GB2331287A

GB2331287A - Bag or sack closure

Info

Publication number: GB2331287A
Application number: GB9803793A
Authority: GB
Inventors: Colin Sanderson
Original assignee: PHILLIPS WESTHILL Ltd; BRIDGENORTH Ltd
Current assignee: PHILLIPS WESTHILL Ltd; BRIDGENORTH Ltd
Priority date: 1998-02-23
Filing date: 1998-02-23
Publication date: 1999-05-19
Anticipated expiration: 2018-02-23
Also published as: AU2539799A; ZA991432B; WO1999042379A1; GB2331287B; GB2331287A9; GB9803793D0

Abstract

In a sack or bag intended for filling with loose material, a lower end 4 has a conventional block-bottom whilst the upper end 5 includes a generally rectangular open filling aperture 20 bounded along two opposing edges by a pair of guide flaps 8,9. The guide flaps serve to direct the material into the container and when filling is complete are overlapped and secured adhesively. The bag may be single or multi-ply of paper, plastic sheeting or metal foil.

Description

Packacina container for loose material 2331287 The invention relates to a

packaging container for the transport of loose material.

It is known to provide a packaging container for loose filling material as a sack or bag having a filling space bounded at each of its two ends by shaped ends, for example by a satchel bottom or block bottom, square bottom, or the like shaped end. The shaped ends each comprise folded in corners situated opposite one another in pairs as well as an inner foldedend side and an outer folded-end side that in turn are situated opposite one another in pairs and in the closed state of the shaped end are stuck to one another and to the folded in corners, one of the two shaped ends forming a bottom and the other a filling end with parts of the ends left unstuck to leave an aperture for filling with the filling material and subsequent closure.

In known packaging containers of this type the aperture at the filling end of the container is formed when the inner folded end side and the folded-in corners are stuck together and the outer folded end side is left unstuck. Closure, after filling, is effected when the outer folded end side is stuck as a covering flap closing the filling opening. In leaving the outer folding end side completely unstuck until after the filling process is completed however, some of the strength and definition of the block-bottom end provided by a factory made blockbottom at the f illing end of a container is lost and cannot be regained in the closure process. In practice it is found that the lack of firm definition at the shoulders of the outer open end side, where in a normal block-bottom end the shoulders would be firmly anchored by gluing these parts during fabrication of the container, creates areas of 2 - weakness which are subject to tearing by careless operators during the filling process and lead also to spreading and widening of the aperture area, overfilling of the container and subsequent problems in securing adequate closure. In known packaging containers of this type attempts have been made to overcome some of these problems by attaching, during fabrication, an additional cover panel stuck to the outside of the outer folded end panel. While this provides a greater area for applying adhesive for final closure and increased foldover, it is found that the attached additional cover panel can mask operator deficiencies where, since there is a tendency for operators to overfill the filling space and distort the aperture, the leading edges of the two folded end panels do not overlap sufficiently and sometimes do not come over sufficiently even to meet. In these instances the only cover to the filled material at this point is that provided by the additional cover panel and this is inadequate when the objective of multi-wall or multi-ply container construction is to ensure that the filled material is protected overall by the designed thicknesses of the packaging materials.

It is therefore an object of the invention to obviate or mitigate the aforesaid disadvantages of the former art.

According to the present invention there is provided a flexible packaging container for loose filling material in the form of a sack or bag defining a space for filling with loose material, in which a generally rectangular end includes an open filling aperture bounded along two opposing edges by a pair of guide flaps comprising marginal edg e portions of a pair of opposing sides folded inwardly such that four diagonal fold lines are formed in each corner of the end, wherein the aperture may be closed by folding the flaps towards each other so that they overlap.

Preferably, each opposing side is formed with a crease line, the marginal edge portion on one side of the crease line being unsecured to container and thereby defining the guide flap whilst on the other side of the crease line the side is secured to the container. once filled, the sack will adopt a parallelepiped shape with rectangular ends. Advantageously, the guide flaps channel the loose material into the filling aperture whilst the rigidity provided by an end f ormed in the above manner ensures that the sack can be filled easily and without waste. Preferably the flaps are sized to overlap not only each other but also to a certain extent the periphery of the aperture. Furthermore, suitable adhesive may be applied to the end either during production or at the point of use of the sack. It may be particularly advantageous to supply the sack with the end fully formed and glued but with a contact adhesive, optionally protected by a cover sheet, applied to one or both flaps for sealing the sack when filled or any of a number of known methods of adhesion which can be applied during production and used later.

