Method for manufacturing two-color molded products

Abstract

To provide a manufacturing method that ensures the quality of two-color molded products by suppressing residual strain and defects such as short shots and sink marks during two-color molding, while efficiently removing excess material.SOLUTION: According to the present invention, there is provided a method for manufacturing a two-color molded product including a first step, a second step, and a third step. In the first step, a first resin is injected into a first cavity formed between a first mold and a second mold by clamping the first mold and the second mold to form a first resin layer. In the second step, a second resin is injected into a second cavity formed between the first resin layer and a third mold by clamping the first mold and the third mold, and into a resin escape portion communicating therewith, to form a second resin layer and a surplus resin portion connected thereto. In the third step, when the first mold and the third mold are opened, the second resin layer and the surplus resin portion are separated, thereby providing a method for manufacturing a two-color molded product.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for producing a two-color molded article. [Background technology]

[0002] Patent Document 1 discloses a method for improving the quality of two-color molded products by providing a protrusion in a position that does not affect the design or performance of the two-color molded product to allow the resin and gas generated from the resin to escape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-280082 Summary of the Invention [Problem to be solved by the invention]

[0004] In two-color molding, a large holding pressure is sometimes maintained after the resin is injected to prevent short shots and sink marks. However, depending on the shape of the two-color molded product, a large holding pressure can cause residual stress or strain, resulting in undesired deformation of the two-color molded product. One way to avoid such deformation is to reduce the resin injection pressure or pressure dwell, but this increases the likelihood of defects such as short shots and sink marks occurring.

[0005] In the two-color molded product of Patent Document 1, a portion for excess resin to escape (hereinafter referred to as a resin escape portion) is provided in a position that does not affect the design or performance of the two-color molded product, but depending on the shape of the two-color molded product and the mold, it may be difficult to provide a resin escape portion in such a position.

[0006] In such cases, a process is required to remove the excess material formed in the resin recess from the two-color molded product, reducing the number of steps and efficiently removing the two-color material while maintaining quality. color The problem was that it was difficult to produce molded products.

[0007] The present invention has been made in view of the above circumstances, and aims to suppress the occurrence of defects such as short shots and sink marks in two-color molding and to efficiently remove excess material, thereby achieving two-color molding. color The present invention provides a manufacturing method that can ensure the quality of molded products. [Means for solving the problem]

[0008] According to the present invention, The following [1] to [8] are provided. [1] A method for manufacturing a two-color molded product including a first step, a second step, and a third step, wherein in the first step, a first resin is poured into a first cavity formed between a first mold and a second mold by clamping the first mold and the second mold to form a first resin layer, in the second step, a second resin is poured into a second cavity formed between the first resin layer and the third mold by clamping the first mold and the third mold and into a resin escape portion communicating therewith to form a second resin layer and a waste portion connected thereto, and in the third step, the second resin layer and the waste portion are separated when the first mold and the third mold are opened. [2] A method for manufacturing a two-color molded product according to [1], wherein in the third step, a first ejector pin that pushes out the two-color molded product and a second ejector pin that pushes out the wasted material portion are displaced at different times, thereby separating the second resin layer from the wasted material portion. [3] A method for manufacturing a two-color molded product according to [2], wherein the waste material portion has a connection portion, a waste material main body, and a pin abutment portion, the first resin layer has a groove-shaped second resin outflow gate formed on its peripheral gate forming surface, the connection portion is disposed between the waste material main body and an outflow gate portion formed by the second resin filled in the second resin outflow gate, the pin abutment portion is connected to the waste material main body and abuts against the second ejector pin, and the second resin layer and the waste material portion are separated at the connection portion. [4] A method for manufacturing a two-color molded product including a first step and a second step, wherein in the first step, a first resin is poured into a first cavity formed between a first mold and a second mold by clamping the first mold and the second mold to form a first resin layer, and in the second step, a second resin is poured into a second cavity formed between the first resin layer and the third mold by clamping the first mold and the third mold and into a resin escape portion communicating therewith to form a second resin layer and a waste portion connected to the second resin layer, the waste portion having a connecting portion and a waste portion main body, a groove-shaped second resin outflow gate is formed in the first resin layer on the gate forming surface of the periphery thereof, the connecting portion is disposed between the outflow gate portion formed by the second resin filled in the second resin outflow gate and the waste portion main body, and the second resin layer and the waste portion are separated at the connecting portion. [5] The method for producing a two-color molded article according to any one of [1] to [4], wherein the second resin is a soft material that is softer than the first resin. [6] A method for producing a two-color molded product according to [3] or [4], wherein a groove-shaped second resin inflow gate is formed in the first resin layer at a position different from the second resin outflow gate on the gate formation surface, and the second resin fills the second resin inflow gate and the second resin outflow gate so as to be flush with the gate formation surface, thereby forming an inflow gate portion and The aforementioned A method for manufacturing a two-color molded product in which an outflow gate portion is formed. [7] A method for manufacturing a two-color molded product according to [3] or [4], wherein a flange portion is arranged on the periphery of the first resin layer so as to intersect with the first resin layer, and the gate formation surface is formed on the surface of the flange portion. [8][ 6

