JP2010221446A - Mold for in-mold coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for in-mold coating which can prevent a coating material from flowing over a runner to the side of a sprue when an in-mold coating method is executed. <P>SOLUTION: In the mold 1 for in-mold coating in which a cavity 12 is formed by a fixed mold 2 and a movable mold 3, a resin product 13 is molded by injecting a molten resin 10 in the cavity 12, and the resin product 13 is coated, a projection 11 is formed in the runner 5 through which the molten resin 10 is passed, and the shrunk resin 10 is adhered to the projection 11 to form a seal part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an in-mold coating mold having a structure that prevents a coating material from flowing out to a runner when an in-mold coating method is performed.

2. Description of the Related Art Conventionally, there has been known a mold that prevents a coating material from flowing into a molten resin injection portion by providing a recess in a runner (see, for example, Patent Document 1). By providing such a recess in the runner, the resin shrinks in the mold direction, eliminates the gap between the resin and the mold, and tries to prevent the coating material from flowing into the molten resin injection part. Is.

Japanese Patent No. 3599441

However, in the technique described in Patent Document 1, since the shrinkage direction of the resin is not only vertical and horizontal, the resin shrinks in a direction that impairs the adhesion between the mold and the resin. Accordingly, there is a problem that a gap is generated between the mold and the resin, and the film raw material cannot be completely prevented from flowing into the molten resin injection portion.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to allow the coating material to flow over the runner to the sprue side when performing the in-mold coating method. It is an object of the present invention to provide a mold for in-mold coating that can prevent this from occurring.

In order to solve the above-mentioned problems, the present invention provides a mold for in-mold coating in which a cavity is formed by a fixed mold and a movable mold, a molten resin is injected into the cavity to mold a resin article, and the resin article is coated. In the mold, a projecting portion is provided on a runner through which molten resin passes, and the contracted resin is brought into close contact with the projecting portion to form a seal portion.

Further, it is desirable that the convex portion has a convex shape formed by two continuous inclined surfaces, and an angle α formed by the inclined surface and the flow direction of the molten resin is 30 ° ≦ α ≦ 60 °.

According to the present invention, since the runner portion has a large volume of resin and large shrinkage, the adhesion of the resin to the convex portion provided on the runner is improved to form a seal portion with high sealing performance. Overflowing into the sprue side can be prevented. In addition, the mold can be easily processed, which contributes to cost reduction.

Moreover, if the angle α is set to an appropriate angle (30 ° ≦ α ≦ 60 °), the adhesion of the resin to the convex portion provided on the runner is improved.

Sectional view of the mold for in-mold coating according to the present invention Enlarged sectional view of the convex part Enlarged sectional view of the convex portion of another embodiment Illustration of in-mold coating method Illustration of in-mold coating method Explanation of the function of the convex part (A) When 30 ° ≦ α ≦ 60 °, (b) When 0 ° <α <30 °, (c) When α≈90 °

  Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, an in-mold coating mold 1 according to the present invention is a mold for performing an in-mold coating method, which is a fixed mold 2, a movable mold 3, a sprue 4, a runner 5, a gate 6, A covering material injection portion 8 for injecting the covering material 7 is provided.

Further, the runner 5, which is an intermediate passage from the sprue 4 to the gate 6, is provided with a convex portion 11 projecting from the runner 5. The cross-sectional shape of the runner 5 may be a rectangular shape, a circular shape, a semicircular shape, or the like, but the shape is not limited.

The convex portion 11 forms a seal portion for the covering material 7 by closely contacting the contracted resin 10 without hindering the inflow of the molten resin 10 into the runner 5. As shown in FIG. An annular convex shape protruding from the runner 5 is formed by the surfaces 11a and 11b. Assuming that the angle α formed between the inclined surface 11a and the flow direction of the molten resin 10 (arrow A direction), it is preferable that 30 ° ≦ α ≦ 60 °.

