Two-color molding device and method of manufacturing two-color molded product

Abstract

To provide a two-color molding device capable of molding a two-color molded product that suppresses deformation of an external appearance of the molded product.SOLUTION: There is provided a two-color molding device, comprising: a cavity mold having a suction mechanism for suctioning and fixing a decorative sheet; a primary molding core mold having a nozzle for injecting a primary molding resin into a first cavity defined between a cavity mold and the primary molding core mold; an air ejector mechanism for ejecting air, in which the air ejector mechanism is provided in the primary molding core mold; means for releasing a primary molded body that is made of a decorative sheet and a primary molding resin formed on a rear surface of the decorative sheet and having the shape of the first cavity, from the primary molding core mold, and for retracting the primary molded body while keeping it fixed and held to the cavity mold; a secondary molding core mold having a nozzle for injecting a secondary molding resin into a second cavity defined between the cavity mold and the secondary molding core mold; and means for removing a secondary molded body made of the primary molded body and the secondary molding resin formed on a rear surface of the primary molded body and having the shape of the second cavity.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a two-color molding apparatus and a manufacturing method for manufacturing two-color molded products used for automotive interior parts such as instrument panels and door trims of automobiles, front panels of home appliances, and the like. [Background technology]

[0002] Conventionally, there is a manufacturing method in which two different types of molding resin are injected into a mold to form a two-color molded product. In addition, in order to enhance the design of the surface of a two-color molded product, a method is also known in which a decorative sheet is inserted into the mold, the mold is closed, and the molding resin is injected into the mold to integrate the decorative sheet and the molding resin, called film insert molding.

[0003] In addition, there has been a recent trend for panel components that come into contact with the hands to have a high-quality texture, and components with a soft feel are being used. A soft feel is achieved by using a soft material for the decorative sheet and a soft, low-hardness resin for the molding resin that is integrated with the decorative sheet.

[0004] As a manufacturing method of this two-color molded product, for example, there is a manufacturing method of a two-color molded product described in Patent Document 1. Fig. 17A is a diagram showing an apparatus for manufacturing a two-color molded product in which a decorative sheet and a molded resin are integrated, described in Patent Document 1. In Patent Document 1, a primary molded body obtained by film insert molding using a cavity mold and a core mold for performing primary molding is left in the cavity mold, the cavity mold for primary molding and the cavity mold for secondary molding are interchanged, a mold consisting of a core mold for secondary molding and a cavity mold for primary molding is closed, and secondary molding resin is injected into the mold to perform secondary molding. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-183139 Summary of the Invention [Problem to be solved by the invention]

[0006] In the manufacturing method of Patent Document 1, after the primary molding, the die can be opened while leaving the primary molded body, in which the decorative sheet and the primary molding resin are integrated, in the cavity die.

[0007] However, in this molding method, the shape of the molded product is limited because the cavity mold needs to have an undercut shape so that the primary molded body does not separate from the cavity mold, as shown in Fig. 17B. Also, in order to release the primary molded body with an undercut shape from the die, the external surface of the primary molded body, which is the product, needs to be pressed with an ejector pin or the like, and there is a risk that a mark of the pressing will remain on the external surface.

[0008] Therefore, an object of the present disclosure is to solve the above-mentioned problems and to provide a manufacturing apparatus for a two-color molded product that can be removed while suppressing deformation of the shape of the outer surface. [Means for solving the problem]

[0009] The two-color molding apparatus according to the present disclosure is The molding machine is provided with: a cavity mold having a suction mechanism for sucking and fixing the decorative sheet; a primary molding core mold having a nozzle for injecting a primary molding resin into a first cavity defined between the cavity mold and the primary molding core mold; an air ejector mechanism for spraying air provided in the primary molding core mold; a means for releasing a primary molded body consisting of the decorative sheet and the primary molding resin formed on the back surface of the decorative sheet and having the shape of the first cavity from the primary molding core mold and fixing and holding the primary molded body to the cavity mold and moving the cavity mold back; a secondary molding core mold having a nozzle for injecting a secondary molding resin into a second cavity defined between the cavity mold and the secondary molding core mold; and a means for removing a secondary molded body consisting of the primary molded body and the secondary molding resin formed on the back surface of the primary molded body and having the shape of the second cavity.

[0010] The method for producing a two-color molded product according to the present disclosure includes a step of sucking and fixing the surface of a decorative sheet to a cavity mold, a step of clamping the cavity mold and a primary molding core mold, a step of injecting a primary molding resin into a first cavity defined between the cavity mold and the primary molding core mold, and a step of releasing a primary molded body consisting of the decorative sheet and the primary molding resin formed on the rear surface of the decorative sheet and having the shape of the first cavity from the primary molding core mold by blowing air while the cavity mold and the primary molding core mold are closed to create a positive pressure inside the first cavity, thereby releasing the primary molded body from the primary molding core mold and releasing the primary molding resin into the cavity mold. the step of fixing and holding the primary molded body in the cavity mold and retracting the cavity mold when opening the primary molding core mold and the primary molding core mold; the step of clamping the cavity mold that fixes and holds the primary molded body and the secondary molding core mold; the step of injecting a secondary molding resin into a second cavity defined between the cavity mold that fixes and holds the primary molded body and the secondary molding core mold; and the step of opening the cavity mold and the secondary molding core mold to remove a secondary molded body consisting of the primary molded body and the secondary molding resin that is formed on the back surface of the primary molded body and has the shape of the second cavity. Effect of the Invention