[0023] The method for manufacturing a two-color molded product according to the present invention is characterized in that the outflow gate portion is located on the periphery of the second resin layer and is located at a position on the periphery of the second resin layer that is farthest from the inflow gate portion in a linear distance along the second resin layer. [Effects of the Invention]

[0009] According to the present invention, the occurrence of defects such as residual distortion in two-color molding, short shots, and sink marks can be suppressed, and excess material can be efficiently removed, thereby achieving two-color molding. color It is possible to ensure the quality of the molded product. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a two-color molded product 1 (a pull handle for an automobile) molded by the manufacturing method of the present invention. [Figure 2] FIG. 2 is a perspective view showing the first resin layer 2 and the second resin layer 3 of the two-color molded product 1. As shown in FIG. [Figure 3] FIG. 3 is a side view of the first mold 20 and the second mold 21 clamped together in the first step of the method for producing the two-color molded article 1. As shown in FIG. [Figure 4] 4A is a cross-sectional view taken along line AA in FIG. 3, FIG. 4B is a cross-sectional view taken along line BB in FIG. 3, and FIG. 4C is a cross-sectional view taken along line CC in FIG. [Figure 5] FIG. 5 is a side view of the first mold 20 and the third mold 25 clamped together in the second step of the method for producing the two-color molded article 1. As shown in FIG. [Figure 6] 6A is a cross-sectional view taken along the line DD in FIG. 5, and FIG. 6B is a cross-sectional view taken along the line EE in FIG. [Figure 7] 7 is a cross-sectional view showing the two-color molded article 1 released from the mold in the third step of the manufacturing method of the two-color molded article 1 and the waste material portion 50 separated from the two-color molded article 1 along the EE cross section of FIG. [Figure 8] Figure 8A is an oblique view showing the second resin inflow gate 10 and the second resin outflow gate 11 formed in the first resin layer 2, and Figures 8B and 8C are enlarged views of areas B and C shown in Figure 8A, respectively. [Figure 9]Figure 9A is an oblique view showing the inflow gate portion 13 and the outflow gate portion 14 formed by filling the second resin inflow gate 10 and the second resin outflow gate 11 with resin, respectively, and Figures 9B and 9C are enlarged views of area B and area C shown in Figure 9A, respectively. [Figure 10] FIG. 10A is a perspective view showing the waste material portion 50 and its surroundings before being separated from the two-color molded product 1, and FIG. 10B is a plan view showing the waste material portion 50 and the outflow gate portion 14. [Figure 11] 11A is a side view showing the wasted portion 50 from the direction of the pin contact portion 53, and FIG. 11B is a cross-sectional view of the wasted portion 50 and the second ejector pin 41 taken along the line FF in FIG. 11A. [Figure 12] FIG. 12 is a perspective view showing a method for measuring the linear distance from the inflow gate portion 13 to the outflow gate portion 14 along the surface of the second resin layer 3. As shown in FIG. [Figure 13] Figure 13A is an oblique view showing a modified example in which the connection portion 51 of the wasted portion 50 has a shape that narrows inward from its upper and lower edges, Figure 13B is an oblique view showing a modified example in which the connection portion 51 of the wasted portion 50 has a shape that narrows from its upper edge to its lower edge, Figure 13C is a plan view showing a modified example in which the thickness t1 of the connection portion 51 of the wasted portion 50 is smaller than the thickness t2 of the outflow gate portion 14, Figure 13D is an oblique view showing a modified example in which the connection portion 51 of the wasted portion 50 has a notched groove on one side, and Figure 13E is an oblique view showing a modified example in which the connection portion 51 of the wasted portion 50 has multiple holes penetrating in the thickness direction. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently.

