JPS61248709A - In-mold coating - Google Patents

Abstract

PURPOSE:To permit to prevent generation of cavities, pinholes and the like of coating even when the coating film is made thin by a method wherein the pressure in the secondary space is evacuated to defoam the primary formed body and, thereafter, a resin coating medium is poured into the secondary space. CONSTITUTION:The secondary space 11 is formed between the upper surface 10a of the primary formed body 10, contacting closely with a bottom force 1, and the lower surface 2a of a top force 2 after forming the primary forming body 10. Under this process, high-pressure air is utilized to prevent floating of the primary formed body 10 from the bottom force 1 by a vacuum upon opening the mold. When the formation of the secondary space 10 is finished, a predetermined control signal is outputted to start the driving of a vacuum pump and evacuate the inside of the secondary space 11 through an evacuating path 26, whereby the defoaming of the primary formed body is effected. When the defaming process is finished by the evacuation, the resin coating medium is injected into the secondary space 11 and the coating film B, having a thickness (h2), may be laminated and formed on the upper surface 10a of the primary formed body 10.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an in-mold coating method in which a resin coating is formed on one side of a primary molded body after the primary molded body is molded in a mating mold. It is.

(Prior Art) In the automobile industry, there has recently been a trend to replace car body constituent members such as bonnets with reinforced fiber-containing plastic moldings in order to reduce the weight of car bodies.

By the way, when molding a reinforced Fam-containing plastic molded article, there is a problem in that air tends to get mixed into the molded article because the reinforced m-fiber-containing plastic has poor fluidity.

From this, when a reinforced fiber-containing plastic molded body is painted and baked, the air (including organic gas) mixed in the molded body, especially the air bubbles near the surface of the molded body, expands and ruptures, causing the coating to deteriorate. This caused problems such as burrows and pinholes.

As a countermeasure against such problems,
As seen in Japanese Patent No. 91, an in-mold coating method is often used in which a primary molded body is formed in a mating mold and then a resin coating is formed on one side of the primary molded body.

That is, by laminating a resin coating film on the surface of the primary molded body, the air mixed into the primary molded body is contained, thereby solving the problem of paint baking, that is, the above-mentioned inconvenience of painting.

(Problems to be Solved by the Invention) However, in order to eliminate the above-mentioned disadvantages of painting using this in-mold coating method, a resin coating film that is sufficient to completely contain the air mixed in the above-mentioned primary molding is required. be done.

For this reason, the conventional approach has been to increase the thickness of the resin coating layer laminated on the primary molded body to eliminate the above-mentioned disadvantages of painting.

The present invention changes the conventional idea of sealing the air mixed into the primary molded body by the thickness of the resin coating layer, as described above, and makes the resin coating layer laminated on the primary molded body thin. Another technical object of the present invention is to provide an in-molt conide method that can fully eliminate the above-mentioned inconveniences of painting.

(Means and effects for solving the problems) The present invention has the following features:
After molding a primary plastic body within a primary space formed by closing a mating mold consisting of a mold and a second mold, the mating molds are slightly separated and one of the molds is closed. A secondary space is formed between the mold and one side of the primary molded body, and a coating film is formed on one side of the primary molded body in the combined mold using a resin paint injected into the secondary space. Based on the in-mold coating method, the resin coating is injected after the pressure in the secondary space is reduced to defoam the primary molded body.

In other words, when the paint is baked, it expands and ruptures, creating holes in the paint.
Air bubbles in the primary molding that cause problems such as vinyl poles are removed before forming the resin coating layer that is laminated on the primary molding, and this allows the resin coating layer to be made sufficiently thin even if it is made thin. , it is possible to eliminate the above-mentioned inconveniences of painting.

(Example) Hereinafter, the present invention will be explained with reference to Examples.

FIG. 1 and FIG. 2 show an in-mold coat forming apparatus used in the example, and this apparatus is used for forming the hood of an automobile. In the figure, 1 is a lower mold as a first mold, 2 is an upper mold as a second mold, and 5 both constitute a mating mold 3 that is molded together. The lower mold 1 is fixed on a fixed surface plate 4, and the upper mold 2 is mounted on a movable surface plate 5 via a riser A having a built-in heating device. The upper die 2 moves the movable surface plate 5 to a press device (
By moving it up and down by a movable surface plate 5 (not shown), it moves up and down integrally with the movable surface plate 5, and is brought into contact with and away from the lower mold 1.

The distance between the upper mold 2 and the lower mold 1 is controlled by a bushback cylinder 6 interposed between the fixed surface plate 4 and the movable surface plate 5 via a spacer 6.

That is, when the downward movement of the movable surface plate 5 is restricted by the bushback cylinder 6 in the extended state, the upper mold 2 has a distance between the lower mold upper surface 1a and the upper mold lower surface 2a equal to the dimension H. It is positioned at the upper movement position. At this time, a space having a thickness H formed between the lower mold 1 and the upper mold 2 acts as a molding space for the plastic molded article, and hereinafter this space will be referred to as a molding space 8.