[0011] According to the two-color molded article manufacturing apparatus and method according to the present disclosure, it is possible to mold a two-color molded article in which deformation of the external surface of the molded body is suppressed. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view showing a cross-sectional structure of a two-color molding device according to a first embodiment. [Figure 2A] FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of a decorative sheet. [Figure 2B] FIG. 4 is a schematic cross-sectional view showing another example of the layer structure of the decorative sheet. [Figure 3A] FIG. 2 is a schematic cross-sectional view showing a cross-sectional configuration of a two-color molded product. [Figure 3B] FIG. 2 is a schematic cross-sectional view showing a cross-sectional configuration of a decorative sheet having an unnecessary portion protruding from a product shape. [Figure 4A] 2 is a schematic cross-sectional view showing a cross-sectional structure of a cavity mold of the two-color molding device according to the first embodiment. FIG. [Figure 4B] 4B is an enlarged cross-sectional view showing the cross-sectional structure of the top part of the cavity mold in FIG. 4A. [Figure 5A] 13 is a top view showing an outer peripheral groove that ejects air of the air ejector mechanism. FIG. [Figure 5B] 5B is a schematic cross-sectional view showing a cross-sectional structure of an outer circumferential groove of the air ejector mechanism of FIG. 5A. [Figure 6A] 1 is a schematic cross-sectional view showing a cross-sectional structure of a primary molding core mold of a two-color molding device according to embodiment 1. FIG. [Figure 6B] FIG. 1 is a cross-sectional view showing the state in which a primary molding core mold and a cavity mold used in the manufacturing method for a two-color molded product of embodiment 1 are clamped together, and a primary molding resin is injected into a first cavity defined between the cavity mold and the primary molding core mold to form a primary molded body. [Figure 7A] 11 is a graph showing an example of a change in internal pressure detected by a pressure sensor. [Figure 7B] 6C is a cross-sectional view showing a parting surface of the primary molding core mold of FIG. 6A and FIG. 6B. [Figure 7C] 7A is a diagram showing an example of the arrangement of outer circumferential grooves for ejecting air of an air ejector mechanism installed in the primary molding core mold of FIG. 6A and FIG. 6B. [Figure 8A] 1 is a schematic cross-sectional view showing a cross-sectional structure of a two-color molded product according to a first embodiment. [Figure 8B] 8B is a plan view showing the outer shape of the two-color molded product in FIG. 8A. FIG. [Figure 9A] 1 is a cross-sectional view of a decorative sheet including a margin according to a first embodiment. FIG. [Figure 9B] 1 is a plan view showing the outer shape of a decorative sheet including a margin according to a first embodiment. FIG. [Figure 10] 4 is a flowchart showing a method for manufacturing a two-color molded product according to the first embodiment. [Figure 11] 4 is a plan view showing an example of the arrangement of outer circumferential grooves that eject air of the air ejector mechanism of the two-color molding device according to the first embodiment. FIG. [Figure 12] 1 is a schematic cross-sectional view showing one step of a method for producing a two-color molded article according to the first embodiment. [Figure 13] 1 is a schematic cross-sectional view showing one step of a method for producing a two-color molded article according to the first embodiment. [Figure 14] 1 is a schematic cross-sectional view showing one step of a method for producing a two-color molded article according to the first embodiment. [Figure 15] 1 is a schematic cross-sectional view showing one step of a method for producing a two-color molded article according to the first embodiment. [Figure 16] 1 is a schematic cross-sectional view showing one step of a method for producing a two-color molded article according to the first embodiment. [Figure 17A] FIG. 1 is a cross-sectional view showing one step of a conventional method for producing a two-color molded product. [Figure 17B] FIG. 1 is a cross-sectional view showing a cavity mold used in a conventional method for producing a two-color molded product. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The two-color molding device according to the first aspect includes a cavity mold having a suction mechanism for sucking and fixing a decorative sheet, a primary molding core mold having a nozzle for injecting a primary molding resin into a first cavity defined between the cavity mold and the primary molding core mold, an air ejector mechanism for ejecting air provided in the primary molding core mold, a decorative sheet, and a primary molding resin formed on the back surface of the decorative sheet and having the shape of the first cavity, from the primary molding core mold and fixedly holding the primary molded body in the cavity mold while retracting the cavity mold; a secondary molding core mold having a nozzle for injecting secondary molding resin into a second cavity defined between the cavity mold and the secondary molding core mold; and a means for removing a secondary molded body consisting of the primary molded body and a secondary molding resin formed on the back surface of the primary molded body and having the shape of the second cavity.

[0014] A two-color molding apparatus according to a second aspect is the above-mentioned first aspect, wherein at least one of the cavity mold and the primary molding core mold or the secondary molding core mold may be tapered.

[0015] The two-color molding apparatus of the third aspect may be the same as in the first or second aspect, and may further include a pressure sensor provided in the primary molding core mold for detecting the pressure within the first cavity defined between the cavity mold and the primary molding core mold.