[0012] An embodiment of a two-color molded article 1 and a method for manufacturing the same will be described in detail below with reference to Figures 1 to 13. In this embodiment, the two-color molded article 1 is applied as a pull handle for an automobile.

[0013] FIG. 1 shows a perspective view of an automobile pull handle molded by two-color molding. As shown in FIG. 1, the two-color molded product 1 includes a first resin layer 2 and a second resin layer 3. The first resin layer 2 (particularly the portion in contact with the second resin layer 3) and the second resin layer 3 have a concave shape in plan view, and the second resin layer 3 is laminated on the concave surface of the first resin layer 2. The "concave shape" refers to the shape obtained by molding the upright wall portion 5 (excluding the upper flange portion 6 and the side flange portion 7) of the first resin layer 2 and the upright wall portion 12 (excluding the inlet gate portion 13 and the outlet gate portion 14) of the second resin layer 3 along the concave shape of the first mold 20, as seen in the cross-sectional view of FIG. 7. However, since this shape is also formed along the convex shape of the third mold 25, it can also be called a "convex shape." The "concave shape" or "convex shape" does not have to be a rectangle with rounded corners as shown in FIG. 7 and may be another shape, such as a trapezoid, and the corners may not be rounded.

[0014] As shown in Fig. 2, the first resin layer 2 includes a bottom 4, a standing wall 5, an upper flange 6, a side flange 7, a bottom flange 8, a hole 9, a second resin inflow gate 10, and a second resin outflow gate 11. The standing wall 5 is formed along the periphery of the bottom 4 so as to rise up relative to the bottom 4. An upper flange 6 is formed on the upper edge of the standing wall 5, and side flanges 7 are formed on the side edges of the standing wall 5. A bottom flange 8 is formed on the periphery of the bottom 4 where the standing wall 5 is not formed.

[0015] The top flange 6, the side flange 7, and the bottom flange 8 are arranged so as to intersect with the standing wall 5. In this embodiment, the angle at which the top flange 6, the side flange 7, and the bottom flange 8 intersect with the standing wall 5 is 90 degrees, but they may intersect at an angle other than 90 degrees. The angle is preferably 60 to 120 degrees, and more preferably 80 to 100 degrees. Specific examples of the angle include 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, and 120 degrees, and may be within a range between any two of the values ​​exemplified here.

[0016] The second resin inflow gate 10 and the second resin outflow gate 11 are respectively formed on the surfaces of the upper flange portion 6 and the side flange portion 7. Furthermore, the second resin inflow gate 10 and the second resin outflow gate 11 are formed so as to connect, i.e., penetrate, the front surface (concave surface) and the rear surface (convex surface) of the first resin layer 2.

[0017] The holes 9 are fastening holes for attaching the two-color molded article 1 to another structure (e.g., the interior of an automobile), and in the embodiment shown in Figures 1 and 2, two holes 9 are formed in each of the left and right side flange portions 7. However, the positions and number of holes 9 are not limited to this, and one or more holes may be formed at any position in the top flange portion 6, the side flange portions 7, and the bottom flange portion 8. Furthermore, the holes 9 are preferably formed when resin is poured into the first cavity 30 described below and the resin hardens to form the first resin layer 2, but the holes 9 may also be formed by drilling or the like after the first resin layer 2 has been formed by resin hardening.

[0018] 2, the second resin layer 3 includes a standing wall portion 12, an outflow gate portion 14, and an inflow gate portion 13. The inflow gate portion 13 is formed by filling a second resin inflow gate 10 with resin near the center of the upper edge of the standing wall portion 12. The outflow gate portion 14 is formed by filling a second resin outflow gate 11 with resin at the bottom of one side edge of the standing wall portion 12. Thus, both the inflow gate portion 13 and the outflow gate portion 14 are formed to protrude from the standing wall portion 12 in the direction from the front surface (concave surface) of the second resin layer 3 toward the rear surface (convex surface).

