AU2003231635B2 - Plastic Sheet Material Useful For Packaging And Packaging Made From Such Sheet Material And Related Methods - Google Patents

Description

-1- Regulation 3.2

AUSTRALIA

PATENTS ACT, 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for service in Australia: Invention Title: AEP INDUSTRIES (NZ) LIMITED Lawrence Joseph Olsen and Andr6 Kramer A J PARK SON, Level 11, 60 Marcus Clarke Street, Canberra ACT 2601 Plastic Sheet Material Useful for Packaging and Packaging Made From Such Sheet Material and Related Methods The following statement is a full description of this invention, including the best method of performing it known to me/us 01-FEB-2006 14:43 A J PARK 64 9 3566990 P.03 IN -2- 0 The present invention relates to plastic sheet material useful for packaging and packaging made from such sheet material and related methods.

In particular although not solely the present invention relates to the manufacture of *a sheet material and packages formed from such a sheet material which incorporates a o recloseable seal.

The use of recloseable seals of an interlocking kind has recently seen many alternative shapes and configurations of packages being formed. Such recloseable seals IND are typically referred to as a rib and groove type but are also commonly referred to as Ce recloseable zippers.

SRecent developments have seen zipper seals being manufactured in advance of o being incorporated in a recloseable package. Such recloseable zippers normally consists Sof two strips often referred to as profile strips having interlockable components which form the recloseable seal thereof. The zipper seals are normally co-extruded and can later be attached to film material. Manufacturers of plastic film are known to provide film material which incorporates a zipper seal and provide this to customers as a roll of material which customers can then run through form, fill and seal machines to produce filled and sealed packages. Such is for example detailed in US Patent 55823933 where there is described the use of a zipper closure located on part of a film of the package away from an edge thereof. The disadvantage of a package formed in this nature is that it is difficult to remove the entire contents from the pack through the opening formed by the zipper.

The object of the present invention is to provide a method and means to manufacture from plastic sheet material a packaging and packaging made from such sheet material or to at least provide the public with a useful choice.

In a first aspect the present invention consists in a means to drive a film formed into a tube about a vertical forming tube of a vertical form, fill and seal machine, along said vertical forming tube, wherein the film is carrying at regular bag length intervals a recloseable zip extending transversely about a semicircle of said tube and having distal end portions located substantially diametrically opposite to each other, said means to drive comprising two endless flexible members provided in juxtaposition with said vertical forming tube to allow said tube of film to pass intermediate of said vertical forming tube and said endless flexible member, each endless flexible member positioned at diametrically opposed positions adjacent said vertical forming tube COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date 2006-02-01 01-FEB-2006 14:44 A .J PARK 64 9 3566990 P.04 c-i a Means to advance said endless flexible member in a longitudinal direction with respect to said vertical forming tube whereby said endless flexible member engages and advances said tube of film material by its engagement therewith longitudinally at regions at and about each end of said semicircle 0 wherein said endless flexible member when in engagement with said film is in cross section of a stepped nature to accommodate the difference thickness of mateirial of said tube of film material at the semicircular region.

Preferably said means to advance consists of two pulleys for each endless member about which each endless member is spanned, at least one of each set of pulleys being rn driven by a motor.

In a second aspect the present invention consists in a vertical form, fill and seal machine for the manufacture of tubed formed plastic bags with a recloseable open top which incorporates a means to drive as herein before described.

In a further aspect the present invention consists in a method of driving a film formed into a tube about a vertical forming tube of a vertical form, fill and seal machine, along said vertical forming tube, wherein the film is carrying at regular bag length intervals a recloseable zip extending transversely about a semicircle of said tube and having distal end portions located substantially diametrically opposite to each other, said means to drive comprising rotating two endless flexible members provided in juxtaposition with said vertical forming tube to allow said tube of film to pass intermediate of said vertical forming tube and said endless flexible member, each endless flexible member positioned at diametrically opposed positions adjacent said vertical forming tube said rotating being a achieved by a means to advance said endless flexible member in a longitudinal direction with respect to said vertical forming tube whereby said endless flexible member engages an advances said tube of film material by its engagement therewith longitudinally at regions at and about each end of said semicircle wherein said endless flexible member when in engagement with said film is in cross section of a stepped nature to accommodate the difference thickness of material of said tube of film material at the semicircular region.

