JP2021074956A - Manufacturing method of resin molded product - Google Patents

Abstract

To provide a protrusion forming part protruding from the other side of a resin base material while forming a good coating layer on one side of the resin base material.SOLUTION: After a resin raw material is injected into a first cavity formed between a mold-closed first core mold 12 and a first cavity mold 16 to mold a resin base material, the first core mold 12 and the first cavity mold 16 are opened so that the resin base material remains in the first core mold 12, and a surface of the resin base material is exposed to an outside air. Next, a paint is injected into a second cavity formed by closing the first core mold 12 and a second cavity mold 18 to mold a coating layer, and the first core mold 12 and the second cavity mold 18 are opened so that the resin base material on which the coating layer is formed remains in the second cavity mold 18, and a back surface of the resin base material is exposed to an outside air. After that, the resin raw material is injected into a third cavity formed by closing the second cavity mold 18 and a second core mold 14, and a fitting part is molded.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a resin molded product, which has a coating layer on the front surface side and is provided on the back surface side so that a protruding portion such as a mounting portion protrudes.

Resin whose surface is painted for the purpose of decorating and protecting the target members for various vehicles such as automobiles, ships, and aircraft, building materials for buildings such as houses, and furniture such as chairs and sofas. Molded products may be provided. For example, such resin molded products are widely used as decorative members for decorating the exterior of vehicles such as pillar outer garnishes and roof garnishes of vehicles such as automobiles, or as decorative members for decorating the interior of vehicles such as instrument panels and door trims. Has been done. Although the coating layer of such a resin molded product can be easily formed by applying a paint to the surface of the resin base material formed by injection molding by using a spray method, a dipping method, or the like. With such a method, it becomes difficult to form a coating layer having a uniform thickness. Therefore, for example, as in Patent Document 1, an injection-molded resin base material is installed in a molding mold so that a gap is left on the coated surface side, and an in-mold coating (in-molding coat) in which paint is injected into the gap is provided. ) Etc. In such in-mold coating, a resin molded product in which a coating layer is formed with a uniform thickness on the coating surface of the resin base material can be obtained by appropriately adjusting the gap formed on the coating surface side (for example, Patent Document). 1).

Japanese Unexamined Patent Publication No. 2009-101670

By the way, the above-mentioned resin molded product is formed so that a mounting portion used for mounting on a mounting target such as a panel of a vehicle body, a reinforcing portion for reinforcing, and the like project toward the back surface side of the resin base material. There is. Such a protruding portion protruding from the back surface of the resin base material can be formed separately from the resin base material and fixed by adhesion or the like, or can be formed by integrally molding with the resin base material. However, when the protruding portion formed separately from the resin base material is fixed by adhesion, there is a problem that the resin base material and the protruding portion are separated due to poor adhesion or deterioration of the bonded portion with time. It can happen. On the other hand, when the resin base material and the projecting portion are integrally molded by injection molding, the detachment problem caused by such poor adhesion can be prevented, but in injection molding, the molten resin cools and hardens. It is known that by shrinking with, a concave molding defect called a sink mark occurs on the surface side of a portion having irregularities such as a portion where a protrusion-shaped forming portion is formed. When such sink marks appear on the surface of the resin base material, the form of the sink marks is transferred to the coating layer formed on the surface side and the coating layer becomes wavy, or the thickness of the coating layer becomes uneven and the decoration such as gloss is formed. It was a factor that impaired sex. Such sink marks can be suppressed by applying so-called "meat theft" that thins the root portion of the protruding portion, but thinning causes a decrease in the strength of the protruding portion and meat. It is difficult to completely prevent sink marks even when stolen.

That is, the present invention provides a method for producing a resin molded product capable of forming a good coating layer on one surface of a resin base material and providing a protruding portion protruding from the other side of the resin base material. The purpose.

