APPARATUS AND METHOD FOR MANUFACTURING A WRAPPED ENDLESS ROD OF SUBSTANTIALLY FLAT CONTINUOUS MATERIAL

Abstract

The method for manufacturing a wrapped endless rod of substantially flat continuous material comprises the steps of providing a substantially flat continuous material, treating the substantially flat continuous material with corona discharge and forming the corona treated substantially flat continuous material into an endless rod. Further steps comprise providing a wrapper, applying adhesive to the wrapper and wrapping the endless rod with the wrapper. Therein the step of applying adhesive to the wrapper comprises applying adhesive over a width of the wrapper and in a central portion of the wrapper.

Claims

1. Method for manufacturing a wrapped endless rod of substantially flat continuous material, the method comprising the steps of: providing a substantially flat continuous material; treating the substantially flat continuous material with corona discharge; forming the corona treated substantially flat continuous material into an endless rod; providing a wrapper; applying adhesive to the wrapper, and wrapping the endless rod with the wrapper, wherein the step of applying adhesive to the wrapper comprises applying adhesive over a width of the wrapper and in a central longitudinal portion of the wrapper, and comprises applying the adhesive in several strips over a length of the wrapper.

2. Method according to claim 1, comprising the step of guiding the substantially flat continuous material between electrode and counter electrode of a corona module.

3. Method according to claim 1, corona treating the substantially flat continuous material during a treatment time in a range between 0.001 seconds and 2 seconds.

4. Method according to claim 1, comprising the step of corona treating one side of the substantially flat continuous material and subsequently corona treating the other side of the substantially flat continuous material.

5. Method according to claim 1, wherein a strip of adhesive is applied along the longitudinal central axis of the wrapper.

6. Method according to claim 1, wherein several strips are arranged in parallel.

7. (canceled)

8. (canceled)

9. Method according to claim 1, wherein the substantially flat continuous material is a plastics material, for example polylactic acid.

10. Method according to claim 1, applying one type of adhesive to the central longitudinal portion of the wrapper and another type of adhesive to a seam portion of the wrapper.

11. Consumable comprising a segment of a wrapped endless rod manufactured according to the method according to claim 1.

12. (canceled)

13. Apparatus for manufacturing a wrapped endless rod of substantially flat continuous material, wherein the apparatus is programmed to perform the method according to claim 1, the apparatus comprising: a rod-forming unit for shaping a substantially flat continuous material into an endless rod; a wrapping device for providing a wrapper and for wrapping the endless rod with the wrapper; an adhesive applicator for applying an adhesive to the wrapper, wherein the adhesive applicator is arranged for applying adhesive to a central portion of the wrapper; a corona module arranged upstream of the rod-forming unit for corona treating the substantially flat continuous material.

14. Apparatus according to claim 13, wherein an electrode of the corona module has a lateral size corresponding to a width of the substantially flat continuous material to be corona treated.

15. Apparatus according to claim 13, wherein a distance between electrode and counter electrode is in a range between 0.1 millimeter and about 25 millimeter.

16. Apparatus according to claim 13, wherein the corona module comprises a first module portion and a second module portion, the first module portion and the second module portion each comprising an electrode-counter electrode pair, wherein the electrode-counter electrode pair of the first module portion is arranged and powered to enable corona treatment of one side of the substantially flat continuous material and the electrode-counter electrode pair of the second module portion is arranged and powered to enable corona treatment of the other side of the substantially flat continuous material.

17. Apparatus according to claim 16, wherein at least one module portion comprises two electrodes arranged next to each other in a transport direction of the substantially flat continuous material.

18. Apparatus according to claim 13, wherein the corona module comprises a high frequency generator for providing frequencies in a range between 10 kHz and 60 kHz and an alternating voltage between 15 kV and 40 kV.

Description

[0044] The invention is further described with regard to embodiments, which are illustrated by means of the following drawings, wherein:

[0045] FIG. 1 shows a schematic overview of an embodiment of a filter making apparatus including corona module;

[0046] FIG. 2 shows a defective semi-finished product;

[0047] FIG. 3 shows a corona module;

[0048] FIG. 4a,4b show different glue pattern;

[0049] FIG. 5 is a measurement set-up for anchoring measurements;

[0050] FIG. 6 depicts test results of anchoring measurements.