In still a fuirther aspect the present invention consists in a means to drive as herein described with reference to figures 24 and Described is a bag comprising; COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date 2006-02-01 01-FEB-2006 14:44 f J PRK 64 9 3566990 O -4- CI two opposed films of plastic material having a bottom region and two side regions to define a receptacle space there between and a mouth region defined between plies at a Stop region of said bag, a recloseable zipper means consisting of a first and second profile strip, each strip comprising of elongate recloseable seal means of an interlocking kind and at least one Selongate flange portion located along at least one side of said recloseable seal means en said zipper means extending substantially from side to side of said bag across said mouth region, en1 wherein er a) the at least one flange of said first profile strip is sealed to the inwardly 0 facing surface of a first of said two opposed films, and b) the at least one flange of said second profile strip is sealed to the inwardly facing surfaces of the other of said two opposed films, and c) each elongate recloseable seal means is sealed to each other at their distal ends immediately inwardly of said side regions of said bag such that said elongate recloseable seal means of said first and second strip to be interlocked with each other are positioned in respect of said two opposed films to define an openable mouth region at said top region of said bag.

Preferably said two opposed plies of film material are formed from one sheet of film material with longitudinally extending edges, wherein said edges have been brought together in an overlapping relationship and longitudinally sealed together.

Preferably said first profile strip has a two flanges each on one side of said elongate recloseable seal means, each of said flanges of said first profile strip sealed there along to said first of said opposed films.

Preferably said second profile strips has only one flange on one side of said elongate recloseable seal means which is sealed there along to said second of said opposed films.

Preferably said bag in a lie flat condition is substantially rectangular is outline shape, wherein the two side regions are of longer length then said top and bottom regions.

Preferably said bag has a tamper evident region beyond said mouth region comprising of two strips of overlapping films of plastic material extending (as part of said same material or secured thereto) from said top region of said bag across the entire mouth region thereof, said strips sealed together over their entire length along a region thereof away from said mouth region of said bag and COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date 2006-02-01 01-FEB-2006 14:44 A J PARK 64 9 3566990 P.06

INO

0 0 c, said strips having along at least a substantial portion of their length and between said mouth region of said bag and the sealed region of said strips, a line ofperforations to allow access to be gained to the mouth region of said bag by tearing there along.

o Preferably the plies of material of said bag immediately below the distal ends of said elongate recloseable seal means are heat sealed to provide two patches of Itt inseparable material of said bag.

en Preferably the at least on flanges of each of said first and second profile strips are e positioned in respect of said two films of plastics material such they are at least sealed N between said mouth region and said elongate recloseable seal means.

o Also described is a film material for making a bag as herein before described Ci comprising a longitudinal sheet of plastic film material having two parallel sides, a plurality of a recloseable zipper means of a length less that half the width (sidcto-side) of said longitudinal sheet of plastic film and consisting of a first and second profile strip, each strip comprising of elongate recloseable seal means of an interlocking kind and at least one elongate flange portion (located along at least one side of said recloseable seal means) the plurality of recloseable zipper means (wherein said strips are interlocked with each other) secured at regular bag length intervals substantially transverse to the general longitudinal direction of said plastic film material to one side of said plastic film material said securing to said film of a flange of one of said first or second profile strips, substantially parallel to and adjacent of said recloseable seal means, and wherein said each of the distal ends of said first and second strip are sealed together at least at said recloseable seal means and to said film of plastics material.

In a further aspect the present invention consists in a method of making recloseable bags comprising: a) taking a plurality of elongate recloseable zip fasteners each of two elongate strips having interlockable elongate elements supported on a flange extending from at least one side and co-extensive with said elongate elements b) connecting said plurality ofrecloseable strip fasteners to a longitudinal sheet of film having two parallel sides and being of a width greater than twice the length of said recloseable strip fasteners, by heat sealing said at least one flange of one of said elements to one side of said sheet of film at bag length intervals inwardly from said sides of said film and transverse to the longitudinal direction thereof, COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date 2006-02-01 01-FEB-2006 14:45 A J PARK 64 9 3566990 P.07 IN -6- 0 c) bringing together said parallel edges of said film to form a tube having a top edge and bottom edge and heat sealing said parallel edges of said film to enclose said recloseable fasteners inside of said tube, d) sealing along said bottom edge of said tube, e) sealing the flange portion of said other of said strips to the overlying portion of said film extending from said edges to the distal ends of said recloseable zip fastener..

en f) cutting said tube a bag length from the bottom edge to form a top edge IN mouth region of a discrete bag.

