JP2010030253A - Synthetic resin made double wall molded article and molding method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic resin made double wall molded article exhibiting high quality decorativeness by the double wall by achieving the technical task to solve the problem wherein the damage of beauty in the appearance is caused by insert molding in the synthetic resin made double wall molded article by the insert molding. <P>SOLUTION: The synthetic resin molded article forming one side wall arranged in a mold as the insert material, a space is formed from the surface of the insert material and the surface of the mold arranged to be opposed to the surface, a pin gate opened vertically to the surface of the mold to face the space is provided to form a diameter enlarge part enlarged toward the downstream side at the tip and the molten resin is injected through the diameter-enlarged part toward the surface of the insert material to fill the space with the resin to form the other side wall to be in close contact with the insert material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a synthetic resin molded product having a double wall and a molding method thereof.

In the product field for cosmetics, there is a demand for a decoration method for imparting a high-class feeling and a differentiated eye-catching effect by packaging.
As one of such decoration methods, there is a method of constructing a container with a double wall, and it is possible to exhibit a high-quality three-dimensional visual effect that the inner wall floats through the transparent outer wall. it can.

As a means for making a double-walled molded product such as a cap body like a cap body, the outer cylindrical body and the inner cylinder body are separately injection-molded, and two members are fitted together A method of assembling, or a method of sequentially injection-molding the outer cylinder body and the inner cylinder body by so-called two-color molding as described in Patent Document 1, for example, and either one of the outer cylinder body and the inner cylinder body There is a method of injection molding with the other as an insert material.
Japanese Patent Laid-Open No. 2000-200522

  Here, in such a double wall molded product with the outer wall made transparent, the properties of the interface between the outer wall and the inner wall, gate traces, weld lines, or outer wall so as not to impair high-quality decoration. In addition, it is necessary to design the shape of each member in consideration of the fact that the joint portion of the inner wall can be seen from the outside, and to determine the molding method.

  The present invention has a technical problem to solve the problem of appearance loss due to insert molding in a double wall molded product made of synthetic resin by insert molding. It aims at providing the synthetic resin double wall molded product which exhibits.

The present invention relates to a synthetic resin double wall molded article and an injection molding method thereof, and will be described below in the order of the molding method and the double wall molded article.
First, the main molding method of the present invention for solving the above problems is as follows.
A synthetic resin molded product that forms one wall in the mold is installed as an insert material.
A gap is formed by the surface of the insert material and the mold surface disposed opposite to the surface,
A pin gate that opens in a direction perpendicular to the mold surface toward the gap is formed into a shape in which a diameter-expanded portion that expands toward the downstream is formed at the tip.
Injecting molten resin toward the surface of the insert material through this enlarged diameter portion, filling the gap and forming the other wall in close contact with the insert material,
It is said.

According to the above-described molding method, the tip end of the pin gate is a diameter-expanded portion that expands toward the downstream, and the gap is opened through the diameter-expanded portion so that the pin gate faces the surface of the insert material. The flow direction of the injected molten resin can be dispersed, the concave deformation of the surface of the insert material caused by the collision of the high temperature molten resin injected at high speed can be suppressed, and the interface of the double wall can be suppressed. Can be formed on a flat surface without unevenness or a gently curved surface,
Even when one wall is made transparent and the decorative property is imparted by the double wall, the decorative property by the double wall can be exhibited with higher quality.

In addition to the main molding method, the other molding method of the present invention includes:
A synthetic resin molded product having a double wall is a top cylindrical molded product composed of a top cylindrical outer cylinder and an inner cylinder,
Install the outer cylinder as an insert material in the hollow cylindrical cavity mold,
The core mold uses a pin gate formed through the axis,
By clamping the mold, the core mold is disposed with respect to the cavity mold so as to form a predetermined gap with respect to the inner surface of the outer cylindrical body,
The molten resin is injected toward the center of the inner surface of the top wall of the outer cylinder through the enlarged diameter portion, and the gap is filled and the inner cylinder is fitted into the outer cylinder to form a close contact. .

The above-described molding method is a method in which a synthetic resin molded product having a double wall is identified as a cylindrical product formed from a cylindrical outer cylinder and an inner cylindrical body,
Since the outer cylinder is used as an insert material, a molten resin is filled into the gap formed by the inner surface of the core mold and the outer cylinder through a pin gate formed along the axis of the core mold. The inner cylindrical body can be formed without forming.

