GB2208222A

GB2208222A - Bag closure

Info

Publication number: GB2208222A
Application number: GB8817406A
Authority: GB
Inventors: Ian Charles Frame
Original assignee: DOBOY Ltd
Current assignee: DOBOY Ltd
Priority date: 1987-07-21
Filing date: 1988-07-21
Publication date: 1989-03-15
Also published as: GB8817406D0

Abstract

A bag, sack or the like is closed by folding-over material of the open edge region of the walls of the bag 3 forming the mouth thereof to provide a folded-over closure to the bag mouth; and securing a closure tape 9 to the folded-over closure and to a strip of the bag 3 adjacent to the folded-over closure in such manner as to facilitate removal of the tape when it is required to open the bag. Tape 9 has regions 12, 13 which are self-adhesive or carry heat-activable adhesive, and includes a pull strip 15. There may be adhesive between the folded over regions and bag wall (Figs 1-3), and the tape may include stitching to secure a sealing tape 17 to a bag wall 18, or to secure two bag ends together, adhesive 20 between the surfaces to be bonded is only activated in selected regions e.g. strips 21, 22, 23 by passing the surfaces to be bonded through the nip between a heated roller 24 provided with raised lands 26, 27, 28 and a pressure roller 25. Both rollers may be patterned and heated. <IMAGE>

Description

BAG CLOSURE METHOD This invention relates to the closing of bags, sacks or other like containers.

In particular, the present invention is concerned with the closing of bags, sacks or other like containers which, when empty, fold flat and which open along an end or side edge.

Various methods and modes of closing such containers are known. For example, it is known to fold over, after the container has been filled with the requisite filling, the end or side having the container mouth or opening, and then to staple, sew, or glue the folded-over region thereby to seal the bag, sack or other container.

In practice, it has been found that these known forms of closing a container are frequently, bothersome to a person who needs to open the bag, sack or other container when it is required to remove the contents, in the sense that the containers sealed by the known methods are not always easy to open. This is often particularly the case when a knife or other tool is required for the opening operations.

It will be appreciated that a difficult situation can arise in the opening of containers which require a tool for the purposes of the opening operations where it is desired to empty the container into a location such as the inlet to a delivery or storage hopper which inlet is positioned such that the container has to be lifted away from the ground or other support before it is opened to avoid spillage of the content. In such circumstances it is of considerable importance from the point of view of the person handling the container that there should be no inpediment to the opening of the container such as would be caused by the need to use a tool or the like to open the container.

A further important factor arises in situations in which it is important to avoid dropping foriegn bodies or materials into the hopper or storage location. In this connection it has been found that when opening bags or containers involving sewn sealing arrangements or other arrangements which need to be cut or otherwise fragmentally removed to open the container it is readily possible for fragments of the sealing means such as threads or pieces of sealing material to fall into the hopper or storage means. It will be appreciated that any such foriegn body or material falling into the hopper, or storage means could be likely to contaminate end products or the like produced from the material being stored. For example, a fragment of string in a loaf of bread presuming that the material being stored is flour.

It is a object of the present invention to provide a method of closing a container of the kind generally mentioned above which facilitates the subsequent opening of the container.

Broadly according to the invention there is provided a method of sealing a bag, sack, or other like container, including the steps of double folding-over the marginal edge regions of the side walls of a container, and securing a tape the like so as to at least cover-in the entrance region between the folded over portion and the adjacent zone of the container wall.

According to further a aspect of the invention there is provided a method of closing a bag, sack or other like container including the steps of; folding-over material of the open edge region of the walls of the container forming the mouth thereof to provide a folded-over closure to the container mouth; and securing a closure tape to the folded-over closure and to a strip of the body of the container. adjacent to the folded-over closure in such manner as to facilitate removal of the tape when it is required to open the container.

Conveniently, the method of attachment produces a pull strip or easier to remove region extending across the width of the container mouth region.

Conveniently, the pull strip or easier to remove region is produced by securing the tape with regions of different adhesive strength the arrangement being such that a region of lesser adhesive strength enables formation of the pull strip or easier to remove region.

According to a further aspect of the invention there is provided apparatus for securing a sealing tape or the like to a bag, or for directly sealing the ends of the bag to each other by means of heat activatable adhesive applied to at least one of the surfaces to be bonded together for the purposes of sealing the bag against loss of content, including means for applying heat to selected regions of the adhesive, and means for applying sealing pressure to at least the regions affected by the heat so as to produce adherance between the surfaces to be bonded.

