Method for producing resin molded product

Abstract

To provide a method for producing a resin molded product that can prevent a deterioration in design when producing the resin molded product in which a base material and a skin material are made of the same material.SOLUTION: A method for producing a resin molded product includes: a mold closing step in which a first mold 51 and a second mold 61 are closed while a skin material 31 containing polypropylene is disposed between a first molding surface 51A of the first mold 51 and a second molding surface 61A of the second mold 61; and a substrate molding step that is carried out after the mold closing step, in which a temperature of the first molding surface 51A is set to 15°C or higher and 40°C or lower, and molten polypropylene is injected between an other surface 31B of the skin material 31 and the second molding surface 61A while one surface 31A of the skin material 31 is in contact with the first molding surface 51A, thereby molding a substrate 21 integrally with the skin material 31.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The technology disclosed in this specification relates to a method for manufacturing a resin molded product.

Background Art

[0002] Conventionally, as a method for manufacturing a resin molded product, the method described in Patent Document 1 below is known. Patent Document 1 describes a method for manufacturing a resin molded product with high recyclability by configuring a base material and a skin material with the same material, and welding the skin material to the base material by injection molding the skin material in a state where the base material is disposed in a mold. Thereby, the base material and the skin material can be integrated without using an adhesive.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In addition, as a method for manufacturing a resin molded product including a base material and a skin material, a method of integrally molding the base material with the skin material by injecting molten resin onto the surface of the skin material opposite to the design surface in a state where the skin material is disposed in a mold can be considered. This method is suitable when the skin material is made of a fabric, a non-woven fabric, etc. and is difficult to manufacture by injection molding. However, when the base material and the skin material are made of the same material as in the above patent document, when the molten resin (a material in the temperature range where the resin constituting the base material melts) touches the skin material, there is a concern that the design surface melts and the design property deteriorates.

[0005] The technology disclosed in this specification has been completed based on the above circumstances, and an object thereof is to provide a method for manufacturing a resin molded product capable of suppressing a situation in which the design property deteriorates when manufacturing a resin molded product in which a base material and a skin material are made of the same material.

Means for Solving the Problems

[0006] As a means for solving the above problems, the method for manufacturing a resin molded product disclosed in this specification includes a mold closing step of disposing a skin material containing polypropylene between a first molding surface of a first mold and a second molding surface of a second mold and then closing the molds, and a base material molding step that is executed after the mold closing step and that molds a base material integrally with the skin material by injecting molten polypropylene between the other surface of the skin material and the second molding surface while bringing one surface of the skin material into contact with the first molding surface with the temperature of the first molding surface being 15°C or higher and 40°C or lower.

[0007] In the base material molding step, after the molten polypropylene melts the other surface of the skin material, it cools and solidifies, whereby the base material is molded integrally with the skin material. Also, in the base material molding step, the temperature of the first molding surface that contacts one surface of the skin material is 15°C or higher and 40°C or lower. Thereby, by setting the temperature of the first molding surface to 40°C or lower, it is possible to suppress a situation in which one surface of the skin material melts due to the heat of the molten polypropylene, and it is possible to suppress a situation in which the design property deteriorates. Also, by setting the temperature of the first molding surface to 15°C or higher, it is possible to suppress a situation in which the molten polypropylene cools too much and the fluidity decreases, so that the molten polypropylene can be reliably filled between the other surface and the second molding surface. Further, since the skin material and the base material are made of the same material (polypropylene), the resin molded product can be melted and reused without separating the skin material and the base material. Furthermore, polypropylene is suitable because it can suppress a situation in which the strength decreases when melted and reused.

[0008] Further, the skin material can be made of fabric. Since it is possible to suppress the situation where one surface of the skin material melts, the texture unique to the fabric is not impaired.

[0009] Also, the thickness of the skin material can be set to 0.58 mm or more. By setting the thickness of the skin material to 0.58 mm or more, it is possible to more reliably suppress the situation where the heat of the polypropylene injected onto the other surface of the skin material is transmitted to one surface of the skin material.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a method for manufacturing a resin molded product capable of suppressing a situation where the design property deteriorates when manufacturing a resin molded product in which a base material and a skin material are made of the same material.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0012] An embodiment of the present invention will be described with reference to FIGS. 1 to 5. In this embodiment, as a method for manufacturing a resin molded product, a method for manufacturing an ornament provided in a door trim for a vehicle will be exemplified. As shown in FIG. 1, the door trim 10 includes a plate-shaped trim main body 11 (trim board) and an ornament 20 (resin molded product). The trim main body 11 is made of, for example, polypropylene. The trim main body 11 is provided with a speaker grill 12 and an inside handle housing portion 13 for housing the inside handle. Further, the trim main body 11 includes an armrest 14 that bulges toward the vehicle interior side.

