GB2317159A

GB2317159A - Closing one or both ends of a generally tubular bag

Info

Publication number: GB2317159A
Application number: GB9719654A
Authority: GB
Inventors: Raizo Kuge; Yoshiji Moteki
Original assignee: Hosokawa Yoko KK
Current assignee: Hosokawa Yoko KK
Priority date: 1996-02-13
Filing date: 1997-01-29
Publication date: 1998-03-18
Anticipated expiration: 2017-01-29
Also published as: GB9719654D0; GB2317159B

Abstract

A self-standing bag comprises a cylindrical bag body (10) having a pair of opposing flat members (11) for forming front and back surfaces of the bag and a pair of opposing side members (21) each of which is inwardly folded in a gusset shape along a folding line, and a rectangular bottom-forming sheet (30) for sealing a lower opening end of the bag body. The sheet (30) is provided with exposed inner surfaces which are formed by folding the bottom-forming sheet in one sense along a central folding line (31) thereof, then folding each of both end portions (31') of the sheet, which lies between each of both ends of the sheet and a reference point (P) distant therefrom by a prescribed distance on said central folding line, along that line in the opposite sense and further folding both end portions along two lines (32) connecting said reference point with two adjacent corners of the sheet so as to form ridge lines (32) protruded inwardly of the bag body. The exposed inner surfaces of the bottom-forming sheet are heat-sealed onto said lower opening end of the bag body so as to form heat sealed portion along the outer peripheral edge of the bottom-forming sheet. Another such sheet may be similarly used to close the top of the bog, eg to form a bag for a bag-in-a-box.

Description

BAG AND METHOD FOR MANUFACTURING SAME The present invention relates to a self-standing bag and to a method for manufacturing such a bag.

As typical examples of a self-standing bag, there are provided a gusset type bag formed of a plastic film material and another bag having a bottom portion specifically worked so as to stand itself. In both the examples, a base plate or sheet is secured in general to the bottom portion of the bag, in order to improve the self-standing characteristics. More specifically, such a bag is composed of a bag body and a folded bottom sheet, in which the bag body and the bottom sheet are heat-sealed together so as to form a heat sealed portion having an oblong shape. The heat sealed portion has two points, and in each of these two points, the bottom sheet and two sheets for forming the bag body are fixed together. The abovedescribed two points are hereinafter referred to as "fixed points".

When the bag having such fixed points is dropped down, a stress caused by the drop of the bag may be concentrated on these fixed points, and hence, the bag may be broken at these fixed points. This problem can be eliminated by forming the bag body with a thin flexible film having a high strength. Such a thin flexible film may degrade the self-standing property of the bag because of a low rigidity of the thin flexible film.

A bag-in-box as a disposal one-way container has widely been used for the transportation and storage of various liquids such as drinks such as mineral water and industrial chemicals.

In such a bag-in-box, a foldable bag or container made of plastic material is used as an inner bag, which is then accommodated in an outer box formed of such as a corrugated board. The inner bag formed of the plastic material has a liquid-tight property, anti-chemical property and gasbarrier property with respect to the liquid contents received therein. The outer box has a rigidity required for the transportation and the storage of the bag-in-box. It is not required for the bag-in-box having such a structure to be recovered in comparison with glass bottles or tin containers, thus providing economical merits. In addition, since the bag-in-box has a foldable structure, the empty bag-in-box can easily be transported and stored, thus providing advantageous effects of reducing distribution costs.

A moulded container formed through a blow-forming process or a flat bag with peripheral edges thereof being heat-sealed together has been used as the inner bag of the above described bag-in-box.

