Injection head for in-mold coating, and injection machine

Abstract

Provided is an injection head for in-mold coating capable of suppressing bubble entrainment during collision mixing while using two or more coating materials. The injection head for in-mold coating is for injecting two or more coating materials into a coating film cavity defined between a resin molded body and a cavity mold, and comprises: a cylindrical cylinder that defines a mixing space for the two or more coating materials; first and second orifices for injecting the two or more coating materials into the mixing space; and a movable member that changes the size of the mixing space.

Description

In-mold coating injection head, injection machine

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to an in-mold coating injection head and injection machine.

[0002] Conventionally, when forming a paint film on a resin molded product, the resin molded product is formed by injection molding in a mold, and then the resin molded product is removed from the mold and a paint is applied and dried.In contrast to this, an in-mold painting technique is known in which a resin molded product is formed by injection molding in a mold, and then the cavity mold is changed and a paint film is formed inside the mold.

[0003] When using a mixed paint of two or more liquids for in-mold coating, one method is to mix the base material 14 and the hardener 15 by colliding them at a constant speed just before pouring them into the mold. In this case, as shown in Figure 2, for example, air bubbles 35 may be entrained when the base material 14 and the hardener 15 are mixed, and the entrained air bubbles 35 remain on the surface of the coating film, resulting in a poor appearance.

[0004] In response to this problem, a technique is known in which the process from mixing paint to pouring into a mold is carried out in a vacuum environment (see, for example, Patent Document 1). By mixing paint and pouring into a mold in a vacuum environment, it is possible to suppress the entrapment of air bubbles.

[0005] Japanese Patent Application Laid-Open No. 2004-181771

[0006] However, carrying out the entire process from mixing the paint to pouring it into the mold in a vacuum environment requires large-scale vacuum equipment, which not only increases costs but also requires additional processes to create the vacuum environment, resulting in longer takt time.

[0007] Therefore, an object of the present disclosure is to provide an injection head for in-mold coating that can suppress the entrainment of air bubbles during collision mixing while using two or more liquid paints.

[0008] The in-mold coating injection head of the present disclosure is an in-mold coating injection head for injecting two or more liquid paints into a coating film cavity defined between a resin molded body and a cavity mold, and is equipped with a cylindrical cylinder that defines a mixing space for the two or more liquid paints, first and second orifices that inject the two or more liquid paints into the mixing space, and a movable member that changes the size of the mixing space.

[0009] The in-mold coating injection head according to the present disclosure is equipped with a movable member that changes the size of the mixing space, so that the mixing space can be limited to a small size when two or more paint components are mixed by collision, thereby suppressing the entrainment of air bubbles.

[0010] 3C is a schematic cross-sectional view showing in-mold coating in which paint is injected from an in-mold coating injection head into a coating film cavity between the surface of a resin molded product and a cavity mold to form a paint film.

[0034] FIG. 3D is a schematic cross-sectional view showing air bubble entrapment that occurs when two or more liquid paints are mixed by collision in a large mixing space.

[0035] FIG. 3E is a schematic cross-sectional view showing the initial configuration of an in-mold coating injection head according to embodiment 1.

[0036] FIG. 3F is a schematic cross-sectional view showing a float for restricting the mixing space in which two or more liquid paints collide and mix in the initial stage of mixing in the in-mold coating injection head of FIG. 3A.

[0037] FIG. 3G is a schematic cross-sectional view showing the state in which the mixed paint pushes the float after FIG. 3A.

[0038] FIG. 3H is a schematic cross-sectional view showing the state in which the float is stored in the float pocket after FIG. 3D.

[0039] FIG. 3I is a schematic cross-sectional view showing the state in which the control piston is lowered to push the mixed paint into the paint flow path in an in-mold coating injection head according to a modified embodiment of embodiment 1, in which a cleaning piston is provided in the paint flow path.

[0039] FIG. 4A is a schematic cross-sectional view showing the state in which the paint in the paint flow path is discharged by the cleaning piston.

