FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2006
PROVISIONAL SPECIFICATION
(See Section 10 and Rule 13)
A METHOD AND A SYSTEM FOR MAKING FORM FILL SEAL POUCHES


HINDUSTAN UNILEVER LIMITED, a company incorporated under
the Indian Companies Act, 1913 and having its registered office
at 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India
The following specification describes the invention

12 DEC 2008

FIELD OF INVENTION
The present invention relates to a method for making flexible side-gusseted pouches on a form-fill-seal machine in which the inner corners of the pouch are resistant to impact in Drop-Test.
The invention has been developed primarily for use in detergent powders and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.
BACKGROUND AND RELATED ART
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.
Pouches, or bags made of plastic films are used for packaging various products like creams, powders, liquids, tablets, noodles, granular detergents and pastes. Pouches enable packaging and selling of these products in small as well as large quantities, typically in the range of 200 g to 10 kg. Broadly speaking, pouches are manufactured in two ways. One way is the so-called "pre-formed pouch" manufacture. In this case, the pouches are made from single-ply plastic films or plastic laminates at one station, moved to a different filling station, and subsequently sealed at a sealing station, off-line. On the other hand, Form-Fill-Seal (FFS) machines are used to make pouches from single-ply
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plastic films or laminates; fill the product and then seal
the open ends of the pouches, in an on-line operation. With
the advent of FFS machines, the industry has seen high
production rates of pouches.
Further, pouches can be manufactured from a single sheet of a film or a laminate (a laminate has two or more layers of films which are bonded to each other) ; or by using two sheets of films or laminates. Pouches are of three types; three-side seal pouches, four-side seal pouches and centre-seal pouches.
In the case where two sheets of films are used; one sheet defines the front surface and the other film defines the back surface of formed pouches, which are usually sealed by application of heat to three edges to first form a three-sealed pocket, followed by filling of the product in the pocket, after which the fourth edge is sealed. One such method is described in WO2006/01814 0 Al (UNILEVER). Such pouches are used for packing small quantities of products, and are generally referred to as sachets.
In the case of pouches manufactured from single sheet of film (either mono layer films or laminates), the sheet is conveyed to a pouch-former where opposite longitudinal edges of the sheet are overlapped and juxtaposed. The juxtaposed overlapping longitudinal edges of the sheet material, upon sealing, form a hose or tube-like structure where the sealed edges define the longitudinal seal of the pouch. Next the leading edge (lower) of the hose is sealed by a first transverse seal to form the top transverse seam of the pouch. The product is then filled in the tube/hose and then
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along their one side. It is said that with this type of sealing arrangement; stress that tends to be concentrated at the crossing point is dispersed and the bag is prevented from being broken. A drawback of this disclosure is that the extra folds of gussets mean utilisation of higher amount of packaging material. This would therefore, be a relatively expensive route and also not practical on a VFFS (Vertical Form-Fill-Seal} machine.
JP/2005/104572A (FUJITA KIKAI KK; HAYASHI SANGYO KK) describes a square-cornered pouch, in which, in addition to the lower horizontal seal, there are two additional vertical seals near the bottom of the pouch (one adjacent to each gusset) such that this extra sealing lines extend vertically to the upper end of the pouch for some distance, whereafter the sealing lines are inclined at 45 degrees with respect to the gusset folds. The pouches also have reinforcing seals having a circular arc which are provided by piling four films of the front face and back face of the bag and the gusset fold and bonding them integrally by fusion. The arcuate seals are adjacent to the inner edges of the gusset fold, and it contacts the extra sealing lines that extend vertically upward. A primary drawback of such pouches is that, as the entire width of the pouch is sealed in the horizontal seal, it becomes essential that either the outermost layer of the laminated film has to be of heat-sealable grade, or a special type of lacquer is used to seal the layer in case the outermost layer is not heat-sealable. This limits the use of this process.