[0016] The two-color molding apparatus according to a fourth aspect is any one of the first to third aspects, wherein the cavity mold is configured to be divided and may have a suction groove for performing suction from a parting line of the mold. This allows the decorative sheet to be fixed and held in the cavity mold by suction.

[0017] The two-color molding apparatus according to a fifth aspect is any one of the first to fourth aspects, wherein the cavity mold has a shape in which a step is provided at a top portion of the cavity mold that comes into contact with the decorative sheet. This creates a greater negative pressure between the decorative sheet and the cavity mold when the mold is clamped, improving the adhesion between the decorative sheet and the cavity mold.

[0018] The two-color molding apparatus of the sixth aspect is any one of the first to fifth aspects above, in which the decorative sheet is prepared in a size larger than the product shape of the molded product, protrudes beyond the product shape, and has a margin that is cut off after molding, and the margin is suction-fixed using a cavity-type suction mechanism.

[0019] A two-color molding apparatus according to a seventh aspect is any one of the first to sixth aspects, wherein the ejector mechanism ejects air from an outer circumferential groove of the fixing pin. This allows air to be ejected into the first cavity defined between the cavity mold and the primary molding core mold.

[0020] The two-color molding apparatus according to an eighth aspect is any one of the first to seventh aspects, wherein the air ejector mechanism is divided into a plurality of flow paths, and each of the plurality of divided flow paths may be controlled independently.

[0021] A method for producing a two-color molded product according to a ninth aspect includes a step of sucking and fixing a surface of a decorative sheet to a cavity mold, a step of clamping the cavity mold and a primary molding core mold, a step of injecting a primary molding resin into a first cavity defined between the cavity mold and the primary molding core mold, and a step of releasing a primary molded body consisting of the decorative sheet and the primary molding resin formed on the rear surface of the decorative sheet and having the shape of the first cavity from the primary molding core mold by blowing air while the cavity mold and the primary molding core mold are closed to create a positive pressure in the first cavity. The method includes the steps of: when opening the mold and the primary molding core mold, fixing and holding the primary molded body in the cavity mold and retracting the cavity mold; clamping the cavity mold that fixes and holds the primary molded body and the secondary molding core mold; injecting a secondary molding resin into a second cavity defined between the cavity mold that fixes and holds the primary molded body and the secondary molding core mold; and opening the cavity mold and the secondary molding core mold to remove a secondary molded body consisting of the primary molded body and the secondary molding resin that is formed on the back surface of the primary molded body and has the shape of the second cavity. A tenth aspect of the method for producing a two-color molded article is the same as the ninth aspect, in which at least one of the cavity mold and the primary molding core mold or the secondary molding core mold may be tapered. The method for producing a two-color molded product according to the eleventh aspect may further include, in the above ninth or tenth aspect, a step of detecting the pressure within the first cavity defined between the cavity mold and the primary molding core mold.

[0022] The method for manufacturing a two-color molded product according to the twelfth aspect is any one of the above ninth to eleventh aspects, in which the decorative sheet is prepared in a size larger than the product shape of the molded product, and any unnecessary portion that protrudes beyond the product shape has a margin that is cut off after molding, and the margin may be fixed by suction.

[0023] The method for producing a two-color molded product according to the thirteenth aspect may be any one of the ninth to twelfth aspects above, in which the cavity mold and the primary molding core mold may be opened when the pressure inside the first cavity is constant.

[0024] Any of the above various aspects can be appropriately combined to achieve the effects of each aspect.

[0025] Hereinafter, a two-color molding apparatus, which is an apparatus for manufacturing a two-color molded product, and a method for manufacturing a two-color molded product according to an embodiment will be described in detail with appropriate reference to the drawings.

[0026] (Embodiment 1) First, a decorative sheet used in the method for producing a two-color molded product according to the present disclosure will be described.

[0027] (Decorative sheet) Fig. 2A is a schematic cross-sectional view showing an example of the layer structure of the decorative sheet 2. Fig. 2B is a schematic cross-sectional view showing another example of the layer structure of the decorative sheet 2. The decorative sheet 2 is a sheet used for insert molding. As shown in Fig. 2A, the decorative sheet 2 is characterized in that an adhesive layer 3 capable of adhering to a molded resin by injection molding is formed on the surface opposite to the appearance surface of the decorative sheet 2. Also, as shown in Fig. 2B, a pattern layer 4 may be laminated between the decorative sheet 2 and the adhesive layer 3. Furthermore, depending on the functions required of the decorative sheet 2, it may be formed of multiple layers such as a binder layer, a protective layer, and a light-reducing layer.

[0028] A soft material is selected as the material for the decorative sheet 2 of the two-color molded product according to the present disclosure in order to achieve a soft feel when touched by hand. Specifically, at least one material selected from the group consisting of monolayer films of polyvinyl chloride resin, polystyrene resin, polyester resin, acrylic resin, olefin resin, etc., laminated films or copolymer films of two or more resins, wood, cloth, and leather can be used.

[0029] The decorative sheet 2 may have a thickness of 5 μm to 1,000 μm, but in consideration of handling properties, it is preferable to use a thickness of 125 μm to 700 μm, and in consideration of molding stability, it is preferable to use a thickness of 250 μm to 600 μm.