Preferably said method further includes sealing said tube said bag length from said bottom edge to form a sealed top edge of said bag.

0 Preferably said method further includes perforating across the substantial width of said top edge between the zip and sealed top edge to provide a severable means of accessing said mouth region of said bag.

Preferably said method further includes intermediate of steps d) and e) the filling of the lower most potion of said tube with a food or other material to a level not above the lower most zip fastener.

Preferably said sealing of said flange of said other strip simultaneously seals the flange portion of said first strip on the other side of the interlocking element thereof already sealed on the same side of the film material where the first strip is already fastened.

Preferably said sealing of said flange of said other strip simultaneously seals the all overlying plies of material immediately below and inwardly of the said interlockable elongate element together.

Further described is a drive belt for the displacement of a film formed into a tube about a vertical forming tube of a vertical form fill and seal machine wherein the film is carrying at regular bag length intervals a recloseable zip extending transversely about a semicircle of said tube and having distal end portions located substantially diametrically opposite to each other, said belt drive comprising of an endless flexible member which includes an outwardly presented film engagement region which, is in cross section of a stepped nature where the inner most step is to engage the film at the semicircular region where said zips are provided and the outermost step is provided to engage the film at the semicircular region where there are no zips provided to the film.

Further described is, in combination, a vertical form fill and seal machine for the manufacture of bags as herein described which incorporated the belt drive as herein described.

COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date 2006-02-01 01-FEB-2006 14:45 A J PARK 01-EB-00814:5 PJ PRK4 9 3588990 P.08 I-7- Furter escrbedis, in combination, a forming tube of a vertical form fill and seal machine which includes the drive belt as herein described.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents en in the aW to which this invention relates, such known equivalents are deemed to be 2 incorporated herein as if individually set forth.

en The invention consists in the foregoing and also envisages constructions of which the following gives examples.

o The term 'comprising' as used in this specification and claims means 'consisting at least in part of, that is to say when interpreting independent claims including that term, the features prefaced by that term in each claim will need to be present but other features can also be present.

One preferred form of the present invention will now be described with reference to the accompanying drawings in which; Figure I is a perspective view of one preferred form of the bag of the present invention, Figure 2 is a perspective view of a part of a sheet material for the forming of a preferred form of a bag% of the present invention, Figure 3 is a sectional view through section CC of figure 2 and figure 9, Figure 4 is a more detailed view of a portion of the view as shown in figure 2, Figure 5 is a sectional view through section AA of figure 1, Figure 6 is a sectional view through the sheet material of the present invention intermediate of one of the preferred steps of forming the package of the present invention, Figure 7 is a sectional view through the sheet material of the present invention intermediate of one of the preferred steps of forming the package ofthe present invention, Figure 8 is a sectional view through section BB of figure 1, Figure 9 is an end view of the preferred form of the sheet material as shown in figure 2, Figure 10 is a view of the top region of a package of the present invention wherein a tamper evident region has been provided, Figure 11I is an end view as shown in directions EE of figure 12 of a sealing/cutting/perforating station of the preferred form of the present invention, Figure 12 is a sectional view through section DDi of figure 11, COMS ID No: SBMI-02540906 Received by IP Australia: Time (I-tm) 12:57 Date 2006-02-01 01-FEB-2006 14:46 A J PARK 01-EB-200 1446 5 PRK64 9 3566998 P.09 INO -8- 0 Figure 13 is a sectional -view through section DD of figure 11 wherein a tube of the sheet material for fanning the bag of the preferred form of the present invention is in between, Figure 14 is, a perspective view of an example of the form, fill and seal operation 0 for the forming of packages from the sheet material of the preferred form of the present invention, Figure 17-22 illustrate in cross section more preferred configurations of heat INO sealing jaws, en Figure 23 is a schematic of the way in which the jaws are displaced, Figure 24 is a sectional view through section XX of Figure 25 and, o Figure 25 is a side view of a belt drive arrangement for the forming tube.

With reference to figure 1 which illustrates the preferred formn of the package of the present invention there is illustrated a package which has been formed from a sheet material preferably as shown in figure 2. The package I is preferably formed from overlying sheets of plastics material, whether such plastics material is of a single layer material or whether it is co-extruded and/or of different material such as LDPE or HDPE/ LLDPE or blend or the like. The bag preferably has side regions 2 and a bottom region 3.

