JPH05310268A - Sealed vessel - Google Patents

Abstract

PURPOSE:To obtain excellent sealability and unsealability, by forming fine recessions in a specified range at the flange inner periphery corresponding to the initial unsealing part of a vessel body and sealing the flange and the cover including the fine recessions with a relatively strong adhesive force. CONSTITUTION:In a sealed vessel having a easy-to-open structure and composed of two or more multi-layer sheet having 300-2000g/25mm laminate strength in the seal layer 6 and the adjacent layer 7 thereto, fine recessions 4 are made along the inner peripheral edge in the flange inner periphery corresponding to the initial unsealing part of the vessel body 1, within the range of 1/5 or shorter length than the inner periphery of the vessel flange and further, 1/2 or narrower depth than the flange width. The flange 2 and the cover material 3 including the fine recessions 4 are sealed 8 with a higher adhesive force than the abovementioned laminate strength. In the fine recessions 4, a number of fine recessions are formed as a pattern by means of ultrasonic treatment, heating or cold press, compression by high frequency, etc.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art The easy-open structure of the most general plastic hermetic container that has been put to practical use has a suitable control of the sealing strength with the container by changing the resin material of the sealing layer (for example, 600 to 1000 g / 25 mm width). ) Is formed, and the interface between the lid and the container is peeled off to open. However, the seal strength depends on the sealing conditions (temperature,
It is easily affected by pressure, time, environmental conditions, adhesion of contents, etc., and variations in strength are likely to occur. If this variation 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 in a hermetically sealed container, conditions for setting a high seal temperature and pressure are generally adopted, and therefore the unsealing property is often sacrificed.

As a measure for solving such a problem, an unsealing mechanism (Japanese Unexamined Patent Publication No. 50-37598) by delamination between a seal layer and a layer adjacent thereto is known. With this method, the peel strength is not affected by the sealing conditions, so it is possible to open with a constant force, but there is the drawback that it is difficult to take out the contents unless the sealing layer is broken at the desired end point of opening. JP 62-2
JP-A-51363 proposes, in an easy-peel imparting container of a type in which a sealing layer of a container body is peeled off, a notch is provided at an inner edge portion of a flange to facilitate breakage of the sealing layer at a desired end point of unsealing. However, in this method, there is a problem that if the inner edge is sealed from the cut portion, it is difficult to open the seal, and if the cut portion and the innermost edge portion of the seal portion are too close to each other, a seal leak easily occurs when an internal pressure is applied. Therefore, at the time of sealing, it is necessary to perform the sealing at a position away from the cut portion, and there are disadvantages that there are many constraints such as the need for precision in the sealing equipment and the need to capture an unnecessarily large flange area of the container body. is there. In order to improve this point, a method of devising the shape of the sealing board to break the sealing layer without requiring excessive sealing accuracy has been proposed, but it is difficult to break if the sealing layer becomes too thick. There are many problems in terms of practicality, such as with.

As an opening mechanism different from these means,
The applicant has developed an easily openable sealed container in which a minute recess is formed in the flange portion of the container body and the opening is completed at that portion (Japanese Patent Laid-Open No. 3-289466). According to this mechanism, even if the position accuracy of the sealing board is poor, it is possible to easily seal and break, so that productivity and usability can be improved.

[0005]

However, in the above-mentioned mechanism, since it is necessary to provide minute recesses in the entire peripheral edge portion of the container flange portion, there is a problem that internal pressure resistance is slightly lowered when the entire surface of the container flange portion is sealed. there were.

An object of the present invention is to solve the above problems and to provide a hermetically sealed container having both excellent seal stability and easy opening property.

[0007]

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.
A container having a structure in which a container body and a lid member each having a seal layer of a flange portion having a thickness of 10 to 80 μm are sealed, the flange inner edge being at least an initial opening portion of the container body. At the position, a minute recess is formed along the inner edge circumferential direction within a range of ⅕ or less of the flange inner edge circumferential length of the container and ½ or less of the flange width of the initial opening portion. In addition, the structural feature is that the flange portion of the container body and the lid member are sealed with an adhesive strength higher than the laminating strength of the seal layer of the container body and the adjacent layer.

FIG. 1 is a sectional view showing a sealed container of the present invention,
2 is a perspective view (partially cutaway) of the sealed container of FIG. 1, in which 1 is a container body, 2 is a flange portion, 3 is a lid member,
Reference numeral 4 is a minute recess formed at the inner edge of the flange, which corresponds to the initial opening of the container body. 3 (a) is an enlarged cross-sectional view of the flange portion corresponding to the initial opening portion, FIG. 3 (b)
Is an enlarged cross-sectional view showing a flange portion other than the initial opening portion, 5 is a sealant layer of the lid material 3, 6 is a seal layer of the flange portion 2 of the container body, 7 is an adjacent layer adjacent to the seal layer, and 8 is It is a seal part.

