JPH07137754A - Plastic container cap and production thereof - Google Patents

Abstract

PURPOSE:To obtain a plastic container cap excellent in the adhesion of the container cap body with a linear, by providing an adhesive layer or an adhesive primer layer at the linear side face of a gas barrier sheet or film, which is laminated at the whole area of the inside face of the top face. CONSTITUTION:A gas barrier layer 2 is laminated over the whole area of the top face 1a and the end thereof is caught in the inside of the skirt-form side wall 1b. Metallic foils or resin films are used for the constituting elements. An adhesive layer or an adhesive primer layer 3 is formed at the face of the linear layer 3 side of the gas barrier layer 2 to increase the adhesion with the linear layer 3. When the gas barrier layer is made of a metallic foil, an adhesive primer layer is formed. When it is made of a resin film, an resin adhesive layer is formed. The linear layer 3 has appropriate arshoning properties and firmly fixed to the gas barrier layer 2 through the adhesive layer or the adhesive primer layer to increase the hermetic function against the container opening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic container lid and a method for producing the same, and more particularly to a plastic having good gas barrier properties and excellent adhesion between a liner material and a container lid shell. The present invention relates to a container lid and a manufacturing method thereof.

[0002]

2. Description of the Related Art Container lids used for various containers are generally
It is composed of a top surface and a skirt-shaped side wall hanging down from the peripheral portion of the top surface, and at present, a plastic container lid is widely used. This plastic container lid is generally made of relatively hard plastic from the viewpoint of strength and rigidity, but in consideration of the sealing property with the container mouth, the inside of the top surface should be
As with a conventional metal lid, a liner layer made of a relatively flexible material is formed. That is, since the liner layer has a cushioning property, the sealing property with the container mouth is secured.

[0003]

A liner layer formed of a relatively soft plastic material has a problem of poor adhesion to a lid body formed of hard plastic. Problems often occur where the layers fall off the lid. The liner layer is usually formed by dropping a melted liner material on the center of the top surface of the lid and molding it. Is dropped in a state where the lid is held by a supporting device that rotates at a high speed. However, because the adhesiveness between the liner material and the lid is poor, the dropped liner material easily moves during high-speed rotation of the lid, and it is difficult to obtain a regular liner shape by embossing. There is also.

For this reason, for example, Japanese Patent Publication No. 63-4462.
No. 7, it is proposed to form a circumferential protrusion near the base of the skirt-shaped side wall on the inner surface of the container lid shell. In other words, the circumferential projection mechanically holds the liner layer to prevent the liner layer from falling off.

However, in the above prior art,
Since the projection is formed on the inner surface of the container lid shell, the molding workability is unavoidable. Further, since the adhesiveness between the liner layer and the container lid shell is not improved, the liner material dropped during the high-speed rotation of the lid during embossing is easy to move and the regular liner shape is maintained. The problem of being difficult to obtain is still unsolved.

Further, the plastic container lid has a poor gas barrier property, and there is a basic problem that gas easily passes through the top surface of the container lid.

Therefore, an object of the present invention is to provide a plastic container lid which has a good gas barrier property and is excellent in the adhesiveness between the liner material and the container lid shell. Another object of the present invention is to provide a method for efficiently manufacturing the above plastic container lid.

[0008]

According to the present invention, a plastic container lid shell having a top surface and a skirt-like side wall hanging down from the peripheral portion of the top surface, and covering the entire area of the inner surface of the top surface. A laminated gas barrier sheet or film, and a liner layer provided on the gas barrier sheet or film, at least the liner layer side surface of the gas barrier sheet or film, A plastic container lid is provided which is provided with an adhesive layer or an adhesive primer layer.

Further, according to the present invention, a gas barrier sheet or film having an adhesive layer or an adhesive primer layer on at least one surface thereof is held in an insert mold to perform plastic injection molding, A container lid shell body in which a gas barrier sheet or film is laminated on the inner surface of the top surface is molded, and a liner material in a molten state is dropped on the gas barrier sheet or film layer of the container lid shell body, and then a mold is formed. A method for manufacturing a plastic container lid is provided, wherein a pressing tool is inserted into a container lid shell to press and spread a liner material to form a liner layer.

[0010]

In the present invention, a gas barrier sheet or film (hereinafter, simply referred to as a gas barrier layer) in which an adhesive layer or an adhesive primer layer is formed between the inner surface of the container lid shell and the liner layer. It is a remarkable feature that the call is provided. That is, since the gas barrier layer is formed inside the top surface, the plastic container lid of the present invention has an extremely good gas barrier property.