In order to overcome the above-mentioned problems and achieve the intended purpose, the invention according to claim 1 of the present application is:
A method for producing a resin molded product having a coating layer on one surface of a resin base material and a protruding portion protruding from the other surface.
The first step of molding the resin base material by closing the first mold and the second mold and injecting the resin raw material into the first cavity formed between the first mold and the second mold. ,
A second step of opening the first mold and the second mold so that the resin base material remains on the first mold side and exposing one surface of the resin base material to the outside air.
The first mold and the third mold in which the resin base material remains are closed, and the paint is injected into the second cavity formed between one surface of the resin base material and the third mold to paint the coating. The third step of forming the layer and
A fourth step of opening the first and third molds so that the resin base material having the coating layer formed on the third mold side remains, and exposing the other surface of the resin base material to the outside air.
The third mold and the fourth mold in which the resin base material remains are closed, and the resin raw material is injected into the third cavity formed between the other surface of the resin base material and the fourth mold. The gist is to include a fifth step of forming the projecting portion.
In this way, after the resin raw material is injected into the first cavity formed between the first mold and the second mold to form the resin base material, between the surface of the resin base material and the third cavity mold. The paint is injected into the second cavity formed in the above to form a coating layer, and then the resin raw material is injected into the third cavity formed between the other surface of the resin base material and the fourth mold to project. By molding the shape-forming portion, it is possible to effectively prevent sink marks on the resin base material at the formation position of the protrusion-shaped forming portion. Therefore, the coating layer can be formed on the resin base material in a good state, and the appearance finish (appearance) of the resin molded product can be improved. Further, by exposing the coating layer forming surface (one surface) of the resin base material to the outside air before molding the coating layer, the coating layer forming surface can be cooled by the outside air to promote curing. A coating layer can be formed on the cured resin base material in a good state. Similarly, by exposing the forming surface (the other surface) of the protruding portion of the resin base material to the outside air before molding the protruding portion, the forming surface (the other surface) of the protruding portion is exposed to the outside air. Since it can be cooled to promote curing, it is possible to effectively prevent sink marks on the resin base material during molding of the projecting portion. In this way, when molding a resin molded product, it is divided into a step of molding the resin base material, a step of forming a coating layer, and a step of molding a protruding portion, and a step before each step is performed. By exposing the surface forming the coating layer and the protruding portion to the outside air, the appearance finish (appearance) can be improved.

The invention according to claim 2 is
In the first step, the resin base material is molded by a first mold provided with a slide core for forming an undercut portion.
When the first mold and the third mold are opened in the fourth step, the slide core of the first mold is projected so as to press the resin base material on which the coating layer is formed against the third mold side. Is the gist.
In this way, by molding the resin base material using the first mold provided with the slide core for molding the undercut shape portion, the first mold and the second mold were opened after the molding of the resin base material. At that time, the resin base material can be reliably held on the first mold side. Further, when the first mold and the third mold on which the coating layer is formed are opened (fourth step), the slide core is projected so as to press the resin base material on which the coating layer is formed against the third mold side. Therefore, the resin base material on which the coating layer is formed can be reliably held by the third mold.

The invention according to claim 3 is
The gist of the third step is to inject a paint made of a thermosetting resin into the second cavity while heating the third mold to form the coating layer.
In this way, by using a paint made of thermosetting resin and injecting the paint into the second cavity while heating the third mold to form the paint layer, the curing of the paint is promoted and the resin molded product The cycle time until demolding can be shortened.

According to the present invention, it is possible to produce a resin molded product in which a good coating layer is formed on one surface of a resin base material and a protruding portion is provided so as to protrude from the other side surface of the resin base material.

It is the schematic of the molding die for molding the resin molded article which concerns on this invention. It is explanatory drawing which shows the manufacturing process of a resin molded article, (a) shows the state which formed the 1st cavity by closing the 1st core mold and 1st cavity mold, (b) is the 1st It shows a state in which a resin is injected into one cavity to form a resin base material. It is explanatory drawing which shows the manufacturing process of a resin molded article, (a) shows the state which the 1st core mold and 1st cavity mold were opened after the formation of a resin base material, and (b) is a resin group. It shows a state in which the second cavity mold faces the first core mold that holds the material. It is explanatory drawing which shows the manufacturing process of a resin molded article, (a) shows the state which formed the 2nd cavity by closing a 1st core mold and a 2nd cavity mold, (b) is the 1st It shows a state in which a paint is injected into two cavities to form a paint layer. It is explanatory drawing which shows the manufacturing process of a resin molded article, (a) shows the state which the 1st core mold and 2nd cavity mold were opened after the coating layer was formed, and (b) is the coating layer. It shows a state in which the second cavity mold holding the formed resin base material faces the second core mold. It is explanatory drawing which shows the manufacturing process of a resin molded article, (a) shows the state which formed the 3rd cavity by closing the 2nd core mold and the 2nd cavity mold, and (b) is the 1st 3 The state in which the resin is injected into the cavity to form the mounting portion is shown. It is explanatory drawing which shows the manufacturing process of the resin molded article, (a) shows the state which the 2nd core mold and the 2nd cavity mold were opened after the formation of the mounting part, and (b) is the molded resin. It shows a state in which the base material is removed from the second core mold. (a) is a schematic perspective view showing the resin molded product as viewed from the front side, and (b) is a schematic perspective view showing the resin molded product as viewed from the back side. It is sectional drawing which broke the resin molded article at the formation position of the attachment part and the extension part.

