JPH0563384B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a package such as a bag or disposable container whose opening is sealed by heat sealing.

[Conventional technology]

For example, one of the requirements for a package in which the opening of a molded container body is heat-sealed with a lid is that it be easy to open by hand. To this end, various measures have been taken, such as making a cut in a part of the lid, but it is also common practice to make the lid so that it can be easily removed from the container body by pulling it by hand. , for that purpose, the peel strength should be set to 1.0 to 2.0.
Must be designed with a width of Kg/14mm.

On the other hand, since it is extremely inconvenient for the heat-sealed part to come off during handling such as hot water treatment or transportation, it is also required that the heat-sealed part does not peel off easily. For example, according to the Japanese Agricultural Standards (JAS), when labeling retort food, a sample of the heat-sealed part of the pouch must be cut out to a width of 15 mm and the peel strength must be measured, and the peel strength must be 2.2 kg or more. has been done. Needless to say, this exceeds the limit that can be easily peeled off by hand.

[Problem of invention]

Considering the above two requirements further, in order to sufficiently protect the contents during the distribution process of the sealed package, the greater the peel strength from the inside of the package, that is, the heat-sealed part, the better. On the other hand, when opening the package, it can be seen that if the peel strength from the outside of the heat-sealed part is weakened, the package can be opened easily.

Therefore, an object of the present invention is to provide a structure of a sealed package that has good protection performance for contents and is easy to open by increasing the peel strength from the inside of the heat-sealed part and decreasing the peel strength from the outside. It is.

[Means for solving problems]

In order to solve the above problems, in the present invention, a protruding strip is provided on one side of the heat-sealed portion provided near the opening that is heat-sealed to each other, and the cross-sectional shape of the protruding strip is The height of the protrusion gradually increases from the outside to the inside of the opening, that is, from the outside edge to the inside edge of the protrusion, and the outside edge and the inside edge form a smooth linear shape.

[Effect]

When the above-mentioned protrusions are provided, the adhesive strength with the heat-sealed mating surface is weak at the outer edge of the protrusion and gradually becomes stronger toward the inner edge, so the peel strength in the direction from the outer edge to the inner edge is is weak, and the peel strength in the opposite direction is high.

〔Example〕

As shown in FIGS. 1 to 3, a flange 3 is provided on the periphery of the opening 2 of the container body 1, and a protruding strip 4 is formed on the upper surface of the flange 3. As shown in FIGS. Further, a lid 10 as a sealing member is heat-sealed to the flange 3 to close the opening 2 and form a sealed package.

The protruding strip 4 is formed around the entire circumference of the flange 3, and has a cross-sectional shape that gradually increases in height from the outside to the inside of the package, that is, from the outside edge 5 to the inside edge 6. have. The maximum height of this protrusion 4 is 0.5 to 4 mm, preferably 1.0 to 2.0 mm.
mm, and the width is 0.5 to 10 mm, preferably 2.0 to 5.0 mm
It is.

FIG. 4 shows various stepped shapes of the protrusion 4. As shown in FIG. In the figure, A shows a shape that gradually increases in thickness from the outer edge 5 to the inner edge 6, and stands out at the inner edge 6, and B shows a similar shape but is hollow inside. In addition, C gradually increases in height from the outer edge 5 and the vicinity of the inner edge 6 becomes a flat surface 7, and D gradually increases in height from the outer edge 5 and reaches the apex 8. Later, it slopes downward in the direction of the inner edge 6. In this case, it is desirable that the upward slope from the outer edge 5 has a gentler angle. Further, the protruding strip 4 does not necessarily need to be provided at the center of the flange 3 in the width direction, and may be located near the outer edge or inner edge of the flange 3.

As is clear from FIGS. 2 and 3, the outer edge 5 and inner edge 6 of the protrusion 4 form a relatively smooth line along the opening 2. As shown in FIGS.

Such a protrusion 4 may be formed on the lower surface of the lid 10. In that case, the upper surface of the flange 3 is kept flat.

Note that the material of the container body 1 and the lid 10 may be any material as long as it can be heat-sealed, and it does not matter whether it is a single body or a laminate. For example, the container body 1 is a molded product of polypropylene, and the lid 10 is a laminate of aluminum foil and thermoplastic resin.