[0019] The first resin layer 2 and the second resin layer 3 are formed of thermoplastic resin. The first resin layer 2 is formed of, for example, a polyolefin such as polypropylene, and the second resin layer 3 is formed of a resin that is softer than the resin of the first resin layer 2, for example, an elastomer. The elastomer may be, for example, a styrene-based thermoplastic elastomer or an olefin-based thermoplastic elastomer.

[0020] Here, the term "soft" as used in this specification and claims refers to a mechanical property determined relatively by comparing the rigidity of a material, for example, its tensile modulus (also called Young's modulus). For example, if the tensile modulus of the first resin layer 2 is 1 GPa and the tensile modulus of the second resin layer 3 is 100 MPa, the second resin layer 3 is considered to be softer than the first resin layer 2. The tensile modulus values ​​of the first resin layer 2 and the second resin layer 3 are those measured in accordance with JIS K 7161-1:2014 after they are cured.

[0021] 1 and 2, the upper surface of the bottom portion 4 of the first resin layer 2 and the front surface of the second resin layer 3, i.e., the concave surface of the standing wall portion 12, are the design surfaces of the two-color molded product 1 and are the parts that an operator recognizes visually and tactilely. When the two-color molded product 1 is attached to another structure (e.g., an automobile door), the operator can close the door by touching the inside of their finger to the front surface of the second resin layer 3 and pulling it toward themselves, i.e., in the direction in which the inlet gate portion 13 protrudes from the standing wall portion 12 of the second resin layer 3.

[0022] The front surfaces of the side flange portion 7 and the bottom flange portion 8 of the first resin layer 2 and the front surface of the outflow gate portion 14 of the second resin layer 3, i.e., the surfaces that can be seen in Figures 1 and 2, are surfaces that are not visible to an operator when the two-color molded article 1 is attached to another structure (e.g., an automobile door) through the hole 9. Furthermore, the front surfaces of the top flange portion 6 of the first resin layer 2 and the inflow gate portion 13 of the second resin layer 3, i.e., the surfaces that can be seen in Figures 1 and 2, are also covered by the automobile interior and therefore not visible to an operator. By being located on such non-design surfaces, the inflow gate portion 13 and the outflow gate portion 14 are configured to be isolated from the operator's sight and touch when the two-color molded article 1 is attached to another structure and the structure is in a usable state.

[0023] The non-design surface is a surface of the two-color molded product 1 that cannot be directly seen or touched by the user when the two-color molded product 1 is actually used. For example, in the case of a pull handle for an automobile, the surfaces of the inlet gate portion 13 and the outlet gate portion 14 can be seen directly in Figures 1 and 2, but when the pull handle is attached to the automobile door and covered with the interior, that is, when the automobile is actually in a state suitable for use by the automobile passengers, they cannot be seen or touched, and therefore can be said to belong to the non-design surface.

[0024] Next, a method for producing the two-color molded article 1 will be described.

[0025] Fig. 3 is a side view showing a state in which the first mold 20 and the second mold 21 are clamped. As shown in Fig. 3, the first mold 20 is a fixed mold that is fixed to an injection molding machine, and the second mold 21 is a movable mold that moves in the direction of arrow X1 in Fig. 3 when clamping and opening the mold. Resin is injected through a predetermined pipe line 22 of the second mold 21.

[0026] 4A to 4C are cross-sectional views of the clamped first mold 20 and second mold 21 taken along cross sections A-A, B-B, and C-C in Fig. 3, respectively. These figures show the first step of producing the two-color molded article 1.

[0027] 4A is a cross-sectional view including a protrusion 23 that is a part of a second mold 21 for forming a groove penetrating the concave and convex surfaces of the first resin layer 2 on the upper edge of the first resin layer 2. The groove forms a second resin inflow gate 10 for pouring the second resin after the first mold 20 and the third mold 25, which will be described later, are clamped together.

[0028] Figure 4B shows a first cavity 30 formed between the first mold 20 and the second mold 21 by clamping the first mold 20 and the second mold 21, and a first resin layer 2 is formed by pouring a first resin into the first cavity 30.