  In addition, by adopting a configuration that opens to the mold cavity through the enlarged diameter portion, the flow direction of the molten resin from the tip of the molten resin pin gate toward the center of the lower surface of the top wall of the outer cylinder located oppositely is dispersed. The interface of the double wall is made uneven by suppressing the concave deformation accompanied by the softening or melting of the resin at the center of the lower surface of the top wall of the outer cylinder due to the collision of the high-temperature molten resin injected at high speed. It can be formed on a flat surface with a smooth surface or a gently curved surface, and even when the outer cylinder body is transparent and the decorative property is given by the double wall, the decorative property by the double wall is also provided. Higher quality can be achieved.

Here, in a configuration in which a conventional pin gate without an enlarged diameter portion is opened in the gap, the high-temperature molten resin injected into the gap linearly collides with the central portion of the lower surface of the top wall of the outer cylindrical body. By the action of the force accompanying the collision, the central portion of the lower surface of the top wall of the outer cylindrical body is softened or melted, a recess is formed, and the injected molten resin enters the recess.
As a result, a small convex portion is formed on the top surface of the top wall of the inner cylindrical body, and when the outer cylindrical body is transparent, this convex portion is recognized from the outside, and the decorating property by the double wall is impaired. , High quality will be impaired.

  Here, in order to suppress the deformation of the insert material due to the collision of the high temperature molten resin, the insert material can be made of a synthetic resin having a softening temperature or a high melting temperature. The temperature of the resin is at least about 200 ° C., and the type of resin that can be used is limited to a very narrow range, and the material cost is generally high.

  Still another molding method of the present invention is to make the vicinity of the center of the lower surface of the top wall of the outer cylindrical body facing the enlarged diameter portion flat in a mold-clamped state.

  With the above configuration, the diffusion effect in the flow direction of the molten resin by the enlarged diameter portion is obtained by making the vicinity of the center of the lower surface of the top wall of the outer cylindrical body facing the enlarged diameter portion of the core mold in a clamped state. In combination, the flow of the molten resin is prevented from being concentrated in one place, and the resin is softened or melted and deformed at the center of the lower surface of the top wall of the outer cylinder used as the insert material in that portion. It can be prevented more effectively.

  Still another molding method of the present invention is that the diameter-expanded portion has a shape that expands in the shape of an inverted truncated cone toward the downstream, and this method specifies the shape of the diameter-expanded portion. .

Next, the main structure of the synthetic resin double wall molded product of the present invention is:
In the molded product in which the inner cylinder of the top cylinder is fitted into the outer cylinder by the injection molding with the outer cylinder having transparency as the insert material, and is fixedly assembled and inscribed,
In the center of the lower surface of the top wall of the inner cylindrical body, a frustum-like protrusion due to the tip shape of the pin gate formed in the core mold is formed in a hanging shape,
Further, in the vicinity of the position facing the protrusion, the interface between the top wall of the outer cylinder and the top wall of the inner cylinder is formed as a flat surface or a gently curved surface.
It is said.

The double-wall molded product having the above-described structure can be molded by the molding method of the present invention described above, but the frustum-shaped protrusion formed at the center of the lower surface of the top wall of the inner cylinder is formed on the core mold. It is formed by the enlarged diameter portion at the tip of the pin gate.
Further, in the vicinity of the position opposite to the position where the protrusion is formed, the configuration in which the interface between the top wall of the outer cylinder and the top wall of the inner cylinder forms a flat surface or a gently curved surface is a conventional pin gate. It is defined that there is no softening or melting of the resin at the center of the lower surface of the top wall of the outer cylinder used as an insert material, and no deformation due to the collision of the high-temperature molten resin injected from
Through the transparent outer cylinder, it is possible to reveal a smooth interface with no irregularities, and with the lens effect of the transparent outer cylinder, the double wall decoration is high-quality. It can be demonstrated.

The structure and the molding method of the present invention relating to the synthetic resin double wall molded product and the molding method of the present invention are as described above, and have the following effects.
That is, according to the main method of the present invention,
The flow direction of the molten resin injected from the pin gate toward the surface of the insert material by adopting a configuration in which the tip end of the pin gate is enlarged in diameter toward the downstream and the gap is opened through the enlarged diameter portion. Can suppress the concave deformation of the surface of the insert material due to the collision of high-temperature molten resin injected at high speed, and the double wall interface has a flat surface with no irregularities or a gently curved surface Can be formed.

