WO2007043931A1 - A method and an apparatus for applying a strip - Google Patents

A method and an apparatus for applying a strip Download PDF

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Publication number
WO2007043931A1
WO2007043931A1 PCT/SE2006/001069 SE2006001069W WO2007043931A1 WO 2007043931 A1 WO2007043931 A1 WO 2007043931A1 SE 2006001069 W SE2006001069 W SE 2006001069W WO 2007043931 A1 WO2007043931 A1 WO 2007043931A1
Authority
WO
WIPO (PCT)
Prior art keywords
edge
sealing strip
strip
web
packaging laminate
Prior art date
Application number
PCT/SE2006/001069
Other languages
French (fr)
Inventor
Håkan ANDERSSON
Original Assignee
Tetra Laval Holdings & Finance S.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tetra Laval Holdings & Finance S.A. filed Critical Tetra Laval Holdings & Finance S.A.
Publication of WO2007043931A1 publication Critical patent/WO2007043931A1/en

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B31MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31BMAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B50/00Making rigid or semi-rigid containers, e.g. boxes or cartons
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B31MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31BMAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B70/00Making flexible containers, e.g. envelopes or bags
    • B31B70/60Uniting opposed surfaces or edges; Taping
    • B31B70/64Uniting opposed surfaces or edges; Taping by applying heat or pressure
    • B31B70/66Uniting opposed surfaces or edges; Taping by applying heat or pressure by high-frequency electric heating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B31MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31FMECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31F5/00Attaching together sheets, strips or webs; Reinforcing edges
    • B31F5/006Attaching together sheets, strips or webs; Reinforcing edges using a strip, e.g. profiled
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B31MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31FMECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31F7/00Processes not otherwise provided for
    • B31F7/006Processes not otherwise provided for edges, e.g. sheet edges
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D5/00Rigid or semi-rigid containers of polygonal cross-section, e.g. boxes, cartons or trays, formed by folding or erecting one or more blanks made of paper
    • B65D5/42Details of containers or of foldable or erectable container blanks
    • B65D5/4279Joints, seams, leakproof joints or corners, special connections between panels
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B31MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31BMAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B50/00Making rigid or semi-rigid containers, e.g. boxes or cartons
    • B31B50/74Auxiliary operations
    • B31B50/742Coating; Impregnating; Waterproofing; Decoating
    • B31B50/743Coating or impregnating edges or corners
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B31MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31BMAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B50/00Making rigid or semi-rigid containers, e.g. boxes or cartons
    • B31B50/74Auxiliary operations
    • B31B50/81Forming or attaching accessories, e.g. opening devices, closures or tear strings
    • B31B50/812Applying tabs, patches, strips or strings on blanks or webs
    • B31B50/8125Applying strips or strings, e.g. tear strips or strings
    • B31B50/8126Applying strips or strings, e.g. tear strips or strings parallel to the direction of movement of the webs or the blanks