Next, a method for producing the resin molded product 100 according to the present invention will be described below with reference to the accompanying drawings with reference to suitable examples. In this embodiment, as shown in FIGS. 8 and 9, a pillar garnish that is attached to and decorated on the outer surface of a pillar (attachment target) of an automobile as a resin molded product 100 will be described as an example. In this resin molded product 100, the resin base material 102 is formed in a dish shape in which the peripheral wall 106 extends from the outer peripheral edge of the flat plate portion 104 to the back surface side (the surface side facing the mounting target side), and the resin base is formed. The coating layer 110 is provided on the front surface side (the surface side facing the side opposite to the mounting target) of the material 102 (plate portion 104 and the peripheral wall 106), and the resin base material 102 (plate portion 104) is mounted on the back surface side. A mounting portion (protruding portion) 112 for mounting is formed. Further, the resin base material 102 is provided with an undercut-shaped extending portion 106a that extends toward the peripheral wall 106 side facing the end portion of the peripheral wall 106 at an appropriate position, and the extending portion 106a is resin-molded. It is a portion that functions as an engaging portion that leaves the resin base material 102 in the molding die (first core die 12 described later) when the product 100 is molded. Further, the mounting portion 112 is provided with a connecting wall 112a that is connected so as to project to the back surface side of the plate portion 104, and an undercut-shaped extending wall 112b that extends in the intersecting direction from the protruding end of the connecting wall 112a. The mounting portion 112 is a portion that functions as an engaging portion that leaves the resin base material 102 in the molding die (second core mold described later) when the resin molded product 100 is molded.

As shown in FIG. 1, the molding mold 10 for molding the resin molded product 100 is a first core mold (first mold) 12 and a second core mold (fourth mold) for molding the back surface side of the resin molded product 100. ) 14, A first cavity mold (second mold) 16 and a second cavity mold (third mold) 18 for molding the surface side of the resin molded product 100. The first cavity mold 16 and the second cavity mold 18 are supported by a common support plate 20 on the side opposite to the molding surfaces 16a and 18a, and the first cavity mold 16 is seconded by a driving means (not shown). The first position where the second cavity type 18 faces the second core type 14 and the second position where the second cavity type 18 faces the first core type 12 and the second position where the second cavity type 18 faces the first core type 12. It is configured to be movable to. Further, the first cavity mold 16 and the second cavity mold 18 face a mold opening position away from the first core mold 12 and the second core mold 14 facing each other by another driving means (not shown). It is configured to be movable to a mold closing position where the cavities C1, C2 and C3 are formed by the core mold 12 of 1 and the core mold 14 of the second core.

As shown in FIG. 1, the first core mold 12 is a first slide core provided so as to be slidable at a molding position and a protruding position with respect to the first mold main body 22 and the first mold main body 22. 24 is provided, and a molding surface 22a for molding the back surface of the resin base material 102 is formed on the first mold body 22, and an undercut of the resin base material 102 is formed between the first mold body 22 and the first mold body 22. An undercut molding surface 24a for molding the shape portion (extending portion 106a) is formed on the first slide core 24. The first cavity mold 16 is formed with a molding surface 16a for molding the surface of the resin base material 102 (plate portion 104, peripheral wall 106). That is, when the first cavity mold 16 is closed with respect to the first core mold 12, the molding surface 22a of the first core mold 12 (the first mold body 22 and the first slide core 24) is formed. A first cavity C1 is formed between the 24a and the molding surface 16a of the first cavity mold 16 (see FIG. 2A), and the molten resin injected into the first cavity C1 is cured to form a resin group. The material 102 (plate portion 104, peripheral wall 106, and extension portion 106a) is formed. The resin base material 102 formed in the first cavity C1 is in a state in which the extending portion 106a is engaged with the undercut molding surface 24a of the first slide core 24, and the first is caused by the engaging state. The resin base material 102 is held by the core mold 12 of the above (see FIG. 3A).

