JPH07121549B2 - Double structure container molding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a so-called dual structure container having a cavity in a body.

[Conventional technology]

In many conventional containers for storing contents such as creamy cosmetics, the body of the container is bulged outward in consideration of the external shape such as a sense of stability and a sense of weight. In this case, the inside of the container cannot be swollen outward because it is necessary to pull out the contents with a finger, and as a result, the outer wall is swollen and the inner wall is almost vertical.

Conventionally, in the production of these double-structured containers, as shown in FIG. 5, a middle container 10 providing an almost vertical inner wall and an outer container 11 providing an outwardly bulging shape are separately molded, and both of them are formed. It was achieved by assembling.

[Problems to be solved by the invention]

However, in the conventional method of assembling the both, an assembling process is required, an adhesive is required for assembling the both, and the adhesive flows to deteriorate the appearance. In the case of high frequency or ultrasonic welding, There are many problems such as the need for the device, the increase in manufacturing cost, and the assembling of the both, which is apt to cause a molding error.

The present invention was devised to solve these problems, and provides a method for molding a double structure container that does not cause the above problems.

[Means for solving problems]

First, the case where the primary molded product 2 is a single layer will be described with reference to FIGS. 1 to 4.

First, the primary molded product 2 is molded by injection molding (see FIG. 1). Next, the primary molded product 2 is installed in the blow mold 6 while holding the mouth portion 3 and the inner mold 7 is assembled in the primary molded product 2, and the bottom of the primary molded product 2 is installed. An air needle 8 is inserted into the central portion of the wall 4 to blow air into the bottom wall 4 (Fig. 2). In this case, the surface of the primary molded product 2 is kept in a softened state so that it can be easily deformed by air blow, and the inside thereof is kept in a molten state.

Then, by forming a cavity 9 by air inside the bottom wall 4 and inside the cylinder wall 5 between the bottom wall 4 and the mouth portion 3, the bottom wall 4 and the cylinder wall 5 are bulged, and the primary molded product 2 Is molded into a shape set by the blow mold 6 and the inner mold 7 (Fig. 3) to obtain a finished product (Fig. 4).

When the primary molded product is a laminated product, as shown in FIG. 6, the air needle 8 is inserted until it reaches the laminated boundary portion 14 to blow air, and as a result, as shown in FIG. The piece (inner piece 12) and the outer piece (outer piece 13) are separated, and the outer piece 13 is swollen to obtain a finished product.

In the case of the primary molded product 2 as shown in FIG. 8, which is formed by so-called sandwich molding in which different kinds of resins forming the surface layer 15 and the core layer 16 are simultaneously injected even if they are the same laminate Also, the same as above
The air needle 8 is made to reach 14 and the air is blown. In this case, the air may be blown to either the upper surface or the lower surface of the core layer 16.

[Action]

The air blown to the central portion of the bottom wall 4 forms a cavity 9 by cutting off molecular bonds inside the primary molded product 2 because the interior of the primary molded product 2 is in a molten state. At this time, the surface of the primary molded product 2 is not in a molten state but in a softened state necessary for blow molding, so that it is not broken by the pressure of the air.

Due to the formation of the cavity 9 by the air, the outer surfaces of the bottom wall 4 and the cylindrical wall 5 bulge outward and come into contact with the inner surface of the blow mold 6, whereby the bulging deformation stops. The inner surfaces of the bottom wall 4 and the cylindrical wall 5 are prevented from being bulged and deformed by the inner mold 7.

When the primary molded product 2 is a laminate, the bond between the inner piece 12 and the outer piece 13 is not as strong as the molecular bond in the single-layer primary molded product, so the air blown to the boundary between the inner and outer pieces 12 and 13 causes the inner piece to separate. The outer piece 12 and the outer piece 13 separate relatively easily.

Also, a laminated primary molded product 2 composed of the surface layer 15 and the core layer 16
Even when the resin is blown, it is possible to easily release the bond between the two different types of resin by blowing to the stacking boundary portion 14,
A cavity 9 is formed.

〔Example〕

In the present invention, at least the following two methods are used to soften the surface of the primary molded product 2 and to melt the inside thereof.

