US3850366A

US3850366A - Multi-layer bags

Info

Publication number: US3850366A
Application number: US00123243A
Authority: US
Inventors: A Saito
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-03-11
Filing date: 1971-03-11
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

BY PULLING THE CORD WITHOUT BREAKING AT LEAST THE INNERMOST LAYER.

1. A MULTI-LAYER BAG COMPRISING A PLURALITY OF LAYERS OF BAG FORMING MATERIAL, SAID LAYERS BEING SUPERPOSED RELATIVE TO EACH OTHER TO FORM A FRONT SHEET AND A REAR SHEET, GUSSETS FORMED AT BOTH LONGITUDINAL SIDE EDGES OF SAID BAG BETWEEN SAID FRONT SHEET AND SAID REAR SHEET, THE UPPER EDGES OF AT LEAST SOME OF THE LAYERS BEING DISPLACED IN THE LONGITUDINAL DIRECTION TO DEFINE STEPWISE BONDING MARGINS WHICH ARE FOLDED BACK AND BONDED TO SAID FRONT SHEET SO AS TO SEAL THE MOUTH OF SAID BAG, AND A BAG OPENING CORD DISPOSED ACROSS SAID BAG NEAR SAID MOUTH AND SECURED BETWEEN SAID LAYERS WITH THE OPPOSITE ENDS PROJECTING BEYOND SAID SIDE EDGES, SAID CORD BEING POSITIONED SUCH THAT SAID BAG CAN BE OPENED

Description

Saito Nov. 26, 1974 MULTl-LAYER BAGS [75] Inventor: Akio Saito, Futasegawa-cho,

V Kakegawa-shi, Japan [73 Assignee: Showa Seitai Kogyo Kabushiki Kaisha, Tokyo, Japan [22] Filed: Mar. 11, 1971 [21] Appl. No.: 123,243

[52] U.S. Cl. 229/55, 229/66 [51] Int. Cl B65d 31/02 [58] Field of Search 229/55, 66, 86

[56] References Cited UNITED STATES PATENTS 185,727 12/1876 Collins 229/86 3,203,620 8/1965 Becker 229/55 UX 3,565,328 2/1971 Hudson 229/55 3,592,380 7/1971 Gerard 229/55 X FOREIGN PATENTS OR APPLICATIONS 288,177 3/1965 Netherlands 229/55 Primary ExaminerDonald F. Norton Attorney, Agent, or FirmWard, McElhannon, Brooks & Fitzpatrick [57] ABSTRACT A multi-layer bag comprises front and rear sheets each consisting of a plurality of superposed layers of bag blanks, and gussets between front and rear sheets along the longitudinal side edges. The layers are displaced relatively to each other in the longitudinal direction to define stepwise bonding margins which are folded back and bonded to the front sheet so as to seal the mouth of the bag. A bag opening cord is disposed across the bag near the mouth and secured between layers with opposite ends projected beyond side edges. The cord is positioned such that the bag can be opened by pulling the cord without breaking at least the innermost layer.

4 Claims, 11 Drawing Figures PATENTEL M2619 .SHEET 10F 4 INVENTOR ATTORNEY PAIENIE RUV26I974 SHEET 2 0F 4 INVENTOR ATTORNEY PAIENIELNBVZSW 3.850.366

" saw 30F 4 INVENTOR ATTORNEY PATENTEL 3,850,366

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INVENTOR ATTORNEY MULTl-LAYER'BAGS BACKGROUND OF THE INVENTION This invention relates to a multi-layer bag having a bag opening cord and more particularly to an improved multi-layer bag wherein mounting of the cord and the opening of the bag are easy.

A multi-layer bag has been prepared by using a plurality of layers of bag blanks and by interposing side gussets between front and rear sheets so that the bag forms a cube when it is filled.

In such a multi-layer bag, in order to form upper and bottom seals the upper and lower edges of the layers comprising the rear sheet are projected beyond the upper and lower edges of the layers comprising the front sheet, and the extent of projection is stepwisely increased on both upper and lower edges from the front layer to the rear layer so as to form a bonding margin .on the upper and lower edges of each layer. Both side gussets are similarly stepped to form bonding margins along the side edges of respective layers, then a suitable bonding agent is applied to respective bonding margins, and the margins of the rear side sheet are folded back onto the front sheet to complete a bag.

The multi-layer bag of the construction just described is advantageous in that the bonding agent can be applied to all bonding margins in one process step, that folding and bonding operations can be made simultaneously for all edges thus simplifying the process step, that the strength of the seals is high and that charging of the content is also easy.

However, this type of multi-layer bag is difficult to open by peeling off its bonded edges. This not only requires considerable time but also the opened edges become irregular thus making it difficult to remove the content. Portions of the layers other than the edges that form the mouth of the bag are broken. Further, scraps of the blank which are formed when the bag is opened are admixed with the content. This is not desirable when the content is a raw material of a synthetic resin such as polyethylene or vinyl chloride.