Furthermore, the sealed package is not limited to the container described above. In addition to flat bags and self-supporting bags, the present invention can also be applied to boxes and the like. For example, in the case of a bag as shown in FIG. 5, a protrusion 4 is formed on one side of the inner surface of the opening 2', or a separate protrusion 4 is fixed. The surface facing the protrusions 4 may be flat.

Next, an example of a method for heat-sealing the lid 10 to the container body 1 will be explained based on FIG. 6.

As shown, the lid 1 is attached to the flange 3 of the container body 1.
0 is placed on the lid 10, and while the lower surface of the flange 3 is supported by the lower mold 30 of the heat-seal hot plate, the upper surface of the lid 10 is heated under pressure with an elastic body 21 such as heat-resistant rubber fixed to the lower end of the upper mold 20. What is important here is to prevent the ridges 4 from being deformed as much as possible by the pressure and heating.

When heat-sealing is performed as described above, a heat-sealed portion is formed in and around the protrusion 4, but the adhesive strength is the weakest near the outer edge 5, and the adhesive strength is weakest near the outer edge 5.
Since the maximum amount occurs in the area, it can be easily removed by pulling up the lid from the outside of the container.
It does not peel off easily from the inside. In addition, in Figure 6,
11 is a base material of the lid, and 12 is an adhesive layer.

The elastic body 21 can be omitted, for example, if the lid and adhesive layer have sufficient thickness to provide a cushioning effect. Further, a groove may be provided on the lower surface of the upper die 20 to accommodate the protrusion of the lid 10 that corresponds to the protrusion 4. In this case as well, the elastic body 21 is of course unnecessary.

Next, more detailed examples and comparative examples will be given.

We have now created 10 round containers with an internal volume of 150 c.c. by heat forming polypropylene sheets with a thickness of 500 μ. The flanges 12 of these containers have a height of 1
A protruding strip with a width of 2.5 mm and a cross section of a nearly right triangle was provided.

On the other hand, 50μ thick soft aluminum foil and thickness
A lid was prepared by bonding a 35 μm modified high-density polyethylene film with a thermosetting urethane adhesive and punching it into a shape that matched the flange of the container.

Each of the containers described above was filled with water, the lids were placed on the flanges, and the containers were heat-sealed with heat-resistant rubber to seal them. The heat sealing conditions were: rubber surface temperature 200° C., pressure 3 Kg/cm ² , and time 1 second.

Furthermore, this sealed container was subjected to retort sterilization at 120°C for 30 minutes.

As a comparative example, we prepared 10 containers and lids that had flat flange tops and were otherwise similar to the examples.
Heat sealing was performed under the same conditions filled with water, and retort sterilization was performed.

When the lids of all of these sealed containers were peeled off by hand, they were easily opened, but when a 15 mm wide sample was cut out from the heat-sealed part and the peel strength from the inside of the container was measured, While the example is 2.5-4.0Kg/15mm width,
The comparative example had a width of 0.1 to 1.2 kg/15 mm.

〔effect〕

According to the present invention, as described above, a protruding strip is provided on one side of the heat-sealed parts that are heat-sealed to each other, and the cross-sectional shape of the protruding strip is changed from the outside to the inside of the package over the entire length of the protruding strip. Since the height gradually increases, the adhesive strength is weak near the outer edge of the protrusion and strongest near the inner edge, making it easy to peel off the heat-sealed portion from the outside of the package. Therefore, the package can be easily opened at any part of the heat-sealed part, does not easily peel off from the inside of the package, and has excellent protection performance for the contents.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an example of a package in which the container body is sealed with a lid, Figure 2 is a plan view of the same, Figure 3 is an enlarged perspective view of the flange of the container body, and Figure 4 is a FIG. 5 is an enlarged sectional view showing various shapes of the convex stripes, FIG. 5 is a perspective view showing a case where the package is a bag, and FIG. 6 is an enlarged sectional view showing a heat-sealed state of the lid and the container body. 1... Container body, 2, 2'... Opening, 3...
flange, 4... protrusion, 5... outer edge, 6... inner edge, 10... lid.

Claims (1)

[Claims] 1 In a package that is sealed by heat-sealing a sealing member to the opening or by heat-sealing one side of the opening to the other side, a convex strip is provided on one side of the heat-sealed parts that are heat-sealed to each other. , over the entire length of the protrusion, the cross-sectional shape is such that the thickness gradually increases from the outside to the inside of the opening, that is, from the outer edge of the protrusion to the inner edge, and the outer edge and the inner side are A sealed package characterized by having a substantially smooth linear shape.