[0029] 4C is a cross-sectional view including a step portion 24 that is part of a second mold 21 for forming a groove that penetrates the concave and convex surfaces of the first resin layer 2 in the lower part of one side edge of the first resin layer 2. The groove forms a second resin outflow gate 11 for pouring the second resin into a resin escape portion 32 after the first mold 20 and the third mold 25, which will be described later, are clamped together. When the first mold 20 and the second mold 21 are clamped together, the resin escape portion 32 is isolated from the first cavity 30, so that the first resin does not flow into the resin escape portion 32. FIG. 4C shows a state in which a second ejector pin 41, which will be described later, is inserted into the resin escape portion 32.

[0030] 5, in the second step of producing the two-color molded article 1, the first mold 20 and the third mold 25 are clamped together, and the second resin is poured into the mold through a predetermined pipe 26 to form the second resin layer 3. The first mold 20 is fixed, and the third mold 25 is movable in the direction of arrow X2 in FIG. 5 during clamping and opening.

[0031] 6A and 6B are cross-sectional views of the clamped first mold 20 and third mold 25 taken along cross sections DD and EE of FIG. 5, respectively.

[0032] As shown in Figure 6A, a second cavity 31 is formed between the first resin layer 2 and the third mold 25, and the second resin passes through the second resin inlet gate 10 to fill the second cavity 31, i.e., the space between the third mold 25 and the concave surface of the first resin layer 2, thereby laminating the second resin layer 3.

[0033] As shown in Figure 6B, the second resin is formed at the bottom of one side edge of the first resin layer 2 and is poured into a resin escape portion 32 that communicates with the second cavity 31 through a second resin outflow gate 11 that penetrates the convex and concave surfaces of the first resin layer 2, thereby forming a waste portion 50 connected to the second resin layer 3.

[0034] In this embodiment, the "periphery" of the first resin layer 2 refers to the top flange 6, side flange 7, and bottom flange 8 shown in Fig. 2 and the like, and the "top edge" and "side edge" of the first resin layer 2 refer to the top flange 6 and side flange 7, respectively. Furthermore, the "periphery" of the second resin layer 3 refers to the edges of the second resin layer 3 along the top flange 6, side flange 7, and bottom flange 8, and the "top edge" and "side edge" of the second resin layer 3 refer to the edges of the second resin layer 3 along the top flange 6 and side flange 7, respectively.

[0035] The injection pressure of the second resin when pouring it into the second cavity 31 and the resin relief portion 32 and the dwell pressure after pouring are low so as not to generate residual stress or residual strain in the first resin layer 2. These pressures are preferably 0.00 MPa to 1.00 MPa, more preferably 0.00 MPa to 0.10 MPa, in gauge pressure, i.e., based on atmospheric pressure. Specific examples of the pressure include 0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, and 1.00 MPa, and may be within a range between any two of the values ​​exemplified here.

[0036] 7, in the third step of manufacturing the two-color molded article 1, when the first mold 20 and the third mold 25 are opened, the second resin layer 3 is separated from the wasted material portion 50, thereby removing the wasted material portion 50 from the two-color molded article 1 and completing the manufacturing of the two-color molded article 1. Specifically, the first ejector pin 40 that pushes out the two-color molded article 1 and the second ejector pin 41 that pushes out the wasted material portion 50 are displaced at different times, thereby separating the second resin layer 3 from the wasted material portion 50.

[0037] When the first ejector pin 40 and the second ejector pin 41 are displaced at different times, the wasted material portion 50 is bent and / or pulled at the connecting portion 51 (described later) to separate and be removed from the two-color molded article 1. In other words, due to the time difference between the release of the two-color molded article 1 and the release of the wasted material portion 50, the wasted material portion 50 is automatically removed from the two-color molded article 1.

[0038] 8A to 8C, a groove-shaped second resin inflow gate 10 is formed on the peripheral gate formation surface of the first resin layer 2. The gate formation surface refers to the peripheral surface of the first resin layer 2 that comes into contact with the second mold 21 when the mold is clamped. Furthermore, a groove-shaped second resin outflow gate 11 is formed on the gate formation surface of the first resin layer 2 at a position different from the second resin inflow gate 10.

[0039] 9A to 9C, the second resin is filled into the second resin inflow gate 10 and the second resin outflow gate 11 so that they are flush with the gate formation surface, thereby forming the inflow gate portion 13 and the outflow gate portion 14. Having the surfaces of the inflow gate portion 13 and the outflow gate portion 14 flush with the gate formation surface makes it easy to attach the two-color molded article 1 to another structure (e.g., an automobile door), and also makes it easy to cover the two-color molded article 1 with another member (e.g., an automobile interior).