However, a moulded container formed through the blow formation process so as to decrease the thickness of each portions of the moulded container, has in general an insufficient strength. It is accordingly necessary to increase the thickness of each portions of the moulded container. Such a moulded container with the increased thickness therefore does not become easily broken when it is emptied and disposed, thus maintaining its bulky condition, resulting in occurrence of problems of inconvenient transportation, storage and disposal of the empty container. Furthermore, since a mould used for this blow formation is generally expensive, it is hard to satisfy various requirements for the formation in an economical manner. Still furthermore, when contents are received in the bag, it is first required to preliminarily blow air in the empty bag to properly maintain its shape, thus being also troublesome. There also arises a problem such that a polyethylene or polypropylene material usually used as a material of a container by means of the blow-forming process has a difficulty in maintaining its barrier property. On the other hand, with the flat bag having the peripheral edge heat-sealed, even when the liquid contents are attempted to be poured out of the inner bag, part of them liably remains in the inner bag and it is difficult to completely take out the liquid content. In addition, as can be understood from the shape of the flat bag, when the flat bag is accommodated in the corrugated board box, there remain spaces at the corner portions of the corrugated board box, and accordingly, various loads when stacking up such boxes or dropping them are applied to the corrugated board boxes, thus leading to a problem. Furthermore, the flat bag has a disadvantage in the fact that a large amount of materials used for forming the flat bag is required, and when forming, for example, the flat bag having a capacity of 20 liters, there is required a material having a total area which is larger by about 40 percent than that of a material for forming a cubical bag having the same capacity.

The present invention was made in view of the problems encountered in the prior art described above.

The first object of the present invention is to provide a self-standing bag which is excellent in impact resisting property at a time of dropping down of the bag in addition to the essential self-standing property.

The present invention provides a cylindrical bag body having a pair of opposing flat members for forming front and back surfaces of the bag and a pair of opposing side members each of which is inwardly folded in a gusset shape along a folding line, and a rectangular bottom-forming sheet for sealing a lower opening end of the bag body, and is characterized in that: the bottom-forming sheet is provided with exposed inner surfaces which are formed by folding the bottom-forming sheet along a central folding line thereof, folding each of both end portions of the bottom-forming sheet, which lies between each of both ends of the bottom-forming sheet and a reference point distant therefrom by a prescribed distance on the central folding line of the bottom-forming sheet, in a direction opposite to an original folding direction of the bottom-forming sheet, and further folding the each of the both end portions of the bottom-forming sheet along two lines connecting the reference point with two adjacent corners or vicinities thereof of the each of the both end portions of the bottom-forming sheet so as to form ridge lines protruded inwardly of the bag body; and the exposed inner surfaces of the bottom-forming sheet are heatsealed onto the lower opening end of the bag body so as to form a heat sealed portion along the outer peripheral edge of the bottom-forming sheet.

According to the bag of the present invention, the bottom-forming sheet is provided with the exposed inner surfaces, and the exposed inner surfaces of the bottom-forming sheet are heat-sealed onto the lower opening end of the bag body so as to form a heat sealed portion along the outer peripheral edge of the bottom-forming sheet. There exists therefore no portion on which stress is concentrated in the bottom forming sheet, thus imparting an excellent impact resisting property at the time of dropping of the bag and an excellent self-standing property to the bag.

In another aspect the present invention provides a method for manufacturing a self-standing bag comprising the steps of: forming a cylindrical bag body having lower and upper opening ends at both ends thereof, respectively, the bag body comprising a pair of opposing flat members for forming front and back surfaces of the bag body and a pair of opposing side members each of which is inwardly folded in a gusset shape along a folding line; folding a bottom-forming sheet along a central folding line thereof, folding each of both end portions of the bottom-forming sheet, which lies between each of both ends of the bottom-forming sheet and a reference point distant therefrom by a prescribed distance on the central folding line of the bottom-forming sheet, in a direction opposite to an original folding direction of the bottom-forming sheet, and then, folding the each of the both end portions of the bottom-forming sheet along two lines connecting the reference point with two adjacent corners or vicinities thereof of the each of the both end portions of the bottom-forming sheet so as to form ridge lines protruded inwardly of the bag body, to form exposed inner surfaces of the bottom-forming sheet; inserting the bottom-forming sheet into at least one of the lower and upper opening ends of the bag body; and heat-sealing the bottom-forming sheet onto peripheral edge portions of the at least one of the lower and upper opening ends of the bag body.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a schematic perspective view illustrating one end of a bag body; Fig. 2 is a schematic perspective view illustrating one manufacturing mode of a bag body; Fig. 3 is a schematic perspective view illustrating a self-standing bag in an unfolded and standing condition; Fig. 4 is a perspective view illustrating one embodiment of a bottomforming sheet for constituting a self-standing bag; Figs. 5 and 6 are schematic perspective views illustrating sequential steps for manufacturing the bag according to the present invention; Fig. 7 is a schematic perspective view illustrating a step for manufacturing an embodiment of a bag for a bag-in-box according to a method of the present invention; Fig. 8 is a schematic perspective view illustrating one embodiment of an opening-sealing sheet used for manufacturing the bag for a bag-in-box according to the method of the present invention; and Figs. 9 and 10 are schematic perspective views illustrating sequential steps for manufacturing the bag for a bag-in-box according to the method of the present invention.