SUMMARY OF THE INVENTION It is therefore an object of this invention to eliminate various difficulties mentioned above.

Another object is to provide a novel bag including a cord which is disposed at the seal and across the bag between layers of the bag blank with both ends projected beyond the side edges of the layers of blank so that the bag can be readily opened by pulling the cord.

A further object of this invention is to provide a novel multi-layer bag which can be opened without breaking at least the innermost layer of the bag by pulling the opening cord.

According to this invention there is provided a multilayer bag comprising a plurality of layers of a blank, said layers are superposed relative to each other to form a front sheet and a rear sheet, gussets formed at both longitudinal side edges of the bag between front and rear sheets, the upper edges of at least some of the layers being displaced in the longitudinal direction to define stepwise bonding margins which are folded back and bonded to the front sheet so as to seal the mouth of the bag, and a bag opening cord disposed across the bag near the mouth and secured between the'layers with the opposite ends projected beyond the side edges,

the cord being positioned such that the bag can be opened to at least the innermost layer.-

BRIEF DESCRIPTION OF THE DRAWINGS The invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 shows an elevational view of a portion of the mouth of a bag embodying the invention;

FIG. 2 shows a sectional view of the bag taken along a line II II in FIG. 1, with the thickness of the bonding agent 5 exaggerated;

FIG. 3 shows a view similar to FIG. 2 but taken along a line III III in FIG. 1;

FIG. 4 shows a sectional view of the bag after the i mouth has been sealed;

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 to 6 of the accompanying drawings, there is shown a bag comprising front and rear sheets A and B each consisting of an inner layer 1, an intermediate layer 2 and an outer layer 3 made of suitable bag forming material. It is to be understood that the side edges of respective layers are bonded together on front surface to form a tubular body C. Between the front sheet A and the rear sheet B, each of the

layers

1, 2 and 3 is folded at its opposite side edges to form a gusset D of a V-shaped cross-sectional configuration.

At the mouth of the tubular body C, the outer layer 3, the intermediate layer 2 and the inner layer 1 of the front sheet A are provided with

upper edges

3a, 2a and la respectively projecting stepwise in the order mentioned. The upper edge of the inner layer 1 is provided with a section la and a section la" which projects beyond sections la to the right of a step or border line la positoned to the right of the portion of layer 1 overlapping the gusset D. Although FIG. 1 shows the left hand portion of the bag, it is to be understood the right hand portion is also constructed in the same manner. At the rear sheet B, the

upper edges

2b and 3b of the intermediate layer 2 and the outer layer 3, respectively, are projected beyond the central section In" of the upper edge 1a of the inner layer 1 of the front sheet A in the order of

edges

2b and 3b. The upper edge lb of the inner layer 1 of the rear sheet B is provided with side sections 1b and a central section 1b on the opposite sides of a step or border line lb and at positions corresponding to the side sections la, border line la' and central section 1a" on the upper edge la of the inner layer 1 of the front sheet A. Side sections lb are positioned between the central section la" and the upper edge 2b of the intermediate layer 2 whereas the central section lb is between the central section 1a" and opposite side sections 1a.

The front side wall D of the gusset D has the same height as the upper edge 1d of the inner layer 1 and both side sections of the upper edge 1a of the inner layer 1 while the

upper edges

2d and 3d of the intermediate layer 2 and outer layer 3 have the same height as the central section 1b" of the upper edge lb of the inner layer 1. At the rear side wall D" of the gusset, the upper edges 3d" and 2d" of the outer layer 3 and intermediate layer 2 have the same height as the

upper edges

2d and 3d of the front side wall D and the upper edge 1d" of the inner layer 1 has the same height as both side sections lb of the upper edge 1b of the inner layer 1 of the rear sheet B.

A bag opening cord 4 is secured between the inner layer 1 and the intermediate layer 2 of the rear sheet B and across the body C of the bag. The opposite ends of this cord 4 are extending outwardly through notches formed on the side edges of the intermediate layer 2 and outer layer 3 of the rear sheet B. The cord 4 is positioned slightly above the upper edge 2a of the intermediate layer 2 of the front sheet.

A plurality of layers comprising the front sheet A are superposed relative to each other such that portions above both side sections 1a of the upper edge 1a of the inner layer 1 are exposed like a step so as to leave exposed

bonding margins

11a, 12b, 13b, 12d, 11d" and 11b. Then, a suitable bonding agent 5 is applied onto these exposed bonding margins. Portions of the layers above the upper edge of the intermediate layer 2 of the front sheet A are folded back along the upper edge 20 thus sealing the mouth of the bag.

