JP7527611B2 - Manufacturing method of resin molded products - Google Patents

Description

The present invention relates to a method for manufacturing a resin molded product in which one side of the resin molded product is decorated by insert molding using a decorative sheet.

Two main methods of molding resin molded products using decorative film to decorate them at the same time as molding them are in-mold molding and insert molding. In-mold molding involves sandwiching a roll of decorative film between metal molds and then injecting resin to transfer the film onto the surface of the resin molded product (see Patent Document 1). In-mold molding requires a process to remove the burrs, since the decorative film protruding from the resin molded product becomes burrs, and there is also the problem of misalignment occurring when the roll of decorative film is sandwiched between metal molds.

Insert molding is a method in which a decorative sheet cut to a specified shape is placed in a mold, and resin is injected into the mold to form the decorative sheet, integrating it with the surface of a resin molded product (see Patent Document 2). Compared to in-mold molding, insert molding does not have the problem of foil burrs and is less likely to become misaligned, but there are problems with cutting chips that occur when cutting the decorative sheet, adhesion of dirt to the surface of the decorative sheet, and difficulty in positioning the decorative sheet if it is circular in shape. There are also problems with resin flowing between the decorative sheet and the mold, or the decorative sheet becoming misaligned, making it particularly difficult to decorate curved surfaces.

JP 2014-172196 A JP 2013-184294 A

The present invention aims to provide a method for manufacturing a resin molded product that allows easy and accurate positioning of the decorative sheet when insert molding is performed using the decorative sheet, prevents the adhesion of dirt and other particles to the surface of the decorative sheet during manufacturing, and prevents the decorative sheet from shifting out of position when resin is injected, and enables decoration of the curved surfaces of the resin molded product.

The manufacturing method of the present invention for a resin molded product is a manufacturing method for a resin molded product in which one side of the resin molded product is decorated by insert molding using a decorative sheet, and includes the steps of preparing a decorative film having a decorative portion and a sandwiching portion located around the decorative portion, in which a cut is formed to separate the decorative portion from the sandwiching portion, and a protective film attached to the decorative surface of the decorative film; arranging the decorative sheet in a mold having a cavity and a core, the cavity being provided with a recess, and a holding portion for holding the decorative sheet being provided within the recess; The method includes the steps of placing the protective film on the holding part so that it faces inward; the core is provided with a protrusion that is inserted into the recess, and the protrusion is provided with a molding part for molding a resin molded product; inserting the protrusion into the recess and clamping and fixing the clamping part of the decorative sheet between the holding part of the cavity and the protrusion of the core; injecting resin into the mold to insert-mold a resin molded product; and removing the resin molded product from the mold. The method is characterized in that the protective film is peeled off, and the surface of the resin molded product is decorated by the decorative part.

It is also possible to provide a concave curved surface in the holding portion of the cavity in the area corresponding to the decorative portion, form the surface of the resin molded product into a convex curved surface, and decorate the curved surface of the resin molded product with the decorative portion.

The planar shape of the decorative portion of the decorative sheet can be circular or elliptical.

Another embodiment of the manufacturing method of the resin molded product of the present invention is a manufacturing method of a resin molded product in which one side of the resin molded product is decorated by insert molding using a decorative sheet, and includes the steps of preparing a decorative film having a decorative portion and a sandwiching portion located around the decorative portion, in which a cut is formed to separate the decorative portion from the sandwiching portion, and a decorative sheet having a protective film attached to the decorative surface of the decorative film; placing the decorative sheet in a mold having a core and a cavity, the core having a recess, and a molding portion for molding the resin molded product within the recess, and a holding portion for holding the decorative sheet. The process includes a step of placing the decorative sheet on the holding part with the protective film facing outward, a step of inserting the convex part into the concave part of the cavity, and fixing the clamping part of the decorative sheet between the holding part of the core and the convex part of the cavity, a step of injecting resin into the mold to insert-mold a resin molded product, and a step of removing the resin molded product from the mold, and is characterized in that the protective film is peeled off, and the surface of the resin molded product is decorated by the decorative part.

It is also possible to provide a concave curved surface on the holding portion of the core in the area corresponding to the decorative portion, form a convex curved surface on the surface of the resin molded product, and decorate the curved surface of the resin molded product with the decorative portion.

