JP2742085B2 - Easy-open sealed container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an easily openable structure in which a lid is easily opened in a container comprising a plastic cup body having a flange portion and a lid member. Related to a sealed container.

[Conventional technology]

2. Description of the Related Art As a packaging container for foods, an easy-open plastic sealed container that can be easily opened is widely used.

The most common easy-open method that has been conventionally performed is to appropriately control the sealing strength with a container (for example, 600 to 1000 g / mm) by changing the composition of the resin that constitutes the sealing layer of the lid material. Peel the interface between the material and the container and open it.

However, the sealing strength depends on the sealing conditions, environmental temperature,
It is susceptible to the attachment of contents, etc., and often produces strong and weak variations. If the variation is biased toward the weak side, there is a danger of leaking of the seal. On the other hand, if the variation is biased toward the strong side, the peeling property is deteriorated and the opening becomes difficult. However, since seal leakage is a fatal defect, in order to avoid this phenomenon and ensure safety, it is necessary to set a high seal temperature and pressure even at the expense of easy openness. In order to solve such a problem, a method of opening the seal layer by delamination between the seal layer and an adjacent layer (for example, Japanese Patent Publication No. 50-37598) has been attempted. However, there is a drawback that the contents are not easily broken and the contents are difficult to be taken out.

Further, a structure in which a cut is formed in a flange portion to facilitate separation of a peeling layer from an adjacent layer has been proposed (Japanese Patent Application Laid-Open Nos. 62-251363, 63-78, 63-25).
No. 037). However, in the case of containers having these structures, since the container periphery of the cut portion must be sealed from the outside in the manufacturing stage, there is a manufacturing problem that strict control is required for setting the position at the time of sealing. . In addition, in the method in which the sealing layer is separated from the sealing layer of the main container, the peeling needs to be started from the peripheral edge because of sealing to the peripheral edge of the flange portion. There is a drawback to receive.

In Japanese Utility Model Application Laid-Open No. 60-146077, a lid material is placed on a container flange portion having a high barrier plastic layer on the inner surface and a polyolefin layer on the outer surface, and the lid material reaches the polyolefin layer through the high barrier plastic layer. A heat-sealing structure is shown. However, in the case of this structure, there is no adhesion or weakness other than the penetrating part, so that it is easily peeled off at the boil and retort treatment stage, and there is a danger that the contents may invade here and bacteria may grow. is there.

[Problems to be solved by the invention]

The present invention is to solve the above-mentioned problems and to provide a seal structure that can be easily opened via interfacial peeling of a seal layer. The purpose of the present invention is to provide a simple seal structure without impairing the sealability. The purpose is to provide openability.

[Means for solving the problem]

In order to achieve the above object, an easily openable sealed container according to the present invention comprises a flange portion of a container laminated with at least two films including a sealing layer A and an adjacent layer B, a sealing layer C and an adjacent layer D. Wherein a lid material laminated with at least two layers of film is heat-sealed to form an annular flat seal layer and a line seal layer on the flat seal layer surface. It is characterized by having a seal structure in which the adjacent layer B and the seal layer C are adhered to each other with an adhesive strength equal to or higher than that of the seal surfaces of the seal layers A and C in the flat seal layer portion.

Hereinafter, the seal structure of the present invention will be described with reference to the drawings.

FIG. 1 is an overall cross-sectional view of an easily-openable container, and FIG. 2 is an enlarged cross-sectional view of a circular section in FIG. 1, wherein a flange of a container in which an adjacent layer B and a sealing layer A are laminated on a container substrate 1 is formed. A flat seal layer 3 and a line seal layer 4 are formed by heat sealing in a state where a lid material in which an adjacent layer D and a seal layer C are laminated is overlapped on the part 2.

The container is made of a sealing layer A and an adjacent layer B
For example, it may be a simple two-layer sheet in which a polyethylene resin is disposed in the sealing layer A and a polypropylene resin is disposed in the adjacent layer B, and the ethylene-vinyl acetate copolymer is further provided on the adjacent layer via an adhesive layer. It may be a six-layer sheet in which a barrier layer of a saponified product or a polyvinylidene chloride-based resin, an adhesive layer, and an outermost layer of polypropylene are arranged. In some cases, other materials such as metal and paper may be laminated on the outside of the multilayer plastic sheet.

However, it is desirable that the thickness of the seal layer A of the multilayer sheet is set in the range of 10 to 70 μ. The reason for this is that if the thickness of the sheet layer is less than 10 μm, sufficient sealing properties cannot be ensured, while if it exceeds 70 μm, the adhesion between the sealing layer C and the adjacent layer B is impaired when sealing. .

The film forming the lid material easily adheres to the sealing layer A and the adjacent layer B of the container body, and particularly, the barrier layer such as aluminum foil, polypropylene, etc., which is tightly bonded to the adjacent layer B and the material of the sealing layer C. And a laminate of at least two films including the adjacent layer D having a good quality.