[0013] The ornament 20 is provided at a position above the armrest 14 in the trim main body 11. As shown in FIG. 2, the ornament 20 includes a plate-shaped base material 21 and a skin material 31 that covers one surface (the surface on the vehicle interior side) of the base material 21. The base material 21 and the skin material 31 are made of polypropylene. That is, the trim main body 11 and the ornament 20 are made of the same material. The skin material 31 is a fabric, and the thickness of the skin material 31 is set to be 0.58 mm or more. Further, the thickness of the skin material 31 is set to be, for example, a value smaller than the thickness of the base material 21, but is not limited thereto.

[0014] As shown in FIG. 2, the ornament 20 is arranged so as to cover the opening 11A formed in the trim main body 11, and the outer peripheral end portion of the ornament 20 is attached to the attachment boss 15 provided on the vehicle exterior side surface of the trim main body 11 by heat caulking. Note that the ornament 20 may be attached to the trim main body 11 by attachment means such as screwing.

[0015] Next, the molding device 40 for manufacturing the ornament 20 will be described. The molding device 40 in the present embodiment is an injection molding device and includes an injection device 41, a first mold 51, and a second mold 61. The injection device 41 is, for example, of a screw type and is provided in the second mold 61 in the present embodiment. The first mold 51 is configured to be movable relative to the second mold 61 by a driving device (for example, an electric motor, an air cylinder, a hydraulic cylinder, etc.) not shown. By moving the first mold 51 closer to and away from the second mold 61, the first mold 51 and the second mold 61 can be closed and opened.

[0016] The first mold 51 has a first molding surface 51A for molding the design surface of the skin material 31. The first molding surface 51A is the surface of the first mold 51 on the side of the second mold 61 and has a concave shape that opens toward the second mold 61. The second mold 61 has a second molding surface 61A for molding the surface of the base material 21 on the side opposite to the skin material 31. The second molding surface 61A is disposed opposite to the first molding surface 51A and has a shape that protrudes toward the first mold 51.

[0017] In the closed mold state where the first mold 51 and the second mold 61 are closed, as shown in FIG. 4, the first molding surface 51A and the second molding surface 61A are spaced apart from each other by a distance equal to the total thickness of the skin material 31 and the base material 21 and are disposed opposite to each other. That is, in the closed mold state, a base material molding space S1 for molding the base material 21 is formed between the skin material 31 and the second molding surface 61A.

[0018] A resin supply passage 62 is formed inside the second mold 61. One end of the resin supply passage 62 is connected to the injection device 41, and the other end is opened to the side of the first mold 51. Thereby, it is possible to inject molten resin from the injection device 41 into the base material molding space S1 through the resin supply passage 62.

[0019] Inside the first molding die 51, a cooling water supply passage 52 is formed. The cooling water supply passage 52 is provided in a form approaching the first molding surface 51A. A cooling water circulation device 53 for circulating the cooling water is connected to the cooling water supply passage 52. By operating the cooling water circulation device 53, the cooling water can be circulated through the cooling water supply passage 52, and the first molding surface 51A can be cooled. More specifically, by controlling the cooling water circulation device 53 to adjust the circulation amount of the cooling water to the cooling water supply passage 52, the temperature of the first molding surface 51A can be maintained within a predetermined temperature range.

[0020] Next, a method for manufacturing the ornament 20 of the present embodiment will be described. The manufacturing method of the ornament 20 in the present embodiment manufactures the ornament 20 using the molding apparatus 40, and includes a mold closing step and a base material molding step that is executed after the mold closing step and integrally forms the base material 21 with the skin material 31.

[0021] <Mold closing step> In the mold closing step, first, as shown in FIG. 3, one surface 31A of the skin material 31 is arranged in contact with the first molding surface 51A of the first molding die 51. Then, as shown in FIG. 4, while arranging the skin material 31 between the first molding surface 51A and the second molding surface 61A, the first molding die 51 and the second molding die 61 are closed. Note that the molding apparatus 40 may include a vacuum suction device, and one surface 31A of the skin material 31 may be brought into contact with the first molding surface 51A using vacuum suction.