Japanese unexamined Patent Application No. JP/02/173149A (YUKAWA SEITAI, Co. Ltd, 2002) aims to solve the same
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problem of pre-formed plastic pouches with side gussets, where failure occurs at the points where the horizontal seal meets the inner ends of the gussets. This has been solved by providing non-sealed curved pockets at the points of intersection. it is known that while using pre-formed pouches for filling and packaging of products, the overall speed of filling and packaging is low as the pouches are formed at one station, and then filled and sealed at a different station. Further, in the case of such pre-formed pouches, as only one bag is handled at a time, there is relatively little shift in the relative alignment of the gussets with the sealing jaws during the sealing operation. Further, as the bags have already been manufactured off¬line, very little shift in the centre-line of the gussets is observed. On the other hand, in the case where plurality of side-gusseted pouches are made in an on-line method using VFFS machines; as the pouches are made in a continuous manner at high throughput rates and efficiency, there is an appreciable shift in the relative alignment of the gussets with the sealing jaws, as well as an appreciable shift in the centre-line of the gussets. This is further compounded by the fact that due to the fall-height of product, especially in the case of fills over 1 kg; where gravity acts on the filled and suspended pouch; the pouches deviate from their ideal mean positions, and this therefore, affects the seal strength at the four inner corners of the pouch. This may be further complicated by the stiffness and thickness of the laminate and the machine settings, including its speed. The appreciable shift in the relative alignment of the gussets with the sealing jaw, as well as the appreciable shift in the centre-line of the gussets, would therefore nullify the effect of the presence of the
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curved pocket provided in the horizontal seals at the inner corners. Thus there would still be a significant amount of failure in the Bag Drop-Test.
Thus, there is a need for a method for making side-gusseted pouches on a vertical form, fill, seal machine which takes care of the shift in the relative alignment of the gussets with the sealing jaws, as well as the shift in the centre¬line of the gussets, where the pouches show relatively lower rate of failure in the Bag Drop-Test.
OBJECT OF THE INVENTION
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art.
It is an object of the present invention to provide a method for making side-gusseted pouches on a Vertical form, fill, seal machine which takes care of the shift in the relative alignment of the gussets with the sealing jaws, as well as the shift in the centre-line of the gussets, where the pouches show relatively lower rate of failure in the Bag Drop-Test.
It is an object of the present invention to provide a method for making side-gusseted pouches on a form, fill, seal machine where the rate of failure of pouches in the Bag Drop-Test is 1%.
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Other objects of the present invention will become apparent to those skilled in the art by reference to the specification.
SUMMARY OF THE INVENTION
According to the first aspect, the present invention provides a method of continuously forming, filling and sealing side-gusseted flexible pouches with product, comprising the steps of:
(i) providing a continuous sheet of film;
(ii) drawing said sheet over a pouch-former to form a film tube having an overlapped vertical film edge;
(iii) sealing said overlapped vertical film edge with a vertical sealer to form a vertical seal, while said film-tube is continuously pulled along machine direction;
(iv) forming gussets on both lateral sides of the tube ;
(v) effecting a horizontal seal across said film-tube, with horizontal sealing jaws, at a predetermined location below said vertical sealer to form the top horizontal seal of a filled pouch and the bottom horizontal seal of a pouch to be filled, optionally with perforations there-between;
(vi) feeding said product within said film-tube;
(vii) sealing open end of said film-tube with said horizontal sealing jaws at a pre-determined location; and.
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(viii) optionally severing filled and sealed pouches to
form individual pouches therefrom, where at the intersection of the horizontal seal with inner ends of the gussets, an un-sealed pocket extending on either sides of the intersection is formed, wherein width of the un-sealed pocket is in the range of 25 to 50 % of the total width of the gusset.