[0039] FIG. 4B is a schematic cross-sectional view showing the initial configuration of an in-mold coating injection head according to embodiment 2. 5A is a schematic cross-sectional view showing the state where the opposing piston pushes the float up to a position opposite the control piston after FIG. 5A. FIG. 5B is a schematic cross-sectional view showing the state where the control piston is pushed up to open the openings of the first and second orifices to the cylinder. FIG. 5C is a schematic cross-sectional view showing the state where the opposing piston is lowered to communicate the mixed paint with the paint flow path after FIG. 5D is a schematic cross-sectional view showing the state where the control piston is lowered to push the mixed paint into the paint flow path after FIG. 5D. FIG. 6A is a schematic cross-sectional view showing the initial configuration of an in-mold coating injection head according to embodiment 3. FIG. 6A is a schematic cross-sectional view showing the state where the block-shaped member moves into the cylinder from the inner side surface of the cylinder after FIG. 6A. FIG. 6B is a schematic cross-sectional view showing the state where the control piston is pushed up. FIG. 6D is a schematic cross-sectional view showing the state where the openings of the first and second orifices are opened to the cylinder to collide and mix two or more paint components. FIG. 6D is a schematic cross-sectional view showing the state where the block-shaped member is moved from inside the cylinder after FIG. 6E.7B is a schematic cross-sectional view showing the initial configuration of an in-mold coating injection head according to embodiment 4. FIG. 7C is a schematic cross-sectional view showing the state in which the control piston is pushed up to open the openings of the first and second orifices to the cylinder. FIG. 7D is a schematic cross-sectional view showing the state in which the mixed paint pushes down the float and the float is stored in the float pocket after FIG. 7B. FIG. 7C is a schematic cross-sectional view showing the state in which the control piston is moved to push out the mixed paint into the paint flow path after FIG. 7D.

[0011] The in-mold coating injection head of the first aspect is an injection head for injecting two or more liquid paints into a cavity for a coating film formed between a resin molding and a cavity mold, and comprises a cylindrical cylinder that defines a mixing space for the two or more liquid paints, first and second orifices that inject the two or more liquid paints into the mixing space, and a movable member that changes the size of the mixing space.

[0012] The in-mold coating injection head according to a second aspect is the first aspect, wherein the movable member can keep the mixing space sealed except for the openings of the first and second orifices.

[0013] The in-mold coating injection head according to the third aspect may be the same as the second aspect, wherein the movable member is movable between a position where the mixing space is sealed and a position where the mixing space is connected to a paint flow path connected to the cylinder.

[0014] The in-mold coating injection head according to a fourth aspect is the third aspect, wherein the movable member has a flow path continuous with the paint flow path at a position that connects the mixing space to the paint flow path.

[0015] The in-mold coating injection head according to a fifth aspect is the first aspect, wherein the movable member is a float member that is movable along the inner side surface of the cylinder.

[0016] The in-mold coating injection head of the sixth aspect may be the first aspect, wherein the movable member is an opposing piston that extends from one end side opposite to the other end side where the openings of the first and second orifices of the cylinder are located to the one end side, and is movable between the other end side and the one end side.

[0017] The in-mold coating injection head according to a seventh aspect is the first aspect, wherein the movable member includes an inner side surface of the cylinder, and the inner side surface may be a block-shaped member that is movable toward the inside of the cylinder.

[0018] An in-mold coating injection head according to an eighth aspect is the same as the first aspect, wherein the movable member has a convex shape on the side facing the mixing space.

[0019] The in-mold coating injection head according to a ninth aspect may be the same as the first aspect, further comprising a control piston that is movable inside the cylinder between a position that blocks the openings of the first and second orifices and a position that opens them.

[0020] The in-mold coating injection head according to the tenth aspect may be the same as that of the first aspect, and may further include a paint flow path connected to the cylinder at an angle to the cylindrical extension direction of the cylinder, for receiving two or more liquid paints from the mixing space, and a cleaning piston for discharging the two or more liquid paints from the paint flow path to the outside.

[0021] An injection machine according to an eleventh aspect includes the in-mold coating injection head according to the first aspect.