The gas barrier layer is formed of a resin or a metal foil having a gas barrier property. Since an adhesive layer or an adhesive primer layer is provided on these, a hard plastic forming the container lid shell is formed. The adhesiveness with the liner material is extremely good as compared with the material. Therefore, no special projection or the like for mechanically holding the liner layer inside the container lid shell is required, and when the liner layer is formed by embossing during high-speed rotational movement, the molten liner material is It is stably held at the dropped position (the inner center of the container lid shell), and the trouble that the regular liner shape cannot be obtained due to its movement or the like is effectively eliminated. Thus, according to the present invention, the plastic container lid can be efficiently manufactured, and high productivity can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to specific examples shown in the accompanying drawings. FIG. 1 is a half sectional view showing a structure of a plastic container lid of the present invention, and FIG. 2 is a partial sectional view showing another example of the plastic container lid of the present invention. Further, FIG. 3 is a diagram showing a process of manufacturing a container lid shell, a gas barrier layer and a combined body, and FIG. 4 is a diagram showing a process of forming a liner layer.

(Construction of Container Lid) In FIG. 1, the container lid of the present invention basically comprises a plastic container lid shell 1, a gas barrier layer 2 and a liner layer 3. .

The container lid shell 1 is composed of a top surface 1a and a skirt-shaped side wall 1b hanging from the peripheral edge of the top surface 1a. A screw portion 1c for engaging with a container neck portion (not shown) is formed on the inner surface of the skirt-shaped side wall 1b, and a tip of the skirt-shaped side wall 1b may be provided with a weakening line such as a perforation line if necessary. A pill fur proof band may be provided. As a constituent material of the container lid shell 1, a relatively hard plastic material such as a polyolefin resin such as polypropylene or a polyamide resin such as nylon is used.

The gas barrier layer 2 is laminated over the entire area of the top surface 1a, and, for example, its end portion cuts into the inside of the skirt-shaped side wall 1b. As a result, since the entire inner surface area of the top surface 1a is completely covered with the gas barrier layer 2, it is possible to effectively prevent gas permeation through the top surface 1a, and the container lid of the present invention is The gas barrier property becomes extremely good.

The constituent material of the gas barrier layer 2 is, for example, aluminum, tin plate, tin-free steel (TFS).
Metal foil such as ethylene-vinyl alcohol copolymer,
Resin films such as vinylidene chloride resin and aromatic polyester resin are used. The thickness of the gas barrier layer 2 may be set so as to exhibit a satisfactory gas barrier property depending on the constituent material.

An adhesive layer or an adhesive primer layer is formed on at least the surface of the gas barrier layer 2 on the liner layer side to improve the adhesiveness with the liner layer.
For example, when the gas barrier layer 2 is a metal foil, an epoxy-phenol type paint, an epoxy-amino type paint,
An adhesive primer layer known per se, such as an epoxy-phenol-vinyl type paint, is formed. When the gas barrier layer 2 is a gas barrier resin film, an adhesive resin layer made of a carbonyl group-containing thermoplastic resin is formed. Suitable examples of such adhesive resins include ethylene-acrylic acid copolymers, ion-crosslinked olefin copolymers, maleic anhydride grafted polypropylene, acrylic acid grafted polypropylene, ethylene-vinyl acetate copolymers, copolymerized polyesters, copolymers. Examples thereof include one type or a combination of two or more types of polymerized polyamide, amide-modified polyester and the like. Of course, these adhesive layers or adhesive primer layers may be formed on both sides of the gas barrier layer 2.

Further, as shown in FIG. 2, a rising portion 2a may be formed at the end portion of the gas barrier layer 2 along the inner wall of the skirt-shaped side wall 1b. This aspect is
Since the adhesion area with the liner layer 3 can be increased, it is extremely advantageous in that the liner layer 3 can be firmly adhered and fixed.

The liner layer 3 formed on the gas barrier layer 2 has an appropriate cushioning property and provides a good sealing property with the mouth of the container. Usually, polyethylene or soft polychlorinated material is used. It is made of vinyl, various thermoplastic elastomers, and other rubber materials. In addition, a thick projection 3a is formed on the peripheral portion of the liner layer 3 so as to be in close contact with the inner surface of the container opening in order to further improve the sealing performance with the container opening.

It is an advantage of the present invention that the liner layer 3 is firmly fixed to the gas barrier layer 2 via the above-mentioned adhesive layer or adhesive primer layer.

