JP7794556B2 - Film Bag - Google Patents

Description

This invention relates to a film bag.

Conventional film bags are disclosed, for example, in Japanese Patent Application Laid-Open No. 2005-131221 (Patent Document 1).

Japanese Patent Application Laid-Open No. 2005-131221

Patent Document 1 above discloses a configuration in which, when the bag is hung on the production line, the bottom seal portion located below the storage chamber is configured in a mountain-like shape that protrudes above the horizontal line connecting the bottom ends of the two side seal portions.

However, this configuration had the problem that wrinkles were likely to form at the bent portion when the sheet was bent.

The purpose of this invention is to provide a film bag that is less likely to wrinkle at the folded portions.

The film bag according to this invention is a film bag with a storage chamber formed by sealing the peripheries of two opposing film sheets. It comprises a first seal portion having an opening, a second seal portion opposite the first seal portion, and a pair of side seal portions connecting the first and second seal portions and extending axially from the first seal portion toward the second seal portion. The second seal portion comprises a horizontal portion extending horizontally facing the storage chamber and connecting the pair of side seal portions, and a pair of legs located on either side of the horizontal portion. The pair of legs extend axially away from the horizontal portion and the first seal portion, and the horizontal length (W1) of the horizontal portion is 30% to 70% of the horizontal distance (W2) between the pair of side seal portions.

A film bag configured in this way can prevent wrinkles from forming in the folded areas.

Preferably, the device further includes a curved portion that curves toward the pair of legs, with the position where the curve begins being located between the horizontal portion and the first seal portion.

Preferably, the second seal portion has at least one corner exposed to the storage chamber in the portion connecting the horizontal portion to the leg portion.

Preferably, multiple corners are provided at a distance from each other.

FIG. 1 is a front view of a paper bag illustrating the concept of the present invention. FIG. 1 is a side view of a paper bag to illustrate the concept of the present invention. FIG. 1 is a front view of a paper bag with legs to illustrate the concept of the present invention. FIG. 1 is a side view of a paper bag with legs to illustrate the concept of the present invention. 1 is a perspective view of a paper bag provided with legs to illustrate the concept of the present invention. FIG. FIG. 2 is a front view of the film bag according to the first embodiment. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. FIG. 2 is a perspective view of the film bag according to the first embodiment as seen from below. FIG. 10 is a front view of a film bag according to a second embodiment. FIG. 10 is a front view of a film bag of a comparative example. FIG. 2 is a front view of the film bag before the center portion is folded. FIG. 10 is a front view of the film bag after the center portion is folded. FIG. 2 is a plan view of a circular film bag. 14 is a cross-sectional view taken along line XIV-XIV in FIG. 13. FIG. 1 is a plan view of a circular film bag filled with water. 16 is a cross-sectional view taken along line XVI-XVI in FIG. 15. FIG. 1 is a plan view of a square film bag. FIG. 1 is a plan view of a square film bag filled with water. 10 is a diagram showing the state in which the side seal portion on the arrow XIX side is pulled inward and curved as the bag expands. FIG. 10 is a side view of the film bag before being lifted, as seen from the direction in which the rod-shaped member extends. FIG. 10 is a side view of the film bag being lifted, seen from the direction in which the rod-shaped member extends. FIG. FIG. 10 is a plan view of the film bag and the rod-shaped member before being lifted. FIG. 10 is a plan view of the film bag and the rod-shaped member during lifting. 23 is a cross-sectional view taken along line XXIV-XXIV in FIG. 22. 24 is a cross-sectional view taken along line XXV-XXV in FIG. 23. FIG. 10 is a plan view of the film bag and the rod-shaped member before being lifted. FIG. 10 is a plan view of the film bag and the rod-shaped member during lifting. FIG. 2 is a plan view of a film bag having legs and a rod-shaped member. FIG. 10 is a plan view of a film bag with legs and a rod-shaped member during lifting. 10 is a diagram showing the direction of the force acting on the right side seal by the wrinkle 36. FIG. 10 is a diagram showing the direction of the force acting on the left side seal by the wrinkle 46. FIG.

(Embodiment 1)
The present inventors have conducted extensive research in the field of film bags to prevent wrinkles from occurring at the folded portions.

Film bags are widely used as containers for holding liquids. Liquids such as food, medicine, and daily necessities are sealed inside the film bags. Film bags are required to be packaged in a compact form when filled with liquid. Large film bags become particularly compact when folded in half. However, when folded, wrinkles can form at the folds. Therefore, we investigated a film bag shape that would prevent wrinkles from forming at the folds.

