METHOD FOR PRODUCING A RESEALABLE POUCH

PROCEDE POUR LA PRODUCTION D'UN SACHET REFERMABLE

English Abstract

A method of producing resealable filled pouches comprises the steps of (i)
folding across part of its original width a length of
thermoplastics sheet to produce a folded sheet having a fold portion running
lengthways of the sheet having a folded edge which fold
portion extends across part of the original width of the sheet and a non fold
portion extending from the fold portion to the other edge of the
sheet; (ii) in a direction at right angles to the folded edge and at regular
intervals along the folded edge, welding the fold portion together
to form individual pockets of equal size having welded wall edges along the
length of the sheet; (iii) cutting the sheet, across the width of
the sheet and along the line of the welds, to produce individual pouches each
having a mouth, welded edges and an extended flap portion,
and (iv) filling each pouch, through its mouth, with desired contents and
folding the extended flap over the mouth so as to form the flap
around the pouch. At the time of forming the fold portion of the sheet, a
resealable fastener is located on the sheet in a direction parallel to
the edges of the sheet and in a position predetermined to be immediately below
the mouths of the pouches wherein the resealable fastener
comprises two interengaging closure strips in engaged position, each closure
strip of which having a base portion. The base portions of
each of the two interengaging closure strips are, while the strips are engaged
with each other, welded to the facing surfaces of the sheet
respectively in the fold portion, and after welding of the resealable fastener
the closure strips are disengaged from each other, the closure
strips being made to engage with each other after the filling of the pouch and
before forming the extended flap over the pouch.

French Abstract

La présente invention concerne un procédé permettant la production de sachets remplis refermables. Ce procédé comporte plusieurs opérations. (i) On prend une feuille de matière thermoplastique que l'on plie en travers d'une partie de sa largeur d'origine de façon à obtenir une feuille pliée dont une partie de pli se développe selon la longueur de la feuille comportant un bord plié, laquelle partie de pli se présente de part et d'autre d'une partie de la largeur de la feuille et une partie sans pli allant de la partie de pli à l'autre bord de la feuille. (ii) En procédant selon une orientation formant des angles droits avec le bord plié et à intervalles réguliers le long du bord plié, on soude la partie de pli ensemble de façon à former des pochettes individuelles de mêmes dimensions dont les bords des parois soudées se répartissent le long de la feuille. (iii) On découpe la feuille en travers de la largeur de la feuille en suivant la ligne des soudures de façon à obtenir des pochettes individuelles présentant chacune une embouchure, des bords soudés et une partie formant un rabat déplié. Enfin, (iv) on remplit chaque pochette pas son embouchure du contenu voulu, puis on replie sur l'embouchure le rabat déplié de façon à disposer le rabat autour de la pochette. Au moment de former la partie de pli de la feuille, une fermeture refermable est située sur la feuille selon une orientation parallèle aux bords de la feuille, et dans une position prédéterminée pour être immédiatement en dessous des embouchures des pochettes. En l'occurrence, la fermeture refermable est constituée de deux bandes de fermeture engageables l'une dans l'autre montées en position d'engagement, chaque bande de fermeture comportant sa propre structure de base. Pendant que les bandes sont engagées l'une dans l'autre, les structures de base des bandes de fermeture engageables l'une dans l'autre sont soudées chacune sur une face apparente correspondante de la feuille dans la partie de pli. En outre, après soudage de la fermeture refermable, les bandes de fermeture sont dégagées l'une de l'autre, les bandes de fermeture se présentant pour un engagement l'une d'ans l'autre après le remplissage de la pochette, et avant de disposer le rabat déplié autour de la pochette.

Claims

6


CLAIMS

1. A method of producing resealable filled pouches comprising the steps
of
folding across part of its original width a length of thermoplastics
sheet to produce a folded sheet having a fold portion running
lengthways of the sheet having a folded edge which fold portion
extends across part of the original width of the sheet and a non fold
portion extending from the fold portion to the other edge of the sheet;
in a direction at right angles to the folded edge and at regular
intervals along the folded edge, welding the fold portion together to
form individual pockets of equal size having welded wall edges along
the length of the sheet;
cutting the sheet, across the width of the sheet and along the line
of the welds, to produce individual pouches each having a mouth,
welded edges and an extended flap portion;
filling each pouch, through its mouth, with desired contents and
folding the extended flap over the mouth so as to form the flap
around the pouch;
wherein, at the time of forming the fold portion of the
sheet, a resealable fastener is located on the sheet in a direction parallel
to the edges of the sheet and in a position predetermined to be
immediately below the mouths of the pouches wherein the resealable
fastener comprises two interengaging closure strips in engaged position,
each closure strip of which having a base portion, and in that the base
portions of each of the two interengaging closure strips are, while the
strips are engaged with each other, welded to the facing surfaces of the
sheet respectively in the fold portion, and wherein after welding of the
resealable fastener the closure strips are disengaged from each other, the
closure strips being made to engage with each other after the filling of the
pouch and before forming the extended flap over the pouch.