Under these conditions the intermediate layer 2 and the outer layer 3 of the rear sheet B are positioned outside of cord 4, as shown in FIGS. 4 and 6. As shown in FIGS. 6 and 7, at the gusset D, bonding margins 11d", 12b, 12d and 13b are bonded to overlay the inner layer 1 so as to prevent the content from leaking through both side corners.

The bonding agent is also applied as dots or lines or stripes between the inner and intermediate layers 1 and 2 and between the intermediate and

outer layers

2 and 3. Before insertion, the bag opening cord is also applied with the bonding agent at spaced apart points or along After sealing the mouth as above described the bag is placed upside down, and the content 6 is charged in the bag through its bottom opening which is now brought to the upper side. The step shaped bonding margins at the bottom edges are bent back to seal the bottom of the bag.

To open the bag which has been sealed as above described, the cord 4 is pulled upwardly as viewed in FIG. 4 to break or tear the intermediate layer 2 and the outer layer 3 of the rear sheet B which are placed above cord 4 in the sealed state shown in FIG. 4. Thus, the inner layer 1 is not broken, but only two layers are required to be broken. Although both side portions including the gussets are not broken, since the width of the gusset is relatively small when compared with the total width of the bag, the content can be taken out readily without any trouble.

In the modified embodiment shown in FIG. 8, insertion of the bag opening cord is made more easy. More particularly, the upper edges of respective layers of the front sheet are cut substantially straight and longitudinal slits 20a, 20b, 20a and 20b are cut through respective layers other than the innermost layer at portions near both side edges. The cord 4 is threaded or knitted through these slits with both its ends projected beyond the side edges of the bag.

With this construction, it is possible to readily secure the cord by merely threading it through respective layers and since the portion 21 of the cord exposed to the outside of the layers are secured to the outermost layer when the mouth is sealed, the layers can be broken by pulling the cord, and also in the case where the slits of respective layers are staggered, as shown in FIG. 8, superposed layers can be broken successively.

In each of the above described embodiments, if the bonding agent were applied to partially close the mouth at both side gussets, the leakage of the content can be prevented effectively. This can be accomplished by applying the bonding agent (preferably of the thermobonding type) to the hatched areas on the inner surface of the intermediate layer at the gusset, as shown in FIG. 9, thus causing these portions to adhere to adjacent layers by applying heat so as to seal the gusset.

Instead of inserting the bag opening cord between layers of the blank, such cord may be placed between surfaces which are bonded together at the time of sealing so as to secure the cord by the bonding agent. Since the upper edge la of the innermost layer of the front sheet is positioned above the upper edge 1b" of the rear sheet as shown in FIG. 1 and remains without being applied with the bonding agent at the time of sealing, after opening the mouth by pulling up the cord 4 it is possible to freely open the upper edge la to remove the content.

FIGS. 10 and 11 respectively corresponding to FIGS. 4 and 5 show the manner of opening of the modified bag. Except for the cord 4, other aspects are identical to those shown in FIGS. 4 and 5.

While in the illustrated bags, the front and rear sheets consist of three layers of blanks, the number of layers of each sheet may be increased or decreased as desired. Likewise, the construction and arrangement of the stepwise bonding margins can also be modified. However, it is essential that the front and rear sheets of the blank should not be bonded together at the mouth and that the bag opening cord should be positioned beneath the upper edge of the innermost layer of the rear sheet.

Thus, this invention provides a novel bag which can be opened bery easily by pulling the bag opening cord to break or tear the layers of the blank overlying the cordlln the illustrated embodiments, since the cord is positioned beneath the innermost layer of the front sheet, it is possible to decrease the number of layers which are required to be broken. Further, as the cord is positoned at the upper portion of the bag when it is filled with the content and since the number of layers to be broken is the same at the gussets, the provision of the gussets does not render it difficult to open the bag. As above described, since at least the innermost layer is not broken by the cord scraps of the layers are not admixed with the content when it is taken out. Further, as the bag opening cord is provided across the bag independently of the gussets, the cord can be readily attached.

What is claimed is:

l. A multi-layer bag comprising a plurality of layers of bag forming material, said layers being superposed relative to each other to form a front sheet and a rear sheet, gussets formed at both longitudinal side edges of said bag between said front sheet and said rear sheet,

the upper edges of at least some of the layers being displaced in the longitudinal direction to define stepwise bonding margins which are folded back and bonded to said front sheet so as to seal the mouth of said bag, and a bag opening cord disposed across said bag near said mouth and secured between said layers with the opposite ends projecting beyond said side edges, said cord being positioned such that said bag can be opened by pulling the cord without breaking at least the innermost layer.

2. The multi-layer bag according to claim 1, wherein respective layers of the front sheet excepting at least the innermost layer are formed with two longitudinal slits at said mouth and said bag opening cord is threaded through said slits.

3. The multi-layer bag according to claim 1, wherein said cord is secured between layers which are positioned to the rear of at least the innermost layer, and