Definitions

  • the present invention relates to a method of applying an edge-sealing strip of a first thermoplastic material to an edge of a packaging laminate web.
  • the packaging laminate web comprises at least the following layers: a first outer layer of said first thermoplastic material, a layer of paper or paperboard, a tie layer of a thermoplastic, a layer of an induction heatable material, and a second outer layer of the first thermoplastic material.
  • the first outer layer constitutes the so-called decorative artwork side of the web, i.e. that side which forms the outside of the future package.
  • the second outer layer constitutes the so-called product side of the web, i.e. that side which will become the inside of the package and thereby will be in contact with the product.
  • the tie layer of thermoplastic material may be of the same type as the first thermoplastic material, but it may also be of a different type.
  • the induction heatable layer may consist of a metal layer, a metal oxide layer or the like. For example, an aluminium foil may be employed.
  • the edge-sealing strip is intended to prevent the product, in a package subsequently formed from the packaging laminate web, running the risk of penetrating in between the layers included in the packaging laminate or running the risk of being sucked into the paper or paperboard layer, so-called edge wi eking.
  • the present invention also relates to an apparatus for realising the method.
  • the seal is strong and tight at least on the product side of the laminate. That it is "strong” implies in principle that the seal proper may not rupture in a tensile test. An eventual breakage or rupture is, if it nevertheless occurs, to occur beside the seal or in some other layer of the laminate.
  • the edge-sealing strip is to surround the paper edge tightly in order not to run the risk of giving rise to edge wicking in top and bottom seals in the intended package.
  • edge-sealing strip On application and sealing of an edge-sealing strip to a packaging laminate web, use is normally made today of a hot air oven for initially heating the edge of the web to a temperature at least above the melting temperature of the first thermoplastic. The strip is subsequently applied on the web and the heat in the edge melts the strip. Thereafter, the edge with the strip is rolled in order to achieve a positive fixing. The edge-sealing strip is not heated up prior to the application, and so all of the energy which is required in order to realise a sufficiently strong seal must come from the packaging laminate. This implies that the packaging laminate needs to be overheated so much that the thermal energy in its product side, and in certain cases also the decorative artwork side, will be sufficient to elevate the temperature in the strip above its melting point.
  • T sealing layer in hot air oven T melting point outer plastic layer + ⁇ T melting energy for strip + ⁇ T cooling distance
  • thermoplastic layer of the laminate consists of a thermoplastic material whose melting point lies below that of the first thermoplastic material, i.e. in the strip and the outer laminate plastic layers.
  • PP polypropylene
  • PP is a material which, int. al. for reasons of mechanical strength and aesthetic appearance, is eminently suitable as an outer material in a packaging laminate. If PP is selected as material in the outermost layers in the laminate, this implies that the edge-sealing strip as well, for reasons of adhesion, should also consist of this material.
  • PP has a melting point which is comparatively quite high, approx. 16O 0 C.
  • PE polyethylene
  • the melting point of PE is approx. HO 0 C.
  • the combination of PP in outer layers and PE in interjacent layers will thereby become even more intractable.
  • the temperature in the hot air oven must lie substantially higher than that at which the PE material melts, and this results in the interjacent layer running the risk of being exposed to heat to an excessively high degree, with severe delamination as a result.
  • one object of the present invention to propose a method by means of which this undesirable high thermal exposure is avoided and in which the consequential problems related thereto may thus be avoided.
  • This object is attained according to the present invention by means of the following steps: advancing the edge of the packaging laminate web through a hot air oven for heating of the edge at least to tacking temperature, tack adhering the edge-sealing strip at least adjacent the edge on the product side of the web, advancing the edge with the tack adhered edge- sealing strip through an induction oven where the active element of the induction oven is turned to face at least towards the product side of the web, and positively pressing together the edge and the strip.
  • the method includes the step of positively compressing the edge and the strip by rolling. Under the action of the heat in the material, the rolling ensures that both of the parts will be completely sealed to one another. This a relatively simple and reliable technique for achieving a strong and homogenous seal and for obviating the risk of the occurrence • of enclosure pockets or gap formations.
  • the method includes the step of folding the edge-sealing strip through approximately 180°, before the tack adhesion, for the formation of a U in order, in conjunction with the adhesion, to permit the U to be adhered to both the product side and the decorative artwork side of the packaging laminate web.
  • the edge-sealing strip may simply be united to both sides of the packaging laminate in one operation in order, in a subsequent operation, to be integrated with the laminate.
