JPS5815305Y2 - square bottom bag - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a square-bottomed bag, and more particularly, to a square-bottomed bag whose bottom can be precisely formed into a square shape using a normal bag-making packaging material.

Conventionally, square bottom bags have been made by laminating the side edges of a rectangular sticker to form a flat cylinder, then folding both sides inward and polymerizing the folded and polymerized state, as shown in Figure 1. Generally, the lower edge is bonded together, and when used, the bottom is inflated and shaped into a rectangular shape, as shown in FIG.

However, in such a conventional square bottom bag, as shown in FIG. 3, a portion A near the junction of the folded and polymerized portion to form four layers and the folded and polymerized portion that remains two layers is the packaging material. Due to the difference in level caused by the high tension between the two, they were not completely adhered to each other, and liquid leakage occurred from this area.

In addition, packaging materials for bag making usually have a polyethylene layer on the inner surface to provide heat-sealing properties, and the outer surface has a layer of polyethylene to provide printability, various barrier properties, stiffness, etc. For this purpose, materials having layers of polyester, oriented polypropylene, oriented polyamide, etc. are generally used, although they are inferior to polyethylene and the like in terms of heat sealability.

When such a packaging material is used, the folded part 1 and the unfolded part 2 are bonded to each other on their inner surfaces, so they can be easily and completely heat-sealed at a general sealing temperature of about 140 to 160°C. However, since the outer surfaces of the folded parts 1 and 1 are in contact with each other, they are generally not fully heat-bonded (Fig. 4).

Therefore, when the bottom of the bag is inflated, as shown in FIG. , none of the folded and polymerized seal parts 3, 3, and 3.3 come into close contact with the bottom surface, and therefore, the bottom portion cannot actually be made into a flat rectangular shape as shown in Fig. 2. The reality is that even if you try to stand it up as a bag, it cannot stand on its own.

In order to eliminate the sloping defect, it has been proposed to use a material coated with polyvinyl chloride, polyethylene, etc. on the outermost surface of the packaging material, and to heat-seal the folded parts 1 and 1 together. This method has the disadvantage that the raw material cost is about 50% to 100% higher because it requires the use of a special coating of polyvinylidene chloride, etc., and it also requires the use of a specially coated material such as polyvinylidene chloride. Since the easy-to-seal plastic layer is exposed, softened polyvinylidene chloride or the like sticks to the heat-seal bar, resulting in poor workability.

In addition, in order to eliminate the above-mentioned defects, it is possible to partially apply polyvinylidene chloride, polyethylene, etc. only to the outermost surface of the part 1 to be folded, but this method requires more steps than the one step of partial coating, so it is time-consuming. This is too expensive and cannot be put to practical use.

The present invention eliminates the sloping disadvantage of conventional square bottom bags.

To explain one embodiment of the present invention with reference to figures, FIG. 6 is a perspective view of a completed square bottom coin according to the present invention, and FIG.
As shown in Figure A, the side edges of a rectangular sheet made of a laminate of polyethylene and stretched polypropylene are heat-sealed into a cylindrical body with the polyethylene layer inside. As shown in the figure, the heat-sealed portion 5 is positioned approximately at the center and folded into a flat shape, and the heat-sealed portion 5 is folded over the folded surface.

Next, as shown in FIG. 7C, the outer part of the lower end is notched 6, and the upper part 7 of the notched part 6 is folded inward as shown in FIG. 7B, and then the lower part is heated with a heat seal bar. It is made of 8 seals.

Therefore, the vertical width a of the heat seal 8 needs to be wider than the vertical width of the notch 6, and the vertical width is the key to the vertical width a.
It is preferable for the strength to be at the level of a professional.

The square bottom bag according to the present invention having the above structure has heat seal 8
In the part immediately above the notched part 6, the folded part 1 and the unfolded part 2 are heat-sealed by the inner polyethylene layer, but the folded part 1
, 1 are not heat sealed because the stretched polypropylene layers are in contact with each other.

That is, the folded and polymerized seal portions are in a state of being separated from each other.

However, since the part of the part 2 that is not folded that corresponds to the notch 6 and the seal part 4 that is not folded and polymerized are both heat-sealed with the polyethylene layer on the inner surface and surround the folded and polymerized part from two directions, the folded and polymerized seal The parts do not separate and open as in the case shown in Fig. 5, but are firmly stuck together.

In other words, when the bottom of the square bottom bag is inflated, the folded and polymerized seal part remains in close contact with the bottom as shown in Figure 8, and the bottom becomes a beautiful square, making it stable and self-supporting. be able to.

At this time, the upper portion 7 of the notched portion 6 is at right angles to the seal portion 4, and the left and right upper portions 7, 7 are planes parallel to each other.

Also, the part shown in Fig. 6B becomes as shown in Fig. 9, and if there is a part that is folded and polymerized to form four layers and a two-layered part that is not folded and polymerized, as shown in Fig. 3, Even if a narrow groove-shaped portion M in the vertical direction that is not heat-sealed due to a step due to the high tension between the packaging materials occurs near the joining point with the intact portion, the lower portion of the folded portion 1 is notched 6. Therefore, the portion corresponding to the notch 6 of the portion 2 that is not folded and the seal portion 4 that does not overlap when folded form a two-layer strong heat seal portion in the horizontal direction, and the heat seal closes the lower end of the portion M. Unlike the conventional square bottom bag shown in FIG. 3, there is no possibility of liquid leakage.

The present invention is not limited to the above-mentioned embodiments, but the first embodiment
As shown in FIG. 0 and FIG.
0 is folded inward and heat-sealed, and a notch 60 is provided in only a part of the folded part 1, so that the folded and overlapped sealed part separates and opens as in the case of Fig. 5. may be prevented.

Since the present invention has the above-mentioned configuration, it is not necessary to coat the entire surface of the packaging material with heat-sealable plastics or to coat only the surface of the part to be folded with heat-sealable plastics. The bag has a flat square bottom and has a remarkable effect in that it can be made completely self-supporting at a low cost.

[Brief explanation of the drawing]

Figures 1 to 5 show a conventional square bottom bag, Figure 1 is a perspective view, Figure 2 is a perspective view showing the state of use, and Figure 3 is an end view taken along line A'-A' in Figure 1. 4 and 5 are perspective views showing the state of use, and FIGS. 6 to 9 show an embodiment of the present invention. FIG. 6 is a perspective view, and FIG. C. 2 is a perspective view showing the production order, FIG. 8 is a perspective view showing the state of use,
FIG. 9 is a perspective explanatory view of the part B in FIG.
11 and 11 show another embodiment of the present invention, FIG. 10 is a perspective view showing a state in the middle of production, and FIG. 11 is a perspective view after completion of production. Explanation of the symbols representing the main parts of the figure 1...The part that is folded in, 2...The part that is not folded in, 3.
...Folded and polymerized seal part, 4...
Seal part that does not overlap when folded, 6... Notch.

Claims (1)

[Scope of utility model registration request] Both sides of the cylindrical sheet are folded inward and polymerized, the outer lower end of the folded and polymerized portion is cut out, and the folded and polymerized portion and the folded portion are cut out with a vertical width wider than the vertical width of the cut portion. A square bottom bag in which the middle part of the overlapped part is heat-sealed, the both sides of the folded and overlapped part are at right angles to the heat-sealed part, and the both sides are made into mutually parallel sides of the body.