[0022] The in-mold coating mold of the twelfth aspect comprises a core mold on which a resin molded product can be placed, a cavity mold capable of forming a cavity for a paint film between the core mold and the surface of the resin molded product placed on the core mold, and an in-mold coating injection head of the first aspect for injecting two or more liquid paints into the cavity for the paint film, and a paint film can be formed by injecting two or more liquid paints into the cavity for the paint film.

[0023] An in-mold coating injection head according to an embodiment will now be described with reference to the accompanying drawings, in which substantially identical components are designated by the same reference numerals.

[0024] (Embodiment 1) <Injection Head> Figure 1 is a schematic cross-sectional view showing in-mold coating in which paint is injected from an in-mold coating injection head 20 into a coating film cavity 13 between the surface of a resin molded product 10 and a cavity mold 12 to form a coating film. Figure 3A is a schematic cross-sectional view showing the initial configuration of the in-mold coating injection head 20 according to embodiment 1. Figure 3B is a schematic cross-sectional view showing a float 24 in the in-mold coating injection head 20 of Figure 3A for restricting the mixing space 22 in which two or more liquid paints 14, 15 collide and mix in the initial stage of mixing. The in-mold coating injection head 20 according to embodiment 1 is an injection head for injecting two or more liquid paints into a coating film cavity defined between a resin molded product and a cavity mold. The in-mold coating injection head 20 also includes a cylindrical cylinder 16 that defines a mixing space 22 for two or more liquid paints, first and second orifices 21a, 21b that inject two or more liquid paints 14, 15 into the mixing space 22, and a movable member 24 that changes the size of the mixing space 22.

[0025] This in-mold coating injection head 20 is equipped with a float 24, which is a movable member that changes the size of the mixing space 22, so that the mixing space 22 can be limited to a small size when two or more liquid paints 14, 15 collide and mix, thereby suppressing the entrainment of air bubbles.

[0026] The components that make up this in-mold coating injection head 20 will be described below.

[0027] <Cylinder> The cylinder 16 has a cylindrical shape that defines a mixing space 22 for the two or more paint components 14, 15. The cylinder 16 may have a cross section that is circular, elliptical, or polygonal, such as rectangular or hexagonal, and may be cylindrical with one end closed and the other end open.

[0028] <First and Second Orifices> The openings of the first and second orifices 21a and 21b are located at the closed end of the cylinder 16. For example, the base agent 14 may be supplied through the first orifice 21a, and the curing agent 15 may be supplied through the second orifice 21b. Two- or more-component paints basically consist of a base agent and a curing agent. The base agent 14 may be, for example, a polyol, and the curing agent 15 may be, for example, an isocyanate. The above examples are merely examples and are not intended to be limiting. Furthermore, when a colored paint is included, a two-component paint may be used, consisting of the colored paint in the base agent and the curing agent, or a three-component paint consisting of only the base agent, a base agent containing the colored paint, and the curing agent. The following description will focus on the two-component paint, but the same applies to three- or more-component paints. If the openings of the first and second orifices 21a and 21b are blocked by the side of the control piston 18, the paints will not be supplied into the cylinder 16. Although the case where two orifices, the first and second orifices 21 a and 21 b, are used will be described here, the present invention is not limited to this. Three or more orifices may be used to supply three or more liquids from separate orifices.

[0029] <First Piston (Control Piston)> The first piston 18 may be movable inside the cylinder 16 between a position where it closes the openings of the first and second orifices 21a, 21b and a position where it opens the openings. By moving the first piston 18 upward (Z direction) in FIG. 3A , the openings of the first and second orifices 21a, 21b can be opened. This allows the mixing of the two or more paint components 14, 15 to begin. On the other hand, by moving the first piston 18 downward (−Z direction) in FIG. 3A , the openings of the first and second orifices 21a, 21b can be closed. The first piston 18 is also referred to as a control piston because it can control the opening and closing of the openings of the first and second orifices 21a, 21b. Furthermore, as shown in FIG. 3E , by moving the first piston 18 downward (−Z direction), the paint can be discharged through the paint flow path 36. In FIG. 3E, the axis (X direction) of the paint flow path 36 is arranged perpendicular to the axis (Z direction) of the cylinder 16, but this is not limited to this, and the axis of the paint flow path 36 may extend in the same Z direction as the cylinder 16.