The planar shape of the decorative portion of the decorative sheet can be circular or elliptical.

The manufacturing method of the resin molded product of the present invention is a manufacturing method of a resin molded product in which one side of the resin molded product is decorated by insert molding using a decorative sheet, and includes the steps of: preparing a decorative film having a decorative portion and a sandwiching portion located around the decorative portion, with a cut formed to separate the decorative portion from the sandwiching portion, and a decorative sheet having a protective film attached to the decorative surface of the decorative film; arranging the decorative sheet in a mold having a cavity and a core, the cavity being provided with a recess, a holding portion being provided within the recess to hold the decorative sheet, and the decorative sheet being arranged on the holding portion so that the protective film is on the inside; the core being provided with a protrusion to be inserted into the recess, the protrusion being provided with a molding portion for molding the resin molded product, and a front end being provided within the recess. The process includes inserting the convex portion, clamping and fixing the clamping portion of the decorative sheet between the holding portion of the cavity and the convex portion of the core, injecting resin into the mold to insert-mold a resin molded product, and removing the resin molded product from the mold. By peeling off the protective film, the surface of the resin molded product is decorated by the decorative portion, so the decorative sheet can be positioned easily and accurately, and the surface of the resin molded product can be beautifully decorated without misalignment or wrinkles. Furthermore, the amount of chips generated when cutting the decorative sheet and the adhesion and damage of dirt to the surface of the decorative sheet are reduced, improving yield and reducing the manufacturing cost of decorated resin molded products.

The holding portion of the cavity is provided with a concave curved surface in the area corresponding to the decorative portion, the surface of the resin molded product is formed into a convex curved surface, and the curved surface of the resin molded product is decorated with the decorative portion, making it possible to decorate the surface of the resin molded product without causing misalignment or wrinkles.

Another embodiment of the manufacturing method of the resin molded product of the present invention is a manufacturing method of a resin molded product in which one side of the resin molded product is decorated by insert molding using a decorative sheet, and includes the steps of: preparing a decorative film having a decorative portion and a sandwiching portion located around the decorative portion, with a cut formed to separate the decorative portion from the sandwiching portion, and a decorative sheet having a protective film attached to the decorative surface of the decorative film; arranging the decorative sheet in a mold having a core and a cavity, the core being provided with a recess, and the recess being provided with a molding portion for molding the resin molded product and a holding portion for holding the decorative sheet, and the decorative sheet being arranged on the holding portion so that the protective film is on the outside; and the cavity being provided with a protrusion to be inserted into the recess, and the protrusion being inserted into the recess. The process includes the steps of inserting the decorative sheet into the mold, sandwiching and fixing the clamping portion of the decorative sheet between the holding portion of the core and the protruding portion of the cavity, injecting resin into the mold to insert-mold a resin molded product, and removing the resin molded product from the mold. By peeling off the protective film, the surface of the resin molded product is decorated by the decorative portion, so the decorative sheet can be positioned easily and accurately, and the surface of the resin molded product can be beautifully decorated without misalignment or wrinkles. Furthermore, the amount of cutting chips generated when cutting the decorative sheet and the adhesion and damage of dirt to the surface of the decorative sheet are reduced, improving yield and reducing the manufacturing cost of decorated resin molded products.

The core holding portion is provided with a concave curved surface in the area corresponding to the decorative portion, the surface of the resin molded product is formed into a convex curved surface, and the curved surface of the resin molded product is decorated with the decorative portion, making it possible to decorate the surface of the resin molded product without causing misalignment or wrinkles.

By making the planar shape of the decorative portion of the decorative sheet circular or elliptical, it is possible to prevent the decorative sheet from shifting and to make it easier to position the decorative sheet.