By focusing on the seal shape of the film bag and the spatial volume under gravity load, we discovered that changing the shape of the film bag made it less likely for wrinkles to form at the folded section.

In order for the film bag to be easily folded, it needs to be designed so that water in the folded area can easily flow along the length of the film bag toward the port and bottom. To achieve this, it is necessary to ensure there is space within the film bag for the liquid to flow when it is folded. Furthermore, ensuring space within the film bag not only makes it easier to fold in half, but also prevents overflow when the film bag is hung from the port and liquid is filled into the film bag.

When water is poured into a film bag that has been sealed around the edges in a perfect square, the water enters the four corners and tries to push outward, which in turn pulls the sheet. As a result, a force acts in the direction that prevents the film bag from expanding in thickness, preventing it from deforming into a shape that ensures sufficient capacity. Therefore, the inventors attempted to solve this problem by adopting a "gusset" like those used in paper bags.

Figure 1 is a front view of a paper bag to illustrate the concept of the present invention. Figure 2 is a side view of a paper bag to illustrate the concept of the present invention. Figure 3 is a front view of a paper bag with legs to illustrate the concept of the present invention. Figure 4 is a side view of a paper bag with legs to illustrate the concept of the present invention. Figure 5 is a perspective view of a paper bag with legs to illustrate the concept of the present invention.

As shown in Figures 1 to 5, fold lines 101 and 102 are provided on the paper bag 100. Fold line 101 is provided on the side of paper bag 100, and fold line 102 is provided on the bottom of paper bag 100. By folding paper bag 100 at fold lines 101 and 102, legs 103 and 104 are formed on the bottom of paper bag 100. Forming legs 103 and 104 makes it easier to ensure thickness A for the paper bag.

By providing a gusset in the paper bag 100, the two sheets of paper are transformed into a rectangular parallelepiped. Although it is not possible to provide a gusset in a film bag, we have devised a shape that allows the film bag to automatically expand when water is poured into it by providing a part that functions equivalent to a gusset.

Figure 6 is a front view of a film bag according to embodiment 1. Figure 7 is a cross-sectional view taken along line VII-VII in Figure 6. Figure 8 is a perspective view of a film bag according to embodiment 1 as seen from below.

As shown in Figures 6 to 8, the film bag 1 has one storage compartment 2 formed by sealing the peripheries of two opposing film sheets 5, 6.

The film bag 1 comprises a first sealed portion 10 having a mouth portion 11, a second sealed portion 20 facing the first sealed portion 10, and a pair of side sealed portions 30, 40 connecting the first sealed portion 10 and the second sealed portion 20 and extending axially from the first sealed portion 10 toward the second sealed portion 20.

The second seal portion 20 has a horizontal portion 21 that faces the storage chamber 2 and extends horizontally between the pair of side seal portions 30, 40, and a pair of leg portions 3, 4 located on either side of the horizontal portion 21.

The pair of legs 3, 4 extend axially away from the horizontal portion 21 and the first seal portion 10. The horizontal length (W1) of the horizontal portion 21 is between 30% and 70% of the horizontal distance (W2) between the pair of side seal portions 30, 40.

A film bag 1 configured in this way can prevent wrinkles from forming in the folded areas.

The side seal portions 30, 40 have curved portions 32, 42 that curve toward the pair of legs 3, 4. The positions 33, 43 where the curve begins are located between the horizontal portion 21 and the first seal portion 10.

At least one corner 24, 25 is provided in the second seal portion 20, in the area connecting the horizontal portion 21 to the legs 3, 4, so as to be exposed to the storage chamber 2. Multiple corners 24, 25 are provided at a distance from each other.

The side seal portions 30, 40 are provided with a pair of side point seals 31, 41 that protrude inward. The side point seals 31, 41 are provided to prevent wrinkles from forming in the side seal portions 30, 40. The pair of side point seals 31, 41 do not have to be provided. The corners 24, 25 make wrinkles 111, 112 more likely to form. The second seal portion 20 is provided with a hole 23 for hanging the film bag 1. The corners 24, 25 are provided on the bottom 22 of the second seal portion 20.

A liquid 50 is sealed in the storage chamber 2. The liquid 50 may be, for example, saline solution, medicine, or water. The film sheets 5 and 6 are expanded so that the circle 2a fits between them.

