JP2536071Y2 - Square bottom bag - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a plastic square bottom bag.

[0002]

2. Description of the Related Art Square bottom bags made of plastic sheets are very widely used for packaging articles having a rectangular parallelepiped shape. These square bottom bags are manufactured by a continuous bag making process using a long film raw material, but in order to cut an upper portion to form an opening and a lower portion to have a square bottom structure, a long film material is used. For the vertical flow, bag making is performed by vertical cutting that makes the top and bottom of the bag parallel to the flow of material, so the opening of the bag body is cut perpendicular to the flow and formed, and the bottom edge is formed. The structure is fused by fusing. Normally, the upper part of this kind of square bottom bag is simply opened by cutting the tubular material, and after storing the goods to be packaged in the square bottom, the excess film on the top is placed on the top of the goods. In many cases, the film is folded, sealed and sealed. In the case of providing a vertically bottomed bag with a square bottom structure, a caseet fold is provided on the left and right edges of a tubular long film, and four pairs of left and right and front and back formed by the left and right gusset folds are provided. From the outer edge to the inner edge of the fold, a fusion line is provided at an inclination of 45 degrees, each fold is fixed, and the lower part of the fusion line is fused to form a bottom, thereby forming a square bottom. It is known to However, the bottom surface of the known square bottom bag has a structure as shown in FIG. 8, but when gravity is applied to the bottom surface with the luggage put in, the tip point D of the square bottom fusion line at the bottom of FIG. There was a drawback that the power was concentrated on this and was easily damaged from here. Further, when manufacturing a square bottom bag having a square bottom surface, the fusion line is concentrated at the center as shown in FIG. 7 to reduce the strength, and the manufacturing process itself is substantially impossible.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a plastic square bottom bag with improved corner bottom strength.

[0004]

Means for Solving the Problems The inventor of the present invention puts a heavy object in the above-mentioned square bottom bag and hangs the bag. It was observed from the intersection of. Therefore, we conceived of dispersing the force concentrated at the intersection of these two fusion lines, and bent the slope of the square bottom fusion line in the vertical direction near the bottom edge fusion line to obtain the bottom edge fusion line. In addition, the object of the present invention was achieved by dispersing the gravity by making the square bottom fusion lines intersect almost vertically.

That is, in the present invention, gusset folds are provided on the left and right sides of a long tubular thermoplastic plastic film, and the four pairs of folds formed by the gusset folds downward from the outer edge to the inner edge of the fold. In a square bottom bag in which each pair of folds is fixed by four 45 degree inclined bottom fusion lines and then a bottom fusion line is formed to horizontally fuse the lower part of the bottom fusion lines, A corner bottom bag is provided, wherein the corner bottom fusion line is vertically bent near an inner edge of the fold and is connected to the bottom fusion line without contacting the inner edge of the fold. Things.

The present invention will be described in detail with reference to the drawings of embodiments. The plastic square bottom bags of FIGS. 1, 2 and 3 are:
A square bottom structure is provided at the bottom of a tubular film. While pulling out the tubular film raw material in the bag making process, the tubular film raw material is gusset-folded so as to have the cross-sectional structure of FIG. Insert a metal plate between the right gusset folds 1 and 2 and between the left gusset folds 3 and 4, apply hot blades from the front and back, and insert the metal plate.
At 2, 3, and 4, square bottom fusion lines 5 and 6 and two corner bottom fusion lines at the back of each are formed, and the folds are fixed. The corner bottom fusion line is provided on a line inclined at an angle of 45 degrees downward from the side edges 9 and 10 of the fold toward the inner edges 11 and 12 of the fold, and curves vertically in the vicinity of the inner edge. Do not touch the inner edge.

Next, a bottom fusion seal 7 is formed below the square bottom fusion wires 5 and 6, and the four films of the gusset folded portion and the two films of the central portion are fusion-fixed by this heat seal. . The bag manufactured in this manner is a bag having the bottom view of FIG. As shown in FIG. 1, the square bottom fusion lines 5 and 6 are bent vertically near the inner edges 11 and 12 of the folds 1 and 3 and intersect at right angles toward the bottom fusion line 7. , Are not connected to the inner edges 11 and 12 of the fold. When the shape of the square bottom bag manufactured in this way is expanded so as to be a rectangular parallelepiped, the bottom surface of the square bottom is as shown in FIG.

The bottom fusion lines 5 'and 6' and the bottom fusion lines 5 'and 6' at the folds 2 and 4 on the back are respectively shown in FIG.
In the bottom view, the ends of the square bottom fusion lines 5 and 5 'and 6 and 6' are connected smoothly and linearly to form a gentle convex shape. Are dispersed so that there is no damage from this part. FIG.
The embodiments shown in FIGS. 5 and 6 make more effective use of the features of the present invention.

This embodiment differs from the previous embodiment in that the gusset fold is folded up to the center of the tubular web as shown in the sectional view of FIG. When a square bottom having such a square bottom is fused by a conventional method, the fusion line is concentrated at the center as shown in FIG. 7, and the strength of the central portion is extremely reduced. In the case of this embodiment, the bottom surface is as shown in FIG. 6, and there is no concentration of the square bottom fusion line as in FIG. 7, and a bag having the same strength as the rectangular parallelepiped square bottom bag can be obtained.

[0010]

[Effects of the Invention] The present invention makes it possible to efficiently and easily produce a plastic square bottom bag that is convenient to use and strong, and has a rectangular parallelepiped shape, for example, a box or a can, particularly an oil can It is convenient for packaging such as square cans.

[0011]

[Brief description of the drawings]

FIG. 1 is a front view of one embodiment of a square bottom bag of the present invention.

[0012]

FIG. 2 is a cross-sectional view of the tubular film provided with gusset folds on the left and right used in the embodiment of FIG. 1 of the square bottom bag of the present invention.

[0013]

FIG. 3 is a bottom view when the square bottom bag of the present invention is formed into a square bottom shape when used.

[0014]

[0014]

FIG. 4 is a front view of a square bottom bag according to another embodiment of the present invention.

[0015]

FIG. 5 is a cross-sectional view of the tubular film provided with gusset folds on the left and right used in the embodiment of FIG. 4 of the present invention.

[0016]

FIG. 6 is a bottom view when the square bottom bag of FIG. 4 is used.

[0017]

FIG. 7 is a bottom view of a square bottom bag according to a conventional method.

[0018]

FIG. 8 is a bottom view of a known square bottom bag.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 fold 2 fold 3 folds 4 folds 5 Square bottom fusion line 5 'Square bottom fusion line 6 Square bottom fusion line 6' Square bottom fusion line 7 Bottom edge fusion part 8 Cutting line 9 Fold outer edge 11 Fold inner edge 12 Inner edge of fold A Bottom surface of square bottom B Curved portion of square bottom fusion line C Curved portion of square bottom fusion line

Claims (2)

(57) [Scope of request for utility model registration] 1. A gusset fold is provided on the left and right sides of an elongated tubular thermoplastic film, and the four folds formed by the gusset fold are inclined downward by about 45 degrees from the outer edge to the inner edge of the fold. Fixing the folds of each pair with the four corner bottom fusion lines, and then forming a bottom fusion line for horizontally fusing the lower part of the corner bottom fusion lines, A square bottom bag characterized in that a connection line is bent in a vertical direction near an inner edge of a fold and is connected to a bottom fusion line without touching the inner edge of the fold. 2. The square bottom bag according to claim 1, wherein the bottom surface is square.