7



2. A method according to claim 1, wherein the thermoplastics sheet is a
sheet of polyethylene.

3. A method according to either claim 1 or claim 2, wherein the sheet is
a laminate of a thermoplastics material with one or more layers of similar
or different thermoplastics material, a metalised or metal coated sheet
material or a paper web.

4. A method according to any one of claims 1 to 3, wherein welding is
carried out by ultra-sonic welding.

5. A method according to any one of claims 1 to 4, wherein the base of
each of the closure strips is provided with one or more flanges.

6. A method according to claim 5, wherein the folded portion of the
sheet is welded up to immediately below the flanges on the closure strip.

7. A method according to any one of claims 1 to 6, wherein the
resealable fastener is cooled immediately following welding to the
thermoplastic sheet.

8. A method according to any one of claims 1 to 7, wherein the
extended flap of each individually formed pouch is folded over the pouch,
after filling thereof, at a position between the filled pouch and the bottom
of the fastener.

9. A method according to any one of claims 1 to 8, wherein the flap,
after being folded over the mouth of the flap, is folded around the base of
the pouch.

10. A method according to any one of claims 1 to 9, wherein the pouches
are filled with tobacco.

1 1. A method according to any one of claims 1 to 10, wherein the
thermoplastics sheet is supplied from a continuous reel.

12. A method according to any one of claims 1 to 11, wherein the
thermoplastic sheet is folded such that the distance from the folded edge
to the mouth of the pouch is equal to the distance from the mouth of the
pouch to the edge of the extended flap.

Description

CA 02358541 2001-07-05
WO 00/40465 PCT/GB00/00020
METHOD FOR PRODUCING A RESEALABLE POUCH
The present invention relates to a method for producing a resealable
pouch such as that used for storing tobacco. The invention further
relates to a method for inserting a resealable fastener into a pouch during
the forming process of a standard tobacco pouch from a continuous reel
of material.
A pouch for tobacco is conventionally formed from a thermoplastic
material, capable of being welded to itself using a combination of heat
and pressure. Typically, the continuous material, or web, is folded on
itself along the length of the web from one side towards the other side,
the fold being approximately a third the way along the width of the web,
thus forming a double thickness web with a fold at one side and an
extension of single thickness material extending from the double thickness
to the opposite side of the web.. Thus, the distance from the folded edge
to the extremity of the double thickness will be approximately the same
as the distance from the double thickness part of the web to the other
edge. The double thickness part of the folded web is then welded, at
fixed intervals across the width of the web, forming a continuous length
of folded material formed into individual pockets of equal size, by the
welds. The welds formed are of a reasonable thickness. The continuous
length of formed pockets are cut by a knife along the welds, forming
individual pouches welded at each side, with an extended flap
approximately equal in length to the depth of the pouch. The individual
pouches are filled with the product, tobacco, through the mouth of the
pouch. The extended flap of the pouch is folded below the mouth of the
pouch, but over the pouch mouth, so as to form the flap around the
pouch. A second fold of the flap is made around the base of the pouch to
form a completely wrapped pouch. This method of wrapping does not
prevent loss of moisture from the contents, or spillage of the contents,
before and during use.

CA 02358541 2006-06-27
73018-20
2
The object of the present invention is to provide a method of
producing a resealable pouch by inserting a resealable fastener into the
pouches during the forming process so as to enable enhanced moisture
retention of the product, or perceived moisture retention by the user, and
to enable a reduction in spillage of the product before and during the use
of the pouch.
The present invention provides a method of producing resealable filled
pouches comprising the steps of
folding across part of its original width a length of thermoplastics
sheet to produce a folded sheet having a fold portion running
lengthways of the sheet having a folded edge which fold portion
extends across part of the original width of the sheet and a non fold
portion extending from the fold portion to the other edge of the sheet;
in a direction at right angles to the folded edge and at regular
intervals along the folded edge, welding the fold portion together to
form individual pockets of equal size having welded wall edges along
the length of the sheet;
cutting the sheet, across the width of the sheet and along the line
of the welds, to produce individual pouches each having a mouth,
welded edges and an extended flap portion;
filling each pouch, through its mouth, with desired contents and
folding the extended flap over the mouth so as to form the flap
around the pouch;
wherein, at the time of forming the fold portion of the
sheet, a resealable fastener is located on the sheet in a direction parallel
to the edges of the sheet and in a position predetermined to be
immediately below the mouths of the pouches wherein the resealable
fastener comprises two interengaging closure strips in engaged position,
each closure strip of which having a base portion, and in that the base
portions of each of the two interengaging closure strips are, while the
strips are engaged with each other, welded to the facing surfaces of the