To make it easier for the legs 3 and 4 to spread apart, curved portions 32 and 42 are used, which are arc-shaped curves that gradually become gentler from the bottom of the legs 3 and 4.

By inducing the inward folding of legs 3 and 4, leg 3 can be made thicker. Therefore, by providing two corners 24 and 25, wrinkles are forced to form in film bag 1. The angle θ1 of corner 24 and the angle θ2 of corner 25 are, for example, 40°.

When the film bag 1 configured as described above is pulled up in the middle and folded in half, drainage from the folds occurs instantly. This is also due to the effect of liquid being pulled from the area around the mouth 11 and the bottom 22, which act as ports, making it possible to manufacture a film bag that is less likely to wrinkle at the folds.

In addition, when the film bag 1 is laid flat, the bulge in the center of the film bag 1 can be suppressed. Furthermore, since the bottom 22 does not protrude to either side, it can be stored compactly in a packing case.

(Embodiment 2)
Fig. 9 is a front view of a film bag according to embodiment 2. As shown in Fig. 9, film bag 1 according to embodiment 2 differs from film bag 1 according to embodiment 1 in that positions 33 and 34 where the curvature of a pair of side seal portions 30 and 40 begins are located below horizontal portion 21.

(Example)
In the example, the film bag 1 shown in Fig. 6, the film bag 1 shown in Fig. 6 with the corners 24 and 25 removed, the film bag shown in Fig. 9, and the comparative film bag shown in Fig. 10 were prepared. The volume of each film bag was 2 ^dm3 . The dimensions of each film bag are shown in Table 1.

Figure 10 is a front view of a film bag of a comparative example. The film bag 201 in Figure 10 has one storage compartment 202 formed by sealing the peripheries of two opposing film sheets. The film bag 201 has a first sealed portion 210 with an opening 211, a second sealed portion 220 facing the first sealed portion 210, and a pair of side sealed portions 230, 240 that connect the first sealed portion 210 and the second sealed portion 220 and extend axially from the first sealed portion 210 toward the second sealed portion 220.

The center of the second seal portion 220 protrudes toward the first seal portion 210. The height of the protruding portion is H1. A hole 223 is provided in the second seal portion 220.

Figure 11 is a front view of the film bag before the center is folded. Figure 12 is a front view of the film bag after the center is folded. A folding test was conducted using the device shown in Figure 11. A rod-shaped member 501 was placed in contact with the center of the film bag in the longitudinal direction, and the bag was then lifted 10 cm to the state shown in Figure 12. This was repeated 100 times. The number of times wrinkles occurred at the contact point 502 with the rod-shaped member 501 was measured. Wrinkles were determined when the sheet was folded twice in the longitudinal direction of the bag and the width was 2 mm or more. The results are shown in Table 1.

In the "Rating" column of Table 1, a rating of AA indicates that no wrinkles occurred on the contact portion 502. A rating of A indicates that wrinkles occurred on the contact portion 502 one to five times. A rating of B indicates that wrinkles occurred on the contact portion 502 six or more times. However, there were no ratings of A in Table 1.

It can be seen that excellent effects were achieved in samples No. 1 to 3. The reasons why the above results were obtained in the examples are explained below.

Figure 13 is a plan view of a circular film bag. Figure 14 is a cross-sectional view taken along line XIV-XIV in Figure 13. Figure 15 is a plan view of a circular film bag filled with water. Figure 16 is a cross-sectional view taken along line XVI-XVI in Figure 15.

A round bag 1 is made from two sheets 5 and 6. In Figures 13 and 14, D1 is 300 mm and the circumference is 942 mm. When water is poured inside, it deforms as shown in Figures 15 and 16, and the diameter becomes smaller. D2 becomes 290 mm and the circumference is 911 mm.

As the diameter of the sealed portion of the circumference decreases, a force acts on it that causes it to shrink more than its actual length, making it more susceptible to wrinkles 5a. For example, if a sheet with a diameter of 300 mm is filled with water about 20 mm thick, the diameter will decrease by about 10 mm and the circumference will shrink by about 30 mm (about 3%).

Figure 17 is a plan view of a square film bag. Figure 18 is a plan view of a square film bag with water inside.

When a square film bag 1 is filled with water, it deforms in a way that shortens its overall length and width, as in Figures 13 to 16, and the four corners protrude outward. At this time, a force acts to bend the seal toward the inside of the bag, making it particularly prone to wrinkles at the corners. Figure 19 shows how the side seal on the side indicated by arrow XIX is pulled inward and bent as the bag expands.