Here, the first slide core 24 is connected to a driving means (not shown) via a shaft body 24b, and can be projected in a direction inclined with respect to the first mold body 22. That is, by moving the first slide core 24 so as to protrude from the molding position where the resin base material 102 is molded toward the protruding position, the resin base material 102 is pushed away from the first mold body 22 and at the same time. The undercut molded surface 24a of the first slide core 24 moves away from the extending portion 106a of the resin base material 102 to release the engagement state, and the resin base material 102 is separated from the first core mold 12. It is designed to be obtained (see FIG. 5 (a)).

Further, in the lower part of the first cavity mold 16, a first resin flow path 30 (sprue, runner, gate) connected to the first cavity C1 is formed between the first core mold 12 (mold body). The first flow path forming recess 26 is formed, and the resin melted from the resin supply unit (not shown) is passed through the first resin flow path 30 formed by closing the mold at the first position. It can be injected into the first cavity C1. Then, in the upper part of the first cavity mold 16, a first escape that forms a first escape space 32 connected to the first cavity C1 with the first core mold 12 (first mold main body 22) is formed. The recess 28 is formed, and bubbles that are mixed when the molten resin is injected into the first cavity C1 or generated when the molten resin is cured in the first cavity C1 can be released to the first escape space 32. It has become like. The resin portion that is cured in the first resin flow path 30 and the first relief space 32 and is connected to the resin base material 102 is a portion that is cut and removed as an unnecessary resin portion in post-processing after molding. In the following, the resin portion that is cured in the first resin flow path 30 and connected to the resin base material 102 may be referred to as the flow path cured resin M.

As shown in FIG. 1, when the molding surface 18a of the second cavity mold 18 is closed with respect to the first core mold 12, the first core mold 12 (the first mold body 22 and the first mold body 22) The molding surface 22a of the first core mold 12 is located at a position where the molding surface 16a of the first cavity mold 16 is positioned with respect to the molding surfaces 22a and 24a of the slide core 24) (see FIG. 2A). , 24a is formed so as to be positioned at a position away from it. That is, the second cavity mold 18 is closed to the first core mold 12 in a state where the resin base material 102 formed with the first cavity mold 16 is held by the first core mold 12. A second cavity C2 is formed between the surface of the resin base material 102 and the molding surface 18a of the second cavity mold 18, and the paint injected into the second cavity C2 is cured to cure the resin base material 102. The coating layer 110 is formed on the surface of the above (see FIG. 4A).

Then, in the lower part of the second cavity mold 18, there is a second cavity C2 between the flow path curing resin M connected to the resin base material 102 held in the first core mold 12 (first mold main body 22). A second flow path forming recess 34 forming a connecting second resin flow path 38 (sprue, runner, gate) is formed, and a second resin flow path is formed by closing the mold at the second position. The paint can be injected into the second cavity C2 from the paint supply unit via 38. Further, in the upper part of the second cavity mold 18, a second escape space 40 connected to the second cavity C2 is connected to the resin base material 102 held in the first core mold 12 (first mold main body 22). A second escape recess 36 is formed, and air bubbles generated when the paint is injected into the second cavity C2 or when the paint is cured in the second cavity C2 are introduced into the second escape space. It is designed to escape to 40. That is, with the second cavity mold 18 closed to the first core mold 12, the molding surface 18a of the second cavity mold 18, the second flow path forming recess 34, and the second relief recess On the first core mold 12 side of the 36, a resin portion (resin base material 102, flow path curing resin M, first) formed at the time of molding in which the first core mold 12 and the first cavity mold 16 are closed. The resin portion that is cured in the escape space 32 of 1 and is connected to the resin base material 102) is located, and the paint injected into the second cavity C2 is the first core mold 12 (the first mold body 22, the first mold body 22). The slide core 24) is not touched. Further, the second cavity type 18 is provided with a heating means such as a heater (not shown) so as to be able to accelerate the curing of the paint injected into the second cavity C2.