[0051] In the filter making apparatus schematically shown in FIG. 1, a substantially flat continuous material such as a web of material 1 is provided on a bobbin 10. When unwound from the bobbin 10, the web 1 is corona treated, folded and wrapped in the apparatus. In this embodiment, the web 1, for example a PLA film, passes a corona module 2 directly after having been unwound from bobbin 10. In the corona module 2, both sides of the web 1 are subsequently corona treated in two corona module portions 21,22. The corona module 2 is described in more detail with reference to FIG. 3. After corona treatment in the corona module 2, the web 1 passes a crimping device 4, for example a set of two crimping rollers. The crimping device 4 provides the web 1 with a crimping structure, for example with substantially parallel corrugations running, preferably, in longitudinal direction of the web, that is, in transport direction of the web 1. The web 1 then passes a shaping device. The shaping device comprises shaping rollers 50, preferably providing the crimped web 1 with a longitudinally running wave-like macro structure overlaying the crimping micro structure. Imposing the overlaying macro structure onto the web 1 causes the web 1 to be pushed together in a transverse direction of the web. In addition, a gathering of the web 1, for example into a rod shape, is supported by the longitudinal wave-like structure and may be performed in a more controlled manner. The shaping device also comprises a funnelling device 51 arranged downstream of the shaping rollers 50. In the funnelling device 51, the web 1 is further shaped into rod-shape, for example by gathering or pushing together. Preferably, when leaving the funnelling device 51, the web 1 has not yet achieved its final form, or is not entirely gathered, respectively. This facilitates the introduction of an object, such as a capsule or flavoured thread 71, into the endless rod of web material. A flavour application system 7 comprising an endless thread 71 and a flavour reservoir 72 is arranged downstream of the shaping device. The thread 71 is mounted on a bobbin 70. Preferably, the flavour reservoir 72 contains menthol. The thread 71 is unwound from the bobbin 70 and entrained with flavour before being transported to the gathered web 1. The flavour application system 7 may be provided with at least one of a flow meter, a valve, a temperature control and a pump for control and provision of a defined amount of flavour to be applied to the thread 71. The flavour application system 7 is arranged above the web 1 in order for gravity to support the introduction of the thread into the web. Gravity may also support a flow of flavouring liquid along the thread 71. Alternatively, or in addition, flavour may be added separately from the thread 71 or may be entirely omitted. In that case, the presence of the thread may have mostly an aesthetic contribution to the aerosol-generating article.

[0052] An endless wrap material 6, for example paper, is provided on a bobbin 60 and supplied from below the endless rod such that the endless rod of web material comes to lie on the wrap material 6. The wrap material 6 runs parallel to the endless rod when being joined with the rod. Before the wrap material 6 and the endless rod are joined, the wrap material is provided with glue. A glue reservoir 62 is in fluid connection with a seam nozzle 64 as well as with an anchor nozzle 63. Glue from the glue reservoir 62 is transported via a glue conduit, for example a tube, to the anchor nozzle and the seam nozzle. With the anchor nozzle 63, anchoring glue is applied to the wrap material, preferably, in a more central region of the wrap material 6. Preferably, anchoring glue is applied in lines transverse to the wrap material 6. The lines or anchoring glue, respectively, are provided for contacting the web material such that the wrapper is securely glued to the web material—thus the rod material is anchored in the wrapper. With the seam nozzle 64, seam glue is applied to the wrap material 6, preferably, along a lateral side of the wrap material 6. Preferably, the seam glue is applied in one longitudinal line, preferably one continuous line. The longitudinal line is provided for gluing the wrap material to itself after the wrap material has been entirely wrapped around the endless rod of web material. Thus, the wrap material forms a secure and preferably continuous seam.

[0053] Preferably, the glue reservoir 62 contains a liquid glue, which may be used for both the anchoring and the seaming of the wrap material. However, if different glue shall be used, a reservoir each for the anchoring and for the seaming may be provided. Different glues may be advantageous, for example, if a wrap material is a paper wrapper and paper glue shall be used for the seam and if, for example, specific plastics glue shall be used for the anchoring of the wrapper to a plastics web material of the endless rod. Also, glues may vary with respect to the settling time for the glue. For example a polyurethane glue and a hot-melt glue may be used for different purposes.

[0054] The so wrapped endless rod of web material may be guided in a rod-shaped bed 52 passing a heating device 53 for heating the wrapped endless rod. The heating facilitates a distribution and fast drying of the glue. After the endless rod has been formed, it is cut in the cutting device 8 into rod segments of predefined length, for example single or double length segments (having the length or the double length of a final product). The rod segments may be transported to a tray or storage 91. The rod segment may also directly be transported to a combiner 92 for being combined with further elements, for example further filter elements or segments of, for example, aerosol generating articles.

[0055] An online control unit 90 is provided after the endless rod has been cut into segments for a quality control of the manufactured segments. At the location of the tray 91, there may be provided an offline control unit 93. An online control unit 90 and offline control unit 93 may, for example, include a length control, diameter control, a weight control, ovality control, a control of the resistance to draw (RTD), the thread centering and other visual quality aspects of the semi-finished or finished good. The offline control unit 93 may for example also be provided with a measuring device for a menthol content or other substances in the rod segment. In the tray 91, the segments may be labelled, for example with a batch number, production date or product code, for example, for tracking of the products.

