JPH0632371A - Sealed container - Google Patents

Abstract

PURPOSE:To provide a highly hermetic container featuring both an excellent sealing stability and the easiness of its opening. CONSTITUTION:The container is formed of a multilayer sheet having at least two sealing layers bonded together at a laminating strength of 300-2000g/25mm and a flange 2 having a sealing layer thickness of 10-80mum of a container body 1 and a lid material 3 are sealed together. The inner edge of the flange of the container body 1 corresponding to an opening tab 7 is provided with line-like cuts being of a length smaller than the width of the flange formed in a plurality of lines and/or into an inverted V-shape in parallel and converging arrangement with the flange edge on the opening side. The flange 2 of the container body and the lid material 3 are sealed together by an adhesive strength higher than the laminating strength between the sealing layer of the container body and the adjoining layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetically sealed container having both excellent hermeticity and unsealing ability.

[0002]

2. Description of the Related Art Conventionally, the most common plastic sealed container has an easy-open structure in which the resin material of the sealing layer is changed to appropriately control the sealing strength with the container (for example, 6
Forming a sealing layer having a width of 0 to 1000 g / 25 mm),
A mechanism (an interface peeling type) for peeling and opening the interface between the lid and the container has been put into practical use. However, the degree of sealing is easily affected by the sealing conditions (temperature, pressure, time, environmental conditions, adhesion of contents, etc.), and variations in strength are likely to occur. In this case, if the variation in the seal strength is biased toward the weak side, the risk of seal leakage sometimes increases, while if it is biased toward the strong side, the peeling property decreases and it becomes difficult to open the seal.
In particular, since seal leakage is a fatal defect for a hermetically sealed container, conditions for setting a high seal temperature and pressure are generally adopted, and thus the unsealing property is often sacrificed.

As a measure for solving such a problem, a packaging film having a delamination mechanism utilizing delamination between a seal layer and a layer adjacent thereto (Japanese Patent Publication No. S50).
No. 37598). However, since the peel strength is not affected by the sealing conditions in the delamination type, it is possible to open with a constant force, but there is a drawback that it is difficult to take out the contents unless the seal layer is ruptured at the opening end desired point. . In this case, in order to facilitate the separation between the peeling layer and the adjacent layer, a container having a structure in which a circumferential or annular cut is provided on the flange surface inside the heat seal portion has been proposed (JP-A-62-251363). JP-A-63-25037).

[0004]

However, in the above container structure, when the notch is provided on the entire circumference of the flange surface, there is a risk of impairing the internal pressure resistance, and when the notch is sealed inside. There is a problem that the openability deteriorates. In addition, in order to seal against circumferential or annular cuts, strict precision is required for sealing equipment and operation, and it is necessary to design with a wider flange area than necessary, etc. There is also a drawback that it increases.

The present invention solves the above-mentioned problems of the prior art by improving the position and shape of the notch formed on the flange surface, and the object thereof is to have excellent seal stability and easy opening property. The purpose is to provide a sealed container.

[0006]

In order to achieve the above object, the hermetically sealed container according to the present invention has a laminate strength of 300 to 2000 g between a seal layer and an adjacent layer adjacent to the seal layer.
In a container having a structure in which a container body and a lid member each having a thickness of a seal layer of a flange portion of 10 to 80 μm and made of a multilayer sheet of two or more layers of / 25 mm are sealed, the container corresponds to an initial opening piece portion A plurality of linear and / or inverted V-shaped linear cuts with a length within the flange width facing the opening side are formed in the inner edge portion of the flange portion in a parallel or convergent form, and the space between the flange portion of the container body and the lid material is a container. A structural feature is that the main body is sealed with an adhesive strength higher than the laminating strength between the seal layer and the adjacent layer.

FIG. 1 is a sectional view showing the whole of the hermetically sealed container according to the present invention, in which 1 is a container body provided with a flange portion 2 and 3 is a lid member. The container body is composed of a multilayer sheet having a sealing layer 4 and an adjacent layer 5 adjacent to the sealing layer 4. An arbitrary resin material is used as the multilayer sheet forming the container body 1. For example, a heat-sealable thermoplastic resin can be used for the seal layer 4, and polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polycarbonate, vinyl acetate copolymer, ionomer, polyvinyl alcohol copolymer, polyamide, vinyl chloride copolymer can be used. In addition to various simple resins such as polymers, those obtained by arbitrarily mixing several kinds of these resins and those obtained by treating each resin with an unsaturated carboxylic acid or the like can be used. Adjacent layer 5
Also has a laminating strength of 300 to 2 with the seal layer 4.
Any resin can be used within the range of 000 g / 25 mm width. As an example of the combination, when polyethylene is the seal layer 4, as the adjacent layer 5, polypropylene, a mixture of polypropylene and polyethylene, a polypropylene-polyethylene copolymer, a polyethylene unsaturated carboxylic acid-treated resin, or the like can be arbitrarily selected. You can

The multi-layer sheet is not limited to two layers and can be constructed as two or more layers having other functions. For example, an ethylene vinyl alcohol copolymer or a vinylidene chloride copolymer may be disposed as a barrier layer on the outside of the above two layers in order to provide the container with storage stability, and polypropylene may be further used as an outer layer for the purpose of improving strength and a water vapor barrier. Etc. may be laminated, and various adhesives may be used to firmly bond these layers.