One is a method of assembling the primary molded product 2 into the blow mold 6 immediately after injection molding. In this case, since it is immediately after injection molding,
The surface is in a softened state and the inside is in a molten state even if no heating process is added.

The primary molded article molded by this method may be, for example, a single layer shown in FIG. 1 or a laminated layer composed of a surface layer and a core layer by simultaneously injecting different resins as shown in FIG. There are things. Immediately after the molding of the primary molded product, the surface is in a softened state and the inside is in a molten state.

Another method is that after the primary molded product 2 molded by injection molding is once cooled, it is heated to a softened state where the surface can be blow-molded, and the inside is hollowed.
It is a molten state that can be formed. This method is applied to, for example, a laminated primary molded product 2 formed by so-called insert molding as shown in FIG. 6 in which the inner piece 12 is injection-molded and then the outer piece 13 is injection-molded. The primary molded product 2 molded by insert molding is
This is because the surface is not necessarily in a softened state and the inside is not necessarily in a molten state.

The containers shown in FIGS. 1 to 4 and the containers shown in FIGS. 6 to 9 are molded mainly for the purpose of obtaining the external shape shown in the drawings, but shown in FIG. The container is a container molded for another purpose. The container shown in FIG. 10 is formed as a container for storing instant food to be cooked, and by forming the cavity 9, the heat conduction of the food heated to high temperature is reduced so that it can be held by hand. It was made so that it was not hot.

Further, for example, in a container that stores a carbonated beverage or the like and is required to have a high gas barrier property, it is possible to fill the cavity 9 with a material having a high gas barrier property to form a container having an excellent gas barrier property.

〔The invention's effect〕

As described above, according to the present invention, the double-structured container can be molded only by adding blow molding to the primary molded product.
An adhesive is required to assemble the two, and the adhesive flows to deteriorate the appearance. In the case of high-frequency or ultrasonic welding, the device is required, and the manufacturing cost is high. Inevitably causes molding errors, etc.-
To solve all of the above.

Further, even when a high-temperature content is stored, the heat is hard to be conducted, and therefore, the user does not feel the heat even when holding it in his / her hand.

Furthermore, by filling the cavity with a material having a high gas barrier property, a container having a good gas barrier property can be obtained, and many other excellent effects are exhibited.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a single-layer primary molded product formed by injection molding, and FIG. 2 is a state in which the single-layer primary molded product is assembled in a blow mold and an air needle is inserted, Third
FIG. 4 is a sectional view showing a state in which air is blown, FIG. 4 is a completed product, and FIG. 5 is a conventional double structure container. FIG. 6 shows a state in which an air needle is inserted into the laminated primary molded product, and FIG. 7 shows a state in which air is blown into it.
FIG. 9 is a state in which an air needle is inserted into another laminated primary molded product, FIG. 9 is a state in which air is blown into it, and FIG. 10 is a sectional view showing yet another embodiment. Explanation of symbols 1: Double structure container, 2: Primary molded product, 3: Mouth part, 4: Bottom wall, 5: Tube wall,
6: Blow mold, 7: Inner mold, 8: Air needle, 9: Cavity, 10:
Medium container, 11: Outer container, 12: Inner piece, 13: Outer piece, 14: Laminated boundary part, 15: Surface layer, 16: Core layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area B65D 1/09 // B29L 22:00

Claims (1)

[Claims] 1. A single-layer or laminated primary molded product (2) molded by injection molding is assembled in a blow mold (6) while holding an opening (3) of the primary molded product (2). With the inner mold (7) assembled in the primary molded product (2), the surface of the primary molded product (2) is in a soft state capable of blow molding and the inside is in a molten state. At times, an air needle (8) is inserted into the central portion of the bottom wall (4) of the primary molded product (2), and inside the bottom wall (4), or when the primary molded product is a laminate, a lamination boundary portion ( 14) blow air into the bottom wall (4) and inside the bottom wall (4)
The bottom wall (4) and the cylinder wall (5) are bulged by forming a cavity (9) by the air inside the cylinder wall (5) between the mouth (3) and the primary wall (3). Double structure container (1) formed by molding a molded product (2) into a shape set by the blow mold (6) and the inner mold (7).
Molding method.