JPH052586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a sealed package whose opening is heat-sealed with a bag, disposable container, or the like.

[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 in advance, but it is also common to make the lid so that it can be easily peeled off from the container body by pulling it by hand. Therefore, the peel strength must be 1.0 to 2.0.
Kg/15mm width is designed.

On the other hand, since it is 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, the sample in the sealed part must be placed in a pouch.
Cut out a 15mm wide piece and measure the peel strength.
It is said that the weight must be 2.3Kg or more. Needless to say, this exceeds the limit that can be easily peeled off by hand.

[Problem of invention]

Further consideration of the above two requirements shows that in order to sufficiently protect the contents during the distribution process of a sealed package, the greater the peel strength from the inside of the package, that is, from the inside of the heat-sealed part, the better. On the other hand, when opening the package, it is found 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 in which the heat-sealed portion has a high peel strength from the inside and a low peel strength from the outside.

[Means for solving problems]

In order to solve the above problems, in the present invention, a protruding strip is formed near the opening of the package, and the cross-sectional shape of the protruding strip is changed from the outside of the package to the inside, that is, from the outer edge of the protruding strip. The height gradually increases in the direction of the inner edge, and the outer edge is made into a zigzag bent line, the inner edge is made into a substantially smooth linear shape, and a flat receiving surface is provided that continues to the lower end of the inner edge of this convex strip, A sealed package was constructed by forming a heat-sealed portion extending from the outer edge of the protruding strip to the inner edge and receiving surface.

[Effect]

When the above-described protrusions are provided, the peel strength with the other side to be heat sealed is greater in the direction from the inside to the outside of the opening than in the direction from the outside to the inside.
While it can be easily opened by hand from the outside of the opening, it will not peel off from the inside of the opening even if the internal pressure increases, for example due to rettle and processing.

〔Example〕

As shown in FIG. 1, 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 FIG. Also,
A lid 10 is heat-sealed to the flange 3 as a sealing member to close the opening 2 and form a sealed package.

As shown in FIG.
It has a cross-sectional shape in which the height gradually increases in the direction from the inner edge 6.

Alternatively, as shown in FIG. 2C, the height may gradually increase from the outer edge 5 and form a flat surface 7 near the inner edge 6. Alternatively, as shown in FIG. 2D, the height may gradually increase from the outer edge 5, reach the apex 8, and then slope downward toward the inner edge 6. In this case, it is desirable that the upward slope from the outer edge 5 has a gentler angle.

Incidentally, as shown in FIG. 2B, the inside of the protrusion 4 may be hollow. Further, the protruding strip 4 does not necessarily need to be provided in the center of the flange 3, and may be located near the outer edge or inner edge of the flange 3, but there is a flat surface following the lower end of the inner edge of the protruding strip 4. Must be. This becomes the receiving surface of the protrusion 4 described later.

Here, the height of the ridge 4 is 0.5 to 4 mm, preferably 1.0 to 2.0 mm, and the width is 0.5 to 10 mm, preferably 2.0 to 5.0 mm.

As shown in FIGS. 3 and 4, the outer edge 5 of the protrusion 4 has a relatively fine zigzag curve, and the inner edge 6 has a substantially smooth linear shape. This curved line does not necessarily have to be provided on the entire circumference; for example, the corner 9 may be a smooth line as shown in FIG.

The shape of the curved line of the outer edge 5 can be selected from various shapes as shown in FIG. In addition, as shown in FIG.
It may be something that is almost in contact with .

The bending line of the outer edge 5 as described above is to facilitate opening by hand, and in order to fully exhibit this effect, it must be at least 30% longer than the length of the inner edge 6.

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 may be a polypropylene molded product, and the lid 10 may be a laminate of aluminum foil and thermoplastic resin.

Further, the protruding strip 4 may be formed on the lower surface of the lid 10. In this case, the upper surface of the flange 3 is kept flat.

As shown in FIG. 6, the sealed package may be a bag. In this case, the protrusion 4 is formed on one of the inner surfaces of the opening 2', or a separate protrusion 4 is fixed. The surface facing the protrusions 4 may be flat. Of course, in this case as well, a flat receiving surface continues from the lower end of the inner edge of the protrusion 4.

In addition to the above-mentioned bags, the present invention can also be applied to boxes and the like.

Next, an example of a method for heat-sealing the lid 10 to the container body 1 will be explained based on FIG. 7.

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 surface of the upper mold 20. What is important here is to keep the original shape as much as possible, even if some melting and flow of the protrusions 4 cannot be avoided due to the pressure and heating.

When heat-sealing is performed as described above, a heat-sealed portion is obtained in which the peel strength from the inside is greater than the peel strength from the outside. The reason for this is not necessarily clear, but when a heat-sealed portion is formed in and around the protrusion 4, the outer edge 5 to the inner edge 6 of the protrusion 4
Since the pressing force increases in the direction of , the molten portion at the upper end of the inner edge 6 flows and is pushed inward, forming a knob-like bulge. At the same time, the adhesive of the lid 10 is caught in this bulge. At this time, the receiving surface continuing from the lower end of the inner edge 6 of the protrusion 4 receives the adhesive and the base material of the lid rolled up in the knob-shaped bulge.