  • the apparatus includes a hot air oven for heating the edge of the packaging laminate web to at least tacking temperature, means for moving an edge-sealing strip into contact with the edge of the packaging laminate web for tack adhesion, an induction oven for heating the edge of the packaging laminate web and the edge-sealing strip tack adhering thereto, and means for positively compressing the edge and the strip together.
  • the induction oven includes an active induction element turned to face at least towards the product side of the web.
  • the apparatus includes means for folding the edge-sealing strip through approximately 180° for the formation of a U for refolding around the edge, such means being placed so that the folding takes place before the strip comes into contact with the edge.
  • the edge-sealing strip will be formed so that, in connection with a subsequent light compression at the packaging laminate edge, it will surround the latter edge in a reliable, symmetric and satisfactory manner.
  • the apparatus includes means for rolling the region comprising the edge of the packaging laminate web provided with the edge-sealing strip.
  • Fig. 1 schematically shows a view of a web of a packaging laminate and, along its one edge, an apparatus for applying an edge-sealing strip.
  • Fig. 1 shows the principle for application of an edge-sealing strip according to the invention.
  • An edge-sealing strip 1 of a thermoplastic material for example PP
  • the laminate material has a decorative artwork side and a product side which each include an outer layer of a thermoplastic material.
  • Said thermoplastic material is of the same type as in the edge-sealing strip 1.
  • the edge 2 of the packaging laminate web 3 is heated up to a temperature at which it can tack adhere to an edge-sealing strip at room temperature merely in that they are brought into contact with one another.
  • the reason why the temperature must, however, be slightly higher than the tacking temperature is that a part of the energy in the edge 2 will, in connection with the adhesion, be transferred into the edge- sealing strip 1.
  • the edge-sealing strip 1 is set in motion at a speed which corresponds to the speed of the packaging laminate web 3. This motion is put into effect by the intermediary of rotary bending rollers 5, 6 which are driven by the movement of the laminate web.
  • the first bending roller 5 is of such a type that the strip 1 centres itself on its running surface.
  • the second bending roller 6 displays a configuration which permits the strip 1 to have, prior to the tack adhering, a U- shaped form which closely approaches the edge of the laminate web 3.
  • single clamping rollers 7 are provided. These act on the sides of the packaging laminate web 3 and the strip 1.
  • the clamping rollers 7 act to ensure that the tack adhesion of the edge-sealing strip takes place at as large a surface of the edge 2 of the packaging laminate web 3 as possible. Thereafter, the laminate web 3 runs together with the edge-sealing strip 1 adhering thereto into an induction heating oven 8.
  • Induction sealing is a known technique and will not be described in greater detail here.
  • the induction oven includes an induction element (not shown).
  • the induction element consists of two interconnected coils, where the one acts on the decorative artwork side and the other acts on the product side. It is most crucial that the sealing on the product side is strong, so in principle it would be sufficient to have a coil on the product side, but is preferable to have a coil from each side in order to achieve a uniform distribution of heat.
  • the laminate web 3 with the edge-sealing strip 1 is heated up to a temperature at which the strip is fused together with the outer layer of the packaging laminate.
  • the integrated material is fed into a further, final station 9 in which it is rolled together in order, at the prevailing elevated temperature, moreover to be positively compressed together a last time.
  • the material is thereby ready for future process steps in the form of, for example, reforming into packaging sleeves.
  • the material will be subjected to an overlapping longitudinal seal where the edge provided with the strip overlaps the opposing longitudinal edge of the material in a seal, This overlap is made so that the edge with the strip is disposed on the inside of the contemplated package.
  • the product side of the edge provided with the strip will thus be in contact with the product, while its decorative artwork side will be sealed to the product side at the opposing edge. If, the strip portion which is located on the decorative artwork side will thereby not to have adhered as well as the strip portion on the product side on strip sealing, that part of the strip will be given another opportunity to be sealed in connection with the overlapping longitudinal sealing.
  • the edge-sealing strip 1 is initially only applied adjacent the edge on the one side of the packaging laminate web 3, the product side.
  • This application of the present invention is best suited for packaging laminate webs which, in a subsequent working phase, are to be formed into a tube (not shown) for continuous filling and transverse sealing.
  • the laminate web 3 will, once the edge-sealing strip has been applied, display a strip portion projecting out from the edge of the laminate web 3.
  • this is of no major importance, since a tube forming of the packaging laminate web 3 takes place shortly after the application of the edge-sealing strip 1.

