JPS6161969B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a tube container, and more specifically, it is an object of the present invention to easily mold a tube container with high gas barrier properties.

As the scope of use of tube containers has expanded, even tube containers made of synthetic resin are increasingly required to have high gas barrier properties.

In order to meet this requirement, synthetic resin tube containers have been manufactured whose bodies are made of laminated sheets using metal foils such as aluminum foils.

Although this tube container was proven to exhibit high gas barrier properties and was found to be extremely effective, it was by no means perfect in terms of gas barrier properties.

In other words, since the body of the tube container is made of a laminated sheet using metal foil, it can exhibit high gas barrier properties. Since the molded head is entirely molded from synthetic resin, the gas barrier properties of the head are not sufficient, and therefore the gas barrier properties of the tube container as a whole are not sufficient.

Various efforts have been made to improve the gas barrier properties of the head of this synthetic resin tube container, but the most representative one is the use of a laminated sheet made of metal foil for the head as well as for the body. It is intended to be used.

It is certainly expected that the gas barrier properties of the head will be on the same level as the gas barrier properties of the body, but as is well known, the head is different from the body. Because it is funnel-shaped, it is difficult to mold the sheet into this upside-down funnel shape, making the molding operation extremely troublesome, or the sheet must have many notches, making it difficult to completely form the sheet. It was not possible to obtain good gas barrier properties.

The present invention was devised to resolve the above-mentioned dissatisfaction with the gas barrier properties of synthetic resin tube containers, and the present invention will be described below with reference to the drawings.

The present invention involves molding a thin inverted funnel-like body made of metal such as aluminum to match the shape of the head of a tube container, and using this inverted funnel-like body as a part of a molding die to form an inverted funnel-like body. The head is formed by insert-molding the outer layer and inner layer in order across the body, and this head is fitted and joined to the upper end of the body made of a laminated sheet made of metal foil such as aluminum foil. . The metal middle layer 2, which is formed into an inverted funnel shape that matches the head of the tube container, is formed by forming a suitable metal such as aluminum into a thin plate shape, and then forming it into an inverted funnel shape by means such as impact molding or press forming. It is a molded product, and it is desirable that its wall thickness be as thin as possible.

After forming the middle metal layer 2 in this way, the outer layer 3 and the inner layer 4 are placed on the outside and inside of the middle metal layer 2 in a form that covers the entire surface of the middle metal layer 2. Molding is performed in order using the insert molding method described in Section 1.

In the case of the illustrated embodiment, the outer layer 3 is first insert-molded using the middle metal layer 2 as part of the mold, and then, as shown in FIG. 2, the inner layer 4 is inserted inside the middle metal layer 2 with the outer layer 3 insert-molded on the outside. The head 1 is formed by molding.

In this way, the outer layer 3 and the inner layer 4 are molded by different injection molding operations, so the outer layer 3 is molded from a synthetic resin that has a beautiful appearance and is hard to scratch, whereas the inner layer 4 is molded from a synthetic resin that has a beautiful appearance and is hard to scratch. Can be molded from synthetic resin with excellent content properties.

Of course, since the outer layer 3 and the inner layer 4 need to be welded to each other at both their upper and lower ends, it is desirable that they be molded from compatible synthetic resin materials.

Once the head 1 has been formed in this way, the lower end of the head 1 is tightly fitted into the upper end of the body 5 which is formed from a laminated sheet using metal foil such as aluminum foil. Head 1 fitted into the upper end
The lower end is attached to the body part 5 by an appropriate means such as ultrasonic welding H.
Join the top end to form a tube container.

When joining the head part 1 and the body part 5, an assembled circumferential step part 6 is attached to the outer peripheral part of the lower end of the head part 1, that is, to the lower end part of the outer layer 3, with a thickness and width that is approximately equal to the thickness of the laminated sheet constituting the body part 5. If the upper end portion of the body portion 5 is fitted and joined to this circumferential assembly step portion 6, the outer surface of the joint portion between the head portion 1 and the body portion 5 becomes a smooth surface, which is convenient. It is.

By the way, as mentioned above, it is desirable that the metal middle layer 2 is as thin as possible. Therefore, when insert molding is performed with the metal middle layer 2 of the outer layer 3 or the inner layer 4 as part of the mold surface, This outer layer 3
Alternatively, since the metal core 2 must not be deformed by the injection pressure for molding the inner layer 4, when injection molding the outer layer 3 or inner layer 4, insert molding is performed with the metal core 2 assembled to the core or cavity. This is desirable.

As described above, in the method of the present invention, the head 1 is molded by insert molding the outer layer 3 and the inner layer 4 using the metal core 2 as part of the mold surface.
The mutual positional relationship between the metal middle layer 2, the outer layer 3, and the inner layer 4 is extremely accurate, and there is no possibility that the metal middle layer 2 will be deformed or a part of it will be exposed to the outside.

Furthermore, since the metal middle layer 2 is formed into a predetermined shape by itself, and only either the outer layer 3 or the inner layer 4 is insert-molded first, and then the other side is insert-molded, the outer layer 3 Further, the metal intermediate layer 2 is not deformed at all during the molding operation of the inner layer 4, and can be molded with peace of mind.

As is clear from the above description, the present invention allows the head 1 having the metal middle layer 2 to be molded easily, reliably, and stably, and the outer layer 3 and the inner layer 4 can be molded in completely separate molding operations. Therefore, it is an extremely effective method for forming tube containers with high gas barrier properties, as it allows the use of optimal materials for each part.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view when an outer layer is impact-molded on the outside of a metal middle layer. FIG. 2 is a longitudinal cross-sectional view of the head of the device shown in FIG. 1, in which the inner layer is impact-molded inside the metal middle layer to complete the head. FIG. 3 is a longitudinal sectional view showing a state in which the head and body are joined after being fitted and assembled. Explanation of symbols, 1: Head, 2: Metal middle layer, 3: Outer layer, 4: Inner layer, 5: Body, 6: Assembly peripheral part,
H: Ultrasonic welding.

Claims (1)

[Claims] 1 A metal middle layer 2 thinly formed from a metal such as aluminum into an inverted funnel shape that matches the head of a tube container is used as part of the mold surface, and the metal middle layer 2 is formed on the outer and inner surfaces of the metal middle layer 2. Outer layer 3 made of synthetic resin material with complete coverage and excellent wear resistance
and the outer layer 3 has excellent content resistance.
A tube in which a head 1 is formed by sequentially insert-molding an inner layer 4 made of a synthetic resin material that is compatible with the molding material, and the lower end of the head 1 is fitted and joined to the upper end of a body 5 made of a laminated sheet. How to form a container.