1 is a perspective view of a decorative sheet used in a method for producing a resin molded product according to a first embodiment of the present invention; FIG. 2 is a cross-sectional view of a decorative sheet used in the first embodiment. FIG. 2 is a perspective view of a cavity used in the first embodiment. FIG. 2 is a perspective view of a core used in the first embodiment. 3A to 3C are cross-sectional views showing steps of a method for manufacturing a resin molded product according to the first embodiment. 3A to 3C are cross-sectional views showing steps of a method for manufacturing a resin molded product according to the first embodiment. 3A to 3C are cross-sectional views showing steps of a method for manufacturing a resin molded product according to the first embodiment. FIG. 2 is a perspective view of the resin molded product manufactured in the first embodiment before a decorative sheet is removed from the resin molded product. FIG. 2 is a perspective view of the resin molded product manufactured in the first embodiment after a decorative sheet has been removed. FIG. 11 is a perspective view of a core used in a second embodiment. FIG. 11 is a perspective view of a cavity used in the second embodiment. 6A to 6C are cross-sectional views showing steps of a method for manufacturing a resin molded product according to a second embodiment. 6A to 6C are cross-sectional views showing steps of a method for manufacturing a resin molded product according to a second embodiment. 6A to 6C are cross-sectional views showing steps of a method for manufacturing a resin molded product according to a second embodiment.

The manufacturing method of the resin molded product of the present invention will be described in detail below with reference to the drawings. First, the manufacturing method of the resin molded product of the first embodiment of the present invention will be described, starting with the decorative sheet 1 used in the first embodiment. FIG. 1 shows a perspective view of the decorative sheet 1 used in the manufacturing method of the resin molded product of the first embodiment of the present invention, and FIG. 2 shows a cross-sectional view. The manufacturing method of the resin molded product of the first embodiment will be described using a circular lid as the resin molded product 10, and a case in which decoration is applied to the surface of the lid will be described. There are no particular limitations on the use, shape, or location of the resin molded product, and the present invention can be applied to resin molded products of various uses and shapes, and the surface to be decorated is not limited to the surface as long as it is one side of the resin molded product.

The decorative sheet 1 used in the manufacturing method of the resin molded product of the first embodiment is a sheet for decorating the surface of the lid, which is the resin molded product 10, and is composed of a decorative film 2 and a protective film 3, as shown in FIG. 1. As shown in FIG. 1, the decorative film 2 is composed of a circular decorative portion 21 that matches the decorative portion of the resin molded product 10, and a clamping portion 22 that is positioned around the decorative portion 21 and has a rectangular outline, and the decorative portion 21 and the clamping portion 22 are separated by an annular cut 23.

The decorative film 2 is a film having a decorative surface on one side of which decoration is applied by printing or the like, and it is sufficient that at least the decorative portion 21 is decorated, and in some cases the clamping portion 22 may also be decorated. The shape of the decorative portion 21 is not limited to a circle, and it may be any shape that matches the decorative portion of the resin molded product 10, and it can be an oval or various other shapes. In addition, the method of decorating the decorative portion 21 is not limited, and various conventional means can be used.

The cuts 23 are lines along which the decorative film 2 is cut to match the shape of the decorative portion of the resin molded product 10. By providing the cuts 23 in the decorative film 2, after the resin molded product 10 is molded, the decorative sheet 1 can be easily removed from the resin molded product 10 while leaving the decorative portion 21 on the surface of the resin molded product 10.

One side of the protective film 3 is an adhesive surface, and the decorative film 2 is attached to the adhesive surface. The adhesive strength of the protective film 3 is sufficient to hold the decorative film 2 and to allow the decorative sheet 1 to be removed while leaving the decorative portion 21 after the resin molded product 10 is molded, and a general adhesive film can be used as the protective film 3. For example, a polyethylene film with an adhesive surface on one side can be used as the protective film 3, but the material is not particularly limited, and various films can be used, and they may be transparent, semi-transparent, or opaque. If the surface of the resin molded product is not flat, the protective film 3 needs to deform during injection molding, so in this case it is preferable to use a material that is easily deformed.

The decorative sheet 1 has the protective film 3 attached to the decorative surface of the decorative film 2, so that the decorative surface can be protected until the molding of the resin molded product 10 is completed, and defects such as the adhesion of dirt to the surface of the decorative film 2 and damage to the surface can be prevented. This improves the yield caused by defects in the decorative film that occur in the conventional manufacturing process, and makes it possible to reduce manufacturing costs.