[0030] <Movable Member> The float 24, which is a movable member, is movably disposed on the side of the cylinder 16 and is initially positioned so as to face the first piston 18. The cylinder 16, the first piston 18, and the float 24 define a mixing space 22 for two or more paint components. In other words, the float 24 can narrow the mixing space 22 and maintain it in a sealed state. This can suppress air bubble entrapment during the collision and mixing of two or more paint components. The float 24 may be designed so that it does not fall off the side of the cylinder 16 under its own weight by appropriately designing its dimensional accuracy relative to the side of the cylinder 16, its surface roughness, etc. In other words, the float 24 may move due to the pressure of the mixed paint components. As shown in FIGS. 3A and 3B , the shape of the float 24 may be convex on the surface facing the first piston 18. This convex shape can further narrow the mixing space 22. Furthermore, by making the intermediate region, where the base resin and hardener sprayed from the first and second orifices 21a and 21b are difficult to reach, convex, the mixing space 22 can be efficiently configured. The convex shape may be multi-stepped. By making the surface stepped, the paint can flow out more easily. The shape of the float 24 is not limited to that shown in FIG. 3B , and may, for example, have a concave upper surface.

[0031] 3A and 3C, the float 24 can maintain the mixing space 22 in a sealed state while moving along the side surface of the cylinder 16. The float 24 may then move off the side surface of the cylinder 16 and be stored in a float pocket 28 provided at the bottom of the cylinder 16. This releases the sealed state of the mixing space and connects it to the paint flow path 36, as shown in FIG. 3D. Storing the float 24 in the float pocket 28 also prevents the float 24 from acting as a plug and blocking the paint flow path 36. A guide (not shown) may be provided to guide the float 24 to the float pocket 28.

[0032] <Core Mold and Cavity Mold> As shown in Fig. 1, a mold used for in-mold coating is composed of, for example, a core mold 11 and a cavity mold 12. The core mold 11 and the cavity mold 12 are arranged so that they can move relative to each other by a drive unit and an opening / closing unit (not shown). A resin molded body 10 is placed in the core mold 11, and the core mold 11 and the cavity mold 12 are clamped together to define a coating film cavity 13 facing the surface of the resin molded body 10 for filling with paint.

[0033] <Operation of the In-Mold Coating Injection Head> Using Figures 3A to 3E, the operation of the in-mold coating injection head 20 according to the first embodiment is described in chronological order. (1) As shown in Figure 3A, in the initial position, the float 24, which is a movable member, is positioned opposite the first piston 18. The cylinder 16, the first piston 18, and the float 24 define a small, sealed mixing space 22 for two or more paint components 14, 15. This small, sealed mixing space 22, where two or more paint components 14, 15 collide and mix, minimizes excess space and reduces air bubble entrapment. (2) As shown in Figure 3C, as the amount of mixed paint increases, the float 24 is pushed downward (in the -Z direction) along the side of the cylinder 16. The mixing space 22 continues to expand while remaining sealed. (3) As shown in Figure 3D, the float 24 moves away from the side of the cylinder 16 and is stored in a float pocket 28 located at the bottom of the cylinder 16. In this case, the sealed state is released, and the mixed paint communicates with the paint flow path 36. (4) As shown in Figure 3E, the first piston 18 is moved downward (-Z direction) to discharge the paint through the communicating paint flow path 36. In this way, the mixed paint can be injected into the mold from the paint film injection head 20.

[0034] (Modification) Figure 4A is a schematic cross-sectional view showing the state in which a second piston 38 is provided in the paint flow path 36 in an in-mold coating injection head 20a according to a modification of the first embodiment. Figure 4B is a schematic cross-sectional view showing the state in which the second piston 38 in Figure 4A discharges paint from the paint flow path 36. The in-mold coating injection head 20a according to the modification differs from the in-mold coating injection head according to the first embodiment in that a second piston 38 is provided in the paint flow path 36, as shown in Figure 4A. As shown in Figure 4B, the paint can be discharged from the paint flow path 36 by moving the second piston 38 in the -X direction. Note that the extension directions of the paint flow path 36 and the second piston may be reversed.

