JPH0549626U - Easy-open container - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an easily openable PET-based container having excellent gas barrier properties, low cost, and heat resistance capable of retort sterilization. [Structure] A gas barrier multi-layer film, an easy-open lid made of a resin sheet having a score part, and a PET container body, and a resin film having an acid anhydride group on the lid side joined to the container opening is used. Then, heat pressure bonding is performed by high frequency induction heating.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a polyethylene terephthalate-based resin container which is suitable for use in foods, beverages, pharmaceuticals, cosmetics, etc. and has an easy-opening property and an excellent sealing property.

[0002]

[Prior Art]

 At present, polyethylene terephthalate resins (hereinafter referred to as PET resins) such as polyethylene terephthalate and polybutylene terephthalate have excellent properties such as excellent transparency and aroma retention and gas barrier properties, and are suitable for beverages, foods or medical products It is widely used as a container in such fields. As a lid for sealing these PET-based containers, screw caps having screw threads have been the mainstream because stable heat sealing cannot be performed conventionally.

Recently, with the expansion of applications of PET-based containers, there is a demand for a lid for a solid substance such as dessert, which does not need to be resealed once opened and has a large opening diameter. However, the conventional screw cap type not only increases the cost but also becomes unnecessary once it is opened, so it is difficult to use this type. As a method for solving these problems, an easily openable heat-seal lid is being considered.

[0004]

[Problems to be solved by the device]

 However, the PET-based resin has a drawback that it rapidly fluidizes when heated to a temperature higher than its melting point, and stable heat sealability cannot be obtained. Furthermore, adjustment of the heat-seal strength is required to facilitate opening, but this was not possible with PET resins.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a PET-based container having an easily-openable lid.

[0006]

[Means for Solving the Problems]

 In the easily openable container of the present invention, the above problem is solved by providing a gas barrier multilayer film made of a resin having an acid anhydride group in a portion in contact with the opening of the PET container.

In the easily openable container of the second aspect, the joint strength between the lid and the container main body is improved by improving the sealing strength by forming at least the two surfaces of the horizontal and vertical portions of the container opening.

In the easily openable container according to the third aspect, the above object is achieved by using maleic anhydride-modified polypropylene for the thermoplastic film on the lid side joined to the opening of the container.

The resin having an acid anhydride group used in the present invention is an olefin polymer having a carboxylic acid anhydride group in the molecule. The olefin polymer is ethylene, propylene, butene-1, hexene-1, octene-1, 4-methyl-1-pentene, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, vinyl acetate, acrylic acid, It can be obtained by high-pressure copolymerizing at least one olefin such as methacrylic acid with a radical-polymerizable carboxylic acid anhydride. Further, it can be obtained by graft-modifying the acid anhydride to the olefin homopolymer or copolymer using a radical initiator such as an organic peroxide. All of these methods are generally widely known.

The radical-polymerizable carboxylic acid anhydride is preferably a cyclic one, and specific examples thereof include maleic anhydride, itaconic anhydride, citraconic anhydride, dodecenyl succinic anhydride and the like. Among these, maleic anhydride is preferably used. In addition, in some cases, it is possible to use two or more of them together.

Further, these resins having an acid anhydride group can be used as a mixture with other resins as long as the adhesiveness can be maintained. Further, if necessary, stabilizers, lubricants, antistatic agents, pigments, fillers and other additives may be added.

[0012]

[Action]

 In the easy-open container of the present invention, the portion of the PET container that contacts the opening is made of a resin having an acid anhydride group. Therefore, the PET container opening and the lid should be welded by high frequency induction heating. In addition, it was possible to achieve a good balance between easy opening and sealing.

[0013]

【Example】

 Hereinafter, the present invention will be described in detail with reference to examples. Embodiment 1 FIG. 1 is a sectional view showing an embodiment of the present invention. The PET container 1 is composed of a PET container body 2 and an easily-openable lid 3. The lid 3 comprises an outer layer part 4 made of polypropylene, a multilayer film 5 and a tab 7. Further, the outer peripheral portion of the lid 3 is formed as a flange portion 8, and a score portion 6 in which the multilayer film 5 is exposed is formed on the inner peripheral side of the flange portion 8, whereby the central portion 9 is covered. It is said to be the opening section.

Further, the lid 3 is fitted to the end portion on the opening side of the container body 2, and as shown in FIG. 2, the high frequency induction is performed on the two surfaces of the horizontal portion 10 and the vertical portion 11 of the flange portion 8. It is welded by heating.

As shown in FIG. 3, the multilayer film 5 has a polypropylene film 22 laminated on both sides of an aluminum foil 21 having gas barrier properties, and a polypropylene film 23 obtained by graft-polymerizing maleic anhydride on one side of the film 22. Are stacked.

Air was injected into the PET container having an opening inner diameter of 73 mm, a thickness of 1.5 mm, and a welding length of the vertical portion of 2 mm, which was made in this manner, and the sealing strength was measured. As a result, the sealing strength was 0.9 kg / cm ² .

Example 2 Example 1 was repeated except that only the horizontal portion of the container opening was joined as shown in FIG. The sealing strength at this time was 0.4 kg / cm ² .

Comparative Example The multilayer film of Example 1 was placed on the opening of the PET container of Example 1 and heat-sealed at a temperature of 240 ° C. The sealing strength at this time was 0.03 kg / cm ² .

[0019]

[Effect of the device]

 Since the PET container of the present invention is provided with a layer made of a resin having an acid-anhydrous group on the lid side portion that contacts the opening of the PET container body, it is subjected to high-frequency induction heating while being mounted in the PET container. Then, a portion made of a resin having an acid anhydride group is melted and welded to the opening of the PET container. Therefore, according to the present invention, it was possible to provide a low-cost, easy-open container having excellent gas barrier properties and heat resistance that enables retort sterilization. Further, in the container according to the second aspect, the joint portion between the lid and the container body has two surfaces, so that the sealing strength is excellent. Further, in the container of claim 2, since the maleic anhydride-modified polypropylene is used for the thermoplastic film on the lid side joined to the opening of the container, it has excellent heat resistance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of a joint portion between the container and the lid shown in FIG.

FIG. 3 is a cross-sectional view of a multilayer film.

FIG. 4 is an enlarged view of a main part of a joint portion between a container and a lid according to another embodiment of the present invention.

[Explanation of symbols]

1 PET Container 2 PET Container Main Body 3 Easy-Open Lid 4 Outer Layer 5 Multilayer Film 8 Flange 21 Aluminum Foil 22 Polypropylene Film 23 Polypropylene Film Graft-Polymerized with Maleic Anhydride

Claims (3)

[Scope of utility model registration request] 1. A polyethylene terephthalate resin container and an easily-openable lid formed by adhering a multilayer film having a gas barrier property, which is formed by adhering a thermoplastic resin film on both sides of a metal foil, and a thermoplastic sheet having a score portion. A container consisting of a main body, wherein the thermoplastic film on the lid side joined to the container opening is a resin having an acid anhydride group,
An easy-open container in which the lid and the container body are thermocompression bonded by high frequency induction heating. 2. The easily openable container according to claim 1, wherein the joint portion between the lid and the container body is at least two surfaces of a horizontal portion and a vertical portion of the container opening. 3. The easy-open container according to claim 1, wherein the thermoplastic film on the lid side joined to the opening of the container is maleic anhydride-modified polypropylene.