Next, the mold used in the manufacturing method of the resin molded product of the first embodiment will be described. The mold is composed of a cavity 5 and a core 6. As shown in FIG. 3, the cavity 5 is provided with a recess 51 for inserting and arranging the decorative sheet 1. The recess 51 has the same planar shape as the decorative sheet 1 because it is provided for inserting the decorative sheet 1 and arranging it at a predetermined position relative to the cavity 5. The recess 51 is provided with a holding portion 52 for holding the decorative sheet 1 and a decorative surface molding portion 53 for molding the decorative portion of the resin molded product 10. The decorative surface molding portion 53 has a circular planar shape, and is formed into a concave curved surface in order to make the decorative portion of the resin molded product 10 a convex curved surface. The flat surface around the decorative surface molding portion 53 is the holding portion 52.

In order to securely hold the decorative sheet 1 when it is inserted into the recess 51, it is also possible to provide a suction groove in the holding portion 52. The suction groove can be arranged, for example, in a ring shape so as to surround the decorative surface molding portion 53, and by sucking the decorative sheet 1 through the suction groove, it is possible to securely hold the protective sheet 1 until the cavity 5 and the core 6 are assembled.

As shown in FIG. 4, the core 6 has a protrusion 61 that is inserted into the recess 51 of the cavity 5 when the core 6 is combined with the cavity 5. The protrusion 61 has a shape that fits into the recess 51, and as shown in FIG. 4, a molding portion 62 for molding the resin molded product 10 is provided on the surface of the tip of the protrusion 61, and a flat holding portion 63 is provided around the opening of the molding portion 62. The shape of the opening of the molding portion 62 is the planar shape of the decorative portion of the resin molded product 10 (circular in this embodiment).

When the convex portion 61 of the core 6 is inserted into the concave portion 51 of the cavity 5 to combine the core 6 with the cavity 5, the holding portion 63 of the core 6 comes into contact with the holding portion 52 of the cavity 5. At this time, as shown in FIG. 6(b), the holding portion 22 of the decorative sheet 1 is sandwiched between the holding portion 63 and the holding portion 52, thereby fixing the decorative sheet 1 in a predetermined position.

The mold is provided with a gate for injecting the resin required for sheet insert molding, but the conventional structure required for such injection molding is not shown and detailed description is omitted since various conventional mold structures can be used. The mold can be modified to various shapes and structures to match the shape of the resin molded product 10, and various patterns can be formed by engraving or other processing.

The planar shapes of the recess 51 of the cavity 5 and the protrusion 61 of the core 6 are rectangular in this embodiment, but are not particularly limited and can be changed to match the shape of the resin molded product. However, since the decorative sheet 1 needs to be positioned by inserting it into the recess 51, any shape that allows the decorative sheet 1 to be positioned is sufficient, and a circular shape is not preferable.

The shape of the decorative surface molding portion 53 at the tip of the recess 51 can be changed to match the shape of the surface of the decorative portion of the resin molded product 10. Not only a concave curved surface as in this embodiment, but also a convex curved surface is possible, as long as the shape can be changed so that the decorative sheet 1 can follow and deform during injection molding.

The manufacturing method of the resin molded product of the first embodiment of the present invention will be described. The manufacturing method of the resin molded product of the first embodiment is a manufacturing method in which the resin molded product 10, which is a lid, is insert molded using the decorative sheet 1 and the mold, and the surface of the resin molded product 10 is decorated. The decorative sheet 1 decorated with a predetermined design as shown in FIG. 1 is prepared, and as shown in FIGS. 5(a) and (b), the decorative sheet 1 is inserted into the recess 51 of the cavity 5 of the mold, and the decorative sheet 1 is placed on the surface of the holding portion 52 in the recess 51.

The decorative sheet 1 is inserted into the recess 51 with the protective film 3 facing inward and in contact with the holding portion 52 of the cavity 5. When the decorative sheet 1 is inserted into the recess 51 and placed in contact with the holding portion 52, as shown in FIG. 5(b), the decorative portion 21 of the decorative film 2 of the decorative sheet 1 is placed so as to overlap with the decorative surface forming portion 53 of the cavity 5. At this time, since the planar shape of the recess 51 of the mold and the planar shape of the decorative sheet 1 are the same, the decorative sheet 1 can be accurately placed in a predetermined position simply by checking the orientation of the decorative sheet 1 and inserting it into the recess 51, and the decorative portion 21 is accurately overlapped with the decorative surface forming portion 53. At this time, if the suction groove is provided in the holding portion 52, the decorative sheet 1 can be more reliably held and maintained.