[0035] (Embodiment 2) <In-mold coating injection head> Figure 5A is a schematic cross-sectional view showing the initial configuration of an in-mold coating injection head 20b according to embodiment 2. The in-mold coating injection head 20b according to embodiment 2 differs from the in-mold coating injection head according to embodiment 1 in that it has an opposing piston 30 for moving the float 24. Furthermore, in the initial position, the float 24 and opposing piston 30 do not face the first piston 18. Furthermore, the first and second orifices 21a, 21b are blocked by the first piston 28.

[0036] <Opposing Piston> In the initial position shown in FIG. 5A , the opposing piston 30 is disposed at the bottom of the cylinder 16, with the float 24 placed on top. The float 24 and opposing piston 30 may be fixed, or the float 24 may simply be placed on top of the opposing piston 30. Furthermore, the upper part of the opposing piston 30 may be integrated with the float 24. As shown in FIG. 5B , by moving the opposing piston 30 upward (in the Z direction), the float 24 can be moved to a position facing the control piston 18. As shown in FIG. 5D , as the amount of mixed paint increases, the opposing piston 30 is pushed downward (in the −Z direction), connecting the mixing space 22 to the paint flow path 36. By providing the opposing piston 30, the movement of the float 24 can be controlled. Furthermore, by integrating the upper part of the opposing piston 30 with the float 24, the movement of the opposing piston 30 and the first piston 18 can be controlled in combination, thereby enabling more precise control of the operation of the injection head 20 a. As in the modified example of the first embodiment, a second piston 38 may be provided in the paint flow path 36 .

[0037] <Operation of the In-Mold Coating Injection Head> The operation of the in-mold coating injection head 20b according to the second embodiment will be described in chronological order using Figures 5A to 5E. (1) As shown in Figure 5A, in the initial position, the float 24 and the opposing piston 30 do not face the first piston 18. Furthermore, the first and second orifices 21a, 21b are blocked by the first piston 28. In other words, two or more coating materials 14, 15 are not supplied from the first and second orifices 21a, 21b. (2) As shown in Figure 5B, the opposing piston 30 is moved upward (in the Z direction) to move the float 24 to a position facing the first piston 18. (3) As shown in Figure 5C, the first piston 18 is moved upward (in the Z direction) to open the first and second orifices 21a, 21b, and two or more coating materials 14, 15 are supplied from the first and second orifices 21a, 21b. As a result, the mixing space 22 for the two or more liquid paints 14, 15 is defined in a small, sealed state by the cylinder 16, first piston 18, and float 24. (4) As shown in Figure 5D, as the amount of mixed paint increases, the opposing piston 30 is pushed downward (in the -Z direction) to connect the mixing space 22 to the paint flow path 36. (5) As shown in Figure 5E, the control piston 18 is moved downward (in the -Z direction) to discharge the paint through the communicating paint flow path 36. In this way, the mixed paint can be injected into the mold from the coating film injection head 20b.

[0038] (Embodiment 3) <In-mold coating injection head> Figure 6A is a schematic cross-sectional view showing the initial configuration of an in-mold coating injection head 20c according to embodiment 3. The in-mold coating injection head 20c according to embodiment 3 differs from the in-mold coating injection head according to embodiment 1 in that the movable member is a block-shaped member 32 that can move toward the inside of the cylinder 16, instead of a float. The direction of movement of the block-shaped member 32 is perpendicular to the axis of the cylinder 16, so the size of the mixing space can be changed regardless of the pressure of the mixed paint.

