"A reclosable flexible pouch and method and apparatus for manufacturing reclosable flexible pouches"

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Field of the invention

The present invention relates to reclosable flexible pouches , also known as stand-up pouches or Doypacks ( a trademark associated with the pouches ) .

The present invention also relates to a method and to an apparatus for manufacturing reclosable flexible pouches .

Prior art

A stand-up pouch or Doypack is a type of flexible packaging which is able to stand erect on its bottom for display, storage , and use . It is a type of plastic bag commonly used for food products . The bottom part of a stand-up pouch is gusseted to provide support for display or use . The most common pouch has bottom gussets to form a "W" which opens to form a flat bottom .

The flexible pouches are usually constructed of multi-layer materials : various plastic films , paper, barrier layers , etc . Pouches are often printed with graphics or sometimes have attached labels . The materials must have speciali zed heat-seal properties to allow conversion into pouches .

The packaging machinery involved typically forms the pouches from pre-printed roll stock . The preformed pouches are shipped to a packager where they are filled, and the top is sealed .

Inclusion of reclosable zip strips in Doypack pouches is common . Typically, the pouch has two opposite flexible sheets having at their top portions internal interlockable plastic strips which are reclosable to keep the pouch airtight after its opening .

Zip strips feature flanged interlockable profiles that create a reliable seal when pressed together . Some types of zip strip employ a slider to open and close the pouch .

The zip component of the packaging is supplied on a continuous roll and is inserted between the upper and lower webs of the packaging film . The zip may be bonded to the packaging film by a heat activated adhesive that is pre-applied to the backing of the zip .

Zip strips are often formed by extrusion, which involves the following problems :

- low process speeds ,

- extremely high temperatures and pressures ,

- need for cooling processes using water,

- impossibility to make intermittent shapes in the direction of advancement of the raw material .

Obj ect and summary of the invention

The obj ect of the present invention is to provide a reclosable f lexible pouch which overcomes the problems of the prior art , and which simpli fies and reduces the costs involved in forming the interlockable zip strips .

According to the invention, this obj ect is achieved by a reclosable flexible pouch having the features of claim 1 .

According to another aspect , the present invention relates to provide a method and apparatus for manufacturing reclosable flexible pouches having the features of claims 8 and 13 .

The claims form an integral part of the technical disclosure provided here in relation to the invention . Brief description of the drawings

The present invention will now be described with reference to the attached drawings , provided purely by way of non-limiting example , wherein :

Figure 1 is a schematic side view of an apparatus for producing reclosable pouches according to the present invention,

Figures 2- 6 are schematic plan views showing di f ferent steps of a method for manufacturing reclosable pouches according to the present invention,

- Figure 7 is a schematic perspective view of the unit indicated by the arrow VI I in figure 1 ,

- Figure 8 is a schematic enlarged detail of the closure formations indicated by the arrow VI I I in figure 4 ,

- Figure 9 is a schematic view showing the closure formations of figure 8 in the interlocked position,

Figures 10- 12 are schematic enlarged views showing di f ferent possible shapes of mutually interlockable proj ections and recesses of the closure formations , and

- Figure 13 is a perspective view of a reclosable pouch according to the present invention .

It should be appreciated that the attached drawings are schematic and not to scale with respect to real products . Various figures may not be represented in the same scale . Also , in various figures some elements may not be shown to better show other elements .

Detailed description

With reference to figure 1 numeral reference 10 indicates an apparatus for producing reclosable flexible pouches . With reference to figures 1 and 2 , the apparatus 10 comprises a feeding device 12 configured for feeding in a machine direction MD a continuous flexible sheet 14 having a longitudinal axis X extending along the machine direction MD .

The continuous f lexible sheet 14 may be unwound from a reel and may be printed with graphics . The continuous flexible sheet 14 is made of a material having heat-seal properties . The continuous flexible sheet 14 may have a multilayer structure comprising various plastic films , paper, air barrier layers , etc, as is common in packaging materials used for packaging food products . The continuous flexible sheet 14 may have at least one outer layer of thermoformable material .

The continuous flexible sheet 14 may be made of a biodegradable and/or compostable material . The biodegradability of materials i s defined according to the standard EN13432 . In a possible embodiment the continuous flexible sheet 14 may be made of biodegradable and compostable bioplastic materials such as MATER-BI® or SPLASTICA.

In a possible embodiment the continuous flexible sheet 14 may be made of a material recyclable with paper . The characteristics of the materials that can be recycled with paper may be def ined by the standard Aticelca® 501 /2017 . The wording and icon "RECYCLABLE WITH PAPER - Aticelca® 501" on packages inform consumers about the recyclabil ity with paper . The Aticelca® 501 /2017 standard defines a test for recyclability of products ( e . g . packaging material , printed material , articles for domestic use , etc . ) made of more than 50% by weight of cellulosic materials .