Preferably, the means for applying pressure includes a pair of rolls or rollers defining a nip through which the surfaces to be bonded can be passed, and wherein one of the rollers is provided with surface defining regions which are effectively raised relative to the remainder of the surface of the roll or roller, and which are arranged for engagement with a said surface to be bonded, therebeing means for heating this roll or roller in such manner as to heat the raised regions whereby during the passage of said surfaces to be bonded through the nip, the adhesive layer is activated at those locations at which said heated raised regions of the roll or roller contact said surface to be bonded thereby to produce adhesion between the surfaces to be bonded only at said locations.

Conveniently, heat activatable adhesive is applied to one side of the tape, which together with the surfaces to which the tape is to be secured is passed through the nip of a pressure zone whilst at the same time being subjected to the application of heat in such manner that selected regions, portions or areas of the adhesive are activated.

Conveniently, non-activated or lesser activated regions, portions or areas define pull strip or easier lift regions for the tape.

Preferably, the sealing of the container is enhanced or reinforced either during the folding-over stages or after such stages.

In a first method for effecting the enhancement or reinforcement adhesive is applied between the folded-over regions of the bag walls.

Alternatively, the reinforcement or enhancement can be effected after application of the tape by stitching the bag adjacent the region of double fold-over by means of a double thread stitching system in such manner that the stitching engages with the tape and bag beneath the region of fold-over.

Preferably, the mouth of the container is trimmed or otherwise shaped to define a precision edge region to the container, which edge region serves as a reference guide for subsequent folding and tape application operations.

A further aspect of the invention is concerned with methods of and apparatus for forming adhesive joints between the edge regions of the material to be joined.

For a better understanding of the invention and to show how to carry the same into effect reference will now be made to the accompanying drawings in which Figure 1 is a sectional view of a first stage in the sealing of a bag in accordance with the proposals of the invention; Figure 2 is a sectional view of a second stage in the sealing of the bag of Figure 1; Figure 3 is a sectional view of a final stage in the sealing of the bag of Figure 1; Figure 4 is a sectional view of a modified method of sealing a bag in accordance with the proposals of the invention.

Figure 5 is a schematic sectional side view of a further modified closure arrangement for a bag, sack or other like contaioner; Figure 6 is a schematic fragmentary perspective view of a bag, sack or other like container when closed by the closure arrangement of the invention; Figure 7 schematically illustrates an embodiment of an adhesive tape used in the arrangement of Figure 1.

Figure 8 is a fragmentary sectional view illustrating the principles of operstion of apparatus for use in the bonding surfaces in accordance with the concepts of the invention; and Figure 9 is a schematic oblique view of a further form of apparatus for sealing a container and for applying a tape in accordance with the proposals of the invention.

Referring now to the drawing and more particularly to Figure 1, the two side walls 1 and 2 of the bag or container 3 are brought as is conventional practice into contacting face-to-face relationship along the full width of the container and the marginal edge regions lA and 2A of the container side walls are folded-over along a fold region generally shown at 4 into the position indicated in the Figure 1.

As will be noted the marginal edge region lA is brought into contact with the adjacent part IB of the associated side wall 1. In the stage of the sealing of a container as shown in Figure 1 a seam or line 5 of adhesive is applied to the surface of the marginal edge lA and/or the adjacent contacting region 1B of the container wall prior to the folding-over or even after the folding-over by introducing adhesive between the facing surfaces lA and 1B by any convenient means and the bringing such surfaces into contact.

At the completion of this stage the folded-over region lA/2A is folded-over once again about a fold region shown at 6 so that the position as shown in Figure 2 is reached.

As will be noted the marginal edge region 2A is brought into face-to-face relationship with a region 1C of the side wall 1, thereby producing a folded over region 7 of triple thickness of folded over material and thus a region of six side-by-side layers of bag wall material.

As before a layer 8 of adhesive is introduced, by any convenient means, between the face 2A and the adjacent wall region lC.

At the completion of this double fold-over procedure the folded-over part is at least partly enclosed or shrouded as shown in Figure 3 by a strip of tape 9 which extends fully lengthwise of the folded over region and encloses at least the entrance 9A defined by the folded over region 7 in conjunction with the adjacent outer surface of the container wall.

The tape 9 is secured to the container and can be of such width that when secured to the folded-over region the marginal edge regions 10 and 11 of the tape extend a short distance down each face of the as container shown in Figure 3. The free edges of these regions 10 and 11 may be offset relative to each other or level with each other. Alternatively the width of the tape 9 can be such that it is located totally to one side of the container as is shown in Figure 4.

The tape 9 can be of the kind which is self adhesive, which can be attached by applying a suitable adhesive by any convenient means or which is heat activatable.

In a modified form of the sealing method of the invention the adhesive between the double folded-over regions of the container walls can be omitted whereby the container is held in the closed condition by the provision of the tape 9.