[0039] <Block-Shaped Member> As shown in FIG. 6A , in the initial configuration, the block-shaped member 32 may, for example, form the inner side surface 34 a of the cylinder 16. Alternatively, as shown in FIG. 6B , the block-shaped member 32 may move from one inner side surface 34 a of the cylinder 16 toward the opposing inner side surface 34 b. In this case, if the cylinder 16 is cylindrical, the two opposing inner side surfaces are concave and only make linear contact rather than surface contact, making it difficult to maintain the mixing space in a sealed state. Therefore, for example, the cross section perpendicular to the axis of the cylinder 16 may be rectangular. This makes the inner side surface 34 a flat and in surface contact with the opposing inner side surface 34 b, thereby maintaining the mixing space in a sealed state. Alternatively, as shown in FIGS. 6D and 6E , after the mixing space 22 is filled with paint, the block-shaped member 32 is moved in the X direction to connect the mixing space 22 to the paint flow path 36. 6F, when the first piston 18 is moved downward (in the −Z direction), the block-shaped member 32 is retracted so as not to obstruct the first piston 32. As in the modified example of the first embodiment, a second piston 38 may be provided in the paint flow path 36.

[0040] <Operation of the In-Mold Coating Injection Head> The operation of the in-mold coating injection head 20c according to the third embodiment will be described in chronological order using Figures 6A through 6F. (1) As shown in Figure 6A, in the initial configuration, the block-shaped member 32 forms the inner side surface 34a of the cylinder 16. As in Figure 5A, the first and second orifices 21a, 21b are blocked by the first piston 28. In other words, two or more coating materials 14, 15 are not supplied from the first and second orifices 21a, 21b. (2) As shown in Figure 6B, the block-shaped member 32 is moved from one inner side surface 34a of the cylinder 16 toward the opposing inner side surface 34b. This causes the inner side surface 34a to become flat and come into surface contact with the opposing inner side surface 34b, thereby maintaining the mixing space 22 in a sealed state. (3) As shown in Figures 6C and 6D, the first piston 18 is moved upward (in the Z direction) to open the first and second orifices 21a and 21b, and the two or more liquid paints 14 and 15 are supplied through the first and second orifices 21a and 21b. This allows the cylinder 16, the first piston 18, and the block-shaped member 32 to define a small, sealed mixing space 22 for the two or more liquid paints 14 and 15. (4) As shown in Figures 6D and 6E, after the mixing space 22 is filled with paint, the block-shaped member 32 is moved in the X direction to connect the mixing space 22 to the paint flow path 36. (5) As shown in Figure 6F, the first piston 18 is moved downward (in the -Z direction) to discharge the paint through the communicating paint flow path 36. As a result of the above, the mixed paint can be injected into the mold from the coating film injection head 20b.

[0041] (Embodiment 4) <In-mold coating injection head> Figure 7A is a schematic cross-sectional view showing the initial configuration of an in-mold coating injection head 20d according to embodiment 4. As shown in Figure 7A, the in-mold coating injection head 20d according to embodiment 4 differs from the in-mold coating injection head according to embodiment 1 in that the float 24 is initially positioned at the tip of the third piston 40. This defines a mixing space 22 between the cylinder 16, first piston 18, third piston 40, and float 24. The first piston 18 mainly controls the opening and closing of the first and second orifices 21a, 21b.

[0042] <Third Piston> The third piston 40 is disposed so as to intersect with the first piston 18. Alternatively, the third piston 40 may be disposed so as to intersect at right angles with the first piston 18, as shown in Fig. 7A. The third piston 40, together with the cylinder 16, the first piston 18, and the float 24, defines the sealed mixing space 22. Furthermore, as shown in Fig. 7E, by moving the third piston 40 downward (in the -Z direction), the paint can be discharged through the communicating paint flow path 36.