After inserting the decorative sheet 1 into the recess 51, in order to assemble the die by combining the core 6 with the cavity 5, the convex portion 61 of the core 6 is inserted into the recess 51 of the cavity 5 as shown in Fig. 5(c) and Fig. 6(a). When the convex portion 61 is inserted into the recess 51, as shown in Fig. 6(a), the tip of the convex portion 61 comes into contact with the decorative film 2 of the decorative sheet 1, and the clamping portion 22 of the decorative sheet 1 is clamped between the holding portion 52 of the cavity 5 and the holding portion 63 of the core 6, and the decorative sheet 1 is fixed.

At this time, the decorative surface molding portion 53 provided in the recess 51 of the cavity 5 is positioned so as to overlap the opening of the molding portion 62 of the core 6 via the protective film 3 and the decorative portion 21 of the decorative sheet 1. However, since the decorative surface molding portion 53 has a concave curved surface, as shown in the cross-sectional view of Figure 6 (a), it does not abut against the decorative sheet 1, and a gap is generated between the decorative surface molding portion 53 and the protective film 3 of the decorative sheet 1. If the decorative surface molding portion 53 were flat, such a gap would not be generated.

In this way, the cavity 5 and the core 6 are combined to assemble the mold, and the cavity 5 and the core 6 are fixed together with the clamping portion 22 of the decorative sheet 1 sandwiched between the holding portion 52 of the cavity 5 and the holding portion 63 of the core 6. The decorative sheet 1 is then firmly fixed in place within the mold while being accurately positioned at a predetermined position.

After the decorative sheet 1 is fixed in the mold in this manner, resin is injected through a gate into the molding section 62 of the mold to injection mold the resin molded product 10. The resin injected into the mold from the gate is injected into the molding section 62 and presses the decorative section 21 of the decorative film 2 of the decorative sheet 1 against the decorative surface molding section 53 of the cavity 5, forming the decorative portion of the resin molded product 10 as shown in FIG. 6(b).

At this time, since the decorative portion 21 is separated from the clamping portion 22 by the cut 23, only the decorative portion 21 of the decorative film 2 deforms to match the decorative portion of the resin molded product 10, and the protective film 3 to which the decorative portion 21 is attached undergoes elastic deformation at the portion to which the decorative portion 21 is attached. In this way, the manufacturing method for resin molded products of the present invention has the effect that wrinkles are less likely to occur in the decorative film 2 when a curved surface is decorated, since the decorative portion 21 of the decorative film 2 is separated from the clamping portion 22 by the cut 23, and only the decorative portion 21 can deform while the clamping portion 22 is fixed.

Furthermore, in the manufacturing method of the resin molded product of this embodiment, since the surface of the decorative portion 21 of the decorative film 2 is protected by the protective film 3, it is possible to prevent the resin from getting around the surface of the decorative portion 21 during injection molding, and it is possible to achieve a beautifully finished decorative surface of the resin molded product 10. In addition, since the decorative portion 21 is attached to the protective film 3, it is possible to prevent the decorative portion 21 from being pushed by the resin and moving, causing misalignment.

When the injection of resin into the mold is finished and the molding of the resin molded product 10 is completed, the core 6 is removed from the cavity 5 to open the surface of the mold as shown in FIG. 7(a), and then the resin molded product 10 is removed from the cavity 5 as shown in FIG. 7(b). When the resin molded product 10 is removed, the decorative sheet 1 is attached to the resin molded product 10 as shown in FIG. 8.

When the decorative sheet 1 is removed from the resin molded product 10 in this state, the decorative portion 21 is integrally formed on the surface of the resin molded product 10, completing the resin molded product 10 in a decorated state, as shown in FIG. 9. When the decorative sheet 1 is removed from the resin molded product 10, the decorative portion 21 is removed, as shown in FIG. 9.

When removing the decorative sheet 1, the decorative portion 21 is separated by the cut 23, so that the decorative sheet 1 can be easily removed from the resin molded product 10 while leaving the decorative portion 21 on the surface of the resin molded product 10 by simply pulling the decorative sheet 1 or the resin molded product 10. Furthermore, since the edges of the decorative portion 21 on the surface of the resin molded product 10 are neatly cut, the precision and beauty of the decorative portion of the resin molded product 10 are improved compared to the conventional technology in which the decorative film is cut after resin molding, and the process of cutting the decorative film after resin molding is no longer necessary, which leads to reduced manufacturing costs.