Next, let's consider the deformation that occurs when film bag 1 is lifted, as shown in Figure 12.

Figure 20 is a side view of the film bag before lifting, as seen from the direction in which the rod-shaped member extends. Figure 21 is a side view of the film bag during lifting, as seen from the direction in which the rod-shaped member extends. As shown in Figures 20 and 21, when lifted, the liquid inside moves to both sides, and a force acts in the direction of expanding the thickness of the film bag 1. At the same time, the length A of the film bag 1 tries to shrink to B.

Figure 22 is a plan view of the film bag and rod-shaped member before lifting. Figure 23 is a plan view of the film bag and rod-shaped member during lifting. Figure 24 is a cross-sectional view taken along line XXIV-XXIV in Figure 22. Figure 25 is a cross-sectional view taken along line XXV-XXV in Figure 23.

The side seals 30, 40 of the film bag 1 form wrinkles and fold inward to maintain balance due to the force that tries to shorten their overall length. Figures 23 and 25 show an example where the fold occurs at the lifted position. In this case, the side seals 30, 40 try to slip in between the upper and lower sheets 5, 6. Furthermore, the upper and lower sheets 5, 6 push out in the directions indicated by arrows 35, 45, covering the side seals 30, 40, creating a double fold.

Figure 26 is a plan view of the film bag and rod-shaped member before lifting. Figure 27 is a plan view of the film bag and rod-shaped member during lifting. However, wrinkles may occur in places other than the contact point with the lifting rod-shaped member 501. In the case shown in Figure 27, double folding does not occur in the folded-in portion. Therefore, by intentionally creating wrinkles in places other than the lifted portion, double folding in the folded-in portion can be prevented. For this reason, side point seals 31, 41 on both sides of the film bag 1 are effective.

Figure 28 is a plan view of a film bag with legs and a rod-shaped member. Figure 29 is a plan view of a film bag with legs and a rod-shaped member during lifting.

It is also possible to create wrinkles on the bottom edge of the film bag 1 using another method. Wrinkles 36 and 46 are created when the bag is lifted. The bottom edge is lifted by the planar extension portion 9, but wrinkles 36 and 46 shrink the bag in the left-right direction, causing the bag to deform into a trapezoidal shape and canceling out the force of shrinkage on the side seal. This prevents wrinkles from forming near the rod-shaped member 501. Figure 30 shows the direction of the force acting on the right side seal by wrinkle 36. Figure 31 shows the direction of the force acting on the left side seal by wrinkle 46.

The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

1,201 Film bag, 2,202 Storage chamber, 2a Circle, 3,4,103,104 Legs, 5,6 Film sheet, 9 Planar extending portion, 10,210 First seal portion, 11,211 Mouth portion, 20,220 Second seal portion, 21 Horizontal portion, 22 Bottom, 23,223 Hole, 24,25 Corner portion, 30,40,230,240 Side seal portion, 31,41 Side point seal, 32,42 Curved portion, 33,34,43,44 Position, 36,46,111,112 Wrinkle, 50 Liquid, 100 Paper bag, 101,102 Fold line, 501 Rod-shaped member, 502 Contact portion.

Claims (3)

A film bag having one storage chamber formed by sealing the peripheries of two opposing film sheets, the film bag comprising: a first sealed portion having an opening; a second sealed portion opposed to the first sealed portion; and a pair of side sealed portions connecting the first and second sealed portions and extending along an axial direction from the first sealed portion toward the second sealed portion, the pair of side sealed portions being formed by sealing the peripheries of the two opposing film sheets;
the second seal portion includes a horizontal portion extending horizontally and connecting the pair of side seal portions facing the storage chamber, and a pair of leg portions located on both sides of the horizontal portion, the pair of leg portions extending along the axial direction so as to move away from the horizontal portion and the first seal portion, and the horizontal length (W1) of the horizontal portion is 30% to 70% of the horizontal distance (W2) between the pair of side seal portions,
The film bag has a pair of side point seals that protrude inward , and further has a curved portion that curves toward the pair of leg portions, and the position where the curve begins is located between the horizontal portion and the first seal portion . The film bag according to claim 1, wherein the second seal portion has at least one corner exposed to the storage chamber in a portion connecting the horizontal portion to the leg portion. The film bag according to claim 2, wherein multiple corners are provided at a distance from each other.