[0022] <Base material molding step> In the base material forming process, as shown in FIG. 5, by operating the cooling water circulation device 53, while the temperature of the first forming surface 51A is set to 15°C or higher and 40°C or lower, with one surface 31A of the skin material 31 in contact with the first forming surface 51A, the molten polypropylene is injected by the injection device 41 through the resin supply path 62 between the other surface 31B of the skin material 31 and the second forming surface 61A (base material forming space S1). As a result, the base material forming space S1 is filled with the molten polypropylene. Also, when the other surface 31B of the skin material 31 touches the molten polypropylene, the polypropylene constituting the other surface 31B melts. Then, the polypropylene filled in the base material forming space S1 is cooled, and the base material 21 is formed integrally with the skin material 31. After that, the first mold 51 and the second mold 61 are opened, and the ornament 20 is demolded. Thereby, the production of the ornament 20 is completed.

[0023] <Ornament Attachment Process> The completed ornament 20 is attached to the trim main body 11 in the ornament attachment process. In the ornament attachment process, as shown in FIG. 2, after inserting the attachment boss 15 into the attachment hole 20A formed at the outer peripheral end of the ornament 20, the tip portion 15A of the attachment boss 15 is melted by hot caulking and fastened to the hole edge portion of the attachment hole 20A. Thereby, the production of the door trim 10 is completed.

[0024] Next, the effects of this embodiment will be described. In the base material forming step, after the molten polypropylene melts the other surface 31B of the skin material 31, it is cooled and solidified, so that the base material 21 is integrally formed with the skin material 31. Further, in the base material forming step, the temperature of the first forming surface 51A that contacts one surface 31A of the skin material 31 is set to 15°C or higher and 40°C or lower. Thereby, by setting the temperature of the first forming surface 51A to 40°C or lower, it is possible to suppress the situation where one surface 31A of the skin material 31 melts due to the heat of the molten polypropylene, and it is possible to suppress the situation where the design property deteriorates. It should be noted that when one surface 31A, which is the design surface of the skin material 31, exceeds 140°C, it has been confirmed that glossiness occurs on the surface and the appearance is impaired. However, by setting the temperature of the first forming surface 51A to 40°C or lower, such a situation can be suppressed.

[0025] Further, by setting the temperature of the first forming surface 51A to 15°C or higher, it is possible to suppress the situation where the molten polypropylene cools too much and the fluidity decreases. Therefore, it is possible to reliably fill the molten polypropylene between the other surface 31B and the second forming surface 61A. Further, since the skin material 31 and the base material 21 are made of the same material (polypropylene), the ornament 20 can be melted and reused without separating the skin material 31 and the base material 21. Furthermore, polypropylene is suitable because it can suppress the situation where the strength decreases when it is melted and reused.

[0026] Also, in this embodiment, the skin material 31 is a fabric. Since it is possible to suppress the situation where one surface 31A of the skin material 31 melts, the texture peculiar to the fabric is not impaired.

[0027] Also, in this embodiment, the thickness of the skin material 31 is set to 0.58 mm or more. By setting the thickness of the skin material 31 to 0.58 mm or more, it is possible to more reliably suppress the situation where the heat of the polypropylene injected onto the other surface 31B of the skin material 31 is transmitted to one surface 31A of the skin material 31.

[0028] In addition, in the present embodiment, since the trim main body 11 and the ornament 20 are made of polypropylene, they can be recycled without separating the ornament 20 from the trim main body 11.

[0029] <Other Embodiments> The technology disclosed in this specification is not limited to the embodiments described by the above description and drawings. For example, the following embodiments are also included in the technical scope. In the above embodiment, the ornament 20 that constitutes the door trim for a vehicle as a resin molded product is exemplified, but it can also be applied to other vehicle interior materials such as side trims, quarter trims, pillar garnishes, etc. Further, the resin molded product is not limited to vehicles. For example, it can also be applied to vehicles such as trains and amusement vehicles as ground vehicles, airplanes and helicopters as flight vehicles, and ships and submarines as marine and underwater vehicles.

Explanation of Reference Numerals

[0030] 20... Ornament (resin molded product), 21... Base material, 31... Skin material, 31A... One surface of the skin material, 31B... The other surface of the skin material, 51... First molding die, 51A... First molding surface, 61... Second molding die, 61A... Second molding surface

Claims

1. A mold closing step of closing the first mold and the second mold while disposing a skin material containing polypropylene between a first molding surface of the first mold and a second molding surface of the second mold; A substrate molding step that is performed after the mold closing step, and while setting the temperature of the first molding surface to 15°C or higher and 40°C or lower, injecting molten polypropylene between the other surface of the skin material and the second molding surface in a state where one surface of the skin material is in contact with the first molding surface, thereby molding a substrate integrally with the skin material. A method for manufacturing a resin molded product comprising the steps of:

2. The method for manufacturing a resin molded product according to claim 1, wherein the skin material is a fabric.

3. The method for manufacturing a resin molded product according to claim 1 or 2, wherein the thickness of the skin material is set to 0.58 mm or more.

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