According to the second aspect the present invention provides a system for continuously forming, filling and sealing side-gusseted flexible pouches with product, comprising:
(i) means for providing a continuous sheet of film;
(ii) means for drawing said sheet over a pouch-former to form a film-tube having an overlapped vertical film edge;
(iii) a vertical sealer for sealing said overlapped vertical film edge,
(iv) means for continuously pulling said film-tube along machine direction;
(v) means for forming gussets on both lateral sides of the film-tube;
(vi) a pair of horizontal sealing jaws at a predetermined location below said vertical sealer, each jaw having a top-sealing section and a bottom-sealing section so as to simultaneously effect the top-horizontal seal of a formed and filled pouch, and the bottom-horizontal seal of a pouch to be filled, while leaving the gusset-ears un-sealed to each other,
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optionally with means for forming perforations there-between; (vii) means for feeding said product within said film-tube; (viii) optionally means for severing filled and sealed
Pouches to form individual pouches therefrom, where said top-sealing section and said bottom-sealing section have depressed areas, so as to form un-sealed pockets at the intersection of the horizontal seal with the inner ends of the gussets of the pouch; wherein width of each of the depressed area is in the range of 25 to 50 % of the total width of the gusset of the pouches formed.
According to the third aspect, the present invention provides a pQuch obtainable by the method according to the first aspect.
According to the fourth aspect the present invention provides use of the pouch formed by the method according to the first aspect for packaging granular detergent composition.
The term "cornprising" is meant not to be limiting to any subsequently stated elements but rather to encompass non-specified elements of major or minor functional importance. In other worcis the listed steps, elements or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above.
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Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material ought to be understood as modified by the word "about".
It should be noted that in specifying any range of concentration or amount, any particular upper concentration can be associated with any particular lower concentration or amount.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of preferred embodiments.
BRIEF DESCRIPTION OF THE FIGURES
A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying figures in which:
Figure 1 is the isometric view of a system according to the invention; and
Figure 2 is front view of a horizontal sealing jaw of the system of Figure-1.
Figure-3 is front view of a pouch formed in the system of Figure-1.
Figure-4 is side-view of the pouch of Figure-3 with the gussets ears opened up.
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Figure-5 is the isometric view of another embodiment of a pouch formed by a system according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the detailed description, like numerals have been used to indicate like features.
Figure-1 is the isometric view of a system for continuously forming, filling and sealing side-gusseted flexible pouches with product according to an aspect of the invention. The system is constructed in the form of an enclosed frame on which all parts for the forming, filling, and sealing of the pouches are mounted.
In this figure, a continuous sheet of film 1 is un- wound from a roll (not shown) and is drawn/conveyed over conveying Aluminium rollers 2 and 3. It then reaches a forming shoulder 4 and later on, a pouch-former 5 {also called a forming tube) . In this pouch-former, the sheet of film 1 is folded over itself so that the opposite longitudinal edges 6 and 7 are juxtaposed to form a common vertical film edge. A vertical sealer 8 then seals this common overlapped vertical film edge to form a film-tube. Pulling means (not shown) then continuously pull the film-tube 9 along machine direction, (shown by a solid arrow) as set on a stroke length lever (not shown) . A pair of gusset pins 10 and 11 (means for forming gussets), disposed on either lateral sides of the film-tube than form gussets on both lateral sides of the film-tube. The film-tube is then sealed in the horizontal direction by a pair of horizontal sealing jaws 12 and 13 at a predetermined location below the vertical sealer
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8. The horizontal sealing jaws have depressed areas, both represented by common numeral 14 which form un-sealed pockets at the intersection of the horizontal seal with inner ends of the gussets of the pouch. The same features are present in the other horizontal sealing jaw 12 (features not seen in this view) . The horizontal sealing jaws simultaneously define the top horizontal seal 15 of the filled pouch 16, and the bottom horizontal seal 18 of the pouch to be filled 19. Perforations 20 are formed between the top horizontal seal 15 and the bottom horizontal seal 18 for later severing the filled and sealed pouches to form individual pouches therefrom. In heat-sealing system, which is used for majority of films/laminates, this severing action takes place separately, whereas in the Poly heat-sealing system, the sealing and severing actions take place at the same time, because knives are mounted on the sealing jaws itself. In the pouch to be filled 19, a product is continuously fed through means in the form of a tube 21, below the vertical sealer 8 and above the pair of horizontal sealing jaws 12 and 13. The open end of the film-tube is then sealed with the horizontal sealing jaws, at a pre¬determined location, which corresponds to a distance of one bag length. The cycle is repeated to form plurality of pouches.
