment has a structure for suppressing the penetration of resin into the surface of the decorative sheet 10 as described above. Specifically, a recessed portion 722 is provided on the molding surface of the second mold 72. The recessed portion 722 is a concave shape for controlling the flow of molten resin. The recessed portion 722 is located in the region of the molding surface of the second mold 72 that faces the edge portion of the decorative sheet 10 on the gate 74 side (hereinafter referred to as the "upstream edge portion 11"). That is, the recessed portion 722 is located in the region of the molding surface of the second mold 72 that overlaps with the upstream edge portion 11 of the decorative sheet 10 in the thickness direction of the resin portion 20. Furthermore, the recessed portion 722 is recessed in a direction away from the upstream edge portion 11 of the decorative sheet 10.

[0032] This recessed portion 722 creates a flow in which the molten resin bulges toward the second mold 72 near the upstream edge 11 of the decorative sheet 10, as shown by the solid arrow in Figure 12. In other words, as a portion of the molten resin flows along the recessed portion 722, the proportion of molten resin flowing away from the upstream edge 11 of the decorative sheet 10 increases. As a result, the flow of molten resin toward the upstream edge 11 of the decorative sheet 10 (the flow indicated by the dashed arrow in Figure 12) is weakened. Consequently, it is possible to suppress the entry of molten resin between the decorative sheet 10 and the first mold 71.

[0033] Figure 13 is a partial cross-sectional view of a molded product 100 manufactured by injection molding. Figure 13 shows a cross-section including a gate mark 23 and a raised portion 24. Due to the recessed portion 722, a raised portion 24 is formed on the back surface 22 of the resin portion 20. The raised portion 24 protrudes away from the upstream edge 11 in the region of the back surface 22 of the resin portion 20 that overlaps with the upstream edge 11 of the decorative sheet 10 in the thickness direction of the resin portion 20. Since the raised portion 24 is formed only on the back surface 22 of the resin portion 20, it does not affect the aesthetic appearance of the front surface of the molded product 100.

[0034] As shown in Figure 13, the surface of the raised portion 24 has a top 240, a first inclined surface 241, and a second inclined surface 242. The top 240 is the portion of the surface of the raised portion 24 that is furthest in the thickness direction from the upstream edge 11 of the decorative sheet 10. The first inclined surface 241 is the surface of the raised portion 24 that is located on the gate mark 23 side of the top 240. The second inclined surface 242 is the surface of the raised portion 24 that is located on the opposite side of the gate mark 23 from the top 240.

[0035] Figure 13 shows a hypothetical back surface 22a, represented by a dashed line, when the thickness of the resin part 20 is designed to be constant. In the example in Figure 13, the angle θ1 of the first inclined surface 241 with respect to this hypothetical back surface 22a is greater than the angle θ2 of the second inclined surface 242 with respect to the hypothetical back surface 22a. The recessed portion 722 of the second mold 72 also has a shape corresponding to the first inclined surface 241 and the second inclined surface 242.

[0036] In this way, during injection molding as shown in Figure 12, the direction of the molten resin flow near the upstream edge 11 of the decorative sheet 10 is directed more toward the recessed portion 722. Therefore, the flow of molten resin toward the upstream edge 11 of the decorative sheet 10 (the flow indicated by the dashed arrow in Figure 12) can be further weakened. As a result, the entry of molten resin between the decorative sheet 10 and the first mold 71 can be further suppressed.

[0037] Figures 14 and 15 are partial cross-sectional views of the molded product 100 showing variations in the shape of the raised portion 24. It is desirable that the raised portion 24 starts rising from a position closer to the gate mark 23 than to the upstream edge 11 of the decorative sheet 10. Specifically, as shown in Figure 14, in a cross-section including the gate mark 23 and the raised portion 24, when considering a circle centered at a position O1 on the surface 21 of the resin portion 20 that is closer to the gate mark 23 than to the upstream edge 11 of the decorative sheet 10, it is desirable that a circle C12 larger than the circle C11 tangent to the hypothetical back surface 22a mentioned above be in contact with the first inclined surface 241. This further suppresses the entry of molten resin between the decorative sheet 10 and the first mold 71.

[0038] Furthermore, it is desirable that the raised portion 24 extends beyond the position opposite the upstream edge portion 11 of the decorative sheet 10. Specifically, as shown in Figure 15, in a cross-section including the gate mark 23 and the raised portion 24, when considering a circle centered on the position O2 where the upstream edge portion 11 of the decorative sheet 10 is located on the surface 21 of the resin portion 20, it is desirable that a circle C22 larger than the circle C21 tangent to the hypothetical back surface 22a mentioned above be tangent to the second inclined surface 242. This further suppresses the entry of molten resin between the decorative sheet 10 and the first mold 71.

[0039] <4. Variation> Although one embodiment has been described above, this disclosure is not limited to the above embodiment. Below, several modifications will be described, focusing on the differences from the above embodiment.

[0040] <4-1. First variation> In the above embodiment, the molded product 100 had one decorative sheet 10. However, the molded product 100 may have two or more decorative sheets 10. Figure 16 shows the injection molding process when there are two decorative sheets 10. In the example of Figure 16, a first decorative sheet 10A similar to the decorative sheet 10 in the above embodiment and a second decorative sheet 10B different from the first decorative sheet 10A are inserted into the mold 70.

[0041] In the example shown in Figure 16, the gate 74 of the second mold 72 is located in the region opposite the second decorative sheet 10B. Therefore, in the molded resin part 20, the gate mark 23 is located in the region of the back surface 22 of the resin part 20 that overlaps with the second decorative sheet 10B in the thickness direction of the resin part 20.