There is first prepared a cylindrical bag body 10 having upper and lower opening ends as shown in Fig. 1. The cylindrical bag body 10 comprises a pair of opposing flat members 11, 1 1 for forming the front and back surfaces of the bag and a pair of opposing side members 21, 21. Each of the side members 21, 21 is inwardly folded in a gusset shape along a folding line 23.

The cylindrical bag body 10 is usually made by bonding four pieces of the same material by means of a so-called mitred-bonding method.

Another bonding method described later may however be applied.

In such a bag body 10, each of the side members 21, 21 of the bag body 10 is folded along the folding line 23 so as to form a folding angle 61.

In this embodiment, the folding angle is limited under 180 degree. The side members 21, 21 may however be unfolded completely so as to make a folding angle 81 of 180 degree.

Then, a rectangular bottom-forming sheet 30 is prepared as shown in Fig. 4. The bottom-forming sheet 30 is folded along a central folding line 31 thereof. Each of both end portions of the bottom-forming sheet 30, which lies between each of both ends of the bottom-forming sheet 30 and a reference point P or P' distant therefrom by a prescribed distance on the central folding line 31 of the bottom-forming sheet 30, is folded in a direction opposite to the original folding direction of the bottom-forming sheet 30 to form a folding line 31'. Then, each of the both end portions of the bottom-forming sheet 30 is folded along two lines connecting the reference point P or P' with two adjacent corners or vicinities thereof of each of the both end portions of the bottom-forming sheet 30 so as to form ridge lines 32 protruded inwardly of the bag body, to form exposed inner surfaces 33a, 33b, 33c, 33d of the bottom-forming sheet 30. In this embodiment, the exposed inner surfaces 33a, 33b, 33c, 33d of the bottom-forming sheet 30 are not fully opened in relation to the shape of the bag body 10, and exposed inner surfaces 33a and 33b, and the exposed inner surfaces 33c and 33d have the respective folding angle 64 which is substantially identical with the above-described folding angle 61 of the side members 21, 21.

Then, the bottom-forming sheet 30 is inserted into at least one of the lower and upper opening ends of the bag body 10 so that the folding lines 31', 31' of the bottom-forming sheet 30 overlap with the folding lines 23, 23 of the side members 21, 21 of the bag body 10, respectively.

Then, as shown in Fig. 5, a hot plate is pressed to the lower peripheral edge portions of the bag body 10 and the exposed inner surfaces 33a, 33b, 33c, 33d of the bottom-forming sheet 30 to form a heat sealed portion along the lower peripheral edge portions of the bag body 10. The thus formed heat sealed portion is shown in oblique lines in Fig. 6.

Superfluous portions 28 of the bottom-forming sheet 30 may be cut away along a line F, if necessary.

The thus manufactured bag is reversed upside down and then unfolded. Such a bag which is in an unfolded and self-standing condition is shown in Fig. 3.

When contents are received in the thus manufactured self-standing bag 1, the contents are usually poured into the bag 1 through the upper opening end thereof. Then, the upper opening end of the bag 1 is heatsealed. A pouring member may be provided to the upper end portion of the bag 1. Without heat-sealing the upper opening end of the bag 1, the bag 1 may be used as an ordinary bag having the upper opening end for receiving something as shown in Fig. 3.

The cylindrical bag body 10 as shown in Fig. 3 may be formed, as shown in Fig. 2, by bonding overlapped vertical portions of vertical edges of each of a pair of flat members 51, 51 and vertical edges of each of a pair of side members 71, 71 each of which inwardly folded in a gusset shape along a folding line 73, so that the pair of flat members 51, 51 face to each other1 and the pair of side members 71, 71 also face to each other. In such a case, material different from that for the side members 71 may be used for forming the flat members 51.