As the multilayer sheet constituting the container body 1, any one can be used. A heat sealable thermoplastic resin can be used for the seal layer 6, and examples thereof include polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polycarbonate, vinyl acetate copolymer, ionomer, polyvinyl alcohol copolymer,
In addition to various simple resins such as polyamide and vinyl chloride copolymer, those in which several kinds of these resins are arbitrarily mixed and those in which each resin is treated with unsaturated carboxylic acid can be used. Also for the adjacent layer 7, any resin can be used as long as the laminating strength with the seal layer 6 is in the range of 300 to 2000 g / 25 mm width. As an example of the combination, when polyethylene is the seal layer 6, the adjacent layer 7
As polypropylene, a mixture of polypropylene and polyethylene, a polypropylene-polyethylene copolymer, a polyethylene-unsaturated carboxylic acid-treated resin and the like can be arbitrarily selected.

The multi-layer sheet is not limited to two layers, but may be composed of 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 layer is not limited to plastic, and any metal layer can be used, and these metal layers can be used as other functional layers.

In the present invention, the laminating strength of the sealing layer 6 and the adjacent layer 7 is set to 300 to 2000 g / 25 mm, and the thickness of the sealing layer 6 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, while 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 6 of the flange portion. In particular, the lid member 3 has a sealant layer 5 which is firmly adhered to the seal layer 6. Preferably. Examples of the multi-layer cover material include a two-layer film in which the sealant layer 5 is polycarbonate, polyethylene, polypropylene and the reinforcing layer is nylon, a sealant layer 5 made of heat-sealable polyethylene terephthalate, an aluminum foil as a barrier layer, and a polyethylene as an outermost layer. Examples include a combination of three layers in which terephthalate is arranged. Further, the lid body 2 is not limited to the film shape, and a molded article form may be used. For example, the sealant layer 5 is 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.

In the present invention, the minute recesses 4 which are provided at least at the inner edge of the flange corresponding to the initial opening portion of the container body 1 are 1/5 or less of the inner peripheral edge length of the flange of the container and 1 / of the flange width of the initial opening portion. It is formed along the inner edge circumferential direction within the range of 2 or less. That is, as shown in FIG. 4, the length (l) of the minute recess 4 is set to 1/5 or less, preferably 1/10 or less of the circumference of the flange inner edge (L), and the width (w) of the minute recess 4 is set. Is set to 1/2 or less of the flange width (W) of the initially opened portion. If the minute recesses 4 exceed the above range, sufficient internal pressure resistance cannot be ensured. It should be noted that, as shown in FIG. 5, the minute recessed portion 4 may be formed so that the flange portion of the initial opening portion slightly projects inside the container and is formed in that portion as long as it does not deviate from the dimensional range described above.

The formation of the minute recesses 4 at the inner edge position of the flange can be carried out by an appropriate method such as ultrasonic treatment, heating or cold pressing, and pressurization using high frequency. Of these, the method of ultrasonic treatment using a convex ultrasonic horn is most effective because it can form a number of uniform and minute concave patterns. However, the number of minute recesses 4 formed at this time is not particularly limited.

The flange portion 2 and the lid member 3 of the container body 1 are finally laminated with the seal layer 6 and the sealant layer 5 and the entire surface including the minute recesses 4 is bonded to form a seal portion 8. The adhesive strength at this time needs to be higher than the laminating strength between the seal layer 6 and the adjacent layer 7 of the container flange. As a bonding method, a known heat sealing method, ultrasonic sealing method, high frequency sealing method or the like is used.

The container form to which the present invention is applied is not limited to the round container shown in FIG. 2, but various shapes such as a square type as shown in FIG. 5, a triangular type as shown in FIG. 6 and a connection type as shown in FIG. It can be used for various types. Further, as shown in the cross-sectional view of FIG.
The structure of forming the seals on both sides of the seal portion 8 is also included in the container aspect of the present invention.

[0018]

9 to 11 are explanatory views showing the opened state of the hermetically sealed container according to the present invention. For example, in the case of the container shown in FIG. 3, when the lid member 3 is pulled upward at the initial opening portion, the peeling proceeds at the interface between the seal layer 6 and the adjacent layer 7 of the flange portion as shown in FIG. At this time, since the minute recesses 4 are formed at the specific positions of the initial opening portion, the smoothness of opening is promoted. The peeled state continues to the minute recesses 4, but when reaching the minute recesses 4, the seal layer 6 is easily cut at the breakage portion 10 in which the tensile breaking force is weakened. Also, FIG.
In the container mode, when the lid member 3 is pulled up as shown in FIG. 10, the minute recesses 4 on the outer periphery and the sealant layer 5 of the lid member are pulled up.
Peeling between the micro recesses 4 and the broken portion 10 'at the inner end of the minute recess 4
First, after being cut, the seal layer 6 is peeled off at the interface between the adjacent layer 7 and the fractured portion 10 of the minute concave portion 4 on the inner periphery, and the seal layer 6 is smoothly cut. When the lid member 3 is subsequently pulled up, the seal layer 6 is not broken except for the initial opening portion by the tensile breaking force, but by the tearing breaking force from the breaking surface of the seal layer 6 generated in the initial opening stage or the flange inner edge or Propagatingly proceeds along the innermost edge of the flange seal portion and is opened in the direction of the arrow in FIG. 11 to completely separate the lid member. The tearing of the seal layer due to this tearing can be performed with a force smaller than the pulling force at the time of initial opening, and the seal layer 6 at the portion not heat-sealed.
Is possible without peeling from the adjacent layer 7. Therefore, the seal layer 6 is easily separated on the flange portion 2.