[0030] The pattern layer 4 and adhesive layer 3 of the decorative sheet 2 can be printed by screen printing or gravure printing, but the method should not be limited.

[0031] Fig. 3A is a schematic cross-sectional view showing the cross-sectional structure of a two-color molded product 26. Fig. 3B is a schematic cross-sectional view showing the cross-sectional structure of a decorative sheet having a margin 5 protruding from the product shape. The shape of the decorative sheet 2 of the two-color molded product according to the present disclosure is prepared to be larger than the product shape of the molded product as shown in Figures 3A and 3B, and the marginal part 5 protruding from the product shape is cut off after molding. The marginal part 5 is fixed by suction in the suction groove 8 of the cavity mold for primary molding, which will be described later.

[0032] <Two-color molding device> Next, a two-color molding device 1 according to the first embodiment used in a method for producing a two-color molded product using the decorative sheet 2 will be described. FIG. 1 is a schematic cross-sectional view showing a cross-sectional configuration of a two-color molding device 1 according to the first embodiment. The two-color molding device 1 according to the first embodiment includes a cavity mold 6 which is a movable mold, a primary molding core mold which is a fixed mold, and a secondary molding core mold which is a fixed mold. Furthermore, this two-color molding device includes an air ejector mechanism which ejects air, a pressure sensor, a means for retracting the cavity mold, and a means for removing the secondary molded body. The cavity mold has a suction mechanism which sucks and fixes the decorative sheet. The primary molding core mold has a nozzle which injects a primary molding resin into a first cavity defined between the cavity mold and the primary molding core mold. The air ejector mechanism is provided in the primary molding core mold. The pressure sensor is provided in the primary molding core mold and detects the pressure in the first cavity defined between the cavity mold and the primary molding core mold. The means for moving the cavity mold backward is to release the primary molded body, which is made of the decorative sheet and the primary molding resin formed on the back surface of the decorative sheet and having the shape of the first cavity, from the primary molding core mold by applying positive pressure to the first cavity while the cavity mold and the primary molding core mold are closed, and to move the primary molded body backward while fixed to the cavity mold when the cavity mold and the primary molding core mold are opened. The secondary molding core mold has a nozzle for injecting the secondary molding resin into the second cavity defined between the cavity mold and the secondary molding core mold. The means for removing the secondary molded body removes the secondary molded body, which is made of the primary molded body and the secondary molding resin formed on the back surface of the primary molded body and having the shape of the second cavity. The means for removing the secondary molded body can be realized, for example, by stopping suction, as described later. The secondary molded body may be removed by a means for ejecting air.

[0033] (movable type) ·Cavity molds for primary and secondary molding The primary molding cavity mold and the secondary molding cavity mold used in the two-color molding apparatus 1 and the method for manufacturing a two-color molded product according to the present embodiment 1 have the same shape. For this reason, hereinafter, the primary molding cavity mold and the secondary molding cavity mold will be referred to as the cavity mold 6.

[0034] Fig. 4A is a schematic cross-sectional view showing the cross-sectional structure of cavity mold 6 of the two-color molding apparatus according to embodiment 1. Fig. 4B is an enlarged cross-sectional view showing the cross-sectional structure of the top part of cavity mold 6 in Fig. 4A. As shown in Fig. 4A, the cavity mold 6 is configured to be divided, and is characterized by having a mechanism with suction grooves 8 that perform suction from the parting lines of the mold. The suction grooves 8 preferably have a width of 10 µm or less, and more preferably have a width of 5 µm or less. The suction grooves 8 are provided at a position that is covered by the marginal portion 5 when the marginal portion 5 is inserted into the cavity mold 6. In other words, the suction grooves 8 are provided at a position where, in the width of the marginal portion 5, X1 is on the outside of the suction grooves 8, and X2 is on the inside of the suction grooves 8, such that X1>X2.

[0035] When suction is performed by the suction mechanism of the cavity mold 6 , a negative pressure is created between the cavity mold 6 and the decorative film 2 , and the decorative film 2 can be fixed tightly to the cavity mold 6 .

[0036] As shown in FIG. 4B, the cavity mold 6 of the two-color molding device 1 according to the present embodiment 1 is characterized in that a step is provided at the top of the mold that contacts the decorative film 2 of the divided cavity mold 6. Specifically, the top outside the suction groove 8 is configured to be closer to the opposing primary molding core mold 13 than the top inside the suction groove 8. By providing a step, when the cavity mold 6 and the primary molding core mold 13 are clamped, the margin 5 can be sandwiched between the cavity mold 6 outside the suction groove 8 and the primary molding core mold 13. This makes it difficult for air to leak from the parting surface 7, and the degree of vacuum between the decorative sheet 2 and the cavity mold 6 is increased, thereby improving the adhesion between the decorative sheet 2 and the cavity mold 6. This X1 portion of the decorative sheet 2 is called the squeeze allowance 11. The cavity mold 6 may have a tapered shape, that is, a shape other than the undercut shape.

[0037] Furthermore, by setting the relationship X1>X2, the area of ​​the squeeze margin 11 becomes larger, and the larger this area is, the more stable the fixing of the decorative sheet 2 to the cavity mold 6 becomes.