Referring now to Figure-2 which shows the front view of the horizontal sealing jaw 13 of the system of Figure-1, the jaw has a bottom-sealing section in the form of seal bar 22 and a top-sea ling section in the form of another seal bar 23 with a knife-edge 24 there-between. At three corners, the jaw is provided with curved/semi-circular depressed areas, all represented by common numeral 14, with their corners
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rounded-off, so as to minimise sharp corners. The gusset alignment area is shown as L in the figure. At one end of the seal bar 23, the height of the seal bar "H-l" is greater than the general height of the seal bar "H". This feature gives extra sealing height to the pouch in the top-horizontal seal, so that an easy-tear notch can be formed in this sealed region with the cavity 25.
Turning now to Figures 3 and 4, the pouch 16 has a top horizontal seal 15 and a bottom horizontal seal 18. The seal height of a portion of the top horizontal seal 15 at one end 27 is greater than the general seal-height of the top-horizontal seal. Both corners of 27 are rounded-off. Three curved semi-circular pockets, all represented by the common numeral 2 6 can be seen at the three inner corners of the pouch, at the intersection of the horizontal seal with the inner ends of the gussets represented by the centre line of the gussets 28. Figure-4 shows the pouch of Figure-3 in a side view, where the gusset-ears have been opened up, to show the total width of the gusset "W". Common numeral 28 indicates the centre-lines of the gussets, and the pockets 2 6 extend across this line. Both corners of each pocket are rounded-off.
Figure-5 shows another embodiment of a pouch formed by a system according to the invention. The pouch has a top and bottom horizontal seals 15 and 18 respectively, with gusset-ears at one end shown by the common numeral 2 9. The seal height of a portion of the top horizontal seal 15 at one end 27 is greater than the general seal-height of the top-horizontal seal. Both corners of 27 are rounded-off. An easy-tear notch 30 is provided in this region, and the notch
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is positioned below the un-sealed pocket 2 6 at the opposite end of the same horizontal seal. Three curved semi-circular pockets; all represented by the common numeral 26, can be seen at the three inner corners of the pouch, and at the intersection of the horizontal seal with the inner ends of the gussets, which are the centre-lines of the gussets 28. The pockets 26 extend across their respective centre-lines. The gusset-ears have been opened up to show the total width of the gusset "W". Both corners of each un-sealed pocket 26 are rounded-off; so as to further reduce stress at the points by reducing sharp corners.
Width of the un-sealed pocket is in the range of 25 to 50 %, more preferably in the range of 30 to 45 %, further more preferably in the range of 30 to 40 %, and most preferably 33 % of the total width of the gusset. It is preferred that the un-sealed pocket is free of sharp corners or bends, and more preferably the corners are rounded-off. It is preferred that the un-sealed pocket is formed at atleast three inner corners of the pouch. It is preferred that the profile of the unsealed pocket is semi-circular, oval or ellipsoidal, more preferably semi-circular.
The terms "pouch" and "bag" have been used interchangeably throughout the specification.
The present inventors have observed that the maximum shift in the centre-line of the gussets is 13.33 % of its total width. Thus for example, for a total gusset width of 60 mm, the ideal situation is when the centre-line of the gusset is at 30 mm, i.e. width of both gusset ears is 30 mm each. However, the present inventors have found that the maximum
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shift in the centre-line could be by 8 mm, which amounts to 13.33 % of the total gusset width. This means that the centre-line of the gussets could be anywhere between 22 to 38 mm, when measured from one end of the gusset. In this case, the width of the individual gussets would be different and not 30 mm each. It is preferred that the width of the un-sealed pocket is more than 200 % of the maximum shift in the . centre-line of the gussets, more preferably atleast 250 % and upto 300 % of the shift in the centre-line of the gusset. It is highly preferred that the width is 250 % of the maximum shift in the centre-line of the gussets. Thus, for example, where the maximum shift in the centre-line of the gusset is 8 mm, the width of the un-sealed pocket is more than 16 mm, more preferably, atleast 20 mm, and upto 24 mm. It is highly preferred that the width of the un-sealed pocket is 20 mm, which is 250 % of 8 mm.