[0042] In this case, the molten resin injected from the gate 74 hits the second decorative sheet 10B and flows from the second decorative sheet 10B towards the first decorative sheet 10A. Therefore, it is difficult for molten resin to enter between the second decorative sheet 10B and the first mold 71. Also, similar to the above embodiment, by providing a recess 722 in the second mold 72, it is possible to suppress the entry of resin between the first decorative sheet 10A and the first mold 71.

[0043] <4-2. Second variation> In the above embodiment, the second mold 72 was provided with one gate 74. However, the second mold 72 may have multiple gates 74. That is, the molded resin part 20 may have multiple gate marks 23 on its back surface 22.

[0044] In this case, the molten resin injected from the gate 74 closest to the decorative sheet 10 will first form a flow near the decorative sheet 10. For this reason, it is preferable to provide a recess 722 in the region that overlaps in the thickness direction with the edge of the decorative sheet 10 on the side of the gate 74 closest to the decorative sheet 10. This prevents the molten resin injected from the gate 74 closest to the decorative sheet 10 from entering between the decorative sheet 10 and the first mold 71.

[0045] In other words, the back surface 22 of the molded resin part 20 may have a raised portion 24 in the region that overlaps in the thickness direction with the edge of the decorative sheet 10 on the side of the gate mark 23 closest to the decorative sheet 10 among the multiple gate marks 23.

[0046] <4-3. Other variations> The shape of the recessed portion 722 of the second type 72 is not limited to the shape shown in the above embodiment. That is, the raised portion 24 of the resin portion 20 is not limited to the shape shown in the above embodiment. For example, the raised portion 24 may have an intermediate surface extending parallel to the surface 21 between the first inclined surface 241 and the second inclined surface 242.

[0047] Furthermore, in the above embodiment, the decorative sheet 10 was shaped. However, the decorative sheet 10 may be used without being shaped. That is, "plate-like" in this disclosure includes both bent plate-like and unbent flat plate-like forms.

[0048] Furthermore, the elements appearing in the above embodiments and modifications may be combined or partially deleted to the extent that no inconsistencies arise. In addition, known elements may be added to the configurations appearing in the above embodiments and modifications as appropriate. [Explanation of symbols]

[0049] 10: Decorative sheet 10A: First decorative sheet 10B: Second decorative sheet 11: Upstream edge 20: Resin part 21 :Surface 22: Back side 22a: A hypothetical back surface when the thickness of the resin part is designed to be constant. 23: Gate marks 24: Protuberance 70: Mold 71: Type 1 72: Type 2 73: Cavity 74: Gate 80: Cutter 90: Heater 100: Molded product 240:Top 241: 1st slope 242:Second slope 711: Concave 722: Recessed area

Claims

1. One or more decorative sheets, A resin part manufactured by injection molding with one or more decorative sheets inserted into a mold, A molded article having, The resin part is plate-shaped and has a front surface and a back surface. The decorative sheet covers a portion of the surface, The aforementioned reverse side is, In the thickness direction of the resin portion, a gate mark located in a region that does not overlap with the first decorative sheet included in one or more decorative sheets, The raised portion located in the region where the gate mark side edge of the first decorative sheet overlaps with the thickness direction, A molded product having the following characteristics.

2. In a cross-section including the gate mark and the raised portion, The aforementioned raised portion is, The first inclined surface located on the gate mark side, A second inclined surface located on the opposite side of the gate mark, It has, The molded article according to claim 1, wherein, when considering a circle centered on the surface of the resin portion at a position closer to the gate mark than the edge of the first decorative sheet on the gate mark side, the circle that contacts the first inclined surface is larger than the circle that contacts the hypothetical back surface when the thickness of the resin portion is designed to be constant.

3. In a cross-section including the gate mark and the raised portion, The aforementioned raised portion is, The first inclined surface located on the gate mark side, A second inclined surface located on the opposite side of the gate mark, It has, The molded article according to claim 1 or 2, wherein, when considering a circle centered on the position where the gate-marked edge of the first decorative sheet is located on the surface of the resin portion, the circle that contacts the second inclined surface is larger than the circle that contacts the hypothetical back surface when the thickness of the resin portion is designed to be constant.

4. In a cross-section including the gate mark and the raised portion, The aforementioned raised portion is, The first inclined surface located on the gate mark side, A second inclined surface located on the opposite side of the gate mark, It has, The molded article according to claim 1, wherein the angle of the first inclined surface with respect to a virtual back surface when the thickness of the resin portion is designed to be constant is greater than the angle of the second inclined surface with respect to the virtual back surface.

5. The one or more decorative sheets include the first decorative sheet and a second decorative sheet separate from the first decorative sheet. The molded article according to claim 1, claim 2, or claim 4, wherein the gate mark is located in a region that overlaps with the second decorative sheet in the thickness direction.

6. The back surface of the resin part has multiple gate marks, The molded article according to claim 1, claim 2, or claim 4, wherein the raised portion is located in a region that overlaps in the thickness direction with the edge portion of the decorative sheet on the gate mark closest to the decorative sheet among the plurality of gate marks.

7. A method for manufacturing molded articles, a) A step of inserting a decorative sheet into the cavity inside the mold, d) A step of filling the cavity with molten resin and curing it to form a plate-shaped resin part having a front surface and a back surface, and fixing the decorative sheet to a part of the surface of the resin part, It has, The aforementioned mold is A first mold for molding the surface of the resin part, A second mold for molding the back surface of the resin part, It has, The aforementioned Type 2 is, In the thickness direction of the resin portion, a gate located in a region that does not overlap with the first decorative sheet included in one or more decorative sheets, The recessed portion located in the region where the gate-side edge of the first decorative sheet overlaps with the thickness direction, A manufacturing method having the following characteristics.

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