The timing for removing the decorative sheet 1 from the resin molded product 10 does not have to be immediately after the resin molded product 10 is removed from the mold. It is also possible to use the decorative sheet 1 as a protective sheet to protect the decorated portion of the resin molded product 10 without removing it from the resin molded product 10 until a process in which the decorative sheet 1 is no longer needed.

The method for manufacturing a resin molded product of the present invention has the excellent effect of allowing decoration to be performed more easily and accurately than before by using the decorative sheet 1 and the mold. Furthermore, since the process after molding the resin molded product 10 only requires removing the decorative sheet 1, the conventional process of cutting the decorative sheet is not required. In addition, the protective film 3 protects the decorative portion 21 before and during resin molding, improving yields and thereby reducing manufacturing costs.

Next, a method for manufacturing a resin molded product according to the second embodiment will be described. The decorative sheet 1 used in the second embodiment is the same as that used in the first embodiment, so a description of the decorative sheet 1 will be omitted, and a mold used in the method for manufacturing a resin molded product according to the second embodiment will be described. The mold is composed of a core 7 and a cavity 8. As shown in FIG. 10, the core 7 is provided with a recess 71 for inserting and positioning the decorative sheet 1, and a molding portion 72 for molding the resin molded product 10 and a holding portion 73 are provided within the recess 71.

The recess 71 has the same planar shape as the decorative sheet 1 because it is provided to insert the decorative sheet 1 and place it at a predetermined position relative to the core 7. The opening of the molding part 72 is located in the recess 71, and the shape of the opening is the planar shape of the decorative part of the resin molded product 10 (circular in this embodiment). The holding part 73 is provided around the opening in the recess 71. In order to securely hold the decorative sheet 1 inserted in the recess 71, it is also possible to provide a suction groove in the holding part 73. For example, by sucking the decorative sheet 1 with the suction groove arranged in a ring shape surrounding the opening of the molding part 72, it is possible to securely hold the protective sheet 1 until the core 7 and the cavity 8 are combined.

As shown in FIG. 11, the cavity 8 has a protrusion 81 that is inserted into the recess 71 of the core 7 when the cavity 8 is combined with the core 7. The protrusion 81 has a shape that fits into the recess 71, and as shown in FIG. 11, a holding portion 82 that abuts against the holding portion 73 of the core 7 and a decorative surface molding portion 83 that closes the opening of the molding portion 72 and molds the decorative portion of the resin molded product 10 are formed on the surface of the tip of the protrusion 81. The decorative surface molding portion 83 has a circular planar shape, and is further formed into a concave curved surface in order to make the decorative portion of the resin molded product 10 a convex curved surface.

When the convex portion 81 of the cavity 8 is inserted into the concave portion 71 of the core 7 to combine the cavity 8 with the core 7, the holding portion 82 of the cavity 8 comes into contact with the holding portion 73 of the core 7. At this time, as shown in FIG. 13(b), the holding portion 22 of the decorative sheet 1 is sandwiched between the holding portion 82 and the holding portion 73, thereby fixing the decorative sheet 1 in a predetermined position.

The mold is provided with a gate for injecting the resin required for sheet insert molding, but the conventional structure required for such injection molding is not shown and detailed description is omitted since various conventional mold structures can be used. The mold can be modified to various shapes and structures to match the shape of the resin molded product 10.

The planar shapes of the recess 71 of the core 7 and the protrusion 81 of the cavity 8 are rectangular in this embodiment, but are not particularly limited and can be changed to match the shape of the resin molded product. However, since the decorative sheet 1 needs to be positioned by inserting it into the recess 71, any shape that allows the decorative sheet 1 to be positioned is sufficient, and a circular shape is not preferable.

The shape of the decorative surface molding portion 83 at the tip of the convex portion 81 can be changed to match the shape of the surface of the decorative portion of the resin molded product 10, and can be a concave curved surface as in this embodiment, as well as a convex curved surface, and can be a curved shape within the range that the decorative sheet 1 can follow and deform during injection molding, or other shapes.