In addition, in the method of molding a top cylindrical molded product having a double wall,
A flat or gently curved surface with no irregularities on the interface of the double wall by suppressing the concave deformation accompanying the softening or melting of the resin at the center of the bottom surface of the top wall of the outer cylinder used as insert material If the outer cylinder is made transparent, a smooth interface with no irregularities can be revealed through the transparent outer cylinder, Combined with the lens effect of the outer cylindrical body, it is possible to provide a double-walled molded product having a tubular shape that exhibits high-quality decoration by the double wall.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below along the examples with reference to the drawings.
1 to 3 show a cap body which is an embodiment of a synthetic resin double wall molded product of the present invention, FIG. 1 is a longitudinal front view, and FIG. 2 is a bottom view. As shown in FIG. 3, the cap main body 1 uses an undercut portion 16 at the lower end portion thereof, and is assembled by fixing and fixing a top cylindrical screwed cylindrical member 21 in an undercut shape. It is used as a cap for containers.
In addition, the fitting part 17 shown by FIG. 2 is for the positioning at the time of assembling and fixing the said screwing cylinder member 21. As shown in FIG.

  The cap body 1 is formed by injection-molding a cylindrical inner cylindrical body 12 made of a synthetic resin colored in black with an outer cylindrical body 2 made of a transparent cylindrical resin as an insert material. The three-dimensional structure in which the black inner cylinder 12 floats in the transparent outer cylinder 2 in combination with the lens effect of the thick outer wall 2 that is thick and transparent. The decorative effect is made to appear.

Further, when the details of the container body 1 are viewed, the tip of the pin gate disposed in the core mold described later when the inner cylinder 12 is injection-molded from the center of the bottom surface of the top wall 13 of the inner cylinder 12. Small frustoconical protrusions 15 are formed in a hanging shape depending on the shape.
Further, the interface in the vicinity of the center portion of the top walls 3 and 13 is a flat surface, and there is no uneven shape due to the collision of the high-temperature molten resin injected at a high speed when the inner cylinder 12 is injection molded, The interface formed by closely contacting the inner surface of the outer cylindrical body 2 and the outer surface of the inner cylindrical body 12 is formed smoothly as a whole,
Through the transparent outer cylinder, a smooth interface with no irregularities appears, and with the lens effect of the transparent outer cylinder, the double wall decoration is demonstrated with high quality. ing.

Next, the molding method of the present invention for molding the cap body 1 will be described with reference to FIGS. Here, FIG. 4 is an explanatory view of a method of injection molding the inner cylinder 12 using the outer cylinder 2 as an insert material, and FIG. 5 is an enlarged view of the vicinity of the pin gate in FIG.
As shown in FIG. 4, a mold 31 used for injection molding is composed of a hollow cylindrical cavity mold 32 and a core mold 33 formed through a pin gate 35 along an axial center. The outer cylinder body 2 is installed as an insert material, and the core mold 33 is disposed with respect to the cavity mold 32 in a state where a predetermined gap G is formed on the inner surface of the outer cylinder body 2 by clamping. The molten resin is injected through the pin gate 35 toward the center of the inner surface of the top wall 3 of the outer cylindrical body 2 to fill the gap G, and the inner cylindrical body 12 is fitted into the outer cylindrical body 2 to form a close contact ( (See FIG. 1).

A diameter-enlarged portion 35p that expands in the shape of an inverted truncated cone toward the downstream is formed at the tip of the pin gate 35 that is formed through the core mold 33, and the molten resin is introduced into the gap G through the diameter-enlarged portion 35p. It is configured to inject.
By injecting the molten resin into the gap G through the enlarged diameter portion 35p in this way, the flow direction of the injected molten resin is not only in the directly upward direction but also in the oblique direction, as shown by the white arrow in FIG. Can also be dispersed.

And by disperse | distributing the flow direction of the molten resin injected as mentioned above, it originates in the collision of the hot molten resin injected at high temperature, and the top wall 3 of the outer cylinder 2 used as an insert material The softening or melting of the resin and the concave deformation at the center of the inner surface can be effectively relieved, and a smooth interface having no irregularities can be made to appear as described above.
Here, in this embodiment, as shown in FIG. 5, the vicinity of the center of the inner surface of the top wall 3 of the outer cylinder 2 facing the enlarged diameter portion 35p, that is, the vicinity of the portion where the injected molten resin collides is a flat surface. Although it is set as the area | region 3f, by carrying out like this, the effect | action of the force resulting from the collision of a high temperature molten resin can be disperse | distributed more effectively.