Abstract

The disclosure relates to a method of applying an edge-sealing strip (1) of a first thermoplastic material to an edge (2) of a packaging laminate web (3). It comprises the steps of advancing the edge (2) of the packaging laminate web (3) through a hot air oven (4) for heating the edge (2) at least to tacking temperature, tack adhering the edge-sealing strip (1) at least adjacent the edge (2) on the product side of the web (3), feeding the edge (2) with the tack adhered edge-sealing strip (1) through an induction oven (8) where the active element of the induction oven (8) is turned to face at least towards the product side of the web (3), and positively compressing the edge (2) and the strip (1) together. The present invention further relates to an apparatus.

Description

A METHOD AND AN APPARATUS FOR APPLYING A STRIP
TECHNICAL FIELD
The present invention relates to a method of applying an edge-sealing strip of a first thermoplastic material to an edge of a packaging laminate web. The packaging laminate web comprises at least the following layers: a first outer layer of said first thermoplastic material, a layer of paper or paperboard, a tie layer of a thermoplastic, a layer of an induction heatable material, and a second outer layer of the first thermoplastic material. The first outer layer constitutes the so-called decorative artwork side of the web, i.e. that side which forms the outside of the future package. The second outer layer constitutes the so-called product side of the web, i.e. that side which will become the inside of the package and thereby will be in contact with the product. The tie layer of thermoplastic material may be of the same type as the first thermoplastic material, but it may also be of a different type. The induction heatable layer may consist of a metal layer, a metal oxide layer or the like. For example, an aluminium foil may be employed.
The edge-sealing strip is intended to prevent the product, in a package subsequently formed from the packaging laminate web, running the risk of penetrating in between the layers included in the packaging laminate or running the risk of being sucked into the paper or paperboard layer, so-called edge wi eking. The present invention also relates to an apparatus for realising the method.
BACKGROUND OF THE INVENTION
For a strip edge seal to be approved, it is required that the seal is strong and tight at least on the product side of the laminate. That it is "strong" implies in principle that the seal proper may not rupture in a tensile test. An eventual breakage or rupture is, if it nevertheless occurs, to occur beside the seal or in some other layer of the laminate. Moreover, the edge-sealing strip is to surround the paper edge tightly in order not to run the risk of giving rise to edge wicking in top and bottom seals in the intended package.
On application and sealing of an edge-sealing strip to a packaging laminate web, use is normally made today of a hot air oven for initially heating the edge of the web to a temperature at least above the melting temperature of the first thermoplastic. The strip is subsequently applied on the web and the heat in the edge melts the strip. Thereafter, the edge with the strip is rolled in order to achieve a positive fixing. The edge-sealing strip is not heated up prior to the application, and so all of the energy which is required in order to realise a sufficiently strong seal must come from the packaging laminate. This implies that the packaging laminate needs to be overheated so much that the thermal energy in its product side, and in certain cases also the decorative artwork side, will be sufficient to elevate the temperature in the strip above its melting point. This results in the temperature in the laminate needing to be raised to a level which lies substantially above the melting point for the first thermoplastic material, For reasons of space and because of the risk of overheating, application of the edge-sealing strip cannot be put into effect immediately adjacent the hot air oven, for which reason the laminate will moreover be cooled down on its way between the hot air oven and the point of application. As a result of this situation, the laminate must be overheated further.
A symbolic temperature relation appears roughly as follows:
T sealing layer in hot air oven = T melting point outer plastic layer + ΔT melting energy for strip + ΔT cooling distance
However, overheating may be associated with certain problems. The laminated material as a whole is subjected to thermal expansion to different degrees. This results in tension in the laminate, which runs the risk of causing delamination. This results in undesirable and hardly controllable effects, not least regarding the longitudinal seal which is later to be carried out along the edge which is provided with the edge-sealing strip. Delamination, which causes the aluminium foil and adjacent plastic layers to loosen from the paper- or paperboard material will, for example, have as a consequence that severe, unacceptable folds occur in the foil adjacent the strip sealing in connection with the application of the strip. If an attempt is made to remedy this situation by reducing the temperature in the hot air oven, the strength in the seal will be insufficient. In addition, overheating becomes particularly problematical when the interjacent thermoplastic layer of the laminate consists of a thermoplastic material whose melting point lies below that of the first thermoplastic material, i.e. in the strip and the outer laminate plastic layers. For example, polypropylene (PP) is a material which, int. al. for reasons of mechanical strength and aesthetic appearance, is eminently suitable as an outer material in a packaging laminate. If PP is selected as material in the outermost layers in the laminate, this implies that the edge-sealing strip as well, for reasons of adhesion, should also consist of this material. PP has a melting point which is comparatively quite high, approx. 16O0C. On the other hand, in many of today's packaging laminates, there are interjacent tie layers of polyethylene (PE). The melting point of PE is approx. HO0C. The combination of PP in outer layers and PE in interjacent layers will thereby become even more intractable. In order to achieve a sufficiently strong seal, the temperature in the hot air oven must lie substantially higher than that at which the PE material melts, and this results in the interjacent layer running the risk of being exposed to heat to an excessively high degree, with severe delamination as a result.