It is preferred that the height of the un-sealed pocket is less than 35 % of the height of the horizontal seal, preferably in the range of 10 to 30 %, and more preferably in the range of 10 to 20 %. Excessive height may weaken the horizontal seal. While the method can be used to form pouches with the un-sealed pockets formed at atleast three corners of the pouch, it is possible to form the pockets at all four corners. It is preferred that the height of the horizontal seal, preferably the top horizontal seal, at one end is in the range of 167 to 240 % of the general height of the seal, wherein a notch/slit is provided on both or one side of the gussets-ears at the end, the notch/slit being positioned below the un-sealed pocket at the opposite end of the horizontal seal. Thus, for example, when the general height of the horizontal seal is 15 rnm; the seal height at
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the end of the seal, where the notch/slit is to be provided, is preferably in the range of 25.05 to 36 mm, more preferably 30 mm. It is preferred that the notch is provided 5 to 10 mm, preferably 5 mm below the un-sealed pocket at the opposite end of the same horizontal seal.
Preferably, the gusset ears are not sealed to each other. Having introduced the un-sealed pockets, it is not essential to seal the gusset-ears to each other for low rate of failure in Bag-Drop test. However, in a less preferred embodiment, if the outermost layer of the laminated film is of heat-sealable grade, or a special type of lacquer is used to seal the layer, in case the outermost layer is not heat-sealable, the gusset-ears could be sealed to each other, thereby further reducing the rate of failure.
Pouches may be manufactured from a variety of materials. It is particularly advantageous, however, that they be constructed, at least partly, from relatively thin, strong material such as Polyethyleneterepthalate (PET), which is polyester; biaxially oriented nylon (BON), linear low density polyethylene (LLDPE), commonly abbreviated as PET/BON/LLDPE film. For example, the following combinations, some with multiple layers or ply of the same material, may be used for making the pouches. It is preferred that 2-ply laminates are used, but, if desired, 3-ply laminates can also be used, although these laminates are less preferred because of their cost.
Polyester/adhesive (or Extrusion Poly)/ Linear Low Density P.E film (2-ply)
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Polyester/ adhesive {or Extrusion Poly)/ Polyester/ adhesive (or Extrusion)/ Linear Low Density P.E. film (3-ply)
Polyester/adhesive (or Extrusion poly)/ Aluminium foil/adhesive {or Extrusion poly)/LLDPE (3-ply)
Polyester/adhesive/Metallised Polyester/adhesive/LLDPE (3-
piy)
Polyester/adhesive/NyIon/adhesive/LLDPE (3-ply)
Polyester/adhesive/Nylon/adhesive/Aluminium foil /adhesive/LLDPE
Nylon/adhesive/LLDPE (2-ply)
Nylon/adhesive/Metallised Polyester/adhesive/LLDPE (3-ply)
Nylon/adhesive/ Aluminium Foil/adhesive/LLDPE (3-ply)
Nylon/adhesive/Nylon/adhesive/LLDPE (3-ply)
Nylon/adhesive/Nylon/adhesive/Aluminium Foil/ LLDPE (3-ply)
Other materials such as Polypropylene may also be used in place of the above or in combination with the other materials. Material thickness may also vary.
It is preferred that the sheet of film is a 2-ply laminate of 10/12 micron Polyethyleneterepthalate and 70/80 micron Polyethylene. Alternatively, and more preferably, a 2-ply
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laminate of 10/12 micron Polyethyleneterepthalate and 7 0/8 0 micron Easy-tear Polyethylene is used to make the pouches.
In an alternate embodiment, the method according to this invention may be used to make "Quad-packs". The general method for making quad-packs is well-known to a person skilled in the art.
The invention will now be described in greater details with the help of the following non-limiting examples.