In order to aid in understanding the invention, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 shows a plan view of an upper portion of a flexible packaging container according to the invention in the form of a satchel bottom or block bottom bag, Figure 2 shows a plan view in enlarged detail of the filling end of the container of Figure 1, Figure 3 is a similar view of the f illing end of Figure 2 shown in a closed state, Figures 4a and 4b show two known alternative forms of construction of the bottom of the container of Figure 1, Figures Sa and 5b are cross-sectional views on the lines I and II respectively of Figure 1, Figures 6a and 6b are similar views on the lines I and II respectively of Figure 4a, Figures 7a and 7b are similar views on the lines I and II respectively of Figure 4b, Figures 8a and 8b are cross-sectional views on the lines I and II respectively of Figure 2, and Figures 9a and 9b are cross-sectional views on the lines I and II respectively of Figure 3.

Referring to the Figures, a flexible packaging container is shown as an empty container, that is to say in the state in which it is supplied by the container manufacturer to a filling factory. In the example illustrated it consists of a single-layer or multi-layer paper or combination paper/plastic/foil construction and has the shape of a sack or bag, the two side walls 1 of which lie flat against each other in the empty state of the packaging as shown and are connected to one another at the edges 2 and 3 of the bag formed by folded crease lines. Formed at the two ends of the bag walls 1, in a manner known per se, is a shaped end 4 or 5 in the f orm of a block bottom produced by manufacturing techniques which are known per se.

The shaped ends or block bottoms 4 and 5 each comprise folded-in corners 6 and 7 which are situated opposite one another in pairs and are folded inwards in triangular shape, and folded end sides 8 and 9 which are similarly situated opposite one another and are folded in trapezoidally. The outer lateral fold line of the inner folded end side 8, which is folded inwards first in the course of production of the shaped ends is designated by 10. The outer lateral fold line for the outer folded end side 9, is designated by 11.

- 5 The lower shaped end 4 forms a bottom while the packaging container is being filled. Application of adhesive during production of the container, whereby the folded-in ends 6 and 7 are stuck to the folded ends sides 8 and 9 and whereby the outer f olded end side 9 may be stuck to the folded end side 8 is shown in more detail in Figures 6 and 7. The lower shaped end 4 may be provided with an outer bottom cover sheet 13 (as shown in Figure 7b and in ghost on Figure 4b) which sheet is glued to the foldedin corners 6 and 7 and to the folded end sides 8 and 9 by the application of adhesive which is indicated by the small crosses of Figures 7a and 7b.

The upper shaped end 5 forms the top of the container while the packaging container is being filled. In the empty state of the packaging container illustrated in the drawings, the folded-in ends 6 and 7 are stuck to the folded end sides 8 and 9 only at the shoulders 16 of the folded end sides by application - of adhesive 17 during production of the container as indicated in Detail A of Figure 2. During production of the container, crease lines 18 and 19 are formed along the length of each of the inner and outer f olded end sides 8 and 9 f orming f laps which bend outwards from the container and which, in this state together with the inner edges of the two folded-in corners 6 and 7 define the filling opening 20 which affords direct access to the filling space 21 which is bounded by the shaped ends 4 and 5 and the f illing of which can be carried out vertically from above, in that a filling pipe or discharge slot from a hopper above can discharge filling material into the filling space 21 through the filling opening 20 in order to carry out the filling operation. During this operation the flaps, which at this stage are the unstuck portions of the inner and outer end sides 8 and 9, are held apart and act as guides to assist in funnelling the filling material into and through the filling opening 20.

1 The filling opening 20 has four sides bounded by the two folded-in corners 6 and 7 and the two folded end sides 8 and 9. The position of the sides created by the inner edges of the two folded-in corners 6 and 7 is determined by the structure of the folded-in corners but will typically be on a line perpendicular to the centre fold line 22 at a point where a 1,ine drawn at 45 degrees from the corner 23 intersects the centre fold line 22. The position of the crease lines 18 and 19 on the inner and outer folded end sides is determined by the limit line 24 on the glued areas 17. In order to fulfil the potentially conflicting requirements of making the container structure as strong as possible and at the came time leave the filling opening wide enough to sustain high rates of filling of the filling material it is recommended, but not mandatory, that the factory gluing of the folded end sides to the folded-in corners shown at Detail A extends typically one-quarter of the distance between the outer lateral fold lines 10 and 11. This defines the position of the crease lines 18 and 19 and determines the optinum width of the filling opening 20 as being one-half of the distance between the outer lateral fold lines 10 and 11, positioned more or less with its lateral centre line on the lateral centre line 22 of the container.

Maximum protection of the filled material is afforded by ensuring that the width of the flap on the Inner folded end side 8 is wide enough, when folded down, to meet the crease line 19 of the outer folded end side 9, ensuring that the flap will comfortably sit in this position across the length of the aperture and the adjoining widths of the tolded-in, ends to which it will finally be stuck. optimum strength of the shaped end 5 is afforded by making the width of the tlap on the outer folded end side wide enough, when finally f olded down and stuck, to reach beyond the crease line 18 of the inner folded end side. After the filling of the filling space 21 the flap of the inner folding end side 8 is folded down to cover and protect the filling material and is stuck to the folded-in ends 6 and 7 with adhesive 25 which is either applied at this stage following completion of the filling operation or which may have been applied during fabrication of the container and is now brought into an effective state. The flap of the outer folding end side 9 is then folded down and stuck to the outer surf ace of the inner f olded end side 8 with adhesive 26 which, similarly, is either applied at this stage following completion of the filling operation or which may have been applied during fabrication of the container and is now brought into an effective state.