[0019]

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

Examples 1 to 3 Three types of multilayer sheets shown in Table 1 were prepared by a coextrusion method. Using these multilayer sheets, round (FIG. 4) and square (FIG. 5) container shapes were formed by an indirect heating type vacuum forming machine. The size of the round container is the container inner diameter (caliber) 6
4 mm, height 30 mm, flange width 6 mm, flange width of initial opening portion 15 mm, flange inner edge circumference 200 mm, minute recess length (l) 20 mm (1/10 of flange inner edge circumference),
Width of minute recess 1.5mm (1/1 of initial opening part flange width
10). In addition, the dimensions of the square container are 123 mm in width, 93 mm in height, 30 mm in height, 6 mm in flange width,
The minute recesses were formed to have a length of 15 mm (about 1/14) and a width of 1.5 mm (1/6 of the flange width of the initial opening portion) so as to project from the corner of the initial opening portion to the inside of the container. An ultrasonic horn head having a large number of minute convex portions with a pitch interval of 0.6 mm was used for forming the minute concave portions. The ultrasonic treatment conditions at this time are output 2 KW (energy used: 225 J),
Pressing force 338pa, time 0.3 seconds, depth 10μ
The minute recesses were formed in dots.

[0021]

[Table 1] [Table Note] PC: Polycarbonate, PP: Polypropylene,
PE: polyethylene, EVOH: ethylene-vinyl alcohol copolymer, () indicates layer thickness (μ)

As the lid member, a sealant layer having a thickness of 50 μ was formed by using the same resin as that of the sealing layer of the container, and stretched polyamide (thickness 30 μ) was dry-laminated. Heat sealing is performed by stacking a sealant layer of a lid material on the seal layer surface including minute recesses of the container flange to obtain a surface pressure of 15
Heat sealing was performed twice under the conditions of kg / cm ² , temperature of 210 ° C., and time of 1 second.

50 of each of the hermetically sealed containers manufactured in this way
When the lids of the individual pieces were opened, the opening of all pieces proceeded stably and smoothly, and the state of the opened surface was extremely good. Also, as a sealability test, fill the container with water as the contents,
Compressed air was injected from the top of the lid material without leaks, and the internal pressure resistance from the inside was measured. As a result, all the tested containers withstand an internal pressure of 1.2 kg / cm ² or more, and have excellent sealing performance. It was confirmed to show.

Comparative Example On the flange surface of the container body obtained in the example, a notch having a depth of 40 μ was formed at a position 1 mm outside along the innermost edge of the flange, and the notch was 1/10 or less of the inner peripheral edge length. Was put over the initial opening part so that The container body and the lid member of the example were heat-sealed under the same conditions to obtain a sealed container. When the same test as in the example was performed on the obtained hermetically sealed container, many peeling defects and internal pressure resistance were caused due to displacement of cuts, displacement of heat seal and the like. Some of these defective products had a string-like whisker in the opening after the opening, and the sealing layer was not properly broken at the time of opening to form a bag, and the contents could not be taken out.

[0025]

As described above, according to the present invention, a minute recess in a specific range is formed in the flange portion corresponding to the initial opening portion, and the structure is such that the minute recess is sealed with the lid member, thereby providing an excellent seal. (EN) A highly efficient hermetically sealed container that has both stability and smooth openability, and does not leak contents even if it receives an external impact during transportation. Besides,
In the sealing process at the time of manufacturing, problems such as complicated position adjustment of the sealing board 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 a 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 an enlarged sectional view showing a flange portion of the sealed container of the present invention.

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

FIG. 5 is a perspective view showing another container form of the present invention.

FIG. 6 is a perspective view showing another container form of the present invention.

FIG. 7 is a perspective view showing another container form of the present invention.

FIG. 8 is an enlarged cross-sectional view of a flange portion showing another container form of the present invention.

FIG. 9 is a schematic cross-sectional view showing an opened state of the hermetically sealed container at an intended opening stage.

FIG. 10 is a schematic cross-sectional view showing another opened state of the hermetically sealed container at an intended opening stage.

FIG. 11 is an explanatory perspective view showing an opened state of the sealed container.

[Explanation of symbols]

 1 Container Main Body 2 Flange Part 3 Lid Material 4 Micro Recess 5 Sealant Layer 6 Sealing Layer 7 Adjacent Layer 8 Sealing Part 9 Dropping Part 10 Breaking Part

Claims (1)

[Claims] 1. A container comprising a multi-layer sheet having 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 at 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, at least at a flange inner edge position corresponding to an initial opening portion of the container main body, a length of 1/5 or less of a flange inner edge peripheral length of the container and 1 / of a flange width of the initial opening portion. Within the range of 2 or less, minute recesses are formed along the inner edge circumferential direction, and the adhesive strength between the flange of the container body and the lid material including the minute recesses is higher than the laminating strength of the seal layer of the container body and the adjacent layer. A hermetically sealed container characterized by being sealed to.