Although various methods are used for producing a multilayer sheet, a coextrusion method, a dry laminating method, a coextrusion laminating method, a thermal laminating method and the like are typical. The adjacent layers are not limited to plastic, and any metal layer can be used, and these metal layers can also be used as other functional layers.

In the present invention, the lamination strength of the seal layer 4 and the adjacent layer 5 is set to 300 to 2000 g / 25 mm, and the thickness of the seal layer 4 at the flange portion is set to 10 to 80 .mu. When the thickness of the sheet layer is less than 10 μm, sufficient sealing performance cannot be secured, and on the other hand, the laminating strength is 20
This is because if it exceeds 00 g / 25 mm and the thickness of the seal layer exceeds 80 μ, peeling resistance at the time of opening becomes large and smooth opening property is impaired.

As the lid member 3, any resin film can be used as long as it can seal with the seal layer 4 of the flange portion, and in particular, it has a sealant layer 6 made of a material that firmly adheres to the seal layer 4. It is preferable. Examples of the multi-layered lid material include a two-layer film in which the sealant layer 6 is polycarbonate, polyethylene, or polypropylene and the reinforcing layer is nylon, a sealant layer 6 made of heat-sealable polyethylene terephthalate, an aluminum foil as a barrier layer, and a polyethylene as an outermost layer. A combination of three layers in which terephthalate is arranged may be mentioned. Further, the lid body 3 is not limited to the film shape, and a molded article form may be used. For example, the sealant layer 6 is a heat-sealable polyethylene terephthalate, and a multilayer sheet having an ethylene vinyl alcohol copolymer as the barrier layer and polypropylene as the outer layer can be formed into a drop lid shape by vacuum forming and used.

As shown in FIG. 2 (partially cutaway perspective view of the container), the flange portion 2 of the container body 1 is formed with a linear cut 8 at the inner edge portion of the flange portion corresponding to the initial opening piece portion 7. It This linear cut 8 has a length (L) within the flange width W, preferably about 1/2 of the flange width W.
A plurality of strips and / or inverted V-shapes are formed in parallel or in a convergent shape facing the opening side so as to be (L). If the formation length (L) of the linear cut 8 exceeds the flange width W, sufficient internal pressure resistance cannot be ensured. FIG. 3 (container plan view) shows an example in which a plurality of cuts 8 are formed in a parallel form,
Further, FIG. 4 shows an inverted V shape and a notch 8 on both sides thereof in a convergent form
It shows an example in which the composite is formed. It is desirable that the depth of the linear cut 8 be within the thickness of the seal layer 4 of the flange portion 2, but there is no problem even if it slightly reaches the adjacent layer 5. The cutting operation can be performed by pressing a blade die having a predetermined shape.

The flange portion 2 and the lid member 3 of the container body 1 are finally overlapped with each other by the seal layer 4 and the sealant layer 5 and are sealed with an adhesive strength higher than the laminating strength of the seal layer 4 and the adjacent layer 5. . At this time, the entire surface including the linear cuts 8 can be sealed, but it is preferable to seal the cutouts 8 except the periphery (dotted line section in FIG. 2) from the aspect of opening property. The sealing operation is performed using a known heat sealing method, ultrasonic sealing method, high frequency sealing method, or the like.

FIG. 5 is an enlarged partial sectional view showing a flange portion corresponding to an initial opening piece portion of the container structure which is sealed except for the periphery of the linear cut 8, and 9 is a bonded seal portion. The container form to which the present invention is applied is not limited to the round container shown in FIG. 2, but may be a square container, a triangular container, or various types in which these containers are connected.

[0015]

As described above, in the seal structure according to the present invention, the sealant layer 6 of the lid material and the seal layer of the flange portion are formed in the state where the linear cut 8 of a specific shape is formed in the flange portion corresponding to the initial opening piece portion 7. Because 4 and is tightly sealed,
Stable internal pressure resistance is imparted during sealing, and smooth delamination proceeds during opening.

As for the delamination at the time of opening, as shown in FIG. 6, when the lid member 3 is pulled upward from the initial unsealing piece, the delamination proceeds at the interface between the seal layer 6 and the adjacent layer 5 in the flange portion. When the peeled surface reaches the site where the linear cut 8 is formed, it is easily cut at the position of the broken portion 10 where the tensile breaking force of the seal layer 4 is weakened. When the lid member 3 is subsequently pulled up, the tearing force from the fracture surface of the seal layer 4 causes the opening to proceed smoothly along the inner edge of the flange or the innermost edge of the flange seal portion, and the lid member is completely separated. .

[0017]

【Example】

Example 1 The total thickness was 850 μm, and the material of the seal layer had a density of 0.9.
55, vacuum molding a two-layer sheet consisting of high density polyethylene (HDPE) with a melt index (MI) of 5 g / 10 min and polypropylene (PP) with an adjacent layer (also serving as an outer layer) of melt index (MI) of 0.5 g / 10 min A container body having an inner diameter of 65 mm, a flange width of 10 mm and a height of 25 mm was prepared. The thickness of the seal layer of the obtained container body was 20 μ, and the laminating strength between the seal layer and the adjacent layer was 1500 g / 25 mm.

Then, a linear cut having a shape shown in FIG. 4 was formed in the inner edge portion of the flange portion corresponding to the initial opening piece portion of the container body with a length half the flange width. The notch was formed by pressing the blade die, and the depth was made equal to the thickness of the seal layer.

As the lid member, a sealant layer having a thickness of 50 μm was formed by using the same resin as the sealing layer of the container, and the sealant layer was dry-laminated with stretched polyamide (thickness 30 μm).

The sealant layer of the lid material was placed on the seal layer surface of the container flange, and the surface excluding the cut portion was heat-sealed. The conditions for the sheet seal are a temperature of 190 ° C and a surface pressure of 2
It was set to kg / cm ² and the time was 1 second.

Each of the sealed containers manufactured in the above manner
For each piece, the container was filled with water and compressed air was injected from above the lid material so as not to leak, and the internal pressure resistance from the inside was measured.
As a result, it was confirmed that the average puncture pressure was 1.2 kg / cm ² and stable sealing performance was maintained. Moreover, when the opening property of the lid was tested, all were smoothly opened without a feeling of peel resistance.

Example 2 As shown in FIG. 3, a parallel-shaped linear cut (5 lines) having a length of ⅔ of the flange width was formed in the inner edge portion of the flange portion corresponding to the initial opening piece portion of the container body. Formed. The seal was adhered to the entire surface including the cut portion. In all other respects, sealed containers (50 pieces) were manufactured under the same conditions as in Example 1.

An internal pressure resistance test was conducted on the obtained sealed container in the same manner as in Example 1. The average puncture pressure was
It showed stable sealing performance at 1.2 kg / cm ² . It was also confirmed that opening of the lid proceeded smoothly without a feeling of peel resistance.

[0024]

As described above, according to the present invention, by forming a linear cut having a special shape at a specific position in the flange portion corresponding to the initial opening portion, excellent seal stability and always smooth opening performance are achieved. A high-performance sealed container that does not leak contents even if it receives an external shock during transportation etc. is provided. Moreover, in the sealing process during manufacturing, complicated problems such as position adjustment of the sealing plate and limitation of the size of the flange are eliminated, so that the sealed container can be manufactured at low cost and with good productivity.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the entire sealed container of the present invention.

FIG. 2 is a partially cutaway perspective view showing the sealed container of the present invention.

FIG. 3 is a plan view of a hermetically sealed container showing an embodiment of the present invention.

FIG. 4 is a plan view of a sealed container showing another embodiment of the present invention.

FIG. 5 is an enlarged sectional view showing a flange portion of the sealed container of the present invention.

FIG. 6 is an enlarged cross-sectional view of a flange portion schematically showing an opened state of the sealed container.

[Explanation of symbols]

 1 Container Main Body 2 Flange Part 3 Lid Material 4 Sealing Layer 5 Adjacent Layer 6 Sealant Layer 7 Initial Opening Piece 8 Cut 9 Sealing Part 10 Breaking Part

Claims (1)

[Claims] 1. A container comprising a multi-layer sheet of two or more layers in which a laminate strength of the seal layer and an adjacent layer adjacent to the seal layer is 300 to 2000 g / 25 mm, and a thickness of the seal layer of the flange portion is 10 to 80 μm. In a container having a structure in which a main body and a lid member are sealed, a plurality of articles are formed in parallel or in a convergent form with a length within a flange width at an inner edge portion of a flange portion corresponding to an initial opening piece portion of the container main body and / or in a convergent form. A sealed container, characterized in that an inverted V-shaped linear cut is formed, and a space between a flange portion of a container body and a lid member is sealed with an adhesive strength higher than a laminating strength of a sealing layer of the container body and an adjacent layer.