[0038] The cavity mold 6 may be attached to a movable platen such as a rotating platen 12 capable of rotating or a sliding platen capable of sliding, and the position for the primary molding and the position for the secondary molding can be interchanged.

[0039] (Fixed type) ·Core mold for primary molding As shown in Figures 6A and 6B, the primary molding core mold 13 is characterized by having a nozzle that injects primary molding resin 19, an air ejector 15 that sprays air from inside the primary molding core mold 13 toward the mold surface, and a pressure sensor 18 that can detect the pressure inside the mold. The primary molding core die 13 may be tapered, that is, not have an undercut shape.

[0040] Next, the primary molding process will be described. The cavity mold 6 to which the decorative sheet 2 is adsorbed and fixed and the primary molding core mold 13 are clamped together, and a primary molding resin 19 is injected from a primary molding nozzle 14 into a first cavity defined between the cavity mold 6 and the primary molding core mold 13.

[0041] In order to achieve a soft feel when the molded body is touched, a soft, low-hardness material is used for the primary molding resin 19. Specifically, a thermoplastic elastomer having a JIS A hardness of 1 to 90 is preferable for the primary molding resin 19, and a JIS A hardness of 1 to 40 can achieve a strong soft feel. As the thermoplastic elastomer having a JIS A hardness of 1 to 90, for example, a styrene-based elastomer, an olefin-based elastomer, a vinyl chloride-based elastomer, a urethane-based elastomer, an ester-based elastomer, or an amide-based elastomer can be used, but is not limited to these as long as it is a resin that can achieve a soft feel.

[0042] The low-hardness thermoplastic elastomer used for the primary molding resin 19 shrinks a lot after molding, especially thermoplastic elastomers with a JIS A hardness of 1 to 40 or less. Therefore, when the mold is opened after the primary molding, the primary molding resin 19 sticks to the primary molding core mold 13 and cannot be released. Therefore, the primary molding resin 19 cannot be fixed and held by the cavity mold 6 that retreats when the mold is opened. In addition, using an ejector pin as a method of releasing the mold is not an effective method because the primary molding resin 19 sticks to the primary molding core mold 13 and the primary molded body 20 may be damaged by applying a force locally only to the ejector pin.

[0043] Therefore, in the manufacturing method for a two-color molded product according to the first embodiment, an ejector mechanism is used to release the primary molded body 20. With the cavity mold 6 and the primary molding core mold 13 clamped together, air is ejected from the air ejector 15 to create a positive pressure inside the mold, creating a gap between the primary molding resin 19 and the primary molding core mold 13, allowing the primary molding resin 19 to be released from the primary molding core mold 13.

[0044] <Air ejector mechanism> Here, the air ejector mechanism will be described. Fig. 5A is a top view showing the outer circumferential groove 22 for ejecting air of the air ejector mechanism, and Fig. 5B is a schematic cross-sectional view showing the cross-sectional structure of the outer circumferential groove 22 of the air ejector mechanism of Fig. 5A. 5A and 5B, a groove is provided on the outer periphery of a fixing pin 21 mounted on the primary molding core mold 13, and air is ejected from this outer periphery groove 22. The width of the outer periphery groove 22 is preferably 20 μm, and in consideration of the possibility of inflow of molding resin, 10 μm is preferable, and if it is 5 μm or less, the inflow of resin can be better prevented.

[0045] Fig. 6A is a schematic cross-sectional view showing the cross-sectional structure of the primary molding core mold 13 of the two-color molding device according to embodiment 1. Fig. 6B is a cross-sectional view showing the state in which the primary molding core mold 13 and the cavity mold 6 used in the manufacturing method for a two-color molded product according to embodiment 1 are clamped together, and primary molding resin 19 is injected into the first cavity defined between the cavity mold 6 and the primary molding core mold 13 to form a primary molded body. The air ejector mechanism 15 used in the method for producing a two-color molded product according to the first embodiment is characterized in that it has separate flow paths, such as flow path A16 and flow path B17, as shown in Figures 6A and 6B, and the air ejection conditions can be controlled by each flow path. The air ejection conditions can be adjusted as appropriate depending on the shape of the molded body and the specifications of the primary molding resin 19 used.

[0046] Fig. 7A is a graph showing an example of a change in internal pressure detected by a pressure sensor. Fig. 7B is a cross-sectional view showing the parting surface of the primary molding core mold 13 of Figs. 6A and 6B. Fig. 7C is a diagram showing an example of the arrangement of an outer circumferential groove for ejecting air of an air ejector mechanism installed in the primary molding core mold 13 of Figs. 6A and 6B. The pressure value inside the mold is detected by the pressure sensor 18 installed in the primary molding core mold 13. As shown in Fig. 7A, after the air is ejected, the pressure inside the mold becomes positive and rises, and when the air has spread throughout the mold, the pressure inside the mold shows a constant value. After that, when the air reaches the parting surface 7 of the mold shown in Fig. 7B, the pressure value shows a tendency to decrease. When the pressure is constant before this tendency to decrease is reached, a gap is generated between the primary molding resin 19 and the primary molding core mold 13.

[0047] Since the cavity mold 6 continues to adsorb and fix the decorative sheet 2, when the cavity mold 6 and the primary molding core mold 13 are opened in this state, the cavity mold 6 can move back while holding the primary molded body 20. In other words, the timing for opening the mold needs to be set by detecting a constant value of the pressure inside the mold and before it shows a tendency for pressure reduction.

[0048] The present inventor has found that a problem with soft and low-hardness resins is that they have a strong tendency to adhere to the mold after molding. For example, when using a soft and low-hardness primary molding resin, the primary molding resin may adhere to the core mold for primary molding. Therefore, opening the mold in the adhered state may lead to damage to the primary molded article. On the other hand, according to the two-color molding apparatus according to Embodiment 1, as described above, by detecting a constant value of the pressure in the mold, mold opening can be performed in a state where a gap is generated between the primary molding resin 19 and the core mold 13 for primary molding. Therefore, the occurrence of damage to the primary molded article can be suppressed.

[0049] Next, the arrangement of the air ejector mechanism 15 will be described. As shown in FIG. 7A, when the air flowing into the mold reaches the parting surface 7 of the mold, the pressure decreases. Therefore, when using a plurality of air ejectors 15, in order to distribute the air in the mold before the air reaches the parting surface 7, as shown in FIG. 7C, when the distance from the parting surface 7 of the air ejector mechanism 15 closest to the parting surface 7 is L and the distance to the adjacent air ejector mechanism 15 is L1, it is preferable to install them such that L1 < L. However, it is not limited to this as long as the pressure in the mold can be made positive pressure and the pressure value can be made constant.

[0050] ·Core mold for secondary molding As shown in FIG. 1, the core mold 23 for secondary molding has a nozzle for injecting the secondary molding resin 25 on the side of the primary molding resin surface of the primary molded article 20. Note that the core mold 23 for secondary molding may have a tapered shape, that is, a shape without an undercut.

[0051] The process of secondary molding will be described. After the cavity mold 6 holding the primary molded article 20 moves by a method such as rotation or sliding and faces the core mold 23 for secondary molding, the cavity mold 6 and the core mold 23 for secondary molding are clamped. Then, the secondary molding resin 25 is injected onto the primary molding resin surface.

[0052] The secondary molding resin 25 is, for example, a thermoplastic resin having a high hardness of at least JIS A hardness of 100. Examples of resins having a high hardness of at least JIS A hardness of 100 include polypropylene resin, acrylic styrene butadiene resin, polycarbonate resin, acrylic resin, nylon resin, styrene resin, acrylic styrene resin, vinyl chloride resin, polyester resin, polyurethane resin, or composites of these resins.

[0053] After the secondary molding, the secondary molded body 26 adheres closely to the secondary molding core mold 23 due to contraction of the secondary molding resin 25. In this state, the suction of the cavity mold 6 is stopped, the cavity mold 6 and the secondary molding core mold 23 are opened, and the cavity mold 6 is moved backward.

[0054] This makes it possible to remove the two-color molded product without using an ejection mechanism from the exterior surface side and suppressing deformation of the exterior surface shape. Note that the method is not limited to the above, and for example, air ejection can be performed by blowing air from the cavity side.

[0055] Hereinafter, the method for producing a two-color molded product according to the first embodiment will be described with reference to FIGS. 8A to 16.

[0056] <Configuration of two-color molded products> Fig. 8A is a schematic cross-sectional view showing a cross-sectional structure of the two-color molded product according to embodiment 1. Fig. 8B is a plan view showing the outer shape of the two-color molded product of Fig. 8A. The two-color molded product according to the first embodiment includes a decorative sheet 2, a primary molded resin 19, and a secondary molded resin 25. The entire back surface of the decorative sheet 2 is covered with the primary molded resin 19, and the entire back surface of the primary molded resin 19 is covered with the secondary molded resin 25 to form a box shape. As shown in Fig. 8B, the size of the two-color molded product is, for example, 400 mm wide x 100 mm long, and 25 mm high, forming a box shape.

[0057] <Decorative sheet> Fig. 9A is a cross-sectional view of the decorative sheet 2 including the margin 5 according to embodiment 1. Fig. 9B is a plan view showing the outer shape of the decorative sheet 2 including the margin 5 according to embodiment 1. The decorative sheet 2 of the two-color molded product is made of, for example, a polyvinyl chloride sheet. A pattern layer 4 and an adhesive layer 3 are laminated in this order on the surface opposite to the appearance surface of the decorative sheet 2. The adhesive layer 3 has the function of adhering to the primary molding resin 19 by injection molding. The decorative sheet 2 has a margin 5 around the outer periphery of the molded product, which is used for fixing and adsorbing to the cavity mold 6. The margin 5 of the decorative sheet 2 is provided to have a width of 30 mm, as shown in FIG. 9A. As a result, the external shape of the decorative sheet 2 including the margin 5 is 460 mm×160 mm, as shown in FIG. 9B.

[0058] <Primary molding resin> The material of the primary molding resin 19 of the two-color molded product is, for example, a styrene-based elastomer with a JIS A hardness of 5. This allows the two-color molded product to feel soft when touched from the decorative sheet side. In addition, the styrene-based elastomer with a JIS A hardness of 5 is soft and has a large post-molding shrinkage of 2%, and also has a strong adhesion to the mold. Therefore, it adheres to the primary molding core mold 13 by vacuum.

[0059] <Secondary molding resin> For example, polypropylene resin is used as the material for the secondary molding resin 25. The two-color molded body according to the present disclosure has a soft feel due to the soft materials, namely, from the external appearance, a polyvinyl chloride sheet and a styrene-based elastomer with a JIS A hardness of 5, but these two layers are not rigid enough to function as a panel, so by using a hard polypropylene resin for the secondary molding resin, it can be used as a panel. Moreover, the surface of the secondary molding resin 25 opposite to the surface of the primary molding resin 19 can also be used to provide a structure for integrating with other parts.

[0060] Next, a method for producing a two-color molded product according to the first embodiment will be described.

[0061] <Manufacturing method for two-color molded products> Fig. 10 is a flowchart showing a method for producing a two-color molded product according to embodiment 1. Fig. 11 is a plan view showing an example of an arrangement of outer circumferential grooves for ejecting air from the air ejector mechanism 15 of the two-color molding device according to embodiment 1. Figs. 12 to 16 are schematic cross-sectional views showing one step of the method for producing a two-color molded product according to embodiment 1. (1) The decorative sheet 2 is inserted into the cavity mold 6, and the suction mechanism installed in the cavity mold 6 is turned on. This causes the margin 5 on the decorative sheet 2 to be sucked and fixed by the suction mechanism of the cavity mold 6. At this time, the position of the suction groove 8 installed in the cavity mold is set to a position 20 mm from the outer end of the margin 5, with the margin 5 having a width of 30 mm. This 20 mm becomes the squeeze allowance 11.

[0062] 12, the cavity mold 6 is advanced, the cavity mold 6 and the primary molding core mold 13 are clamped, and the squeeze allowance 11 of the margin 5 is sandwiched between the cavity mold 6 and the primary molding core mold 13. This seals the outer periphery of the decorative sheet 2 and increases the degree of vacuum in the gap between the cavity mold 6 and the decorative sheet 2, thereby improving the adhesion between the cavity mold 6 and the decorative sheet 2.

[0063] (3) After the mold is closed, a primary molding resin 19 is injected from a primary molding nozzle 14 of the primary molding core mold 13 into a first cavity defined between the cavity mold 6 and the primary molding core mold 13. After the primary molding resin 19 is cooled, the primary molding resin 19 adheres closely to the primary molding core mold 13 due to post-shrinkage of the primary molding resin 19, causing the primary molding resin 19 to stick to the primary molding core mold 13.

[0064] (4) In order to eliminate the sticking of the primary molding resin 19, a method is used in which an air ejector mechanism installed in the primary molding core mold 13 ejects air into the first cavity between the cavity mold and the primary molding core mold.

[0065] The air ejector mechanism 15 used in the manufacturing method for a two-color molded product according to the first embodiment is characterized in that it has separate flow paths, and as shown in FIGS. 6A and 6B, a flow path A16 and a flow path B17 are installed on the top and side portions of a box shape.

[0066] As shown in FIG. 11, the air ejector mechanisms on the box-shaped top surface portion are arranged such that when the distance to the parting surface of the air ejector mechanism closest to the parting surface is 80 mm, the distance to the adjacent air ejector mechanism is 75 mm, so that air is distributed throughout the mold before it reaches the parting surface 7.

[0067] (5) Furthermore, from the results of a compression test of the primary molding resin 19, it has been found that when the air pressure reaches 0.4 MPa, the primary molding resin 19 is released from the primary molding core mold 13. As a result, air is ejected so that the pressure sensor installed in the mold indicates a constant value of 0.4 MPa or more. At this time, as shown in Figs. 6A and 6B, air ejectors 15 are also arranged on the side surfaces of the box shape, so that they can be used appropriately in combination with the air on the top surface.

[0068] (6) Next, settings are made to open the mold before the pressure sensor 18 detects a constant value of 0.4 MPa or more and indicates a tendency for reduced pressure, and the cavity mold 6 is retracted. Since suction of the marginal portion 5 in the cavity mold 6 continues even when the mold is opened, the cavity mold 6 can retract while the primary molded body 20 is fixed and held in the cavity mold 6.

[0069] (7) After the cavity mold 6 has retreated, as shown in FIG. 13, the positions of the cavity mold 6 holding the decorative sheet to be subsequently subjected to primary molding and the cavity mold 6 holding the primary molded body 20 to be subsequently subjected to secondary molding are interchanged by rotating them on a turntable.

[0070] (8) Furthermore, as shown in FIG. 14, the cavity mold 6 is advanced to the primary molding core mold 13, and the cavity mold 6 and the primary molding core mold 13 are clamped together, and at the same time, the cavity mold 6 is advanced to the secondary molding core mold 23, and the cavity mold 6 and the secondary molding core mold 23 are clamped together. (9) Next, as shown in FIG. 15, a primary molding resin 19 is injected from the primary molding core mold 13 to form a primary molded body 20, and a secondary molding resin 25 is injected from the secondary molding core mold 23 to form a secondary molded body 26.