If desired, the sealing tape can be reinforced by stitching passing through the marginal regions 10,11 of the tape 9 by a double thread stitching process conventionally used in the sealing of bags. As is well known the stitching arrangement of the double thread stitching system is such that by pulling upon a predefined one of the lengths of stitching threads the stitching separates and also tears through the material of the container 3 and tape 9 thereby allowing opening the sealed container.

It is convenient to note that the use of the stitching could limit the use of the bag or container to situations in which it is not important to avoid the possibility of any debri thaj might arise from the separation of the stitching from contaminating the content of a hopper or like storage container in which the the container is being emptied. In situations in which it is important that any material fragments arising from the tearing of material should not be allowed to fall into a hopper or the like it would be preferable to use as the sealing method that involving the solely the use of a tape with or without adhesive between the folded over parts of the container mouth.

Referring to Figures 5, 6 and 7 of the drawings these relate to the securing of the tape 9 to the container in such manner as to facilitate the removal of the tape. As may be seen the mouth or open end l of a bag, sack or other like container 3 is double folded as previously discussed.

The tape 9 extends for the full width of the container 3 so as fully to enclose the entrance 9A.

The tape 9 of Figure 5 can conveniently be regarded as involving four distinct regions. A first region 12 which is secured by adhesive to the outer surface of the outer folded-over portion, a second region 13 which is secured by adhesive to a strip of the container body running parallel to the entrance 9A, a third region 14 bridging the said entrance 9A, and a fourth region 15 which may be conveniently regarded as a pull strip or easier to remove region for facilitating the removal of the tape 9.

The adhesive that is applied to the tape 9 is such that it is of a sufficient strength as to retain the folded-over portion in its folded over container closing state, but not of sufficient strength as to resist the peeling of the tape 9 away from the container 3 when it is required to open the container.

The method for the application of the adhesive applied to the tape 9 may take various forms. For example, the adhesive may be applied to the regions 12 and 13 or to the regions 12, 13 and 14 leaving the region 15 uncoated with adhesive.

Alternatively, the adhesive may be applied to the full width of the tape 9 and the pull strip region 15 formed by folding the tape along a marginal edge portion thereof to produce a non-adhesive-region which serves as the pull strip 15.

In connection with the method of sealing a bag, sack or other like container using the concepts of the invention it is an important requirement that the material of the container defining the mouth or opening of the container is trimmed or otherwise cut to provide a precision edge region to the container, which edge region serves as a reference guide for the subsequent requisite folding and tape application operations.

Figure 6 is very schematic view of a container when sealed by the arrangements of the present invention.

Figure 7 provides an indication of a possible mode of applying adhesive to the tape 9.

In order to open the container when closed by the arrangement of the invention it is merely necessary to exert pull on the pull strip 15 generally in the direction of the arrow 16 sufficiently to cause the tape region 13 to separate from the container but not sufficient to pull the tape 9 away from the folded-over region. Once the strip region 13 has thus been separated from the container the folded-over part of the container mouth can be unfolded and the container opened.

It will be noted that throughout these opening operations the tape remains securely attached to the container and that no material detrius or fragments are produced which could lead to the dropping of foriegn bodies into the location into which the content of the container is discharged.

Furthermore, it will be understood that the particular nature of the adhesives used will be chosen according to the material or materials used for the container.

Referring now to Figure 8 this shows in cross section a tape 17 that is required to be secured to a surface 18 of a wall 19 of a bag or other container adjacent an open end thereof. The tape 17 is provided with a coating or layer 20 of an adhesive which is heat activated in order to render the layer adhesive.

With such an adhesive only those portions thereof that are heated to a temperature at which the adhesive is activated can be caused to adhere to a second surface.

In accordance with the present invention since it is required to so attach the tape 17 to the surface 18 that at least one predetermined region or portion of the tape 17 is or are readily removable only preselected areas of the adhesive on the tape are heated. In the arrangement shown it is assumed that the preselected areas at which adhesion is required comprises three strips 21, 22 and 23 aligned parallel to each other and running lengthwise of the tape.

The three strips of activated adhesive are produced by passing the tape 17 and wall 19 to be bonded together through the nip between two rolls or rollers 24 and 25 which are rotatable about axes parallel to each other. The roll or roller 24 is provided with three circumferential spaced lands 26, 27 and 28 which are spaced apart by a distance equal to the spacing required between said strips 21, 22 and 23 of required adhesion of the tape 17 to the surface 18.

The ,roll or roller 25 has a smooth surface and is merely intended to act as a pressure roll or roller with respect to the roll or roller 24.

Arrangements (not shown) are provided for heating the roll or roller 25 such that the lands 26, 27 and 28 attain a temperature which, on passing the tape and material 18 through the aforesaid nip, will cause activation of the strips 21, 22 and 23 of adhesive immediately opposite the lands 26, 27 and 28.