With reference to figure 2 , the continuous flexible sheet 14 has two longitudinal side portions 16 , 18 opposite to each other with respect to the longitudinal axis X and two opposite longitudinal side edges 20 , 22 parallel to the longitudinal axis X .

With reference to figures 1 , 3 and 7 , the apparatus 10 comprises a forming unit 23 configured for integrally forming in the two longitudinal side portions 16 , 18 of the continuous flexible sheet 14 first and second interlockable closure formations 24 , 26 extending longitudinally adj acent to respective longitudinal side edges 20 , 22 .

With reference to figures 8 and 9 , each of the first and second interlockable closure formations 24 , 26 has a success ion of proj ections 28 and recesses 30 which are integrally formed on the surface of the two longitudinal side portions 16 , 18 of the continuous flexible sheet 14 as the continuous flexible sheet 14 moves through the forming unit 23 .

As shown in figure 9 , the proj ections 28 of the first closure formation 24 are configured for interlocking with the recesses 30 of the second closure formation 26 and the proj ections 28 of the second closure formation 26 are configured for interlocking with the recesses 30 of the first closure formation 24 .

In the configuration of figure 3 in which the continuous flexible sheet 14 is flat at the exit of the forming unit 23 the proj ections 30 of each of the first and second closure formations 24 , 26 are transversally aligned to corresponding recesses 30 of the other closure formation 24 , 26 and the recesses 30 of each of the first and second closure formations 24 , 26 are transversally aligned to corresponding proj ections 28 of the other closure formation 24 , 26 .

The first and second interlockable closure formations 24 , 26 may be equal to each other and of fset with respect to each other m the longitudinal direction X .

With reference to figure 7 , the forming unit 23 may comprise two ultrasonic forming devices 32 , each including an anvil 34 and a respective ultrasonic horn 36 . The anvil 34 may be formed by a wheel rotating about an axis transverse to the machine direction MD . The ultrasonic horn 36 may include a vibrating rod cooperating with the outer surface of the anvil 34 . In a possible embodiment , the ultrasonic horn may be formed by a vibrating roller rotating about an axis transverse to the machine direction MD .

The first and second interlockable closure formations 24 , 26 may be formed by a method similar to that disclosed in W02010/ 085492 . This document discloses an apparatus and process for forming microhooks on a substrate for use as hook-type fasteners in touch fastening systems , wherein vibration energy is used to soften a substrate which is positioned between a mould and a source of vibration . The mould includes a plurality of cavities into which the softened substrate is forced to form the proj ections . The substrate may comprise a film, sheet , web, composite , laminate , etc . The source of vibration may be an ultrasonic horn . The process to form such micro-hooks may be operated in a continuous , semi-continuous or intermittent manner .

With reference to figure 7 , each anvil 34 has a plurality of cavities 38 open on its outer cylindrical surface . The ultrasonic horns 36 compress the respective longitudinal side portions 16 , 18 of the continuous flexible sheet 14 against the outer cylindrical surfaces of the respective anvils 34 as the continuous flexible sheet 14 moves in the machine direction MD . The vibrating energy produced by the ultrasonic horns 36 liqui fies or fluidi fies locally the thermof ormable material of the outer layer o f the continuous flexible sheet 14 , which penetrates in a fluid or liquid state in the cavities 38 of the anvils 34 . The material of the continuous flexible sheet 14 which penetrates in the cavities of the anvils 34 cools in contact with the walls of the cavities 38 and forms proj ections 28 alternated to recesses 30 integral with the continuous flexible sheet 14 .

As schematically shown in figure 7 , at the exit of the forming unit 23 the continuous flexible sheet 14 has integrally formed first and second closure formations 24 , 26 . The two anvils 34 of the two ultrasonic forming devices 32 are operated with a precise angular of fset , such that the proj ections 30 of the first closure formation 24 are transversally aligned to corresponding recesses 30 of the second closure formation 26 and the recesses 30 of the first closure formation 24 , are transversally aligned to corresponding proj ections 28 of the second closure formation 26 , and vi ce versa .

The first and second closure formations 24 , 26 may be formed intermittently in the machine direction MD . The intermittent arrangement of the closure formations 24 , 26 may be obtained by providing on the outer surface of each anvil 34 an intermittent pattern of cavities 38 . Alternatively, each anvil 34 may have a continuous pattern of cavities 38 and the intermittent closure formations 24 , 26 may be formed by intermittently turning of f the ultrasonic horns 36 . As a further alternative , each anvil 34 may have a continuous pattern of cavities 38 and the intermittent first and second closure formations 24 , 26 may be formed by intermittently detaching the ultrasonic horns 36 from the outer cylindrical surfaces of the respective anvils 34 .