The bag manufactured in accordance with the method of the present invention, in which there exists no portion on which stress is concentrated in the bottom-forming sheet, unlike the conventional bag, is excellent in impact resisting property and self-standing property.

According to another embodiment of the present invention, there is first prepared a cylindrical bag body 10 having upper and lower opening ends as shown in Fig. 7. The cylindrical bag body 10 comprises a pair of opposing flat members 11, 11 and a pair of opposing side members 21, 21.

Each of the side members 21, 21 is inwardly folded in a gusset shape along a folding line 23. Such a cylindrical bag body 10 is prepared by bonding overlapped vertical portions of vertical edges of each of the flat members 42, 42 each having a flat face 11 and vertical edges of each of the side members 62, 62 each having a side face 21, so that the pair of flat members 42, 42 face to each other, and the pair of side members 62, 62 also face to each other. In this embodiment, one of the pair of flat faces 11, 11 is provided with a mouth member 50 through which a liquid is supplied in or taken out from the bag body 1 0. The mouth member 50 is formed by forming a hole on the one of the flat faces 11, 11, and fitting a mouth piece made of a plastic material, for example, to the above-mentioned hole.

In such a bag body 10, each of the side members 21, 21 of the bag body 10 is folded along the folding line 23 so as to form a folding angle 05.

In this embodiment, the folding angle 65 is limited under 1 80 degree. The side members 21, 21 may however be unfolded completely so as to make a folding angle 65 of 180 degree.

Then, a pair of opening-sealing sheets 35, 35 are prepared as shown in Fig. 8. Each of the opening-sealing sheets 35, 35 is folded along a central folding line 36 thereof. Each of both end portions of the opening-sealing sheet 35, which lies between each of both ends of the opening-sealing sheet 35 and a reference point P or P' distant therefrom by a prescribed distance on the central folding line 36 of the opening-sealing sheet 35, is folded in a direction opposite to the original folding direction of the opening-sealing sheet 35 to form a folding line 36'. Then, each of the both end portions of the opening-sealing sheet 35 is folded along two lines connecting the reference point P or P' with two adjacent corners or vicinities thereof of each of the both end portions of the opening-sealing sheet 35 so as to form ridge lines 37 protruded inwardly of the bag body, to form exposed inner surfaces 38a, 38b, 38c, 38d of the opening-sealing sheet 35. In this embodiment, the exposed inner surfaces 38a, 38b, 38c, 38d of the opening-sealing sheet 35 are not fully opened in relation to the shape of the bag body 10, and the exposed inner surfaces 38a and 38b, and the exposed inner surfaces 38c and 38d have the respective folding angle 66 which is substantially identical with the above-described folding angle 66 of the side members 21, 21.

Then, as shown in Fig. 9, the pair of opening-sealing sheets 35 thus prepared are inserted respectively into the lower and upper opening ends of the bag body 10 so that the folding lines 36', 36' of each of the openingsealing sheets 35 overlap with the folding lines 23, 23 of the side members 21, 21 of the bag body 10, respectively.

Then, a hot plate is pressed to the upper and lower peripheral edge portions of the bag body 10 and the exposed inner surfaces 38a, 38b, 38c, 38d of each of the opening-sealing sheets 35, 35 to form heat sealed portions along the upper and lower peripheral edge portions of the bag body 10, respectively. The thus formed heat sealed portions are shown in the oblique lines in Fig. 10. Superfluous portions 39 of the opening-sealing sheets 35 may be cut away along a line F', if necessary.

The thus manufactured bag for a bag-in-box is adapted to be accommodated in a corrugated board box to form a bag-in-box. When filling the bag with contents such as mineral water, the mineral water is poured into the bag through the mouth member 50 formed on the flat face 11.

The bag for a bag-in-box, manufactured in accordance with the method of the present invention can be folded in a small size, thus permitting effective transportation, storage and disposal of the bags in an empty condition. In addition, the bag has a rectangular shape in an outward appearance, so that when it is accommodated in a rectangular corrugated board box, there exists substantially no space at inner corner portions of the box, thus improving its strength in stacking them and its impact resisting property in comparison with the corrugated board box itself. Further more, due to this rectangular shape, it is not necessary to preliminarily blow air into the bag prior to the filling of the bag with contents, and an improved barrier property is also easily attainable by laminating each of the pair of flat members and each of the pair of side members with a barrier layer.