  Further, in the molded product with the pin gate 35 having the enlarged diameter portion 35p formed at the tip as described above, a cone is formed at the center of the lower surface of the top wall 13 of the inner cylindrical body 12 in order to perform gate cutting at the portion where the flow path is most contracted. A trapezoidal protrusion remains in a hanging shape.

  On the other hand, according to the normal pin gate without this enlarged diameter portion 35p, the flow direction of the molten resin injected is concentrated in the directly upward direction as shown by the white arrow in FIG. Since high-temperature molten resin concentrates on the center of the lower surface of the top wall 3 of the outer cylindrical body 2 and collides at a high speed, a recess 4 is formed. As a result, as shown in FIG. Is formed at the center of the top surface of the top wall 13 of the inner cylinder 12 so that the interface between the outer cylinder 2 and the inner cylinder 12 is uneven. Deteriorating the quality decoration.

As mentioned above, although the embodiment about the synthetic resin double wall molded article of the present invention and its molding method was explained along the example, the embodiment of the present invention is not limited to the above-mentioned example.
The above embodiment is for a cap-shaped cylindrical cap body having a double wall, but the operational effects of the molding method of the present invention are not limited to such a bottomed cylindrical shape, for example, The present invention can also be applied to a container main body having a double wall in which the outer cylinder and the inner cylinder have a bottomed cylindrical shape, and a molded article having a general double wall.

  As described above, the synthetic resin double-wall molded product according to the molding method of the present invention is a cosmetic that suppresses the appearance deterioration due to insert molding and exhibits high-quality decoration by the double wall. A wide range of development in the field of containers is expected.

It is a vertical front view which shows one Example of the molded article of this invention. It is a bottom view of the molded article of FIG. It is a vertical front view which shows the state which fitted the screwing cylinder member to the molded article of FIG. It is explanatory drawing which shows one Example of the shaping | molding method of this invention for shape | molding the molded article of FIG. It is explanatory drawing which expanded the pin gate vicinity of FIG. It is explanatory drawing which shows the comparative example which concerns on the shaping | molding method of FIG. 4 similarly to FIG. It is a vertical front view of the molded product by the molding method of FIG.

Explanation of symbols

1; Molded product (cap body)
2; Outer cylinder (insert material)
3; top wall 3f; flat surface region 4; concave portion 12; inner cylinder 13; top wall 14; convex portion 15; projection 16; undercut portion 17; fitting portion 21; Cavity mold 33; core mold 35; pin gate 35p;

Claims (5)

A method of molding a synthetic resin molded product having a double wall using insert molding, wherein a synthetic resin molded product forming one wall in a mold is installed as an insert material, and the surface of the insert material A gap is formed by a mold surface disposed opposite to the surface, a pin gate opening in a direction perpendicular to the mold surface toward the gap, and a diameter-expanded portion that expands downstream toward the tip. The formed shape is formed, the molten resin is injected toward the surface of the insert material through the enlarged diameter portion, the gap is filled, and the other wall is formed in close contact with the insert material. Forming method. A synthetic resin molded product having a double wall is formed as a top-cylindrical molded product composed of a top-cylindrical outer cylinder and an inner cylinder, and is inserted as an insert material in the top-cylindrical cavity mold. A cylindrical body is installed, and the core mold is formed by penetrating the pin gate along the axis, and the core mold is formed with a predetermined gap with respect to the inner surface of the outer cylindrical body by clamping. So that the molten resin is injected toward the center of the inner surface of the top wall of the outer cylinder through the enlarged diameter portion, and the gap is filled to remove the inner cylinder. The molding method according to claim 1, wherein the molding method is carried out by fitting into a cylindrical body. The molding method according to claim 2, wherein in the mold-clamped state, the vicinity of the central portion of the lower surface of the top wall of the outer cylinder facing the enlarged diameter portion is a flat surface. The molding method according to claim 1, 2, or 3, wherein the expanded diameter portion has a shape that expands in a reverse frustoconical shape toward the downstream. A molded product in which the inner cylinder of the top cylinder is inserted into the outer cylinder and assembled and fixed in an inscribed manner by injection molding using the outer cylinder having a top cylinder and transparency as an insert material. In the center of the bottom surface of the top wall of the inner cylindrical body, a frustum-shaped protrusion due to the shape of the tip of the pin gate formed on the core mold is formed in a hanging shape, and in the vicinity of the position facing the protrusion, the outer A synthetic resin double-wall molded product, characterized in that the interface between the top wall of the cylinder and the top wall of the inner cylinder is formed as a flat surface or a gently curved surface.

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