(Manufacturing Method) In manufacturing the container lid of the present invention, first, a gas barrier sheet or film having an adhesive layer or an adhesive primer layer formed on at least one surface thereof is punched into a desired shape. As shown in FIG. 3, the sheet or film 2 is held at the tip of the insert mold 5 and inserted into the shell mold 6, and the plastic material is injected into the space between the two, whereby the gas barrier layer 2 is formed. The container lid shell body 1 in which is laminated is molded. The injection conditions such as the injection pressure may be known per se.

The insert mold 5 is usually a screw core 5a which can be moved up and down, and a screw core 5a.
A core head 5b fixed to the tip is used, and a gas barrier sheet or film 2 is held by the core head 5b. The holding of the sheet or film 2 can be easily performed by applying a magnetic force, vacuum, or the like. For example, when the sheet or film 2 is made of a magnetic material such as tinplate, the core head 5b can be used as a magnetic material to hold it by magnetic force, and when it is a non-magnetic material such as aluminum, a vacuum tube is used. Connected to the core head 5b,
The sheet or film 2 can be held by the suction force.

After completion of the injection molding, when the insert mold 5 is pulled out, the sheet or film 2 is adhered and fixed to the molded container lid shell 1, so that it is easily separated from the insert mold 5 (core head 5b). Thus, the container lid shell 1 in which the gas barrier sheet or film 2 is laminated inside the top surface is obtained.

Next, as shown in FIG. 4, the liner layer 3 is formed by embossing using the embossing tool 6, whereby the plastic container lid of the present invention is obtained. In this embossing molding, the molten liner material is dropped onto the center of the gas barrier sheet or film 2 and the embossing tool 6 is lowered, whereby the melted liner material is pressed and spread to form the liner layer 3 Is formed. In the present invention, since the adhesiveness between the melted liner material and the gas barrier sheet or film 2 is good, the dropped liner material is stably held in that position without moving and has a regular liner shape. It is possible to perform stamping and molding.

The embossing can be carried out by a conventionally known method. For example, as the embossing tool 6, the peripheral sleeve 6 is used.
a, a center punch 6b, and an outer punch 6c located between the two, and by descending them in any order, the molten liner material is spread into a desired shape to form the liner layer 3 Can be formed.

At the time of the above-mentioned embossing molding, for example, a concave portion 2 is formed in the central portion of the gas barrier sheet or film 2.
By forming b, it is possible to more reliably hold the position of the dropped molten liner material.

[0027]

In the plastic container lid of the present invention, the gas barrier layer is formed between the top surface of the container lid shell and the liner layer, so that gas permeation through the top surface is prevented. Not only can it be effectively suppressed, but since the adhesiveness between the gas barrier layer and the liner layer is good, there is no need to form protrusions or the like on the top surface for fixing the liner layer, and there is no moldability. Very good. Further, since the liner material has good adhesiveness to the gas barrier layer, when the liner layer is formed by embossing, a molten state dropped on the gas barrier layer during embossing during high-speed rotation. The liner material does not move and can be stably held at a predetermined position, and stable embossing molding can be performed, and a liner layer with a regular shape can be formed. There is.

[Brief description of drawings]

FIG. 1 is a half sectional view showing the structure of a plastic container lid of the present invention.

FIG. 2 is a partial cross-sectional view showing another example of the plastic container lid of the present invention.

FIG. 3 is a diagram showing a process of producing a container lid shell, a gas barrier layer, and a combined body.

FIG. 4 is a diagram showing a step of forming a liner layer.

Claims (3)

[Claims] 1. A plastic container lid shell having a top surface and a skirt-shaped side wall hanging from a peripheral portion of the top surface, and a gas barrier sheet or a gas barrier sheet laminated over the entire area of the inner surface of the top surface. A film and a gas barrier sheet or a liner layer provided on the film, and an adhesive layer or an adhesive primer layer is provided on at least the liner layer side surface of the gas barrier sheet or film. A plastic container lid characterized in that 2. The plastic container according to claim 1, wherein the gas barrier sheet or film has a rising portion extending from a peripheral edge portion on the inner side of the top surface along the inner side surface of the skirt-shaped side wall. lid. 3. A gas barrier sheet or film having an adhesive layer or an adhesive primer layer provided on at least one surface thereof is held in an insert mold to perform plastic injection molding, and the inner surface of the top surface A container lid shell in which gas barrier sheets or films are laminated is molded, a molten liner material is dropped on the gas barrier sheet or film layer of the container lid shell, and then a stamping tool is used to attach the container lid. A method of manufacturing a plastic container lid, which comprises inserting a liner material into a shell and spreading it to form a liner layer.