In a possible embodiment , the forming unit 23 may be a thermomechanical forming unit , in which the material of the longitudinal side portions 16 , 18 of the continuous f lexible sheet 14 is locally liqui fied or fluidi fied by heating and compression .

In order to form proj ections and cavities with dimensions suf ficient for an ef fective interlocking, the continuous flexible sheet 14 may be a monolayer sheet of thermof ormable material or a multilayer sheet having an outer layer of thermof ormable material , having a weight comprised between 10-300 g/m ² .

The cavities 38 of the anvil 34 may be shaped to form proj ections 28 and recesses 30 with di f ferent shapes and dimens ions . Figures 10- 12 schematically show di f ferent possible shapes of the proj ections 28 and recesses 30 of the closure formations 24 , 26 .

In the embodiment of figure 10 each of the proj ections 28 has a rounded head portion 40 connected to a narrower shank portion 42 , and each of the recesses 30 has a V-shape with curved sides .

In the embodiment of figure 11 each of the proj ections 28 has a rectangular shape and each of the recesses 30 has a U-shape .

In the embodiment of figure 12 the rectangular proj ections 28 and the U-shaped recesses 30 have respective rounded corners .

With reference to figures 1 and 4 , the apparatus 10 comprises a folding unit 44 configured for folding the continuous flexible sheet 14 about at least one folding line 46 parallel to the longitudinal axis X .

In a possible embodiment , the folding unit 44 may be configured for folding the continuous flexible sheet 14 about three folding lines 46 parallel to the longitudinal axis X m a W-shaped configuration which opens to form a flat bottom .

After the longitudinal folding, the two longitudinal side portions 16 , 18 of the continuous flexible sheet 14 are overlapped to each other so that the first and second closure formations 24 , 26 face each other .

The folded continuous flexible sheet 14 has a closed edge at the folding line ( s ) 46 and an open edge at the mutually facing side edges 20 , 22 .

With reference to figures 1 and 5 , the apparatus 10 comprises a sealing unit 48 configured for j oining to each other the two longitudinal side portions 16 , 18 of the continuous folded flexible sheet 14 along sealing lines 50 extending between the closed edge 46 and the open edges 20 , 22 of the continuous folded flexible sheet 14 . The sealing unit 48 may be a welding unit , for example an ultrasonic or thermocompression welding unit .

With reference to figures 1 and 5 , the apparatus 10 comprises a cutting unit 52 configured for cutting the continuous folded flexible sheet 14 along cutting lines extending over the welding lines 50 , such that each cutting line is preceded and followed by a portion of a respective welding line 50 . The cutting lines extend along the whole width of the said continuous folded flexible sheet 14 so that downstream of the cutting unit 52 a continuous array of individual reclosable pouches 52 is formed .

The individual reclosable pouches 52 are then filled . After filling, the mutually facing first and second closure formations 24 , 26 are interlocked with each other and the reclosable pouches 52 are sealed between the edges 20 , 22 and the mutually interlocked closure formations 24 , 26 , e . g . by welding . Figure 13 schematically shows a reclosable pouch 52 according to the present invention .

The reclosable flexible pouch 52 comprises a flexible sheet 14 folded about at least one folding line 46 (preferably about three parallel folding lines 46 ) .

The flexible sheet 14 has first and second mutually facing front portions 16 , 18 having respective side edges j oined to each other along two sealing lines 50 . The first and second mutually facing front portions 16 , 18 have respective top edges 20 , 22 and first and second interlockable closure formations 24 , 26 ad acent to respective top edges 20 , 22 .

The first and second interlockable closure formations 24 , 26 are integrally formed with the respective mutually facing front portions 16 , 18 .

Each of the first and second interlockable closure formations 24 , 26 has a succession of proj ections 28 and recesses 30 extending along a longitudinal direction X and configured for interlocking with the recesses 30 and proj ections 28 of the other closure formation 24 , 26 .

The proj ections 28 of each of the first and second interlockable closure formations 24 , 26 are transversely aligned to corresponding recesses 30 of the other closure formation 24 , 26 and the recesses 30 of each of the first and second interlockable closure formations 24 , 26 are transversely aligned to corresponding proj ections 28 of the other closure formation 24 , 26 .

In a possible embodiment , the first and second interlockable closure formations 24 , 26 are equal to each other and o f fset with respect to each other along the longitudinal direction X . The main advantages of the method according to the present invention are the following :

- low process temperatures ,

- low power and energy required, - high dimensional stability and precision of the reclosable closure formations ,

- high manufacturing speeds ,

- possibility of forming the closure formations in line with the formation of the pouches , - possibility of customi zing the shapes of the closure formations by appropriately forming the anvils 34 .

Of course , without prej udice to the principle of the invention, the details of construction and the embodiments can be varied, even signi ficantly, with respect to those illustrated here without departing from the scope of the invention as defined by the following claims .