JPH11130050A - Packaging plastic-sheet and packaging plastic-case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dogleg bending from occurring even in the case where sheets or cases are piled up in a large number in a bundlelike shape while being folded double individually and to make an unfolding work executable easily and efficiently by a method wherein breaking strength is made different for creases adjoining with one another in the direction where plate parts are provided in continuity. SOLUTION: Plate parts 2, 3, 4 and 5 forming respectively side faces for a case are provided, being connected respectively with creases 6, 7 and 8, and the plate part 2 is extended beyond a crease 11 and an overlap width 12 is made up therewith. The crease 6 is made the same in breaking strength as the crease 8 while the crease 7 is made the same in breaking strength as the crease 11, and the breaking strength for the former pair is made larger than the breaking strength for the latter pair. The plate parts 2 and 5 are folded down respectively along the creases 6 and 8 and sticking is made at the overlap width 12, and a flat folded body being folded double with the plate parts 2 and 5 being opposite to the plate parts 3 and 4 is made up, and the flat folded bodies are piled up in a large number in a bundlelike shape for storage. Repulsive energy is accumulated around the creases 6 and 8 in an extent larger than that around the creases 7 and 11, and the parts around the creases 6 and 8 are automatically unfolded by a springback phenomenon when the external pressure is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging plastic sheet and a packaging plastic case which constitute a packaging plastic case for storing and selling tobacco, chocolate, pharmaceuticals, cosmetics and the like.

[0002]

2. Description of the Related Art In recent years, tobacco, chocolate, pharmaceuticals,
2. Description of the Related Art Packaging plastic cases are widely used for storing small items such as cosmetics. This kind of plastic case is
It is constructed by folding a plastic sheet for packaging and then bonding it. Usually, this plastic sheet is often transported and delivered in bundles stacked in large numbers while being folded along a fold curve so as to bond the side plate portion and the back plate portion to each other. This is also stored in the form of a two-fold bundle.

[0003]

However, when a plastic sheet is folded or folded in a folded form like a sheet 101 shown in FIG. Due to the influence of the weight of the sheets stacked on top of each other, the curved portions 103 and 105 facing each other were curved in the same direction, and the whole was easily curved in a C-shape. When assembling a plastic case from such a curved sheet, the sheet has to be expanded in advance, which is troublesome both manually and by a machine.

Accordingly, the present invention has been made after diligent studies have been made to solve the above-mentioned problems, and it is possible that even when folded into a large number and folded into a bundle, the curve may be curved in a V shape. In addition, it is an object of the present invention to provide a plastic sheet for packaging capable of easily and efficiently performing an expanding operation, and a plastic case for packaging formed by bending the plastic sheet.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a plastic sheet for packaging characterized in that the breaking strengths of adjacent folding curves in the direction in which the plate portions are connected are different. Features.

In this plastic sheet, the breaking strength of the fold curve is set to a value different from that of the adjacent one, and the fold curve having the high rupture strength is folded at the fold to form a V-shape while the break strength becomes small. The plate portions on both sides of the folding curve can be made substantially flat to form a two-folded flat bent body.

[0007] At this time, in the state where the plastic sheet is folded in two, the breaking strength of the opposing fold curves can be made substantially the same.

Further, the present invention provides a packaging plastic case which is formed by folding a plastic sheet for packaging having different breaking strengths of folding curves adjacent to each other in the direction of connecting the plate portions along the folding curve. There are also features.

The plastic case for packaging is:
It is preferable that the packaging plastic sheet is folded in two and the breaking strengths of opposing folding curves are substantially the same.

[0010]

FIG. 1 is a plan view showing a plastic sheet 1 for packaging according to the present invention. Sheet 1
Plates 2, 3, 4, and 5 corresponding to respective side surfaces of a plastic case (not shown) are connected to each other via folding curves 6, 7, and 8, respectively. A folded piece portion 10 is continuously provided via a wire 9. Further, one side portion of the plate portion 2 is extended through a fold curve 11, and the extended portion is used as a glue margin piece portion 12.

As a material of the sheet 1, a plastic sheet such as polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS) can be used because of good folding resistance. The PET (PET) sheet is preferable in terms of good transparency and high rigidity. Among them, amorphous PET (PET that is not stretched or less, “A-PET”)
Is preferred because it has better transparency and is unstretched, so that the strength is high regardless of the sheet direction.

Further, the thickness of the sheet 1 is usually set at 0.1.
1 mm to 0.8 mm. When it is thicker than 0.8 mm, the pressure required for bending becomes large, and when it is thinner than 0.1 mm, the plate portion is easily bent or broken. In particular, in consideration of folding resistance and rigidity, 0.2 mm to 0.2 mm.
6 mm is preferred.

In the sheet 1, the fold curves 6, 7, 8 and 11 are set to two values, large and small, without making their breaking strengths uniform. Here, the breaking strength of a fold curve means a tensile force at which rupture occurs in the fold curve when the fold curve of a predetermined length is pulled in a direction perpendicular to the forming direction thereof. In the sheet 1, the folding curves 6 and 8 are made equal so that the breaking strengths of adjacent folding curves are made different from each other, while the folding curves 7 and 11 are made equal, and the former (fold curve 6
And 8) are set to values larger than the latter (fold curves 7, 11).