As shown in FIG. 1, the second core mold 14 is provided with a second mold main body 42 and a second slide core slidably provided at a molding position and a protruding position with respect to the second mold main body 42. It is equipped with 46. The second mold body 42 has an abutting portion that abuts on the back surface of the resin base material 102 when the second cavity mold 18 holding the resin base material 102 is closed with respect to the second core mold 14. 44 is provided, and a molding surface 44a for forming one side surface of the connecting wall 112a forming the mounting portion 112 (the outer surface opposite to the extending wall 112b in the embodiment) is formed in the abutting portion 44. There is. Further, the second slide core 46 abuts on the back surface of the resin base material 102 at the molding position, and undercuts the undercut-shaped portion (extending wall 112b) of the mounting portion 112 with the abutting portion 44. A molding surface 46a is formed. That is, when the second cavity mold 18 holding the resin base material 102 is closed with respect to the second core mold 14, the second core mold is closed by the back surface of the resin base material 102. A third cavity C3 is formed between the molding surface 44a of the abutting portion 44 of 14 and the molding surface 46a of the second slide core 46 (see FIG. 6A), and the melt injected into the third cavity C3 is formed. By curing the resin, the mounting portion 112 (connecting wall 112a, extending wall 112b) is formed. A resin flow path (sprue, runner, gate) (not shown) connected to the third cavity C3 is formed in the mold body of the second core mold 14, and melts from the resin supply portion via the resin flow path. The resin can be injected into the third cavity C3. Then, the resin base material 102 on which the mounting portion 112 is formed in the third cavity C3 is in a state in which the mounting portion 112 (extending wall 112b) is engaged with the undercut molding surface 46a of the second slide core 46. The resin base material 102 is held by the second core mold 14 depending on the engaged state (see FIG. 7A).

Here, the second slide core 46 is connected to a driving means (not shown) via a shaft body 46b, and can be projected in a direction inclined with respect to the mold body of the second core mold 14. That is, by moving the second slide core 46 so as to protrude from the molding position for molding the resin base material 102, the resin base material 102 is pushed away from the second mold body 42, and the second slide core is pushed out. The undercut molding surface 46a of the 46 moves away from the extending wall 112b of the mounting portion 112 to release the engaging state, so that the resin base material 102 can be separated from the second core mold 14. ..

Next, the method for producing the resin molded product 100 according to the present invention will be described using the molding mold 10 described above. First, as shown in FIG. 2A, the first cavity mold 16 is moved from the mold opening position to the mold closing position at the first position, and the mold is closed with respect to the first core mold 12, and the first A first cavity C1 is formed between the core mold 12 and the first cavity mold 16. Then, as shown in FIG. 2B, in this state, the resin was melted from the resin supply portion via the first resin flow path 30 formed between the first core mold 12 and the first cavity mold 16. The resin is injected into the first cavity C1 and the injected resin is cured to form a resin base material 102 having a plate portion 104, a peripheral wall 106, and an extending portion 106a (first step). Here, the resin that is injected into the first cavity C1 to form the resin base material 102 is not particularly limited, and a thermoplastic resin suitable for the application of the resin molded product 100 can be used. In particular, by using a polar resin such as acrylonitrile-butadiene-styrene (ABS) or polycarbonate (PC), or a mixed resin of polycarbonate and acrylonitrile-butadiene-styrene (PC / ABS), it is laminated on the surface side of the resin base material 102. It is possible to effectively prevent the formed coating layer 110 from peeling off and maintain a good state.