SUMMARY OF THE INVENTION
It is, therefore, one object of the present invention to propose a method by means of which this undesirable high thermal exposure is avoided and in which the consequential problems related thereto may thus be avoided. This object is attained according to the present invention by means of the following steps: advancing the edge of the packaging laminate web through a hot air oven for heating of the edge at least to tacking temperature, tack adhering the edge-sealing strip at least adjacent the edge on the product side of the web, advancing the edge with the tack adhered edge- sealing strip through an induction oven where the active element of the induction oven is turned to face at least towards the product side of the web, and positively pressing together the edge and the strip.
Employing this method, it is possible to reduce the cooling distances and this, together with the heating being put into effect in two stages, does not require overheating of the materials to the same extent as was necessary according to the prior art. The resultant negative effects are reduced and it will also be possible to employ the method according to the present invention for laminates with interjacent thermoplastic layers displaying a lower melting point than that of the outer thermoplastic layers. According to one preferred embodiment of the present invention, the method includes the step of positively compressing the edge and the strip by rolling. Under the action of the heat in the material, the rolling ensures that both of the parts will be completely sealed to one another. This a relatively simple and reliable technique for achieving a strong and homogenous seal and for obviating the risk of the occurrence of enclosure pockets or gap formations.
According to yet a further preferred embodiment of the present invention, the method includes the step of folding the edge-sealing strip through approximately 180°, before the tack adhesion, for the formation of a U in order, in conjunction with the adhesion, to permit the U to be adhered to both the product side and the decorative artwork side of the packaging laminate web. As a result, the edge-sealing strip may simply be united to both sides of the packaging laminate in one operation in order, in a subsequent operation, to be integrated with the laminate.
It is also an object of the present invention to propose an apparatus for reducing the method into practice. The apparatus is characterised in that it includes a hot air oven for heating the edge of the packaging laminate web to at least tacking temperature, means for moving an edge-sealing strip into contact with the edge of the packaging laminate web for tack adhesion, an induction oven for heating the edge of the packaging laminate web and the edge-sealing strip tack adhering thereto, and means for positively compressing the edge and the strip together. In one preferred embodiment of the apparatus according to the present invention, the induction oven includes an active induction element turned to face at least towards the product side of the web. It will hereby be ensured that the generated heat is principally emitted to the product side of the laminate where it is most essential to ensure that no enclosure pockets or channels are to be found. Preferably, use is made of an induction element comprising two coils where one is turned to face towards the product side and the other is turned to face towards the decorative artwork side, i.e. an inductor which acts on both sides of the laminate. In yet a further preferred embodiment of the present invention, the apparatus includes means for folding the edge-sealing strip through approximately 180° for the formation of a U for refolding around the edge, such means being placed so that the folding takes place before the strip comes into contact with the edge. As a result, the edge-sealing strip will be formed so that, in connection with a subsequent light compression at the packaging laminate edge, it will surround the latter edge in a reliable, symmetric and satisfactory manner.
According to still a further preferred embodiment, the apparatus includes means for rolling the region comprising the edge of the packaging laminate web provided with the edge-sealing strip.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present invention will now be described in greater detail liereinbelow, with reference to one embodiment shown on the accompanying Drawing. In the accompanying Drawing:
Fig. 1 schematically shows a view of a web of a packaging laminate and, along its one edge, an apparatus for applying an edge-sealing strip.
DETAILED DESCRIPTION OF ONE EMBODIMENT Fig. 1 shows the principle for application of an edge-sealing strip according to the invention. An edge-sealing strip 1 of a thermoplastic material (for example PP) is applied at one longitudinal side 2 belonging to a packaging laminate web 3. As was described by way of introduction, the laminate material has a decorative artwork side and a product side which each include an outer layer of a thermoplastic material. Said thermoplastic material is of the same type as in the edge-sealing strip 1.