In the preferred form the overlying sheets of material are provided from a single flat sheet inwardly folded to bring the sides of the sheet together. With reference to figure 2 the sides 4 are able to be brought together by folding them along lines to define the edge regions 2 and with reference to figure I the sides 4 end up overlapping and inwardly from the edge regions 2. In the preferred form the folds defining the edge regions 2 of the package are substantially symmetrical across the width of the sheet material however the present invention is certainly not limited to the overlapping sides 4 of the package to be substantially centrally between the edge regions 2.

The bag of the present invention as shown in the preferred form in figure 1 also has a top region 5 which defines a mouth to provide access to the interior of the bag. The mouth region functions to allow material to be inserted and taken from the package.

Across substantially the entire mouth region of the bag there is provided a recloseable zipper means 6. The recloseable zipper means is of a kind consisting of a first and second profile strip 7, 8 (reference to figure 5) having elongate recloseable seal means 9 and flange portions 10, 11, 12 on at least one side of the elongate recloseable seal means. The flange portions provide the regions which allow for the scaling of the recloseable zipper means to for example a plastic film or sheet. With reference to figure 2 the present invention includes the provision of a sheet material capable of being fanned into discrete COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date (Y-M-cI) 2006-02-01 01-FEB-2006 14:46 F J PAfRK 64 9 3566990 -8a-

INO

0 Spackages as shown in figure 1. The sheet material is preferably of an elongate nature having longitudinal edges 4 wherein between and transverse to the longitudinal direction the recloseable zipper means are provided at bag length intervals. With reference to figure 6 the sides 4 of the sheet material as shown in figure 2 are able to be brought together and O sealed longitudinally to form a tube. In order for the recloseable zipper means not to be folded the width (side to side) of the sheet material figure 2 is at least twice the length of the recloseable zipper means located thereon. This will allow the side 4 to be brought ,D together in a partially overlapping condition and allow for a sealing be achieved there between. As shown in figure 7 the sealing is of an overlapping kind wherein the opposing I faces of the sheet material are broad in contact however alternatively the overlapping may o be such as to bring together the same major surfaces of the sheet material for sealing. In 0, the preferred form such sealing is by a heat sealing however alternative forms such as adhesive sealing may also be employed.

The recloseable zip elements are applied to the sheet material of a kind shown in figure 2 by sealing along the at least one flange of one oftheprofile strips. With reference to figure 3 it can be seen how one profile strip has been heat sealed to the sheet material at only one flange thereof. Should the profile strip have two flanges (and this is shown in figure 3) the other flange may or may not necessarily be also heat sealed to the sheet material. It is preferably not sealed to the sheet and hence only one seal along substantially the entire length of the flange of a first profile strip 7 is provided.

Securing of the recloseable zipper means to the sheet material may also include the sealing of the distal ends thereof to the sheet material. With reference to figure 4 sealing of the distal ends is at least at the elongate recloseable seal means 13 and may also be across part of the at least one flange of each of the first and second profile strips. Such end sealing ensures that both profile strips are secured together. Such securing is obviously however very undesirable across the length of the profile strips as hence no access would be able to be obtained to the package of the present invention. Therefore in one preferred form the first profile strip 7 has a flange extending from one side of the elongate recloseable seal means where the second profile strip does not have such a flange or perhaps does not have such a flange extending to the same extent as the first profile strip. A single bar heat seal for example may then provide a sealing of the recloseable zipper means to the sheet material without also joining the two profile strips together across the same distance. With reference to Figure 15 the sealing of the profiles strips 7, 8 may be that on both flanges 10, 11, 12, 38, there is a sealing thereof to the respective and adjacent films. Alternatively and as shown in Figure 16 (which also includes a mouth COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date 2006-02-01 01-FEB-2006 14:46 A J PARK 64 9 3566990 P.11 8b- Va 0 edge seal to provide complete air tightness to the pack) the inward most flanges of the profile strips may be sealed to the adjacent files of the bag. In another of the preferred Sforms the first seal of the first profile strip 14 (as in figures 3 and 4, is on that flange ofthe first profile strip further most away from the mouth region to be formed from the sheet o material, The sides 2 of the sheet material are brought together in a direction to enclose the t recloseable zipper means within the tube. With reference to figure 7 there is shown the Spreferred recloseable zipper means 6.