Next, as shown in FIG. 3A, the first cavity mold 16 is moved from the mold closing position to the mold opening position so that the resin base material 102 remains on the molding surfaces 22a and 24a of the first core mold 12. And open the mold (second step). At this time, the first slide core 24 of the first core mold 12 is held at the molding position. That is, the resin base material 102 formed in the first cavity C1 has an undercut-shaped extending portion 106a, and the extending portion 106a undercuts the first slide core 24 of the first core mold 12. By opening the mold in a state of being engaged with the molding surface 24a, the resin base material 102 can be held by the first slide core 24 and can be reliably left on the molding surfaces 22a and 24a of the first core mold 12. .. After that, the first cavity mold 16 and the second cavity mold 18 are moved to the second position, and the molding surface 18a of the second cavity mold 18 faces the first core mold 12.

As shown in FIGS. 3 (b) and 4 (a), the second cavity mold 18 is moved from the mold opening position to the mold closing position at the second position and the mold is closed with respect to the first core mold 12. The second cavity C2 is formed between the surface of the resin base material 102 held by the first core mold 12 and the molding surface 18a of the second cavity mold 18. Then, as shown in FIG. 4B, a second resin flow path formed between the surface of the flow path curing resin M and the second flow path forming recess 34 of the second cavity type 18 in this state. The paint is injected into the second cavity C2 from the paint supply unit via 38, and the injected paint is cured to form the coating layer 110 on the surface of the resin base material 102 (third step). Here, the paint is not particularly limited, and a paint suitable for the intended use of the resin molded product 100 can be used, and an epoxy resin paint, a urethane resin paint, an acrylic resin paint, or the like can be preferably used. In particular, by using a polar resin such as a urethane resin paint, it is possible to effectively prevent peeling of the coating layer 110 laminated on the surface side of the resin base material 102 and maintain a good state, and at the same time, it is brilliant. It is possible to form a coating layer 110 having excellent gloss and a coating layer 110 having high weather resistance. Further, as the urethane resin paint, a two-component type in which a polyol and a polyisocyanate are mixed is preferable. By using such a two-component urethane resin paint, it is possible to suppress the influence of climate and the like on the curing of the paint and maintain a constant coating state. Further, it is preferable to use a paint made of a thermosetting resin raw material as the paint. By adopting a paint made of a thermosetting resin raw material, the second cavity mold 18 is heated by a heating means such as a heater to accelerate the curing of the paint and to remove the resin molded product 100. A coating layer 110 can be formed between them, and the molding cycle can be shortened.

Next, as shown in FIG. 5A, the second cavity mold 18 is molded from the mold closing position so that the resin base material 102 on which the coating layer 110 is formed remains on the molding surface 18a side of the second cavity mold 18. It moves to the opening position and opens the mold with respect to the first core mold 12 (fourth step). At this time, the first slide core 24 of the first core mold 12 moves in a direction inclined with respect to the first mold main body 22 toward the protruding position. That is, by opening the second cavity mold 18 so as to project the first slide core 24, the engagement state between the extending portion 106a of the resin base material 102 and the first slide core 24 is released. While the first slide core 24 moves so as to press the resin base material 102 against the molding surface 18a side of the second cavity mold 18, the resin base material 102 is reliably pressed against the molding surface 18a side of the second cavity mold 18. Can be left. Further, the mold opening of the second cavity mold 18 with respect to the first core mold 12 is performed before the paint injected into the second cavity C2 is completely cured. By performing this before the coating material is completely cured, the resin base material 102 can be adhered to the molding surface 18a side of the second cavity type 18 by the van der Waals force of the coating material. The second cavity mold 18 can be opened while leaving the resin base material 102 on the molding surface 18a side. Further, from the paint supply portion to the second cavity C2 via the second resin flow path 38 formed between the surface of the flow path curing resin M and the second flow path forming recess 34 of the second cavity type 18. By injecting the paint and preventing the paint from touching the first core mold 12, the injected paint does not adhere to the first core mold 12, and the molding surface of the second cavity mold 18 is formed. The second cavity mold 18 can be opened while reliably leaving the resin base material 102 on the 18a side. After that, the first cavity mold 16 and the second cavity mold 18 are moved to the first position, and the molding surface 18a of the second cavity mold 18 faces the second core mold 14 (see FIG. 5 (b)). ).