In a hot air oven 4, the edge 2 of the packaging laminate web 3 is heated up to a temperature at which it can tack adhere to an edge-sealing strip at room temperature merely in that they are brought into contact with one another. This implies that the laminate edge need only be heated to a slightly higher temperature than that at which tacking is possible. The reason why the temperature must, however, be slightly higher than the tacking temperature is that a part of the energy in the edge 2 will, in connection with the adhesion, be transferred into the edge- sealing strip 1.
From a feeding device (not shown) running parallel with the packaging laminate web 3, the edge-sealing strip 1 is set in motion at a speed which corresponds to the speed of the packaging laminate web 3. This motion is put into effect by the intermediary of rotary bending rollers 5, 6 which are driven by the movement of the laminate web. The first bending roller 5 is of such a type that the strip 1 centres itself on its running surface. The second bending roller 6 displays a configuration which permits the strip 1 to have, prior to the tack adhering, a U- shaped form which closely approaches the edge of the laminate web 3. Immediately after the bending roller 6, single clamping rollers 7 are provided. These act on the sides of the packaging laminate web 3 and the strip 1. The clamping rollers 7 act to ensure that the tack adhesion of the edge-sealing strip takes place at as large a surface of the edge 2 of the packaging laminate web 3 as possible. Thereafter, the laminate web 3 runs together with the edge-sealing strip 1 adhering thereto into an induction heating oven 8. Induction sealing is a known technique and will not be described in greater detail here. However, the induction oven includes an induction element (not shown). In this preferred embodiment, the induction element consists of two interconnected coils, where the one acts on the decorative artwork side and the other acts on the product side. It is most crucial that the sealing on the product side is strong, so in principle it would be sufficient to have a coil on the product side, but is preferable to have a coil from each side in order to achieve a uniform distribution of heat.
In the oven 8, the laminate web 3 with the edge-sealing strip 1 is heated up to a temperature at which the strip is fused together with the outer layer of the packaging laminate. In order to completely ensure that no gap or enclosure pocket runs the risk of occurring between the edge-sealing strip 1 and the packaging laminate, the integrated material is fed into a further, final station 9 in which it is rolled together in order, at the prevailing elevated temperature, moreover to be positively compressed together a last time.
The material is thereby ready for future process steps in the form of, for example, reforming into packaging sleeves. During these coming stages, it is highly likely that the material will be subjected to an overlapping longitudinal seal where the edge provided with the strip overlaps the opposing longitudinal edge of the material in a seal, This overlap is made so that the edge with the strip is disposed on the inside of the contemplated package. The product side of the edge provided with the strip will thus be in contact with the product, while its decorative artwork side will be sealed to the product side at the opposing edge. If, the strip portion which is located on the decorative artwork side will thereby not to have adhered as well as the strip portion on the product side on strip sealing, that part of the strip will be given another opportunity to be sealed in connection with the overlapping longitudinal sealing.
In one alternative embodiment of the present invention, it is possible that the edge-sealing strip 1 is initially only applied adjacent the edge on the one side of the packaging laminate web 3, the product side. This application of the present invention is best suited for packaging laminate webs which, in a subsequent working phase, are to be formed into a tube (not shown) for continuous filling and transverse sealing. In this case, the laminate web 3 will, once the edge-sealing strip has been applied, display a strip portion projecting out from the edge of the laminate web 3. However, this is of no major importance, since a tube forming of the packaging laminate web 3 takes place shortly after the application of the edge-sealing strip 1. However, in order to make possible an application of the edge-sealing strip 1 only at one side of the packaging laminate web 3, it is necessary that the arrangement of the rotary bending rollers 5, 6 according to the above-described embodiment be modified. Without going into greater detail as to how this is appropriately to be put into effect, in principle it is a matter of ensuring that the edge-sealing strip is fed transversely to the surface of the web 3 and that, in association with the region where it is to be applied, it is passed over a bending/compression roller (not shown) which angles the edge- sealing strip 1 through 90° so that the packaging laminate web 3 and the edge-sealing strip 1 are brought together for the formation of a tack adhesion of the same type as described above. In all other respects, the method according to this embodiment corresponds to that previously described.
The present invention should not be considered as restricted by the foregoing description, but only by the scope of the appended Claims.

Claims

CLAIMS:
1. A method of applying an edge-sealing strip (1) of a first thermoplastic material to an edge (2) of a packaging laminate web (3), said laminate web comprising at least the following layers: a first outer layer of said first thermoplastic material, a layer of paper or paperboard, a tie layer of a thermoplastic, a layer of an induction heatable material, as well as a second outer layer of the first thermoplastic material, characterised by the steps of: advancing the edge (2) of the packaging laminate web (3) through a hot air oven (4) for heating the edge (2) at least to tacking temperature, tack adhering the edge-sealing strip (1) at least adjacent the edge (2) on the product side of the web (3), feeding the edge (2) with the tack adhered edge-sealing strip (1) through an induction oven (8) where the active element of the induction oven (8) is turned to face at least towards the product side of the web (3), and positively compressing the edge (2) and the strip (1) together.
2. The method as claimed in Claim 1, characterised by the step of positively compressing the edge (2) and the strip (1) together by rolling.
3. The method as claimed in Claim 2, characterised by the step of folding the edge-sealing strip (1) approx. 180°, prior to the tack adhering, for the formation of a U in order, in connection with the adhering, to permit adhering thereof to both the product side and the decorative artwork side of the packaging laminate web (3).
4. An apparatus for applying an edge-sealing strip (1) of a first thermoplastic material to an edge of a packaging laminate web (3), said laminate web comprising at least the following layers: a first outer layer of said first thermoplastic material, a layer of paper or paperboard, a tie layer of a thermoplastic, a layer of an induction heatable material, as well as a second outer layer of the first thermoplastic material, characterised in that the apparatus comprises: a hot air oven for heating the edge of the packaging laminate web (3) to at least tacking temperature, means for moving an edge-sealing strip (1) into contact with the edge (2) of the packaging laminate web (3) for tack adhering, an induction oven (8) for heating the edge (2) of the packaging laminate web (3) and the edge-sealing strip (1) tack adhered thereto, and means for positively compressing the edge (2) and the strip (1) together.
5. The apparatus as claimed in Claim 4, characterised in that the induction oven includes an active induction element facing at least towards the product side of the web,
6. The apparatus as claimed in Claim 4, characterised in that it includes means (6) for folding the edge-sealing strip approximately 180° for the formation of a U for folding around the edge (2), and that said means is placed so that the folding takes place before the strip comes into contact with the edge (2).
7. The apparatus as claimed in Claim 6, characterised in that it includes means for rolling the region comprising the edge (2) of the packaging laminate web (3) provided with the edge-sealing strip (1).
PCT/SE2006/001069 2005-10-11 2006-09-20 A method and an apparatus for applying a strip WO2007043931A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0502237-1 2005-10-11
SE0502237A SE529188C2 (en) 2005-10-11 2005-10-11 Method and apparatus for applying strip

Publications (1)

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WO2007043931A1 true WO2007043931A1 (en) 2007-04-19

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WO (1) WO2007043931A1 (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3081213A (en) * 1958-05-02 1963-03-12 Union Carbide Corp Edge coating
US3456863A (en) * 1967-06-14 1969-07-22 Inland Container Corp Wrapped edge manufacturer's joint
US4721242A (en) * 1985-06-04 1988-01-26 Tetra Pak Finance & Trading S.A. Pack for liquids having edge protection, process for the production thereof and apparatus for carrying out the process
DE4409255A1 (en) * 1994-03-18 1995-09-21 Rovema Gmbh Folded carton for e.g. liq. and powder prods.
EP0763472A1 (en) * 1994-05-23 1997-03-19 Tetra Laval Holdings & Finance SA Plastic coated paper container with cut edges protected against moisture
US5620135A (en) * 1994-04-07 1997-04-15 Ruediger Haaga Gmbh Container

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3081213A (en) * 1958-05-02 1963-03-12 Union Carbide Corp Edge coating
US3456863A (en) * 1967-06-14 1969-07-22 Inland Container Corp Wrapped edge manufacturer's joint
US4721242A (en) * 1985-06-04 1988-01-26 Tetra Pak Finance & Trading S.A. Pack for liquids having edge protection, process for the production thereof and apparatus for carrying out the process
DE4409255A1 (en) * 1994-03-18 1995-09-21 Rovema Gmbh Folded carton for e.g. liq. and powder prods.
US5620135A (en) * 1994-04-07 1997-04-15 Ruediger Haaga Gmbh Container
EP0763472A1 (en) * 1994-05-23 1997-03-19 Tetra Laval Holdings & Finance SA Plastic coated paper container with cut edges protected against moisture

Also Published As

Publication number Publication date
SE529188C2 (en) 2007-05-22
SE0502237L (en) 2007-04-12

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