Further, instead of the convex portion 11, as shown in FIG. 3, an annular convex portion 21 that protrudes from the runner 5 is formed by the inclined surface 21 a, the parallel surface 21 b, and the inclined surface 21 c that are continuous with the flow of the molten resin 10. You can also

Here, if an angle α formed between the inclined surface 21a and the flow direction of the molten resin 10 (arrow A direction), the inner diameter L1 of the runner 5, the minimum inner diameter L2 of the convex portion 21, and the length T of the parallel surface 21b are 30 °. It is preferable that ≦ α ≦ 60 °, L1 ≧ 1.05 × L2, and T ≧ 0 [mm]. The case where T = 0 corresponds to the convex portion 11 shown in FIG.

The operation of the in-mold coating mold 1 according to the present invention configured as described above will be described. As shown in FIG. 4, the in-mold coating mold 1 has a cavity 12 formed by a fixed mold 2 and a movable mold 3, and a molten resin 10 supplied from a nozzle 9 of an injection molding machine to the cavity 12. Resin product 13 is molded by injection through sprue 4, runner 5, and gate 6.

Next, in the in-mold coating mold 1, after molding the resin product 13, as shown in FIG. 5, the coating material 7 is poured into the gap 14 formed by the resin product 13 and the cavity 12 from the coating material injection portion 8. The coating material 7 is coated on the surface (design surface) 13 a of the resin product 13. At this time, the covering material 7 passes from the gate 6 to the runner 5 through the gap 14 formed by the resin product 13 and the cavity 12.

  However, as shown in FIG. 6, the convex portion 11 is sandwiched by the contraction force of the resin 10, and the covering material 7 that has flowed into the runner 5 is sealed. It does not flow over to the sprue 4 side.

Here, when the angle α satisfies 30 ° ≦ α ≦ 60 °, as shown in FIG. 7A, the gold is more than the force with respect to the flow direction (arrow A direction) of the resin 10 caused by the shrinkage of the resin 10. Since the pressing force (in the direction of arrow B) to the mold 2 is increased, the convex portion 11 and the resin 10 are in close contact with each other, and the inflow of the covering material 7 to the sprue 4 side can be prevented.

When the angle α is 0 ° <α <30 °, as shown in FIG. 7B, the force in the flow direction (arrow A direction) of the resin 10 caused by the contraction of the resin 10 increases and the gold Since the pressing force (in the direction of arrow B) on the mold 2 is small, the close contact between the convex portion 11 and the resin 10 is weak, and it is difficult to reliably prevent the covering material 7 from flowing into the sprue 4 side.

When the angle α is around 90 °, as shown in FIG. 7C, the contact area between the resin 10 and the convex portion 11 is reduced, and the pressing force (in the direction of arrow B) to the mold 2 is weak. Therefore, it is difficult to prevent the covering material 7 from flowing into the sprue 4 side.

According to the present invention, when performing the in-mold coating method, it is possible to prevent the covering material from flowing into the sprue side beyond the runner, and the mold processing is easy and contributes to cost reduction. An in-mold coating mold can be provided.

DESCRIPTION OF SYMBOLS 1 ... In-mold coating die, 2 ... Fixed die, 3 ... Movable die, 4 ... Sprue, 5 ... Runner, 6 ... Gate, 7 ... Coating material, 8 ... Coating material injection part, 9 ... Nozzle, 10 ... Molten resin, 11, 21 ... Projection, 11a, 11b, 21a, 21c ... Inclined surface, 12 ... Cavity, 13 ... Resin product, 13a ... Surface, 14 ... Gap, 21b ... Parallel surface.

Claims (2)

A cavity is formed by a fixed mold and a movable mold, and a molten resin is injected into the cavity to mold a resin product. A mold for in-mold coating, characterized in that a sealing portion is formed by providing a portion and the contracted resin is in close contact with the convex portion. The in-mold coating mold according to claim 1, wherein the convex portion forms a convex shape with two continuous inclined surfaces, and an angle α between the inclined surface and the flow direction of the molten resin is 30 ° ≦ α. A mold for in-mold coating, wherein ≦ 60 °.