JPH0516630U - Easy-open container lid - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an easy-open lid that can be heat-sealed to a PET container. [Structure] An easy-open container lid in which a multi-layer film having a gas barrier property obtained by adhering a thermoplastic resin film to both sides of a metal foil and a thermoplastic resin sheet having a score part are joined together. The easily-openable container lid is characterized in that the thermoplastic resin film bonded to the main body is a PET film that can be heat-welded to the PET resin by high-frequency induction heating. The tensile strength of the PET film is 0.7 or less of the tensile strength of the metal foil.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 TECHNICAL FIELD The present invention relates to an easily openable container lid of a polyester terephthalate resin container used for foods, beverages, medical products and the like.

[0002]

[Prior Art]

 At present, polyethylene terephthalate-based resin containers (hereinafter referred to as PET containers) such as polyethylene terephthalate and polybutylene terephthalate have excellent properties such as excellent transparency and aroma retention and gas barrier properties, and beverages, It is widely used as a container in the field of food or medical products. Most of the lids for sealing these PET containers are screw caps having screw threads that can be resealed because most of them are liquid containers. Recently, with the expansion of applications of PET containers, there is a demand for a lid for a solid material such as a dessert, which does not require resealing 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 this type is difficult to adopt. As a method for solving these problems, an easily openable heat-seal lid is being considered.

[0003]

[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 an easily-openable lid for use in a PET-based container.

[0004]

[Means for Solving the Problems]

 The present invention provides an easy-open container lid in which a multi-layer film having a gas barrier property obtained by adhering a thermoplastic resin film to both sides of a metal foil and a thermoplastic resin sheet having a score portion are joined to each other. The easily-openable container lid is characterized in that the thermoplastic resin film bonded to the main body is a PET film that can be heat-welded to the polyethylene terephthalate resin by high frequency induction heating. Furthermore, by adjusting the tensile strength of the PET-based film to 0.7 or less of the tensile strength of the metal foil, an easily openable container lid with better openability can be obtained. The PET film used in the present invention refers to homopolymers and copolymers such as polyethylene terephthalate and polybutylene terephthalate.

[0005]

[Action]

 Since the PET film is used as the material of the container lid that is welded to the container and the metal foil is arranged in contact with the film, stable heat sealing property can be obtained by high frequency heating. Furthermore, by making the opening part different from the heat-sealing part, the opening property can be arbitrarily adjusted according to the purpose.

[0006]

【Example】

Hereinafter, the container lid of the present invention will be described in detail with reference to the drawings. Example 1 An aluminum foil having a thickness of 20 μ was used as a metal foil, a PET film having a thickness of 20 μ was used as a PET film, a polypropylene film having a thickness of 30 μ was used as the other thermoplastic film, and a polypropylene film having a thickness of 800 μ was used as a thermoplastic resin sheet. An easily openable container lid as shown in FIG. 1 was formed. In FIG. 1, the lid body 1 is composed of a top plate portion 2, a flange portion 3, a tab 4 and a gas barrier multi-layer film 5, and a score portion 6 is formed between the top plate portion 2 and the flange portion 3. High frequency heat sealing was performed by combining the lid and a stretch blow PET container molded so as to be fitted in the heat seal portion 7 of the lid. The sealing strength of this container was 1.2 kg / cm ² , showing a good sealing property. Here, the sealing strength means the internal pressure of the container when air is gradually injected into the sealed container and the sealing portion of the container is peeled off. The unsealing strength was 2.5 kg / piece, which was a good result. Here, the unsealing strength is the stress when the container is fixed and the tab portion of the lid is pulled up by Tensilon to break the lid core portion of the lid. The ratio of the tensile strength of the PET film to that of the aluminum foil (hereinafter referred to as the tensile strength ratio) was 0.36.

Example 2 High frequency heat sealing was performed in the same manner as in Example 1 except that a 20 μm thick polybutylene terephthalate film was used instead of the PET film. The sealing strength and unsealing strength of this container were 1.2 kg / cm ² and 2.8 kg / piece, respectively. The tensile strength ratio was 0.20.

Example 3 A high frequency heating seal was carried out in the same manner as in Example 1 except that the PET film had a thickness of 40 μm and the container was a multilayer sheet consisting of PET / PP / EVO H / PP from the inner layer. . The sealing strength, opening strength and tensile strength ratio of this container were 1.3 kg / cm ² , 3.8 kg / piece and 0.65, respectively.

Examples 5 to 9 and Comparative Examples 1 and 2 By changing the thickness and type of the PET film and the aluminum foil of Example 1, a lid having a tensile strength ratio shown in Table 1 was formed, and the unsealing property was evaluated. did. The results are shown in Table 1. The openability was evaluated according to the following three grades. ○: The PET film has almost no elongation when opened, and the opening strength is 3 kg / piece or less. 5kg / piece or more

[0010]

[Table 1] (Note) The sealing strength was all 1 kg / cm ² or more. From Table 1, it is clear that when the tensile strength ratio exceeds 0.7, the PET-based film expands upon opening, and stable openability cannot be obtained.

[0011]

【The invention's effect】

 INDUSTRIAL APPLICABILITY The container lid of the present invention provides an easily openable lid that can be heat-sealed to a PET-based container and can be used for a wide range of purposes.

[Brief description of drawings]

FIG. 1 is a sectional view of an easy-open lid according to an embodiment of the present invention.

[Explanation of symbols]

 1 Lid body 2 Top plate part 3 Flange part 4 Tab 5 Gas barrier multi-layer film 6 Score part 7 Heat seal part

Claims (2)

[Scope of utility model registration request] 1. A multi-layer film having gas barrier properties, comprising a thermoplastic resin film adhered on both sides of a metal foil,
In an easy-open container lid in which a thermoplastic resin sheet having a score portion is joined, the thermoplastic resin film joined to the container body is a PET film capable of being heat-welded with a polyethylene terephthalate resin by high frequency induction heating. An easily openable container lid characterized in that 2. The easy-open container lid according to claim 1, wherein the PET film has a tensile strength of 0.7 or less that of the metal foil.