The most preferable combination of materials for the seal structure of the present invention is a composition in which the container seal layer A is composed of polyethylene and the adjacent layer B is composed of polypropylene, and the seal layer C of the lid material is a mixture of polyethylene and polypropylene or a mixture of polybutene and the mixture. This is an embodiment composed of objects.

The flat seal layer 3 is formed in an annular shape by the seal layers A and C over the entire circumference of the flange surface with a mathematical strength capable of easily separating the interface. In this case, the seal strength is 300-500g /
It is desirable to set it within the range of 15 mm. The line sealing layer 4 is formed at the inner end of the flat sealing layer 3, and the sealing layer C of the lid material penetrates the sealing layer A of the container and the adjacent layer B
Is directly and firmly bound. In this case, it is important that the adhesive strength of the line seal layer 4 is higher than that of the seal layers A and C in the flat seal layer 3. And good sealing properties cannot be imparted. The preferable sealing strength of the wire sealing layer 4 is 1500 to 3000 g / 15 mm.

The flat seal layer 3 and the line seal layer 4 can be formed by pressing from above the lid material using a convex-shaped sealing disk. In order to form the flat seal layer 3 and the line seal layer 4 separately, the flat seal layer 3 is formed in an annular flat sealing machine in a first stage, and a V-shaped or U-shaped projection is formed in a second stage. A method is employed in which the wire seal layer 4 is formed by intense heat pressure using a seal disk having a portion. In order to form both layers simultaneously, a method of heat-sealing using a sealing plate having a predetermined projection inside or part of an annular flat plate sealing plate is adopted.

[Action]

Since the easily-openable container of the present invention has both the flat seal layer 3 and the line seal layer 4 as described above, the interface is not opened by the treatment such as boiling and retorting.

Upon opening, when the lid is pulled up from the opening side, first, peeling is started from the seal interface between the seal layer A of the container and the seal layer C of the lid material. Since the seal strength of the flat seal layer 3 is weak, the interface peeling proceeds lightly in this initial stage. Next, when the interface peeling between the seal layers A and B reaches the line seal layer 4, the initial peeling requires some force due to the strong sealing strength between the seal layer C and the adjacent layer B. Is performed, the opening progresses while the tensile force is concentrated on one point of the narrow ring-shaped line sealing portion. Due to such a rail effect, the seal can be smoothly opened to the end without any resistance despite the strong sealing strength.

〔Example〕

With a total thickness of 850μ, the material of the seal layer A has a density of 0.955,
Melt index (MI) 5 g / 10 min high density polyethylene (HDPE), Adjacent layer B (also serving as outer layer) is composed of polyethylene (HDPE) and melt index (MI) 0.5 g / min polypropylene (PP). Two-layer sheets were made by co-extrusion. Then, this sheet was vacuum-formed to obtain a container body having an inner diameter of 70 mm, an outer diameter of flange of 82 mm and a height of 30 mm. The thickness of the flange of the container body was 800 μm, and the thickness of the sealing layer was 20 μm.

A seal layer C of a sheet mainly composed of the same polyethylene (HDPE) and polypropylene (PP) having a different composition and a polypropylene (HD)
PE) laminated with a lid material formed by laminating the adjacent layer D,
Heat sealing was performed at a temperature of 185 ° C. and a pressure of 10 kg / cm ² using a sealing plate having a projection at the inner end of the flat plate sealing plate.

In this manner, the adjacent flat layer B and the seal layer C of the line seal layer 3 are directly sealed with a different adhesive strength from the seal layers A and C of the flat seal layer 4 so that the annular flat structure having a seal strength of 2500 g / 25 mm. To form a sealed container.

The following table shows the openability (sensory test) when the lid was opened for each of the above sealed containers.

As can be seen from the results in the table, when the sealing strength of the line seal layer portion (adhesion between B and C) was lower than that of the flat seal layer portion (adhesion between A and C), good openability was not obtained.

〔The invention's effect〕

According to the seal structure of the present invention, the lid can be easily opened via interfacial peeling of the seal layer without impairing the sealability by combining a flat seal layer and a line seal layer having different seal strengths. it can.

Therefore, perfect sealing performance and easy open performance are always guaranteed.

[Brief description of the drawings]

FIG. 1 is an overall sectional view showing an easily-openable sealed container of the present invention, and FIG. 2 is an enlarged sectional view of a circular section in FIG. FIG. DESCRIPTION OF SYMBOLS 1 ... Container base material 2 ... Flange part 3 ... Flat seal layer 4 ... Wire seal layer A ... Container seal layer, B ... Adjacent layer of container C ... Seal layer of lid material, D .... Adjacent layer of lid material

Claims (1)

(57) [Claims] 1. A flange portion of a container in which at least two films including a sealing layer A and an adjacent layer B are laminated, and a lid member in which at least two films including a sealing layer C and an adjacent layer D are laminated. In a sealed container having an annular flat seal layer and a line seal layer formed on the surface of the flat seal layer, wherein the line seal layer portion is equal to or more than the seal surface of the seal layers A and C in the flat seal layer portion. An easily-openable sealed container having a seal structure in which the adjacent layer B and the seal layer C are bonded to each other with an adhesive strength of: