JP3040257B2 - Sealed container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed container having excellent sealing stability and an easy open mechanism in a container comprising a plastic cup body having a flange portion and a lid member.

[0002]

2. Description of the Related Art As a container for packaging various foods, a plastic sealed container having an easy-open structure, which can be easily opened, is widely used. Conventionally, the most common easy-open structure of a plastic sealed container that has been practically used is to change the resin material of a sealing layer constituting a cover member to change the sealing strength with the container within an appropriate range (usually 60 times).
(0 to 1000 g / 25 mm width), peeling off the sealing interface between the lid material and the container and opening it (interface peeling type). However, in this type of interfacial peeling type, the sealing strength is easily affected by sealing conditions (temperature, pressure, time, environmental conditions, adhesion of contents, etc.), and the strength tends to vary. This variation increases the risk of leakage of the seal when biased toward the weak side, and conversely, when biased toward the strong side, the peelability decreases and the package cannot be easily opened. In particular, since a seal leak is a fatal defect in a sealed container, a condition for setting a higher seal temperature and pressure is generally employed, and therefore, the opening property is often sacrificed.

[0003] As a measure for solving such a drawback, an opening mechanism by delamination between a seal layer and a layer adjacent thereto (Japanese Patent Laid-Open No. 50-37598) is known (interlayer delamination type). According to this method, since the peel strength is not affected by the sealing conditions, it is possible to open the package with a constant force. However, there is a drawback that the content is difficult to be taken out unless the seal layer is broken at the desired end point. JP 6
Japanese Patent Application Laid-Open No. 2-251363 proposes an easy-peeling container of a type in which a seal layer of a container body is peeled off, in which a notch is provided in an inner edge portion of a flange to facilitate breakage of the seal layer at a desired opening end point. I have. However, in this method, there is a problem that it is difficult to open the seal if the seal is formed on the inner edge from the cut portion, and that if the cut portion and the innermost edge of the seal portion are too close, the seal leaks easily when receiving an internal pressure. For this reason, it is necessary to perform sealing at a position away from the cut portion during sealing,
There are disadvantages in that there are many restrictions, such as the need for precision in the sealing equipment and the need for an unnecessarily large container flange area. In order to improve this point, there has been proposed a method in which the shape of the sealing disc is devised to break the seal layer without requiring much sealing accuracy, but when the seal layer becomes too thick, it is difficult to break. There are many problems in terms of practicality such as

The present inventors have proposed an opening mechanism different from these means, in a container body having an infinite number of minute recesses formed on the entire surface or a part of the peripheral surface of the seal layer of the flange portion, between the seal layer surface and the lid member. An easily openable sealed container having a sealing structure in which a lid material is adhered to the container so that the sealing strength is equal to or higher than the lamination strength of the sealing layer of the container body and the adjacent layer has been developed (Japanese Patent Application Laid-Open No. 3-200560).

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open Publication No. Hei 3-20
According to the seal structure described in Japanese Patent No. 0560, even if the positional accuracy of the seal disk is poor, sealing and breaking can be easily performed, so that productivity and usability can be greatly improved. However, in this structure, the internal pressure resistance tends to slightly decrease when the entire surface of the container flange is sealed due to the formation of minute recesses on the entire peripheral edge of the container flange, and this has been left as a problem to be solved. .

The present invention has been made to solve the above-mentioned problem by changing a position where a minute concave portion is formed.
Accordingly, an object of the present invention is to provide a sealed container having both excellent seal stability and easy-open property.

[0007]

In order to achieve the above object, a sealed container according to the present invention has a lamination strength of 300 to 2000 g between a sealing layer and an adjacent layer adjacent to the sealing layer.
/ 25 mm, a container having a structure in which a container body and a lid material are sealed with a container having a thickness of 10 to 80 μm and a seal layer of a flange portion having a thickness of 10 to 80 μm, which corresponds to an upper end portion of a side surface of the container body. entirely or top innumerable <br/> minute recesses fine small recesses in a portion of the peripheral surface is not applied to the flange portion
The structure is characterized in that the structure is formed in such a manner that the gap between the flange portion of the container body and the cover material is sealed with an adhesive strength higher than the lamination strength of the sealing layer and the adjacent layer of the container body.

FIG. 1 is a sectional view showing the whole of a sealed container according to the present invention, wherein 1 is a container main body having a flange portion 2, and 3 is a lid. The container body 1 is formed of a multilayer sheet having a sealing layer 4 and an adjacent layer 5 adjacent thereto. The resin material of the multilayer sheet constituting the container body 1 may be any resin material. 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,
In addition to various simple resins such as a vinyl chloride copolymer, those obtained by optionally mixing several kinds of these resins or those obtained by treating each resin with an unsaturated carboxylic acid or the like can be used. Also for the adjacent layer 5, the lamination strength with the seal layer 4 is 300.
Any resin can be used as long as it is in the range of ２０００2000 g / 25 mm. As an example of the combination, when polyethylene is the sealing layer 4, polypropylene, a mixture of polypropylene and polyethylene, a polypropylene-polyethylene copolymer, a polyethylene-unsaturated carboxylic acid-treated resin, or the like may be arbitrarily selected as the adjacent layer 5. it can.

[0009] The multilayer sheet is not limited to two layers, and may be configured 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-mentioned two layers in order to impart preservability to the container, or a polypropylene may be further provided as an outer layer for the purpose of improving strength or a water vapor barrier. And the like may be laminated, and various adhesives may be used for firmly bonding these layers.

[0010] Various methods are used to produce a multilayer sheet, and typical examples include a coextrusion method, a dry lamination method, a coextrusion lamination method, and a thermal lamination method. In addition, as an adjacent layer, not only plastic but also any metal layer can be used, and these metal layers can also be used as other functional layers.

In the present invention, the reason why the lamination strength of the sealing layer 4 and the adjacent layer 5 is set to 300 to 2000 g / 25 mm and the thickness of the sealing layer 4 at the flange portion is set to 10 to 80 μm is that the lamination strength is 300 g / 25 mm. If the thickness of the sheet layer is less than 10 μm, it is not possible to secure a sufficient sealing property,
This is because if the thickness exceeds 00 g / 25 mm and the thickness of the seal layer exceeds 80 μm, the peeling resistance at the time of opening increases, and the smooth opening property is impaired.

The cover member 3 can be made of any resin film as long as it can seal with the seal layer 4 of the flange portion. The cover material 3 has a sealant layer 6 made of a material which adheres tightly to the seal layer 4. Is preferred. Examples of the lid material having a multilayer structure include a two-layer film in which the sealant layer 6 is made of polycarbonate, polyethylene, or polypropylene and the reinforcing layer is nylon, or a sealant layer 6 made of heat-sealable polyethylene terephthalate, an aluminum foil as a barrier layer, and polyethylene as the outermost layer. Examples include a combination of three layers in which terephthalate is arranged. The lid 3 is not limited to a film shape, but may be a molded product. For example, it is also possible to use a multilayer sheet in which the sealant layer 6 is a heat-sealable polyethylene terephthalate, the barrier layer is an ethylene vinyl alcohol copolymer, and the outer layer is a polypropylene, which is formed in a drop lid shape by vacuum forming.

As shown in FIG. 2 (perspective view), a minute concave portion 7 is formed on the inner peripheral surface of the seal layer portion corresponding to the upper end portion of the side surface of the container body 1. The minute concave portion 7 can be formed on the whole or a part of the inner peripheral surface. In the case where the minute concave portion 7 is formed in a part, as shown in FIG. 3 (plan view), it is installed at an appropriate length on the inner peripheral surface of the upper end portion of the side surface of the container body 1 located on the initial opening side. The width of the minute recess 7 is not particularly limited, but is formed such that the upper end does not touch the flange 2 as much as possible. The formation of the minute concave portion 7 is performed by, for example, ultrasonic treatment, heating or cold pressing,
It can be performed by an appropriate method such as pressurization using high frequency. Among them, the method of performing ultrasonic processing using a convex ultrasonic horn is most effective because an infinite number of uniform and fine concave patterns can be formed. Further, the number of the minute concave portions 7 to be formed is not particularly limited.

The flange portion 2 and the lid member 3 of the container body 1 are finally overlapped with each other by the sealing layer 4 and the sealant layer 6, and are subjected to a known heat sealing method, ultrasonic sealing method, high frequency sealing method or the like. And glued. FIG. 3 is an enlarged partial sectional view of a flange portion of the sealed container according to the present invention after sealing, and 8 is a bonded seal portion. The shape of the container to which the present invention is applied is not limited to the round container shown in FIG. 2, but may be used in various types such as a square, a triangle, or a combination of these.

[0015]

Since the sealed container according to the present invention is constructed as described above, when the lid member 3 is pulled upward at the time of opening, the sealing layer 4 of the flange portion 2 and the adjacent layer 5 are opened as shown in FIG. Peeling proceeds at the interface. This peeling state continues up to the inner edge of the flange portion 5, but at this point, the tensile destructive force of the seal layer 4 is weakened by the presence of the minute concave portion 7 formed on the inner peripheral surface of the upper end portion of the side surface of the container body. It is easily cut at the breaking portion 9.

As described above, in the container structure of the present invention, since the entire surface of the flange portion 2 is sealed, a high level of internal pressure resistance is maintained at the time of sealing, and the seal layer 4 is easily broken by the action of the minute concave portion 7 at the time of opening. And open smoothly. Therefore,
It is possible to always have both excellent seal stability and easy openness.

[0017]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples.

Example 1, Comparative Example The overall thickness was 850 μm, and the material of the sealing layer was 0.955 in density.
A high-density polyethylene (HDPE) having a melt index (MI) of 5 g / 10 min, and an adjacent layer (also serving as an outer layer) comprising a polypropylene (PP) having a melt index (MI) of 0.5 / min.
The layer sheets were made by co-extrusion. Then, this sheet was vacuum formed, and the inner diameter was 65 mm, the flange width was 10 mm, and the height was 25.
mm container body was formed. The thickness of the sealing layer of the obtained container body was 20 μm, and the lamination strength between the sealing layer and the adjacent layer was 1500 g / 25 mm.

Next, an ultrasonic treatment is performed by applying a small projection ultrasonic horn having a projection number of 256 / cm ² to the entire inner peripheral surface corresponding to the upper end portion of the side surface of the container main body, and applying a width to the inner seal layer. A small concave portion of 5 mm was formed (entire peripheral surface formation).
The ultrasonic treatment was performed under the conditions of an output of 2 KW (use energy: 225 J), a pressing force of 338 KPa, and a time of 0.3 second, and a minute concave portion having a depth of 10 μ was formed.

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

A sealant layer of a lid material was superimposed on the seal layer surface of the container flange, and the entire surface was heat-sealed. The conditions for sheet sealing were as follows: temperature 190 ° C., surface pressure 2 kg / cm ² , time 1 second.

Each of the sealed containers 50 thus manufactured
The openability (peel resistance) of the lid was tested for each piece. In addition, as a sealability test, fill the container with water as the contents,
Compressed air was injected from the top of the lid so as not to leak, and the internal pressure resistance from the inside was measured. The results are shown in Table 1 in comparison. For comparison, an openability and an internal pressure resistance test were also performed on a sealed container manufactured in the same manner using a container body having no minute concave portion, and the results are also shown in Table 1 (Comparative Example).

Example 2 A minute concave portion was formed with a length of 30 mm and a width of 5 mm along the inner peripheral surface of the upper end portion of the side face located on the initial opening side of the container body (partial peripheral surface formation). The other conditions were the same as in Example 1, 50 sealed containers were manufactured, and the same test as in Example 1 was performed to test the openability and internal pressure resistance. The results are shown in Table 1.

[0024]

[Table 1]

[0025]

As described above, according to the present invention, a minute concave portion is formed on the whole or a part of the inner peripheral surface corresponding to the upper end portion of the side surface of the container body, so that excellent sealing stability and always smooth opening can be achieved. It is possible to provide a high-performance hermetic container which has both properties and does not leak its contents even if it receives an external impact during transportation or the like. In addition, in the sealing process at the time of manufacture, since problems such as complicated adjustment of the position of the seal board and limitation of the size of the flange are eliminated, a sealed container can be manufactured at low cost and with high productivity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the whole of a sealed container of the present invention.

FIG. 2 is a perspective view showing a sealed container in which a minute concave portion is formed on the entire inner peripheral surface of the upper end portion of the side surface of the container body.

FIG. 3 is a plan view showing a sealed container in which a minute concave portion is formed on a part of the inner peripheral surface of the upper end of the side surface of the container body.

FIG. 4 is an enlarged sectional view showing a flange portion of the sealed container according to the present invention.

FIG. 5 is an enlarged sectional view of a flange portion schematically showing an opened state of the sealed container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container main body 2 Flange part 3 Lid material 4 Seal layer 5 Adjacent layer 6 Sealant layer 7 Micro concave part 8 Seal part 9 Breakage part

Claims (1)

(57) [Claims] 1. A container comprising two or more multilayer sheets having a laminate strength of 300 to 2000 g / 25 mm between a seal layer and an adjacent layer adjacent to the seal layer, wherein the thickness of the seal layer at the flange portion is 10 to 80 μm. fine a container structure in which sealing a body and a lid, the countless minute recesses on the entire surface or a part of an inner peripheral surface corresponding to the side surface upper portion of the container body
The upper end of the small recesses are formed so as not placed on the flange portion, characterized in that between the flange portion of the container body and the lid member and the seal layer of the container body and sealed structures in higher bond strength than the lamination strength of the adjacent layers And sealed container.