ONI

C(

COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date 2006-02-01 q -9- In sealing the other (second) profile strip, 8 to the then overlying portions of the sheet material a seal is applied to the at least one flange of the second profile strip 8.

With reference to figure 5 or 16 the second profile strip preferably has only one flange and hence only one seal of the elongate recloseable seal means of that strip is provided.

The sealing of both profile strips to the sheet material is preferably achieved by a heat seal which extends between the distal ends of the strips.

It can hence be seen with reference to figure 1 that the recloseable zipper means provides a first strip to one side of the mouth region of the package and another strip to the other side of the mouth region of the package. The elongate recloseable seal means are then hence positioned across the mouth region to allow interlocking thereof to provide a substantially secure seal.

The package of figure 1 is preferably also provided with a tab heat seal to seal the overlying plies of material immediately below and inwardly from the elongate recloseable seal means. With reference to figure 10 such plies include the flange of the first strip, one side of the sheet to form the walls of the package and the other side of the sheet to form the wall of the package. These tabs 15 are preferably provided in this region to ensure that the contents of the package does not get trapped immediately below the distal ends of the strips. These tabs are preferably formed by heat sealing all of the plies of the material in this region so that they become secured together and to eliminate any space or void which may exist there.

In the preferred form the steps of sealing both the upper flange of the first profile strip and the upper flange of the second profile strip (flanges 11, 12) is preferably achieved simultaneously by the use of a heat sealing bars. The profile strips which allow for such heat sealing to occur between the flanges and the sheet material but not between the flanges of each of the strips themselves is of a kind as described in US Patent 5238306 its contents by way of reference hereby disclosed. The flanges where heat sealing of the two strips occur simultaneously onto the separate sheets of material are provided with the profiled ribs 40 facing each other. Another form of this method can be provided where one side of a heat seal bar is heated whereas the other bar on the other side of the bag is cooled.

With reference to figure 10 the packaging of the present invention may also be provided with a tamper evident region 16 which is either an extension of the sheet of material of the present invention or may alternatively be an additional strip which is attached to the sheet material at the mouth region. The tamper evident region preferably is provided in the form of seal 17 of the strip and immediately below that seal and between the seal and the recloseable zipper means a region of perforation 18 which allows for severable access to the recloseable zipper means and hence the mouth region of the package to be obtained.

As the package of the present invention is preferably manufactured from a sheet material having a plurality of recloseable zipper means and preferably as part of a form, fill and sealing machine it is suggested that the station at which the closing of the lower most bag from the elongate sheet of material simultaneously separates this lower most bag therefrom to form a discrete bag as well as forming the bottom seal of the next lower most bag. With reference to figure 13 it can be seen that the lower most bag 19 with its bottom seal 20 in place in the preferred form prior to the top region of the bag being sealed the interior of the bag is filled with substance such as a food product or the like. The sealing jaw arrangement 21 preferably consists of pairs of opposed pressure applying means 22, 23 between which the plies of material forming the package of the present invention are positioned at their appropriate positions. Pairs of jaws are preferably of a heat sealing kind wherein preferably one of each pair is heated. In one preferred form both of the pairs are heated and with the selection of the correct material for the plies of material of the bag heat sealing appropriate regions is able to be achieved. In an alternative form of the present invention the first of the pairs 23 of the jaw arrangement 21 may be heated and at least one of the complementary of each pair may be cooled. This may be desirable where full through seal of all of the plies at that point is not desirable. Cooling will hence allow for at least some control in respect of which plies of material are sealed together and which are not. With reference to figure 13 there is preferably provided first pair of sealing jaws 24 which provide the bottom seal of the subsequent bag to be filled and sealed. A preferred second pair ofjaws provide the preferred seal of the lower most bag along line 17 as shown in figure Jaws 26 seal those portions of the sheet material folded over and onto the other side of the recloseable zipper means as well as that portion (if any) of the zipper means which was already attached to the sheet material on the other side of the elongate recloseable seal means. With the use of a recloseable zipper means of a kind that is described in US5238306 and with the appropriate dwell times of the heat pressure applying operation (including the appropriate temperatures) the application of heat and pressure by the sealing means 26 will ensure there is separation between the overlying flanges of both strips of said zipper and that the only significant sealing which occurs is between the flanges of each strip and the opposed sheets of plastics film material.

Sealing means 24, 25 and 26 apply a heat seal substantially across the entire mouth region of said bag.