[0040] 10A and 10B are respectively a perspective view showing the wasted material portion 50 in a state where it has not been separated from the two-color molded product 1, and a plan view showing the wasted material portion 50 integrally with the outflow gate portion 14. In these figures, each portion of the outflow gate portion 14 and the wasted material portion 50 is shown in a different color.

[0041] 10A , the washer portion 50 has a connection portion 51, a washer main body 52, and a pin abutment portion 53. The connection portion 51 is disposed between the washer main body 52 and the outflow gate portion 14 formed by the second resin filled in the second resin outflow gate 11, and the pin abutment portion 53 is connected to the washer main body 52 and abuts against the second ejector pin 41. In the third step, the second resin layer 3 and the washer portion 50 are separated at the connection portion 51.

[0042] 10B, the connecting portion 51 is formed in a plate shape, and its thickness t is preferably 0.50 mm to 2.00 mm (1.00 mm in this embodiment), and more preferably 0.80 mm to 1.50 mm. Specific examples of the thickness t include 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, and 2.00 mm, and may be within a range between any two of the values ​​exemplified here.

[0043] If the thickness t of the connection portion 51 is less than 0.50 mm, it becomes difficult to pour the resin into the resin escape portion 32 through the second resin outflow gate 11, and if it is greater than 2.00 mm, it becomes difficult to separate the wasted material portion 50 at the connection portion 51. If the thickness t is within the above range, the wasted material portion 50 is easily formed and also easily removed from the two-color molded product 1.

[0044] The thickness t of the connection portion 51 is the shortest straight-line distance connecting its front and rear surfaces, and the front surface of the connection portion 51 is the surface that comes into contact with the third mold 25 when the molds are closed, and the rear surface of the connection portion 51 is the surface that comes into contact with the first mold 20 and is located on the opposite side of the front surface.

[0045] 10B, the length d of the connection portion 51, i.e., the shortest linear distance connecting the outflow gate portion 14 and the dead wall main body 52, is preferably 0.50 mm to 5.00 mm (3.00 mm in this embodiment), and more preferably 1.50 mm to 4.00 mm. Specifically, the length d may be, for example, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 2.00, 2.10, 2.20, 2.30, 2.40, 2.50, 2.60, 2.70, 2.80, 2.90 , 3.00, 3.10, 3.20, 3.30, 3.40, 3.50, 3.60, 3.70, 3.80, 3.90, 4.00, 4.10, 4.20, 4.30, 4.40, 4.50, 4.60, 4.70, 4.80, 4.90, 5.00 mm, and may be within a range between any two of the numerical values ​​exemplified here. This prevents the connection portion 51 from remaining in the two-color molded article 1 when the excess thickness portion 50 is separated from the two-color molded article 1.

[0046] 11A and 11B are a side view of the wasted portion 50 as seen from the pin abutment portion 53 side and a cross-sectional view of the wasted portion 50 and the second ejector pin 41 along the section F-F shown in the side view, respectively.

[0047] As shown in FIGS. 11A and 11B, the pin contact portion 53 is formed in a hollow cylindrical shape, and the inner peripheral surface of the hollow cylinder contacts the outer peripheral surface of the second ejector pin 41.

[0048] As described above, the gate formation surface of the first resin layer 2 and the surfaces of the inlet gate portion 13 and the outlet gate portion 14 that are on the same plane as the gate formation surface are non-design surfaces. In other words, the inlet gate portion 13 and the outlet gate portion 14 are positioned so that they do not come into contact with the operator's visual or tactile senses when the two-color molded article 1 is attached to another structure (e.g., an automobile) and the structure is in a state suitable for use by the operator.

[0049] The outflow gate 14 is located on the periphery of the second resin layer 3 and is located at a position farthest from the inflow gate 13 in terms of the linear distance along the second resin layer 3 compared to any other position on the periphery of the second resin layer 3. That is, the length of the shortest line drawn along the surface of the second resin layer 3 from the inflow gate 13 to the outflow gate 14 is longer than the length of the shortest line drawn along the surface of the second resin layer 3 from the inflow gate 13 to any other position on the periphery of the second resin layer 3 other than the outflow gate 14. More specifically, as shown in FIG. 12 , the linear distance is determined by the length of the longer of the two shortest lines L12 and L13 drawn along the surface of the second resin layer 3 from a center point P1 of the inflow gate 13 on the periphery of the second resin layer 3 to two end points P2 and P3 of the outflow gate 14 on the periphery of the second resin layer 3. In the example of FIG. 12 , the length of line L13 is determined as the linear distance.