A method for manufacturing a resin molded product according to a second embodiment of the present invention will be described. As with the first embodiment, the method for manufacturing a resin molded product according to the second embodiment is a manufacturing method in which the resin molded product 10, which is a lid, is insert-molded using the decorative sheet 1 and the mold, and the surface of the resin molded product 10 is decorated. The decorative sheet 1 decorated with a predetermined design as shown in FIG. 1 is prepared, and as shown in FIGS. 12(a) and (b), the decorative sheet 1 is inserted into the recess 71 of the core 7 of the mold, and the decorative sheet 1 is placed on the surface of the holding portion 73 of the recess 71.

The decorative sheet 1 is inserted into the recess 71 with the protective film 3 facing outward and the decorative film 2 abutting the holding portion 73 of the core 7. When the decorative sheet 1 is inserted and positioned in the recess 71, the decorative portion 21 of the decorative film 2 of the decorative sheet 1 is positioned so as to overlap with the opening of the molding portion 72 of the core 7, as shown in FIG. 12(b). At this time, since the planar shape of the recess 71 of the mold and the planar shape of the decorative sheet 1 are the same, the decorative sheet 1 can be accurately positioned in the specified position simply by checking the orientation of the decorative sheet 1 and inserting it into the recess 71, and the decorative portion 21 is accurately overlapped with the opening of the molding portion 72.

After inserting the decorative sheet 1 into the recess 71, in order to assemble the die by combining the cavity 8 with the core 7, the protrusion 81 of the cavity 8 is inserted into the recess 71 of the core 7 as shown in Fig. 12(c) and Fig. 13(a). When the protrusion 81 is inserted into the recess 71, as shown in Fig. 13(a), the tip of the protrusion 81 comes into contact with the protective film 3 of the decorative sheet 1, and the clamping portion 22 of the decorative sheet 1 is clamped between the holding portion 73 of the core 7 and the holding portion 82 of the cavity 8, and the decorative sheet 1 is fixed.

At this time, the decorative surface molding portion 83 provided at the tip of the convex portion 81 is positioned so as to overlap the opening of the molding portion 72 of the core 7 via the decorative portion 21 of the decorative sheet 1 and the protective film 3, but since the decorative surface molding portion 83 has a concave curved surface, it does not abut against the decorative sheet 1, as shown in the cross-sectional view of Figure 13 (a), and a gap is generated between the decorative surface molding portion 83 and the protective film 3 of the decorative sheet 1. If the decorative surface molding portion 83 were flat, such a gap would not be generated.

In this way, the core 7 and the cavity 8 are combined to assemble the mold, and the core 7 and the cavity 8 are fixed together with the clamping portion 22 of the decorative sheet 1 sandwiched between the holding portion 73 of the core 7 and the holding portion 82 of the cavity 8. The decorative sheet 1 is then firmly fixed in place within the mold while being accurately positioned at a predetermined position.

After the decorative sheet 1 is fixed in the mold in this manner, resin is injected through a gate into the molding portion 72 of the mold to injection mold the resin molded product 10. The resin injected into the mold from the gate is injected into the molding portion 72 and presses the decorative portion 21 of the decorative film 2 of the decorative sheet 1 against the decorative surface molding portion 83 of the cavity 8, forming the decorative portion of the resin molded product 10 as shown in FIG. 13(b).

At this time, the decorative portion 21 is separated from the clamping portion 22 by the cut 23, and therefore the manufacturing method of the resin molded product of the present invention has the effect that wrinkles are less likely to occur in the decorative film 2 when a curved surface is decorated. In addition, the manufacturing method of the resin molded product of the present invention has the effect that the resin is prevented from getting around the surface of the decorative portion 21 during injection molding, and the decorative surface of the resin molded product 10 can be finished neatly, because the decorative film 2 of the decorative sheet 1 is protected by the protective film 3, and further has the effect that the decorative portion 21 can be prevented from being pushed by the resin and moving, causing misalignment.

When the injection of resin into the mold is finished and the molding of the resin molded product 10 is completed, the cavity 8 is removed from the core 7 to open the surface of the mold as shown in FIG. 14(a), and then the resin molded product 10 is removed from the recess 71 of the core 7 as shown in FIG. 14(b). When the resin molded product 10 is removed, the decorative sheet 1 is attached to the resin molded product 10 as shown in FIG. 8.