[0071] (10) After the secondary molding, the secondary molding body 26 adheres closely to the secondary molding core mold 23 due to post-shrinkage of the secondary molding resin 25. For this reason, the suction mechanism of the cavity mold 6 is released before the cavity mold 6 and the secondary molding core mold 23 are opened, and then the cavity mold 6 is moved backward when the cavity mold 6 and the secondary molding core mold 23 are opened. At this time, the secondary molding body 26 is held by the secondary molding core mold 23, as shown in FIG.

[0072] As a result, after secondary molding, the two-color molded product can be released from the mold without using a mechanism that touches the exterior surface of the two-color molded product, such as an ejector pin, so that it can be removed while suppressing deformation of the exterior shape. [Explanation of symbols]

[0073] 1 Molding equipment 2. Decorative Sheet 3 Adhesive layer 4. Picture layer 5 Margins 6 Cavity Type 7 Parting Surface 8 Suction groove 9 Cavity type inner top 10 Cavity outer top 11 Crushing Fee 12 Turntable 13 Primary molding core mold 14 Primary molding resin nozzle 15 Air ejector mechanism 16 Flow Path A 17 Flow Path B 18 Pressure Sensor 19 Primary molding resin 20 Primary molded body 21 Fixing pin 22 Outer Circumferential Groove 23 Secondary molding core mold 24 Secondary molding resin nozzle 25 Secondary molding resin 26 Secondary molded product (two-color molded product)

Claims

1. a cavity mold having a suction mechanism for suctioning and fixing the surface of the decorative sheet; a primary molding core mold having a nozzle for injecting a primary molding resin into a first cavity defined between the cavity mold and the primary molding core mold; an air ejector mechanism provided in the primary molding core mold for ejecting air; a means for releasing a primary molded body consisting of the decorative sheet and the primary molding resin formed on the rear surface of the decorative sheet and having the shape of the first cavity from the primary molding core mold, and fixing and holding the primary molded body to the cavity mold and retracting the cavity mold; A secondary molding core mold having a nozzle for injecting a secondary molding resin into a second cavity defined between the cavity mold and the secondary molding core mold; a means for removing a secondary molded body including the primary molded body and the secondary molded resin formed on a rear surface of the primary molded body and having a shape of the second cavity; A two-color molding device comprising:

2. 2. The two-color molding apparatus according to claim 1, wherein at least one of the cavity mold and the primary molding core mold or the secondary molding core mold is tapered.

3. The mold further includes a pressure sensor provided in the primary molding core mold for detecting a pressure in the first cavity defined between the cavity mold and the primary molding core mold. The two-color molding apparatus according to claim 1 .

4. The cavity mold is configured by dividing it, and has a suction groove that performs suction from a dividing line of the mold. The two-color molding apparatus according to claim 1 .

5. The cavity mold has a shape in which a step is provided at a top portion of the cavity mold that comes into contact with the decorative sheet. The two-color molding apparatus according to claim 1 .

6. The decorative sheet is prepared in a size larger than the product shape of the molded product, has a margin that protrudes from the product shape and is cut off after molding, and the margin is sucked and fixed by the suction mechanism of the cavity mold. The two-color molding apparatus according to claim 1 .

7. The two-color molding device according to claim 1 , wherein the ejector mechanism ejects air from an outer circumferential groove of a fixing pin.

8. The two-color molding device according to claim 1 , wherein the ejector mechanism is divided into a plurality of flow paths, and each of the plurality of flow paths can be controlled independently.

9. a step of suctioning and fixing a surface of a decorative sheet to a cavity mold; a step of clamping the cavity mold and a primary molding core mold; A step of injecting a primary molding resin into a first cavity defined between the cavity mold and the primary molding core mold; a step of releasing a primary molded body consisting of the decorative sheet and the primary molding resin formed on the rear surface of the decorative sheet and having the shape of the first cavity from the primary molding core mold by blowing air into the first cavity while the cavity mold and the primary molding core mold are closed, and retracting the cavity mold while fixing and holding the primary molded body to the cavity mold when the cavity mold and the primary molding core mold are opened; a step of clamping the cavity mold, which fixes and holds the primary molded body, and a secondary molding core mold; a step of injecting a secondary molding resin into a second cavity defined between the cavity mold that fixedly holds the primary molded body and the secondary molding core mold; A step of opening the cavity mold and the secondary molding core mold to remove a secondary molded body consisting of the primary molded body and the secondary molding resin formed on the back surface of the primary molded body and having the shape of the second cavity; A method for producing a two-color molded product comprising the steps of:

10. The method for producing a two-color molded product according to claim 9 , wherein at least one of the cavity mold and the primary molding core mold or the secondary molding core mold is tapered.

11. The method for producing a two-color molded product according to claim 9, further comprising the step of detecting a pressure in the first cavity defined between the cavity mold and the primary molding core mold.

12. The decorative sheet is prepared in a size larger than the product shape of the molded product, and the unnecessary portion protruding from the product shape has a margin portion that is cut off after molding, and the margin portion is fixed by suction. The method for producing the two-color molded product according to claim 9 .

13. The method for producing a two-color molded product according to claim 9 , wherein the cavity mold and the primary molding core mold are opened in a state where the pressure inside the first cavity is constant.

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