EXAMPLES
EXAMPLE-1
2250 pouches were made by the method in accordance with the invention and as described with reference to Figure-5. The pouches were made from a 2-ply laminate (10/12 micron Polyethyleneterepthalate and 70/80 micron easy-tear Polyethylene). Of the 2250 pouches, 1500 pouches were filled with 1 kg high bulk-density {BD} detergent powder, and 750 pouches were filled with 500 g of a low BD detergent powder. Specifications of the pouches were as follows:
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Table-1

Total width of the gussets 60 mm
Width of the semi-circular pockets 20 mm {33% of the width of the gusset)
Height of the semi-circular pockets 4 . 5 mm
Shift in the centre-line of the gussets There was a shift of 7 mm; gusset-ears were 23 mm and 37 mm respectively
Height of the top horizontal seal 15 mm
Height of the top horizontal seal at the end where easy-tear notch was provided 30 mm
Height of the bottom horizontal seal 15 mm
Of these 1500 pouches, 100 (from each set) were randomly selected for the Bag Drop-Test. The selected pouches were dropped on the floor from a height of four feet, four times, such that they fell on the bottom horizontal seal, so that the inner corners of the seal experienced the stress. The number of pouches which opened at atleast one gusset seal was recorded. For the control experiment, 1000 pouches were made from the same laminate, of which 500 were filled with 500 g low BD detergent powder, the remaining were filled with 1 kg high BD powder. The control pouches did not have any un-sealed pocket, other specifications being identical to the pouches according to the invention. Of the 1000 control bags, 100 (from each set) were also subjected to bag-drop test. The results are provided in Table-2 below.
Table-2

Pouch code Number of pouches tested Number of pouches failing "6
failure
Control 100 (of each set) 8 (in both sets) 8 %
Invention 100 {of each set) 1 (in both sets) 1 %
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The data in the above table indicates that the % failure in the case of inventive pouches was only 1 %, which is highly desirable.
EXAMPLE-2
In another experiment, pouches were made from different materials and had variation in the width of the semi¬circular un-sealed pockets. The total width of the gusset in all cases was 60 mm and shift in the centre-line of the gusset was 8 mm, i.e. one gusset-ear was 38 mm, while the other was 22 mm. The pouches were filled with 1 kg high BD detergent powder. Some pouches were filled with 1 kg low BD powder. The pouches were subjected to drop-test as in Example-1 above. Details of the pouches and the results are shown in Table-3 below.
Table-3

Expt Laminate Structure Width of Pocket/mm Width
of
pocket
as % of
total
gusset
width Width of pocket as % of shift in centre¬line failure
1* A NIL - - 2
B 12 20 150 19
B NIL - - 18
2* A NIL - - 2
B 15 25 187 7
B NIL - - 15
3* A NIL - - 2
C 20 33 250 1
B 20 33 250 1
C NIL - - 16
3** C 20 33 250 1
C NIL - - 16
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Note: In the above Table
Expt stands for Experiment
Laminate structure A was 10 PET / 10 PET / 70 Poly (3-ply)
Laminate structure B was 12 PET / 70 Poly (2-ply)
Laminate structure C was 12 PET / 80 Poly (2-ply)
* pouches were filled with 1 kg low BD detergent powder
** pouches were filled with 1 kg high BD detergent powder
Thus it can be seen from the results in the above table that pouches made in accordance with the preferred aspects of the method according to the invention showed only 1% failure in Bag Drop-Test.
It will be appreciated that the illustrated examples provide a method for making side-gusseted pouches on a vertical form, fill, seal machine which takes care of the shift in the relative alignment of the gussets with the sealing jaws, as well as the shift in the centre-line of the gussets, where the pouches show relatively lower rate of failure in the Bag Drop-Test.
It will be appreciated that the illustrated examples provide a method for making side-gusseted pouches on a form, fill, seal machine where the rate of failure of pouches in the Bag Drop-Test is 1%.
It should be understood that the specific forms of the invention herein illustrated and described are intended to be representative only as certain changes may be made therein without departing from the clear teachings of the disclosure.
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