On the other hand, in the state where the downward movement of the movable surface plate 5 is regulated by the bushback cylinder 7 in the contracted state, the upper mold 2 has a distance between the lower mold upper surface 1a and the upper mold lower surface 2a, which is equal to the dimension h1. It is positioned at the lower movement position. At this time, lower mold 1
A space with a thickness hl formed between the upper die 2 and the upper mold 2 has a thickness hl
This is a space for molding the primary molded body 10. In the following description, this space will be referred to as a primary space 9.

In addition, a space having a thickness corresponding to the stroke h2 (h2=H-h) of the upper mold 2 is one surface 10a of the primary molded body 10.
This space acts as an injection space for the resin paint to be coated, and this space will be referred to as the secondary space 11 hereinafter.

On the other hand, on one side of the molding space 8, a tab forming space 12 having a tongue-like planar shape is formed continuously to the molding space 8. In this tab forming space 12, an oblique injection injector 13 attached to the upper mold 2 is arranged facing.

As shown in FIG. 2, the injector 13 has an injector body 16 that is integrally provided with a nozzle portion 15 having a nozzle 14, and a paint reservoir 17 that communicates with the nozzle 14 at the axial center of the injector body 16. A substantially hollow cylindrical shut-off bottle 18 passing through the nozzle 14 in the axial direction is slidably attached to the nozzle 14.
The opening/closing control is performed by selectively slidingly displacing the shutoff bin 18 in the vertical direction using an operating cylinder (air cylinder) 19. That is, as shown in FIG. 2, the shutoff bin 18 is displaced up and down in accordance with the introduction or interruption of air into the pressure chamber 20, thereby opening or closing the nozzle 14. When the nozzle 14 is open, paint supplied from the static mixer 21 to the paint reservoir 17 passes through the nozzle 14 and is injected into the tab forming space 12 and the secondary space 11.

Further, an air passage 22 connected to an air supply source (not shown) is provided in the shut-off pin 18, and the air passage 22 opens at the tip 18a of the shaft-off bin 18, and the opening is connected to the valve seat. 23, the check valve 24, which is seated on and off from the valve seat 23, is urged in the valve closing direction by a spring 25.

This check valve 24 is opened when the air pressure in the air passage 22 exceeds a set pressure, and high-pressure air is blown into the molding space 8 . That is, the air supply source supplies air in response to an upward movement signal (for example, a drive signal for the bushback cylinder) when the upper die 2 moves upward to the upward movement position after forming the primary molded body. By supplying high-pressure air whose pressure has been regulated into the passage 22, the high-pressure air is blown out from the nozzle 14.

On the other hand, a pressure reduction passage 26 is opened in the lower surface 2a of the upper mold 2, and the pressure reduction passage 26 is connected to a vacuum pump (not shown). is a porous member 27 that is flush with the lower surface 2a of the upper mold.
is provided to prevent resin paint from flowing into the decompression passage 26, which will be described later.

The process of molding a bonnet using the in-mold coater having such a configuration will be described below with reference to FIG. 5.

First, in the apparatus shown in FIG. 1, the lower mold l and upper mold 2 are completely separated by a press device, and the fiber-containing resin plate 28 is placed on the upper surface la of the lower mold l (Fig. 5 (1) ))
.

Next, the press device is operated with the bushback cylinder 7 extended, and the upper mold 2 is lowered together with the movable surface plate 5, and is positioned at the upper movement position (this positioning of the upper mold 2 (This is done by the upper surface of the spacer 6 placed on the bushback cylinder 7 coming into contact with the lower surface of the movable surface plate 5).

Following this molding preparation process, the bushing back cylinder is switched from the extended position to the contracted position, and at the same time, the press device starts pressurizing operation, and the upper mold 2 is pushed down from the upward moving position to the movable position. , the fiber resin plate is compressed under pressure between the upper mold 2 and the lower mold 1 to form a -dimensional space 9.
The primary molded body 10 is molded inside (FIG. 5(2)).

After forming the primary molded body 10, with the operation of the press device stopped, the bushback cylinder 5 is extended, the upper die 2 is positioned at the upward movement position, and the primary molded body is brought into close contact with the lower die 1. A secondary space 11 is formed between the upper surface 10a of the molded body 10 and the lower surface 2a of the upper mold 2. In this step, high-pressure air is used to prevent the primary molded body 10 from lifting off from the lower mold 1 due to negative pressure when the mold is opened.

That is, before the bushback cylinder 7 is extended, a control signal is output, the air supply source is activated, and high-pressure air sufficient to open the check valve 24 is supplied to the air passage 22. After high-pressure air is supplied to the air passage 22, the pushback cylinder 7 starts operating and the upper mold 2 moves upward, gradually forming a gap ( That is, since the secondary space 11) is formed, the check valve 24 gradually opens in response to this, and high-pressure air is blown out into the secondary space ll. At the initial stage, the high-pressure air blown into the secondary space 4 acts to eliminate the negative pressure generated when the mold is opened, and after that, the air pressure forces the primary molded product 10. It acts as if it is pressed against the lower mold 1 side.