As described above, various means can be considered as means for setting the breaking strength of the folding curve to different values. For example, when the width of the groove forming the fold curve is made to differ in size or the depth is changed, one of the fold curves is perforated (FIG. 2).
(A)), the other is formed as a continuous groove (FIG. 3 (b)), or one is formed as one groove and the other is formed as two grooves (FIG. 3).
The number of grooves may be varied as in (a)). In addition, when making the depth of a groove | channel differ, one may be made into a one-stage structure (FIG. 2B) and the other may be made into a two-stage structure (FIG. 3B).

As described above, by setting the breaking strength of the bending curve differently in two values, large and small, the repulsive force (spring back) in the warping direction generated between the respective plate portions is changed, and the folding is performed. A difference in bendability can be provided as described later.

The sheet 1 having the above-described structure is provided on each of the plate portions 2.
And 5 are folded at the fold curves 6 and 8 respectively.
As shown in FIGS. 4 and 5, the glue margin piece portion 12 is bonded to form a flat folded body 13 which is folded in two so that the plate portions 2 and 5 and the plate portions 3 and 4 face each other. A plurality of folded bodies 13 are transported and stored in a bundle. In this state, the fold curves 6 and 8 are bent at a V-shaped acute angle, and the fold curves 7 and 11 are substantially flat. As described above, since the breaking strengths of the bending curves 6 and 8 are higher than those of the bending curves 7 and 11, repulsive energy greater than the bending curves 7 and 11 is accumulated in the vicinity of the bending curves 6 and 8. Therefore, the flat folded body 13 maintains the flat state when it is pressed by external pressure or its own weight in a bundle of a plurality of folded sheets, but once the external pressure is released, the folding curves 6 and 8 are bent.
Due to the repulsive energy in the vicinity, a phenomenon similar to a so-called springback occurs, and the portions near the folding curves 6 and 8 automatically expand. Therefore, it is easy to insert a finger or a member for expansion into the flat bent body 13, and if it is inserted, it can be immediately expanded. Note that the repulsive energy stored in the vicinity of the folding curves 7 and 11 is not as large as the folding curves 6 and 8, and thus does not hinder the expansion. In this way, the sheet 1 can reduce the force required for forming the plastic case and can do this efficiently.

(Example) A-PET sheet (thickness 0.3)
mm, manufactured by Kanebo Co., Ltd.) and the breaking strength of the fold curves corresponding to the fold curves 7 and 11 is 5 by the shape of the sheet 1 described above.
~ 6kg / 15mm width (Measurement machine: INTESCO IW-2
0, tensile strength: measured at 200 mm / min), while the breaking strengths of the folding curves corresponding to the folding curves 6 and 8 are 9-1.
A plastic sheet for packaging was punched out at 0 kg / 15 mm. The breaking strength of each folding curve is shown in FIG.
The grooves were formed as shown in (b), and the depths of the grooves were changed to different values. Then, when the plastic case for packaging was assembled using an automatic box making machine (vertical mold), it was successfully manufactured.

(Comparative Example) Next, as a comparative example, the material and the shape were the same as those of the example, and the breaking strength of each folded curve was 5 to 5.
A plastic sheet for packaging was punched out to match 6 kg / 15 mm, and the plastic case for packaging was assembled using an automatic box making machine (vertical mold).

[0019]

The plastic sheet for packaging of the present invention
While the plate portion is bent in a V-shape at the fold curve where the breaking strength becomes large, a flat bent body can be formed in a manner that the plate portions on both sides of the small fold curve become substantially flat. Curves can be stacked and bundled. When the plastic case for packaging is formed from this flat bent body, the force required for the use of the springback can be reduced because the springback can be used, and the manufacturing can be made more efficiently. In addition, when the flat folded body is used, there is no occurrence of a U-shaped rebound, so that the storage space can be reduced.
It can be easily carried.

[Brief description of the drawings]

FIG. 1 is a developed view showing one embodiment of a plastic sheet body of the present invention.

FIG. 2 shows an example of a folding curve, where (a) is a perforated shape,
(B) is a partially enlarged perspective view of a continuous groove.

FIGS. 3A and 3B show another example of a folding curve, in which FIG. 3A is a partially enlarged perspective view of a two-stage configuration, and FIG.

FIG. 4 is a plan view showing an example of a flat bent body.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a side view showing a conventional sheet folded in two.

[Explanation of symbols]

 1 Plastic sheet 2,3,4,5 Plate part 6,7,8,9 Folded curve 10 Folded piece part 11 Folded curve 13 Flat folded body

Claims (4)

[Claims] 1. A plastic sheet for packaging, characterized in that the breaking strengths of folding curves adjacent to each other in the direction in which the plate portions are connected are different. 2. The plastic sheet for packaging according to claim 1, wherein in the folded state, the breaking strengths of the opposing fold curves are substantially the same. 3. A packaging plastic case which is formed by folding a packaging plastic sheet having different breaking strengths of folding curves adjacent to each other in the direction in which the plate portions are continuously provided, along the folding curves. 4. The plastic case for packaging according to claim 3, wherein when the plastic sheet for packaging is folded in two, the breaking strength of opposing fold curves is substantially the same.