After this, similar to the first embodiment, when the decorative sheet 1 is removed from the resin molded product 10, the resin molded product 10 is completed with the decorative portion 21 integrally molded on the surface and decorated, as shown in FIG. 9. The decorative sheet 1 removed from the resin molded product 10 is in a state where the decorative portion 21 has been removed, as shown in FIG. 9.

When removing the decorative sheet 1, the incision 23 allows the protective film 3 and the clamping portion 22 of the decorative film 2 to be easily and neatly removed from the resin molded product 10 simply by pulling the decorative sheet 1 or the resin molded product 10.

The decorative sheet 1 can be removed from the resin molded product 10 at various times, such as immediately after the resin molded product 10 is removed from the mold, or at a process in which the decorative sheet 1 is no longer needed.

REFERENCE SIGNS LIST 1 Decorative sheet 2 Decorative film 21 Decorative portion 22 Clamping portion 23 Cutout 3 Protective film 5, 8 Cavity 51, 71 Recess 52, 73 Holding portion 53, 83 Decorative surface molding portion 6, 7 Core 61, 81 Convex portion 62, 72 Molding portion 63, 82 Holding portion 10, 10' Resin molded product

Claims (4)

A method for manufacturing a resin molded product in which one surface of the resin molded product is decorated by insert molding using a decorative sheet, comprising:
A step of preparing a decorative sheet having a decorative film having a decorative portion and a sandwiching portion located around the decorative portion, the decorative portion and the sandwiching portion separated by a cut formed therein, and a protective film attached to a decorative surface of the decorative film;
a step of placing the decorative sheet in a mold having a cavity and a core, the cavity being provided with a recess, the recess being provided with a holding portion for holding the decorative sheet, and the decorative sheet being placed on the holding portion so that the protective film faces inward and is in contact with the holding portion of the cavity;
a step of inserting the protrusion into the recess of the core, the protrusion having a molding portion for molding a resin molded product, the step of inserting the protrusion into the recess and clamping and fixing the clamping portion of the decorative sheet between the holding portion of the cavity and the protrusion of the core;
A step of insert-molding a resin molded product by injecting a resin into the mold;
and removing the resin molded product from the mold.
By peeling off the protective film, the surface of the resin molded product is decorated by the decoration portion ,
Since the sandwiching portion and the notch are formed in the decorative sheet, when the decorative sheet is removed from the resin molded product after molding, the protective film and the sandwiching portion can be removed.
A method for producing a resin molded product , wherein the planar shape of the decorative portion of the decorative sheet is circular or elliptical . The method for manufacturing a resin molded product according to claim 1, characterized in that the holding portion of the cavity is provided with a concave curved surface in a portion corresponding to the decorative portion, the surface of the resin molded product is formed into a convex curved surface, and the curved surface of the resin molded product is decorated with the decorative portion. A method for manufacturing a resin molded product in which one surface of the resin molded product is decorated by insert molding using a decorative sheet, comprising:
A step of preparing a decorative sheet having a decorative film having a decorative portion and a sandwiching portion located around the decorative portion, the decorative portion and the sandwiching portion separated by a cut formed therein, and a protective film attached to a decorative surface of the decorative film;
a step of placing the decorative sheet in a mold having a core and a cavity, the core being provided with a recess, the recess being provided with a molding section for molding the resin molded product and a holding section for holding the decorative sheet, the decorative sheet being placed on the holding section with the protective film facing outward and the decorative film abutting against the holding section of the core;
a step of inserting the protrusion into the recess in the cavity, and clamping and fixing the clamping portion of the decorative sheet between the holding portion of the core and the protrusion of the cavity;
A step of insert-molding a resin molded product by injecting a resin into the mold;
and removing the resin molded product from the mold.
By peeling off the protective film, the surface of the resin molded product is decorated by the decoration portion ,
Since the sandwiching portion and the notch are formed in the decorative sheet, when the decorative sheet is removed from the resin molded product after molding, the protective film and the sandwiching portion can be removed.
A method for producing a resin molded product , wherein the planar shape of the decorative portion of the decorative sheet is circular or elliptical . A method for manufacturing a resin molded product as described in claim 3, characterized in that a concave curved surface is provided in the holding portion of the core corresponding to the decorative portion , a convex curved surface is formed on the surface of the resin molded product, and the curved surface of the resin molded product is decorated by the decorative portion.