-11- Sealing means 27 are to provide the sealing of webs of material at points 15 as substantially shown in figure 10. These sealing means do not extend across the entire width of the package and with reference to figure 11 it can be seen that these are substantially spaced apart to provide the preferred of sealing as shown in figure There is also preferably provided a perforation means 28 and a cutting means 29.

These are preferably located to provide the preferred perforation as shown in figure as well as the separation of the discrete lower most package from the sheet material.

With reference to Figure 17-22 more alternative and more preferred forms of the sealing jaws to be incorporated in the present invention are shown. In these figures the sealing jaws illustrated are each of substantially a unitary body or a body which will move in unison.

The sealing jaws illustrated have a design which is compact in its height and allows the features of sealing and separating to be provided more proximate to each other. Such proximate location of these features 41, 42 and 43 has the benefit of reducing the amount of bag length that is required to seal the profile strips and separate a bag from the continuous feed tube, hence reducing material costs.

With reference to Figure 17 which has sealing points which provide a single line seal, there is provided an upper seal line providing means 41 which seals the bottom of the next in line bag. The seal line providing means 42 provides the mouth seal 17 whereas the single line seal providing means 43 provides the seal of the flange or flanges of the profile strip on one side of the complementary profile ribs 9. Such may be on the outward or inward flange of the profile strips 7, 8.

Between the single line seal providing means (and not shown) can be the separation and/or perforation means.

Between 41 and 42, there is preferably provided a separation means which is preferably a knife edge. This knife edge may act from one side of the sealing jaws into the other side.

Likewise between 42 and 43, a perforation means such as a perforating knife may be provided to provide the perforations 18 as shown in Figure A scrollable member 45 extends across the sealing surfaces of at least one of the sealing jaws.

Heating of the sealing jaws may be provided through a heating conduit 54 which may be provided by way of a heating element.

Figure 18 illustrates twin line seals to achieve the sealing as that described of the sealing jaws of Figure 17.

01-FEB-2006 14:47 A J PARK 64 9 3566990 P.12 INO -12- O With reference to Figures 19-22, the lower seals 43 are preferably provided to extend from each of the unitary members of the sealing jaws but are separated by a means t to provide insulation 44. With reference to Figure 21, with the provision of such Sinsulation providing means 44, the lower seals can have a separately controlled 0 temperature provision which may be provided through a conduit 46. Such temperature provision may be a heating element or may alternatively be a cooling element. Indeed one of the sealing jaws one side) may be heated whilst the other side is cooled.

0 With separate heat control over the lower seals of the sealing jaws, a significant degree of control over the speed of the sealing steps can be achieved. Dependent on choice of material, increased or reduced temperatures may be necessary at the lower seals og€ as compared to the upper seals. With the ability to vary the temperature of the lower seals N compared to the upper seals, an increased production rate is expected.

The insulation providing means 44 may for example be a rubber spacer. The use of a rubber spacer also allows for the displacement of the lower sealing jaws to be varied from the remainder of the seal providing means of the sealing jaws. This can be important where materials of different or varied thickness are incorporated in the pack of the present invention.

With reference to Figure 17-22, those part halves ofthe sealingjaws which provide the substantially "U-shaped" recess is preferably provided with a silicone insert against which the opposite and complementary portions of the sealing jaws can press.

An example where the two sealing jaws 22-23 are moved in an engaged condition is shown in Figure 23.

One of the parts of the sealing jaw, and for example shown in Figure 23, the sealipg jaw 23 is displaceable relative to the other part 22. The displacement is preferably provided by an over-centre toggle providing arrangement which is preferably linkages 52- 53 which at one end are secured to the seal bar 23 and at the other a stationary point of the apparatus. With the application of a force to one or both of the link arms 52-53, a displacement of the sealing jaw 23 to and from the sealing jaw 22 can be achieved. A stop may be provided where the appropriate and sufficient degree of over-centre of the linkages is achieved. The over-centre nature allows for a significant of pressure between the jaws to be achieved at a minimal demand of force required to be applied to the linkages.

As the present invention includes the method of forming the bag which utilises a reclose and is preferably achieved on a vertical form, fill and seal machine, as for example shown in Figure 14, there are issues which need to be addressed in respect of COMS ID No: SBMI-02540906 Received by IP Australia: Time 12:57 Date 2006-02-01 cr (1 13a suitable adaptation of standard form, fill and seal machines where no transverse reclose is provided to the film.