[0050] In this way, since the outflow gate portion 14 is located at the farthest position from the inflow gate portion 13 on the periphery of the second resin layer 3 in terms of the straight-line distance along the second resin layer 3, when the second resin is poured from the second resin inflow gate 10 into the second cavity 31, the position at which the resin reaches the longest distance from the second resin inflow gate 10 becomes the second resin outflow gate 11, so that sink marks and short shots can be concentrated in the wasted portion 50, and the occurrence of sink marks and short shots in other places in the second cavity 31 can be suppressed.

[0051] Although the embodiments have been described above, the technical ideas of the present disclosure can also be adopted in the following aspects.

[0052] In the above-described embodiment, the connecting portion 51 of the wasted portion 50 has a plate-like shape. However, the connecting portion 51 may have a shape as shown in FIGS. 13A to 13E by modifying the shape of the third mold 25 at the position where the resin escape portion 32 is formed so that the wasted portion 50 can be easily separated from the two-color molded product 1. The connecting portion 51 of the wasted portion 50 shown in FIG. 13A has a shape that narrows from its upper and lower edges toward the inside. The connecting portion 51 of the wasted portion 50 shown in FIG. 13B has a shape that narrows from its upper edge toward its lower edge. The thickness t1 of the connecting portion 51 of the wasted portion 50 shown in FIG. 13C is smaller than the thickness t2 of the outflow gate portion 14. The connecting portion 51 of the wasted portion 50 shown in FIG. 13D has a notched groove 54 on its front surface. Similar grooves may be provided on the rear surface or both surfaces of the connecting portion 51. The connecting portion 51 of the wasted portion 50 shown in FIG. 13E has multiple holes 55 penetrating from its front surface to its rear surface. The number of holes may be one.

[0053] In the above-described embodiment, the pin abutment portion 53 of the wasted portion 50 has a hollow cylindrical shape as shown in Fig. 11B, but it may have a shape other than a circle, for example, a polygonal shape, or may be solid. Furthermore, the wasted portion 50 may be provided with a plurality of pin abutment portions 53.

[0054] In the above-described embodiment, only one set of second resin inflow gate 10 and inflow gate portion 13 is provided, but multiple sets of second resin inflow gate 10 and inflow gate portion 13 may be provided. However, it is preferable that all of the second resin inflow gates 10 and inflow gate portions 13 are located on non-design surfaces, for example, on the gate-forming surface of the first resin layer 2. Furthermore, while the second resin inflow gate 10 is a groove having a rectangular cross-sectional shape, it may have a cross-sectional shape other than a rectangle, for example, a polygon such as a triangle or a pentagon, a semicircle, or a combination thereof. The above can also be applied to the second resin outflow gate 11 and outflow gate portion 14.

[0055] In the above-described embodiment, the two-color molded article 1 is released from the mold before the waste material portion 50, and the waste material portion 50 is automatically removed from the two-color molded article 1 due to the time difference between the release of the two-color molded article 1 and the release of the waste material portion 50. However, the waste material portion 50 may be released from the mold before the two-color molded article 1, so that the waste material portion 50 is automatically removed from the two-color molded article 1. Furthermore, the waste material portion 50 may be separated from the two-color molded article 1 after the two-color molded article 1 is removed from the first mold 20.

[0056] In the above-described embodiment, there is one each of the first ejector pin 40 and the second ejector pin 41, but in other embodiments, there may be a plurality of each of the first ejector pin 40 and the second ejector pin 41.