In this state, when the protruding strip 4 is peeled off from the outside, when it reaches the inner edge 6, the knob-shaped bulge protrudes smoothly from the inner edge 6, so the knob-shaped bulge is removed without any particular resistance. through the opening to reach the opening.

On the other hand, when peeling is started from the inside of the protruding strip 4, first the knob-like bulge protrudes opposite to the peeling direction, which becomes an obstacle and the peel strength increases rapidly. Therefore, it is considered that the peel strength is maximized near the inner edge 6 of the protruding strip 4.

In addition, in FIG. 7, 11 is the base material of the lid, and 12
is the adhesive layer.

If the adhesive layer 12 has a sufficient thickness and has a cushioning effect, the elastic body 21 of the upper die 20 is not required. Moreover, on the lower surface of the upper mold 20,
It is also possible to provide a groove that corresponds approximately to the protrusion of the lid 10. In this case as well, the elastic body 21 is not necessary.

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

Example 1 Now, 10 round containers each having an internal volume of 150 c.c. were made by thermoforming polypropylene sheets with a thickness of 500 μm. The flanges of these containers have a height of 1 mm and a width of 1 mm.
A 2.5 mm protrusion with a sawtooth outer edge as shown in Figure 3 was provided.

On the other hand, a 50μ thick soft aluminum foil and a 35μ thick polyethylene-polypropylene blend film were bonded together using a thermosetting urethane adhesive, and then punched into a shape that matched the flange of the container to create a lid.

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

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

Comparative Example 1 Ten containers similar to those in Example 1 were prepared, except that polypropylene containers with a flat surface and serrated protrusions were used, filled with water in the same way, and filled with water using the same lid. Heat sealing was performed under the following conditions, and retort sterilization was performed.

When the lids of all the sealed containers of Example 1 and Comparative Example 1 were peeled off by hand, they were easily opened, but a 15 mm wide sample was cut from the heat-sealed part and the peel strength from the inside and outside of the container was measured. When measured, each of those of Example 1 was 2.5 to 4.0Kg/15
mm width and 0.6~0.8Kg/15mm width,
The peel strength of Comparative Example 1 was 0.8 to 1.0 Kg/15 mm width, and the peel strength from the inside to the outside and from the outside to the inside of the opening were almost the same.

Here, peel strength is calculated by recording the change in peel resistance with respect to the peel position as the peel line of the sample moves continuously when a constant tensile load is applied to one end of the sample (heat seal curve ), are averaged.

Comparative Example 2 A sealed package was obtained in the same manner as Comparative Example 1, except that a polypropylene container having a radius around the flange portion was used. The peel strengths from the inside to the outside and from the outside to the inside of the opening of the sealed package after retort sterilization are almost the same;
It was 0.8~1.2Km ² /15mm wide.

〔effect〕

According to the present invention, as described above, a protruding strip is provided on one side of the heat-sealed portions that are heat-sealed to each other, and the cross-sectional shape of the protruding strip is gradually increased in height from the outside to the inside of the sealed package. In addition, the outer edges of the protrusions are made into zigzag curves, and the inner edges are made into almost smooth lines, so that the peel strength in the direction from the inside to the outside of the protrusions is greater than the peel strength in the direction from the outside to the inside. At the outer edge of the protrusion, the adhesive line forms an acute angle to the peeling direction, making it easy to separate by hand. On the other hand, near the inner edge of the protrusion, the peel strength is maximum and the adhesive line is at an acute angle to the peeling direction. Since the lines are substantially perpendicular to the peeling direction, the package does not peel off even if the internal pressure increases rapidly due to retort processing, etc., and a package with excellent protection performance for contents can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of the sealed package, Fig. 2 is an enlarged sectional view showing the flange portion of the same as above, and Fig. 3 is an enlarged sectional view showing an example of the sealed package.
The figure is a perspective view of the same as above, FIG. 4 is a plan view of the sealed package, FIG. 5 is a plan view showing various shapes of protrusions provided on the flange, and FIG. 6 is a plan view of another form of the sealed package. FIG. 7 is an enlarged sectional view showing a method of heat sealing with a package. 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 the opening with a sealing member or by heat-sealing one side of the opening to the other side, a protruding strip is provided on one side that is mutually heat-sealed,
The cross-sectional shape of this protruding strip is such that the height gradually increases from the outside to the inside of the opening, that is, from the outer edge to the inner edge of the protruding strip, and the outer edge is a zigzag curve and the inner edge is almost smooth. A flat receiving surface is provided following the lower end of the inner edge of the protruding strip, and a heat-sealed portion is formed from the outer edge of the protruding strip to the inner edge and the receiving surface, and the opening in this heat-sealed portion is A sealed package characterized in that the peel strength in the direction from the inside to the outside is greater than the peel strength in the direction from the outside to the inside.