As shown in FIG. 6A, the second cavity mold 18 is moved from the mold opening position to the mold closing position at the first position, the mold is closed with respect to the second core mold 14, and the second mold main body is formed. The abutting portion 44 of the abutting portion 44 and the second slide core 46 are abutted against the back surface of the resin base material 102 held in the second cavity mold 18, and the molding surface 44a of the abutting portion 44 and the underside of the second slide core 46 are abutted. A third cavity C3 is formed between the cut and molded surface 46a. In this state, as shown in FIG. 6B, the resin melted from the resin supply unit is injected into the third cavity C3 via a resin flow path (not shown) provided in the second core mold 14, and the injected resin is injected. To form the mounting portion 112 on the back surface of the resin base material 102 (fifth step). The resin that is injected into the third cavity C3 to form the resin base material 102 is not particularly limited, and a resin suitable for the intended use of the resin molded product 100 can be used, and acrylonitrile-butadiene-styrene (ABS), A thermoplastic resin such as polycarbonate (PC) can be preferably used. Here, by using the same resin material as the resin base material 102, the mounting portion 112 can be effectively bonded to the back surface of the resin base material 102.

Next, as shown in FIG. 7A, the second cavity mold 18 is moved from the mold closing position to the mold opening position so that the resin base material 102 on which the mounting portion 112 is formed remains on the second core mold 14 side. Then, the mold is opened with respect to the second core mold 14. At this time, the second slide core 46 is held at the molding position. That is, the mounting portion 112 formed in the third cavity C3 has an undercut-shaped extending wall 112b, and the extending wall 112b undercuts the second slide core 46 of the second core mold 14. By opening the mold in a state of being engaged with the surface 46a, the resin base material 102 can be held by the second slide core 46 and can be reliably left on the second core mold 14 side. The mold opening of the second cavity mold 18 with respect to the second core mold 14 is performed after the coating layer 110 is cured. Here, by heating the second cavity type 18 with a heating means such as a heater and forming the coating layer 110 with the coating material made of a thermosetting resin raw material, the curing of the coating material can be promoted. It is possible to shorten the molding cycle by shortening the time from injecting the paint into the two cavities C2 until the second cavity mold 18 is opened with respect to the second core mold 14.

Then, as shown in FIG. 7B, after the second cavity mold 18 is opened with respect to the second core mold 14, the second slide core 46 is directed toward the protruding position and the second mold main body is formed. It moves in a direction inclined with respect to 42. That is, by projecting the second slide core 46, the second slide core 46 can be disengaged from the extension wall 112b of the mounting portion 112 and the slide core of the second core mold 14. By pushing the resin base material 102 away from the second core mold 14, the resin base material 102 forming the mounting portion 112 is removed from the second core mold 14. Then, after the mold is removed, the unnecessary resin portion (the flow path cured resin M or the resin portion cured in the first escape space 32) connected to the resin base material 102 is cut and removed by a cutting device (not shown) or the like to remove the resin. A resin molded product 100 having a coating layer 110 on the front surface of the base material 102 and a mounting portion 112 protruding from the back surface can be obtained (see FIG. 9).

In this way, after the resin raw material is injected into the first cavity C1 formed between the first core mold 12 and the first cavity mold 16 to form the resin base material 102, the surface of the resin base material 102 is formed. The paint is injected into the second cavity C2 formed between the and the second cavity mold 18 to form the coating layer 110, and then between the back surface of the resin base material 102 and the second core mold 14. By injecting the resin raw material into the third cavity C3 formed in the above and molding the mounting portion 112 so as to protrude from the resin base material 102, sink marks occur in the resin base material 102 at the forming position of the mounting portion 112. Can be effectively prevented. Therefore, the coating layer 110 formed on the surface of the resin base material 102 can be formed with a uniform thickness, and the appearance finish (appearance) of the resin molded product 100 can be improved.