This air introduction is continued until the upper mold 12 reaches the upward movement position (FIG. 5(3)). Therefore, after the mold opening is completed, the primary molded body 10 is reliably held closely to the lower mold 1, and the thickness dimension of the secondary space 11 becomes uniform over the entire area.

When the formation of the secondary space 10 is completed, a predetermined control signal is output, the drive of the vacuum pump is started, and the inside of the secondary space 11 is evacuated through the decompression passage 26 to become a depressurized state and degassed. Figure 5 (4)).

That is, air bubbles 29 are mixed in the pressure-molded primary molded body 10 due to air and organic gas mixed during molding (FIG. 3(b)).

The air (gas) in these bubbles 29 expands and ruptures due to the heat during the paint baking process on the surface of the primary molded body 10, which is the main cause of creating cavities, pinholes, etc. in the paint. be. Therefore, by the depressurization treatment in the secondary space performed in this step, the primary molded body 10 is placed in a negative pressure atmosphere, the air bubbles 28 near its surface are forcibly ruptured, and the third As shown in Figure (a), the air is defoamed, and many calderas (depressions) 30 are formed on the surface of the primary molded body IO.

After the defoaming process by reducing the pressure is completed, the shutoff pin 18 is pulled up from the closed position to the open position by the operating cylinder 19, the nozzle 14 of the nozzle part 15 opens, and the resin paint flows into the secondary space 11. The coating film B having a thickness of h2 is formed in a layered manner on the upper surface 10a of the primary molded body 10 (in-mold coat) (see Fig. 5).
5)). At this time, since the resin paint enters the Carterra 30 that opens on the upper surface 10a of the primary molded body 10, the coating film B coated on the primary molded body 10 enters the Carterra 29, as shown in FIG. Due to the anchoring effect of the filled resin, it is closely held on the primary molded body 10. In addition, the above resin paint is used in the evacuated secondary space 1
Since the liquid is injected into the secondary space 1, there is an advantage that the liquid flows well into the secondary space 11, and the moldability of the coating film B is excellent.

After the paint is cured, the upper mold 2 is separated from the lower mold 1 to form a finished product 31 (i.e., a resin coating film B of an appropriate thickness is laminated on the surface 10a of the primary molded plastic body 10). bonnet) is removed (Fig. 5 (
Ef)).

This completes the series of molding operations, after which the paint baking process will be carried out.

According to the above embodiment, after molding the next molded product, the secondary space is put into a pressurized state and one of the molds is opened by a predetermined amount, so that it is possible to prevent the primary molded product from lifting up due to negative pressure when the mold is opened. Therefore, the secondary space, that is, the thickness of the coating film can be kept uniform over the entire area.

In addition, before injection of the resin paint, the pressure in the secondary space is reduced to degas the primary molded body 10, so air bubbles near the surface of the primary molded body 10 burst and gas is vented, which is caused by paint baking. Problems such as cavities and pinholes in the paint can be sufficiently removed, making it possible to make the paint film thinner. In addition, the coated resin is also filled in the caldera (depression) 30, creating a so-called anchoring effect.
Adhesion between the primary molded body and the coating film increases. Furthermore, since the resin paint is injected under reduced pressure, it is possible to improve the film formability of the coat paint.

Although one embodiment of the present invention has been described above, it goes without saying that the upper mold 2 may be lowered after the resin paint is injected.

(Effects of the Invention) As is clear from the above description, according to the present invention, a coating film is formed on the next molded product after degassing treatment by reduced pressure. Even as a thing,
Inconveniences in the subsequent paint baking process, that is, the occurrence of paint holes, pinholes, etc. due to the expansion and bursting of air bubbles mixed in the primary molded body can be sufficiently prevented. In addition,
The resin filled in the hollow after defoaming allows the coating film coated on the primary molded body to be closely held.

[Brief explanation of the drawing]

Figures 1 to 5 are diagrams showing one embodiment of the present invention. Figure 1 is an overall longitudinal cross-sectional view of an apparatus used in the in-mold coating method, and Figure 2 is for high-pressure air jetting and resin paint injection. A cross-sectional view of the injector. Figure 3 (a) is a cross-sectional view showing pinhole fracture in the primary molded body under reduced pressure. Figure 3 (b) is a cross-sectional view showing pinholes in the primary molded body. Figure 4 is a cross-sectional view showing the pinhole fracture in the primary molded body. Showing the state of adhesion between the product and the coating film 2 Lower mold 2 2 Upper mold 3: Combined mold 9 Primary space 1O Knee molded body 11: Secondary space 13: Injector 14: Paint jet nozzle 22: High pressure air passage 26: Decompression passage Figure 3 (α) (b)

Claims (1)

[Claims] (1) After molding a primary plastic body in the primary space formed by closing a combined mold consisting of a first mold and a second mold, the combined molds are slightly separated. A secondary space is formed between one of the molds and one side of the primary molded body, and the resin paint injected into the secondary space forms one side of the primary molded body in the combined mold. In the in-mold coating method for forming a coating film, the resin coating is injected after the pressure in the secondary space is reduced to defoam the primary molded body. Mold coat method.