[0043] <Operation of the In-Mold Coating Injection Head> The operation of the in-mold coating injection head 20d according to embodiment 4 will be described in chronological order using Figures 7A to 7E. (1) As shown in Figure 7A, in the initial configuration, the float 24, which is a movable member, is positioned opposite the third piston 40. The float 24 may also be positioned in contact with the tip of the third piston 40. The first and second orifices 21a, 21b are closed by the first piston 18. (2) As shown in Figure 7B, the first piston 18 is moved in the -X direction to open the first and second orifices 21a, 21b, and two or more coating materials 14, 15 are supplied through the first and second orifices 21a, 21b. As a result, the mixing space 22 is hermetically sealed by the cylinder 16, the first piston 18, the third piston 40, and the float 24. At this time, because the float 24 is positioned opposite the third piston 40, the mixing space 22 can be narrowly defined. This suppresses air bubble entrainment during the collisional mixing of the paint. (3) As shown in FIG. 7C, as the amount of mixed paint increases, the float 24 is pushed and moves downward (in the −Z direction) along the side of the cylinder 16. At this time, the mixing space 22 expands while remaining sealed. The float 24 then leaves the side of the cylinder 16 and is stored in the float pocket 28 at the bottom of the cylinder 16. In this case, the sealed state is released, and the mixed paint communicates with the paint flow path 36b. (4) As shown in FIG. 7D, by moving the first piston 18 in the X direction, the paint around the first and second orifices 21a and 21b is discharged toward the third piston 40. (5) As shown in Figure 7E, the third piston 40 is moved downward (-Z direction) to discharge the paint through the communicating paint flow path 36. In this way, the mixed paint can be injected into the mold from the paint film injection head 20d.

[0044] The in-mold coating injection head according to the present disclosure is equipped with a movable member that changes the size of the mixing space, so that the mixing space can be limited to a small size when two or more paint components are mixed by collision, thereby suppressing the entrainment of air bubbles, making it useful for in-mold coating.

[0045] REFERENCE SIGNS LIST 10 Resin molded product 11 Core mold 12 Cavity mold 13 Cavity for coating film 14 Base agent 15 Hardener 16 Cylinder 18 First piston 20, 20a, 20b, 20c, 20d, 50 Injection head 21a, 21b Orifice 22 Mixing space 24 Float 26 Paint 28 Float pocket 30 Opposed piston 32 Block-shaped member 34a, 34b Inner side surface 35 Air entrainment 36 Paint flow path 38 Second piston 40 Third piston

Claims

1. An in-mold coating injection head for injecting two or more liquid paints into a coating film cavity defined between a resin molding and a cavity mold, comprising: a cylindrical cylinder that defines a mixing space for the two or more liquid paints; first and second orifices that inject the two or more liquid paints into the mixing space; and a movable member that changes the size of the mixing space.

2. An in-mold coating injection head according to claim 1, wherein said movable member is capable of keeping said mixing space sealed except for the openings of said first and second orifices.

3. An in-mold coating injection head as described in claim 2, wherein the movable member is movable between a position in which the mixing space is sealed and a position in which the mixing space is connected to a paint flow path connected to the cylinder.

4. An in-mold coating injection head according to claim 3, wherein the movable member has a flow path continuous with the paint flow path at a position where the mixing space communicates with the paint flow path.

5. An in-mold coating injection head according to claim 1, wherein the movable member is a float member that is movable along the inner side surface of the cylinder.

6. An in-mold coating injection head as described in claim 1, wherein the movable member is an opposed piston that extends from the other end side of the cylinder opposite to the one end side where the openings of the first and second orifices are located to the one end side and is movable between the other end side and the one end side.

7. The in-mold coating injection head according to claim 1, wherein the movable member includes an inner side surface of the cylinder, and the inner side surface is a block-shaped member that is movable inside the cylinder.

8. The in-mold coating injection head according to claim 1, wherein the movable member has a convex shape on the side facing the mixing space.

9. An in-mold coating injection head as claimed in claim 1, further comprising a first piston movable inside said cylinder between a position where it closes the openings of said first and second orifices and a position where it opens them.

10. An in-mold coating injection head as described in claim 1, further comprising: a paint flow path connected to the cylinder at an angle to the cylindrical extension direction of the cylinder, for receiving the two or more liquid paints from the mixing space; and a second piston for discharging the two or more liquid paints from the paint flow path to the outside.

11. An injection machine equipped with the in-mold coating injection head according to claim 1.

12. An in-mold coating mold capable of forming a coating film by injecting two or more liquid paints into the coating film cavity, comprising: a core mold on which a resin molded product can be placed; a cavity mold capable of forming a coating film cavity between the core mold and the surface of the resin molded product placed on the core mold; and the in-mold coating injection head described in claim 1 for injecting two or more liquid paints into the coating film cavity.

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