Claims

1. A self-standing bag comprising a cylindrical bag body having a pair of opposing flat members for forming front and back surfaces of the bag and a pair of opposing side members each of which is inwardly folded in a gusset shape along a folding line, and a rectangular bottom-forming sheet for sealing a lower opening end of the bag body, characterized in that: said bottom-forming sheet is provided with exposed inner surfaces which are formed by folding the bottom-forming sheet along a central folding line thereof, folding each of both end portions of the bottom-forming sheet.

which lies between each of both ends of the bottom-forming sheet and a reference point distant therefrom by a prescribed distance on said central folding line of the bottom-forming sheet, in a direction opposite to an original folding direction of the bottom-forming sheet, and further folding said each of the both end portions of the bottom-forming sheet along two lines connecting said reference point with two adjacent corners or vicinities thereof of said each of the both end portions of the bottom-forming sheet so as to form ridge lines protruded inwardly of the bag body; and said exposed inner surfaces of the bottom-forming sheet are heat sealed onto said lower opening end of the bag body so as to form a heat sealed portion along the outer peripheral edge of the bottom-forming sheet.

2. A method for manufacturing a self-standing bag comprising a cylindrical bag body having a pair of opposing flat members for forming front and back surfaces of the bag body and a pair of opposing side members each of which is inwardly folded in a gusset shape along a folding line, and a rectangular bottom-forming sheet for sealing at least one of lower and upper opening ends of the bag body, which is characterized by comprising the steps of: forming a cylindrical bag body having lower and upper opening ends at both ends thereof, respectively, said bag body comprising a pair of opposing flat members for forming front and back surfaces of the bag body and a pair of opposing side members each of which is inwardly folded in a gusset shape along a folding line; folding the bottom-forming sheet along a central folding line thereof, folding each of both end portions of the bottom-forming sheet, which lies between each of both ends of the bottom-forming sheet and a reference point distant therefrom by a prescribed distance on said central folding line of the bottom-forming sheet, in a direction opposite to an original folding direction of the bottom-forming sheet, and then, folding said each of the both end portions of the bottom-forming sheet along two lines connecting said reference point with two adjacent corners or vicinities thereof of said each of the both end portions of the bottom-forming sheet so as to form ridge lines protruded inwardly of the bag body, to form exposed inner surfaces of said bottom-forming sheet; inserting said bottom-forming sheet into at least one of said lower and upper opening ends of the bag body; and heat-sealing said bottom-forming sheet onto peripheral edge portions of said at least one of the lower and upper opening ends of the bag body.

3. A method for manufacturing a bag for a bag-in-box comprising a cylindrical bag body having a pair of opposing flat members and a pair of opposing side members each of which is inwardly folded in a gusset shape along a folding line, and a pair of opening-sealing sheets for sealing lower and upper opening ends, each of which is inwardly folded in a gusset shape along a folding line, which is characterized by comprising the steps of: heat-sealing four overlapped vertical portions of vertical edges of each of the pair of flat members and vertical edges of each of the pair of side members, to form a cylindrical bag body having upper and lower opening ends; folding each of a pair of opening-sealing sheets along a central folding line thereof, folding each of both end portions of each of the pair of openingsealing sheets, which lies between each of both ends of the opening-sealing sheet and a reference point distant therefrom by a prescribed distance on said central folding line of the opening-sealing sheet, in a direction opposite to an original folding direction of the opening-sealing sheet, and then, folding said each of the both end portions of each of the pair of opening-sealing sheets along two lines connecting said reference point with two adjacent corners or vicinities thereof of said each of the both end portions of the opening-sealing sheet so as to form ridge lines protruded inwardly of the bag body, to form exposed inner surfaces of each of the pair of opening-sealing sheets; inserting the pair of opening-sealing sheets into the lower and upper opening ends of the bag body, respectively; and heat-sealing the pair of opening-sealing sheets onto peripheral edge portions of the lower and upper opening ends of the bag body, respectively.

4. A bag substantially according to any of the embodiments or having the common features of those embodiments as described herein with reference to or as illustrated in the accompanying drawings.