CA 02358541 2001-07-05
WO 00/40465 PCT/GB00/00020
3
sheet respectively in the fold portion, and wherein after welding of the
resealable fastener the closure strips are disengaged from each other, the
closure strips being made to engage with each other after the filling of the
pouch and before forming the extended flap over the pouch.
The fastener is supplied in the form of two interengaging closure
strips, supplied in the engaged position. Each strip is typically formed
with a protrusion, designed to engage with the complimentary strip, and
flanges extending from the sides of the protrusion. It is a requirement
that the closure strips are introduced and fixed into position, whilst
engaged, so as to ensure perfect alignment between the two
complimentary strips to ensure resealability. Any misalignment between
the two complimentary strips will act so as to prevent full re-closure of
the fastener or render the resealing action unworkable by the user. It is
also a requirement of the process to ensure the closure is in the
unengaged position when the pouch reaches the filling position. Both
these actions are achieved in the manner described below.
The pouch is formed in the manner described for a standard pouch,
the resealable fastener, in its engaged position, being introduced into the
forming process as the thermoplastic sheet is folded. The fastener is
guided into the folded sheet into the position at which it is to be secured,
i.e., immediately below what will become the mouth of the pouch,and the
flanges of the closure strips are then welded to the pouch material in the
correct position. Welding the fastener into the pouch while engaged
ensures alignment is maintained between the complimentary strips. Care
should be taken to ensure that the flanges from opposing complimentary
closure strips do not become welded together. Subsequent to the
closures being welded to the pouch material the material and closure
strips may be chilled, by a cooling mechanism, so as to prevent stretching
or puckering of the material, which may occur due to retained heat.
Subsequent to the fasteners being welded, and chilled if required, to
the pouch material the closure strips which up to this point in time are


CA 02358541 2001-07-05
WO 00/40465 PCT/GB00/00020
4
engaged together are disengaged, whilst maintaining the positioning of
the complimentary strips relative to each other. The opposing closur-a
strips are welded together using a high-energy method of welding, such
as ultra-sonic welding, at fixed points along their lengths which points
coincide with the positions at which the side welds, to form the pouches,
will be made. These welds are generally of a similar width as the side
welds and act to ensure proper location of the opposing closures by
closing the closures at the point of the weld, and "crushing" the closure
with the ultra-sonic weld, or similar high-energy weld. The use of an
ultra-sonic weld, or similar high-energy weld, ensures the opposing
closures are securely welded together, such that the weld will not break
under normal use of the pouch, and also acts to produce a thin weld,
which does not adversely affect the visual impact of the pouch. It is
important to note that, at this point, the closure, welded into mouth of
the pouch, is in the unengaged position, and that the closure has to
remain generally unengaged for the remainder of the forming and filling
process. Also note that the ultra-sonic weld is designed to extend slightly
beyond the width of the fastener for reasons that will become apparent.
When the fastener has been welded in the position, relating to the
width of the pouch, welds are made from the weld at the closure to the
fold in the web, in the same manner as for the standard side weld.
However, the side weld preferably does not extend to the same distance
as the original weld, as the closure weld would cause adverse interference
with side weld. Therefore, the side weld preferably welds from the fold in
the web to immediately below the closure flanges, and acts to interfere
with the extension of the closure weld below the flanges. This
interference is important to ensure an airtight weld is maintained from the
web fold to above the fastener. The guide strip used preferably extends
throughout the pouch forming process up to the point the side welds are
made, thus aiding with positive location and tracking of the closure and
material.


CA 02358541 2001-07-05
WO 00/40465 PCT/GB00/00020
The continuous web of formed pouches, with the resealable fastener
secured into the mouths of the pouches, is cut down the centre of the
weld to form individual pouches sealed at each side, the resealable
fastener remaining generally open. Any partial closing of the fastener that
may have occurred can be eliminated by a blast of compressed air aimed
at the mouth of the pouch. The individual pouches are then filled,
subsequent to all formation of the individual pouches, through the mouth
of the pouch. Although the preferred application of the invention is in the
production of resealable pouches of tobacco, it is possible to fill the
pouches with different products, such as food products.
The above description does not preclude the side weld and cutting
action occurring simultaneously to produce a very thin side seal whilst still
producing a thin weld through the closure.
After deposition of the product into the pouch, the fastener is closed
by means of pressure exerted onto the fastener. The pouch is preferably
folded in a similar manner to that used in conventional pouch production;
the first fold occurring between the filled pouch and the bottom of the
fastener. The fastener is positioned such that the fold occurs in the same
place as it does in a conventional pouch and hence does not affect the
capacity of the pouch. A second fold of the flap around the base of the
pouch can be made as in the conventional pouch.