[0057] The present invention is particularly useful when the second resin layer 3, which is a soft material, is located on the concave side of the first resin layer 2, as in the shape of the two-color molded article 1 in the above-described embodiment, or more specifically when the vertical wall portion 5 of the first resin layer 2 and the vertical wall portion 12 of the second resin layer 3 have a concave general configuration in a plan view of the two-color molded article 1, as shown in Fig. 7, and a member such as a bottom 4 is provided only on either the upper or lower edge of the vertical wall portion 5, i.e., a member formed on the concave side of the first resin layer 2 and installed so as to intersect with that edge. However, the present invention can achieve the same effect in other cases, for example, even when the bottom 4 is not provided on either the upper or lower edge of the vertical wall portion 5. [Explanation of symbols]

[0058] 1: Two-color molded product 2: First resin layer 3: Second resin layer 4: Bottom 5: Vertical wall 6: Upper flange 7: Side flange 8: Bottom flange 9: Hole 10: Second resin inflow gate 11: Second resin outflow gate 12: Vertical wall 13: Inlet gate 14: Outlet gate 20: First mold 21: Second mold 22: Pipeline 23:Protrusion 24 :Double part 25: Third mold 26: Conduit 30: First cavity 31: Second cavity 32: Resin relief area 40: First ejector pin 41: Second ejector pin 50: Bad meat club 51: Connection part 52: Bad meat body 53: Pin contact part 54: Groove 55: Hole L12: line L13: line P1: Center point P2: End point P3: End point X1: Arrow X2: Arrow t: thickness t1: thickness t2: Thickness

Claims

1. A method for producing a two-color molded article including a first step, a second step, and a third step, In the first step, a first resin is poured into a first cavity formed between a first mold and a second mold by clamping the first mold and the second mold to form a first resin layer; In the second step, a second resin is poured into a second cavity formed between the first resin layer and the third mold by clamping the first mold and the third mold, and into a resin escape portion communicating therewith, to form the second resin layer and a reduced-thickness portion connected thereto; In the third step, the second resin layer is separated from the wasted portion when the first mold and the third mold are opened.

2. The method for producing the two-color molded product according to claim 1, In the third step, a first ejector pin that pushes out the two-color molded product and a second ejector pin that pushes out the wasted material portion are displaced at different times, thereby separating the second resin layer from the wasted material portion.

3. The method for producing a two-color molded product according to claim 2, The dead-wall portion has a connection portion, a dead-wall main body, and a pin abutment portion, a groove-shaped second resin outflow gate is formed in a gate formation surface of the periphery of the first resin layer; The connection portion is disposed between the outflow gate portion formed by the second resin filled in the second resin outflow gate and the waste wall body, the pin abutment portion is connected to the waste body and abuts against the second ejector pin, A method for manufacturing a two-color molded product, wherein the second resin layer and the excess thickness portion are separated at the connection portion.

4. A method for producing a two-color molded product including a first step and a second step, In the first step, a first resin is poured into a first cavity formed between a first mold and a second mold by clamping the first mold and the second mold to form a first resin layer; In the second step, a second resin is poured into a second cavity formed between the first resin layer and the third mold by clamping the first mold and the third mold, and into a resin escape portion communicating therewith, to form the second resin layer and a reduced-thickness portion connected thereto; The dead wall portion has a connection portion and a dead wall main body, a groove-shaped second resin outflow gate is formed in a gate formation surface of the periphery of the first resin layer; The connection portion is disposed between the outflow gate portion formed by the second resin filled in the second resin outflow gate and the waste wall body, A method for manufacturing a two-color molded product, wherein the second resin layer and the excess thickness portion are separated at the connection portion.

5. The method for producing a two-color molded article according to any one of claims 1 to 4, A method for manufacturing a two-color molded product, wherein the second resin is a soft material that is softer than the first resin.

6. The method for producing a two-color molded product according to claim 3 or 4, a groove-shaped second resin inflow gate is formed in the gate formation surface of the first resin layer at a position different from the second resin outflow gate, A method for manufacturing a two-color molded product, wherein the inflow gate portion and the outflow gate portion are formed by filling the second resin into the second resin inflow gate and the second resin outflow gate, respectively, so that they are flush with the gate formation surface.

7. The method for producing a two-color molded product according to claim 3 or 4, A method for manufacturing a two-color molded product, in which a flange portion is arranged on the periphery of the first resin layer so as to intersect with the first resin layer, and the gate formation surface is formed on the surface of the flange portion.

8. The method for producing a two-color molded product according to claim 3 or 4, a method for manufacturing a two-color molded product, wherein the outflow gate portion is located on the periphery of the second resin layer and is located at a position on the periphery of the second resin layer that is farthest from the inflow gate portion in a linear distance along the second resin layer.

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