Here, before molding the coating layer 110, the first core mold 12 and the first cavity mold 16 are opened so that the resin base material 102 remains in the first core mold 12, and the resin base material 102 is formed. The forming surface (surface) of the coating layer 110 comes into contact with the outside air. As a result, the surface of the resin base material 102 on which the coating layer 110 is formed can be cooled by the outside air to promote curing, so that the coating layer 110 formed on the surface of the resin base material 102 can have a uniform thickness. it can. Further, before molding the mounting portion 112, the first core mold 12 and the second cavity mold 18 are opened so that the resin base material 102 on which the coating layer 110 is formed remains in the second cavity mold 18. The forming surface (back surface) of the mounting portion 112 on the resin base material 102 comes into contact with the outside air. As a result, the surface of the resin base material 102 on which the mounting portion 112 is formed can be cooled by the outside air to promote curing, so that it is possible to effectively prevent sink marks on the resin base material 102 during molding of the mounting portion 112. .. As described above, when the resin molded product 100 is molded, it is divided into a step of molding the resin base material 102, a step of forming the coating layer 110, and a step of molding the mounting portion 112, and before each step is performed. By exposing the surface forming the coating layer 110 and the mounting portion 112 to the outside air at the stage of, the finish (appearance) of the appearance can be improved.

Further, by molding the resin base material 102 using the first core mold 12 provided with the first slide core 24 for molding the undercut shape portion, the first core mold is formed after the resin base material 102 is molded. When the 12 and the first cavity mold 16 are opened, the resin base material 102 can be reliably held on the first core mold 12 side. Further, when the first core mold 12 and the second cavity mold 18 formed by the coating layer 110 are opened (fourth step), the resin base material 102 on which the coating layer 110 is formed is placed in the second cavity. By projecting the first slide core 24 so as to press against the molding surface 18a side of the mold 18, not only the van der Waals force of the paint but also the resin base material in which the coating layer 110 is formed by the protrusion of the first slide core 24. The 102 can be reliably held on the molding surface 18a of the second cavity mold 18.

Further, using a paint made of a thermosetting resin raw material, the paint is injected into the second cavity C2 while heating the second cavity mold 18 to form the paint layer 110, thereby promoting the curing of the paint. The cycle time until the resin molded product 100 is removed from the mold can be shortened.

(Change example)
The embodiment is not limited to the above-described embodiment, and can be changed as follows, for example.
(1) In the embodiment, the first cavity type 16 and the second cavity type 18 are supported by the support plate 20, moved to the first position and the second position by a common driving means, and the first core. The mold 12 and the second core mold 14 are configured to be mold-closed and mold-openable, but the first cavity mold 16 and the second cavity mold 18 are provided independently, and each is provided by an individual driving means. You may want to move.
(2) In the embodiment, the first cavity type 16 and the second cavity type 18 are moved to the first position and the second position so that the facing core type and the cavity type are exchanged. The core mold and the cavity mold facing each other may be exchanged by moving the mold 12 and the second core mold 14.

12 1st core type (1st type), 14 2nd core type (4th type)
16 1st cavity type (2nd type), 18 2nd cavity type (3rd type)
24 1st slide core, 102 resin base material, 110 coating layer 112 mounting part (protruding part), C1 1st cavity, C2 2nd cavity C3 3rd cavity

Claims (3)

A method for producing a resin molded product having a coating layer on one surface of a resin base material and a protruding portion protruding from the other surface.
The first step of molding the resin base material by closing the first mold and the second mold and injecting the resin raw material into the first cavity formed between the first mold and the second mold. ,
A second step of opening the first and second molds so that the resin base material remains in the first mold and exposing one surface of the resin base material to the outside air.
The first mold and the third mold in which the resin base material remains are closed, and the paint is injected into the second cavity formed between one surface of the resin base material and the third mold to paint the coating. The third step of forming the layer and
A fourth step of opening the first and third molds so that the resin base material having the coating layer formed on the third mold remains, and exposing the other surface of the resin base material to the outside air.
The third mold and the fourth mold in which the resin base material remains are closed, and the resin raw material is injected into the third cavity formed between the other surface of the resin base material and the fourth mold. A method for producing a resin molded product, which comprises a fifth step of molding a projecting portion. In the first step, the resin base material is molded by a first mold provided with a slide core for forming an undercut portion.
When the first mold and the third mold are opened in the fourth step, the slide core of the first mold is projected so as to press the resin base material on which the coating layer is formed against the third mold side. The method for producing a resin molded product according to claim 1. The third step according to claim 1 or 2, wherein a coating material made of a thermosetting resin is injected into the second cavity while heating the third mold to form the coating layer. A method for manufacturing a resin molded product.

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