In some instances it is possible that the effective area cf the outer folded end side may be increased by attaching an outer cover sheet 27 which is glued to the external surface of the outer folded end side 9, and to the external surface of the inner folded end side 8 and to the folded-in corners 6 and 7, effectively covering the top surface of the upper shaped end 5. Such cover sheet may be attached by adhesive to the outer folded end side 9 during fabrication of the container or be attached to the container as a separate cover sheet following completion of the filling operation and closure and gluing of the outer folded end side as aforesaid. The adhesive 28 and 29 by which the outer cover sheet is stuck to the container may be applied completely or partially during fabrication or after completion of the filling operation and may be the subject of known techniques which would allow pre-gluing and later being brought into an effective state.

All suitable materials such as plastic sheeting, paper, foils, laminates and possible combinations of these - 8 materials may be considered as material for the packaging container.

claims:

I. A flexible packaging container for loose filling material in the form of a sack or bag defining a space for filling with loose material, in which a generally rectangular end includes an open filling aperture bounded along two opposing edges by a pair of guide flaps comprising marginal edge portions of a pair of opposing sides folded inwardly such that four diagonal fold lines are formed in each corner of the end, wherein the aperture may be closed by folding the flaps towards each other so that they overlap.

2. A flexible container as claimed in ClAim 1, wherein the each opposing side is formed with.& crease line, the marginal edge portion on one side of the crease line being unsecured to container and thereby defining the guide flap whilst on the other side of the crease line the side is secured to the container.

3. A flexible container as claimed in any preceding claim, having a parallelepiped shape with rectangular ends.

4. A flexible container as claimed in any preceding claim, wherein the flaps are sized to overlap not only each other but also to a certain extent the periphery of the aperture.

5. A flexible container as claimed in any preceding claim, wherein one guide flap is increased in area by securing an outer cover sheet thereto.

Claims

6. A flexible container as claimed in any preceding Claim. wherein the

open filling aperture is substantially rectangular and lies an a lateral centre-line of the container.

- 10 7. A flexible container as claimed in any preceding Claim, wherein an adhesive. which can be activated once the container has been filled, is provided on one or both contacting surfaces of the guide flaps.

8. A flexible container as claimed in Claim 7, wherein means are provided f or applying adhesive to one or both contacting surfaces of the guide flaps once the container has been filled.

9. A f lexible container as claimed in claim 7 or Claim 8 wherein the adhesive is heat curable.

10. A flexible container as claimed in 'any preceding Claim. having a multi-layer sheet const-ruction.

11. A flexible packaging container for loose filling material substantially as described herein with reference to the accompanying drawings.

- ii - Amendments to the claims have been filed as follows 1, -- 1. A flexible packaging container for loose material comprising a sack or bag of which an open end has a filling opening defined by two longer sides and two shorter ends by folding inwardly portions of walls at said open end and securing together overlapping areas of said folded wall portions, wherein two narrower folded wall portions, the free edges of which define the ends of said filling opening, are overlapped by two wider folded wall portions which can in turn overlap one another to close said filling opening, and wherein said narrower folded wall portions and each of said wider folded wall portions are secured together in an overlapping area terminating at a line coinciding with a respective side of said filling opening and disposed between the inward fold line of the wider wall portion and the free edge thereof, whereby free unsecured regions of said two wider wall portions extending from the lines of termination to the free edges thereof provide guide flaps bounding the sides of said filling opening.

2. A flexible container as claimed in Claim 1, having a parallelepiped shape.

3. A flexible container as claimed in any preceding Claim, wherein the guide flaps are sized to overlap not only each other but also the ends of the filling opening.

A flexible container as claimed 4. in any preceding Claim, wherein one guide flap is increased inarea by securing an outer cover sheet thereto.

5. A flexible container as claimed in any preceding Claim, wherein the filling opening lies on a lateral centre-line of the container.

- IZ - 6. A flexible container as claimed in any preceding Claim, wherein an adhesive, which can be activated once the container has been filled, is provided on one or both contacting surfaces of the guide flaps.

7. A flexible container as claimed in Claim 6f wherein the adhesive is heat curable.

8. A flexible container as claimed in any preceding Claim, having a multilayer sheet construction.

9. A flexible container as claimed in any preceding Claim, which container has been filled and sealed by folding said guide flaps inwardly and securing them when overlapped.

10. A flexible packaging container for loose filling material substantially as described herein.

11. A filled and sealed flexible packaging container for loose filling material substantially as described herein.

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