It will be appreciated and with reference to Figure 14, that when the reclose is advanced over the folding shoulder and down the filling tube 48 that the total material thickness at points where the reclose has been preapplied to the sheet of film, will be thicker. As standard form, fill and seal machines incorporate a feed belt 49 which locates against the film advancing down the feed tube 48 which drives the tube of material downwardly by pressing it against the feed tube 48.

Prior art machine have provided for the increase in thickness of the materials at points where the reclose is applied, by providing a recess in the feed tube 48. However such recess is normally required to extend across the semi circle (in cross section) of the feed tube down which the reclose advance. Such can include expensive machining to remove the material from the feed tube, which is normally an extruded or rolled sheet metal material. With reference to Figure 24, an alternative arrangement is shown wherein a recess is provided in the feed belt 48 wherein such recess 50 is of a shape to accommodate the increase thickness as provided by the reclose elements.

With reference to Figure 24 which is a cross sectional view through section XX of Figure 25, it can be seen how the feed belt 49 has a recess provided on that side of the semi-circle of the feed tube 48 down which the reclose elements travel.

With reference to Figure 23 a wear strip backing plate 52 may be provided on an outwardly facing surface of the feed tube 48 to improve the wear characteristics and also reduce friction between the film material and the regions against which the film material is pressed whilst it is being advanced by the feed belt 49.

The wear strip backing plates may also be provided with a complementary recess for allowing the advancement of the reclose carrying film regions to pass there through.

Provided as backing to the feed belts 49, there is a backing timing belt 51, as it can be appreciated that timing in respect of the features providing the forming of the bag is important as these do need to remain synchronised.

Claims (4)

1. 01-FEB-2006 14:47 A J PARK 01-EB-00614:7 PJ PRK64 9 3566990 P.13 -14- o What We Clain, is I. A means to drive a film formed into a tube about a vertical forming tube Of a vertical form, fill and seal Machine, along said vertical forming tube, wherein thefilm is carrying at regular bag length intervals a recloseable zip extending transversely about a semicircle of said tube and having distal end portions located substantially diametrically opposite to each other, said Means to drive comprising two endless flexible members provided in juxtaposition with said vertical forming V.0 tube to allow said tube of filmn to pass intermediate of said vertical forming tube and said en endless flexible member, each endless flexible member positioned at diametrically en opposed positions adjacent said vertical forming tube a means to advance said endless flexible member in a longitudinal direction with respect to said vertical forming tube whereby said endless flexible member engages and advances said tube of film material by its engagement therewith longitudinally at regions at and about each end of said semicircle wherein said endless flexible member when in engagement with said film is in cross section of a stepped nature to accommodate the difference thickness of material of said tube of film material at the semicircular region.
2. 2. A means to drive as claimed in claim I wherein said means to advance consists of two pulleys for each endless member about which each endless member is spanned, at least one of each set of pulleys being driven by a motor.
3. 3. A vertical form, fill and seat machine for the manufacture of tubed formed plastic bags with a recloseable open top which incorporates a means to drive as claimned in claims 1 or 2.
4. 4. A method of driving a film formned into a tube about a vertical forming tube of a vertical form, fill and seal machine, along said vertical forming tube, wherein the film is carrying at regular bag length intervals a reoloseable zip extending transversely about a semicircle of said tube and having distal end portions located substantially diametrically opposite to each other, said means to drive comprising COMS ID No: SBMI-02540906 Received by IP Australia: lime 12:57 Date 2006-02-01 01-FEB-2006 14:47 A J PARK 64 9 3566990 P.14 oN rotating two endless flexible members provided in juxtaposition with said o vertical forming tube to allow said tube of film to pass intermediate of said vertical forming tube and said endless flexible member, each endless flexible member positioned at diametrically opposed positions adjacent said vertical forning tube said 5 rotating being a achieved by a means to advance said endless flexible member in a o longitudinal direction with respect to said vertical forming tube whereby said endless flexible member engages and advances said tube of film material by its engagement therewith longitudinally at regions at and about each end of said semicircle NO wherein said endless flexible member when in engagement with said film is in M 10 cross section of a stepped nature to accommodate the difference thickness of material of said tube of film material at the semicircular region. A means to drive as herein described with reference to figures 24 and COMS ID No: SBMI-02540906 Received by II' Australia: lime 12:57 Date 2006-02-01