JP2555063Y2 - Gas barrier multilayer cap - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic cap, and more particularly, to a multilayer cap having oxygen barrier properties.

[0002]

2. Description of the Related Art As a plastic cap used for a container for storing and preserving medicines, foods, etc., a single-layer cap made of plastic is often used. Is enough
In order to unavoidably compensate for this, it is common practice to heat seal a gas barrier sheet with aluminum foil etc. laminated on the container opening or to laminate and coat a gas barrier sheet on the inner surface or outer surface of the cap to maintain gas barrier properties. I have.

[0003] However, the former heat-heeled sheet loses its function once peeled off, and in the latter case, the step of laminating and covering the gas barrier sheet on the single-layer cap is said to increase. There was a problem.

In order to solve the above problem, a multilayer cap having a three-layer structure in which a gas barrier resin layer is provided in an intermediate layer has been disclosed (Japanese Utility Model Laid-Open No. 62-2).
00561). However, since the base material of the cap is polypropylene, the polyolefin resin such as polyethylene and the gas barrier resin have poor interlayer adhesion,
It has the drawback that delamination tends to occur and sufficient gas barrier properties cannot be obtained.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a plastic cap used for a container for storing and preserving medicines, foods, etc., wherein the cap is provided with an adhesive layer of three types.
It is an object to provide a gas barrier multilayer cap of layers.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a gas barrier in which a cap includes a gas barrier resin and a synthetic resin has a layer structure of three types and five layers by injection molding. It is a multi-layer cap.

The configuration of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view illustrating one embodiment of a gas barrier multilayer cap according to the present invention. FIG. 2 is an explanatory view showing a partially enlarged cross section of a portion A in FIG. The cap 1 has a gas barrier resin layer 4 such as a saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH) or polyvinylidene chloride as a central layer, and a polypropylene resin having content suitability or strength suitability as an innermost and outermost layer. Base layer 2 such as polystyrene resin, and gas barrier resin layer 4 described above.
And a bonding layer 3 for bonding the innermost and outermost base layers 2 to each other. The adhesive layer 3 can be appropriately selected depending on the types of the base material layer 2 and the gas barrier resin layer, and a maleic acid graft-modified polypropylene resin or the like as a polypropylene-modified resin is used.

The manufacturing method is disclosed in "Multilayer molding nozzle and injection molding method" proposed by the applicant, Japanese Patent Application No. 01-27.
No. 1154, it can be realized by one injection molding.

[0009]

The gas barrier multi-layer cap of the present invention has the appearance of a conventional single-layer cap made of polypropylene or the like because it has a gas barrier resin layer in the intermediate layer. If the plug is closed again after plugging, the gas barrier function is maintained. Further, since the adhesive layer is provided between the intermediate layer and the base layer, a sufficient interlayer adhesive strength can be obtained even between the base layer and the intermediate layer having no adhesiveness.

[0010]

[Embodiment] According to the manufacturing method proposed by the applicant, 3
The different types of resins were simultaneously injected at the same time to form a multilayer cap having a five-layer structure with a diameter of 100 mm for the front and back sides. That is,
A polypropylene resin having a melt index (MI) of 15 as the innermost and outermost layers 2, EVOH as the intermediate layer, and EVOH as the outer layer.
As an adhesive layer between the layer and an adhesive layer between the inner layer and the EVOH layer,
Using maleic acid graft modified polypropylene resin,
Both resins have a resin temperature of 240 ° C and a mold temperature of 40 °
C.

As a comparison with this multilayer cap, the oxygen permeability of the same cap molded with a single layer of polypropylene was measured. In addition to the small value, it was found that delamination did not occur even when an impact or deformation was applied, and that it had sufficient interlayer adhesion strength.

[0012]

[Effect of the Invention] By using the multilayer cap of the present invention, it is possible to maintain the barrier property only by the cap without using another gas barrier sheet or the like, and to bond between the intermediate layer and the base material layer. Since the agent layer is provided, sufficient interlayer adhesive strength can be obtained even between the base layer having no adhesiveness and the intermediate layer.

[0013]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a gas barrier multilayer cap according to an embodiment of the present invention.

FIG. 2 is a partially enlarged explanatory view of a portion A of FIG. 1 according to one embodiment of the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cap 2 ... Base material layer 3 ... Adhesive layer 4 ... Gas barrier resin layer

Claims (1)

(57) [Scope of request for utility model registration] The cap includes a gas barrier resin,
A gas-barrier multilayer cap having a layer structure made of three types and five layers of synthetic resin by injection molding .