Following activation of the adhesive the combination of the adhesive activation and the action of the pressure roll or roller 25, the tape 17 becomes bonded to the surface 18 along the strips 21, 22 and 23 once the previously activated adhesive has cured or otherwise set following its removal from the effects of the heated roll or roller.

It will be appreciated that when it is required to remove the tape 17 from the surface 18 the tape will be held in place only by the three strips 21, 22 and 23 of bond defined by the previously activated adhesive. Consequently, the holding power of the bonding will be correspondingly less than would be the case if the total surface area of the tape had been bonded to the surface 18. In other words the subsequent removal of the tape to allow opening of the bag is facilitated.

It will be appreciated that the particular arrangement of the regions of bond can be selected as required by suitable patterning of the working surface of the heated roll or roller 24.

In the arrangement of Figure 9 the heated roll or roller 24 is provided with a 'diamond' pattern of raised lands 28 which extend over a predetermined axial length of the roll or roller. In practice, the pattern of adhesive activation corresponds on a one-to-one relation-ship to the form of the pattern provided upon the heated roller.

Whilst the Figures indicate that only one side of the tape 17 is secured by the use of selected regions of the adhesive layer. If required, in the case where the tape bridges the open end region of a bag both rolls or rollers could be patterned and heated. The patterning of the two rolls can be similar or different as thought convenient. It will be understood that what ever the combination of patterned roll or roller and the pressure roll or roller it is imporatant to ensure that adequate sealing pressure is exertable in the nip over the regions in which adhesive has been activated.

Furthermore, if required, the heating of the tape can be such that the adhesive provided on a first region of the tape that is to be secured to a first surface is activated over the whole area of said first region, and that the adhesive elsewhere on the tape is activated at selected regions only, in the manner discussed hereinbefore, when securing the tape to a second surface. With this arrangement the tape will be firmly attached to the first surface whereby the tape remains adhered to the first surface when the tape is pulled away from the second surface.

Claims

1. A method of sealing a bag, sack or other like container or the like, including the steps of double folding-over the marginal edge regions of the side walls of a container and securing a tape the like so as to at least cover-in the entrance region between the folded over portion and the adjacent zone of the container wall.

2. A method of closing a bag, sack or other like container including the steps of; folding-over material of the open edge region of the walls of the container forming the mouth thereof to provide a folded-over closure to the container mouth; and securing a closure tape to the folded-over closure and to a strip of the body of the container adjacent to the folded-over closure in such manner as to facilitate removal of the tape when it is required to open the container.

3. A method as claimed in claim 1 or 2, wherein the method of attachment produces a pull strip or easier to remove region extending across the width of the container mouth.

4. A method as claimed in claim 3, wherein the pull strip or easier to remove region is produced by securing the tape with regions of different adhesive strength the arrangement being such that a region of lesser adhesive strength enables formation of the pull strip or easier to remove region.

5. A method as claimed in claim 1, 2, 3, or 4, wherein the sealing of the container is enhanced or reinforced during the container mouth folding-over stages, during application of the tape or after application of the tape.

6. A method as claimed in claim 5, and wherein the enhancement or reinforcement includes application of adhesive between the folded-over regions of the bag walls.

7. Apparatus for securing a sealing tape or the like to a bag sack or other like container or for directly sealing the ends of the bag to each other by means of heat activatable adhesive applied to at least one of the surfaces to be bonded together for the purposes of sealing the bag against loss of content, including means for applying heat to selected regions of the adhesive, and means for applying sealing pressure to at least the regions affected by the heat so as to produce adherance between the surfaces to be bonded.

8. Apparatus as claimed in claim 7, wherein the means for applying pressure includes a pair of rolls or rollers defining a nip through which the surfaces to be bonded can be passed, and wherein one of the rollers is provided with surface defining regions which are effectively raised relative to the remainder of the surface of the roll or roller, and which are arranged for engagement with a said surface to be bonded, therebeing means for heating this roll or roller in such manner as to heat the raised regions whereby during the passage of said surfaces to be bonded through the nip, the adhesive layer is activated at those locations at which said heated raised regions of the roll or roller contact said surface to be bonded thereby to produce adhesion between the surfaces to be bonded only at said locations.

9. Apparatus as claimed in claim 7 or 8, and wherein heat activatable adhesive is applied to one side of the tape, which together with the surfaces to which the tape is to be secured is passed through the nip of a pressure zone whilst at the same time being subjected to the application of heat in such manner that selected regions, portions or areas of the adhesive are activated.

10. Apparatus as claimed in claim 9, 10 or and wherein non-activated or lesser activated regions, portions or areas define pull strip or easier lift regions for the tape.

12. Apparatus for securing a tape to a bag.

container or the like, substantially as hereinbefore described with reference to Figures 8 and 9 of the accompanying drawings.