[0056] Preferably, tension rollers 30 and driving rollers 31 are provided in the apparatus for a controlled transport of the web of material 1 and a continuous, preferably constant, tensioning of the web. Synchronization means may be provided between crimping device 4 and a transport means such as a continuous belt, for example, at the position of the online control unit 90. By the synchronization means a linear speed of the endless rod and of the yet to be gathered substantially flat continuous material fed into the crimping device 4 may be synchronized.

[0057] Instead of having an apparatus, where the corona treatment is performed inline, a base material may also be corona treated previously and then supplied to the filter making apparatus.

[0058] FIG. 2 schematically shows a semi-finished product manufactured from rod segments, for example as produced in an apparatus similar as shown in FIG. 1, however without the corona module and without corona treating of the PLA foil. Two rod segments comprising a plug of PLA foil 1 wrapped with a paper wrapper 6 are aligned with their longitudinal axis with a further rod-shaped segment 11 arranged in between the PLA plugs. The further rod-shaped segment 11 may be a further filter element or may also be a plug of an aerosol-forming substrate, for example a tobacco plug. The further rod-shaped segment 11 is a double segment and combined with the two rod segments with an additional wrapper 13. During the combining step, the weak adhesion between PLA plug 1 and paper wrapper 6 makes the plug shift in the wrapper 6 by a shift distance 12. Such a shift distance may be up to a several millimetres. If a shift distance 12 is above a predefined distance, the product is typically regarded as being defective and will be removed.

[0059] In FIG. 3 a PLA film 1 is guided through a corona module 2 comprising two corona module portions 21, 22. The PLA film may be guided via guide rollers 200 into and out of the corona module 2. The set-up of the two corona module portions 21, 22 is substantially identical. The two corona module portions 21, 22 are arranged such that the PLA film is guided through the module portions 21, 22 in an s-form such that one side of the PLA film is corona treated in the first module portion 21. The other side of the PLA film is corona treated in the second module portion 22 arranged downstream and subsequently to the first module portion 21. A corona module portion 21,22 comprises a transport drum 20,23 as a counter-electrode. Preferably, transport drum 20,23 is at ground potential. The PLA foil 1 substantially performs a U-turn and lies closely against the transport drum 22,23 when being guided around the transport drum 20,23. A corona module portion also comprises an electrode 212,222 connected to a power generator unit 211,221 providing power and frequency of a voltage applied to the electrode 212,222. Electrode 212,222 and power generator 211,221 are arranged in a housing 210,220. The housing 210,220 is movably mounted for being moved away and towards the transport drum 20,23 for mounting and maintenance purposes. Preferably, the distance between electrode 212, 222 and counter electrode 20,23 may be set by the movable housing 210,220. The retracted positions of the housing is indicated with dotted lines 2100,2200. The electrode 212,222 comprises a concave shape corresponding to the circumference of the transport drum 20,23. The PLA foil 1 is guided between electrode 212,222 and counter electrode 20,23 and may thereby be corona treated on the side of the PLA foil facing the respective electrode.

[0060] In FIGS. 4a and 4b sections of an endless wrap material 6 are shown. Individual strips of adhesive 630 are applied along the width 602 of the wrap material 6. The strips 630 are intended for an anchoring of the wrap material 6 to the web material 1. The strips 630 do not extend entirely up to the lateral edges of the wrap material, such as not to cover a seam region for a wrapper seam or a seam glue line applied in the seam region, respectively. However, when being wrapped around a rod-shaped PLA plug, the strips preferably extend along the entire circumference of the PLA plug.

[0061] If the anchoring strips 630 are also used for a seam of the wrap material 6, the strips may also extend up to the lateral edges of the wrap material.

[0062] The strips 630 are applied and distributed along the length of the wrap material. Preferably, they are arranged equidistantly over the length of the wrap material 6. Individual wrapper segments 601 are indicated by cutting lines 80,81. The cutting lines 80,81 correspond to a position the endless rod is subsequently cut into rod segments. Preferably, a strip pattern has predetermined values of, for example, the distances between strips, the number of strips and the width of strips. Preferably, the predetermined values are selected according to a length 603 of an individual wrapper segment 601.

[0063] In FIG. 4a, two strips 630 per wrapper segment 601 are provided, while the wrap material 6 is cut between strips. In FIG. 4b, only one strip 630 at half length of the wrap material 6 per segment is provided.

[0064] A width 602 of the wrap material 6 may be between 23 millimeter and 30 millimeter, for example 28 millimeter. A length 603 of the individual wrapper segments may be between 8 millimeter and 20 millimeter, for example 12 millimeter. A width between strips 630, where one strip per wrapper segment is provided is preferably identical to a wrapper segment length 603. However, all these values may be adapted to a cross section and length of a rod segment to be cut from the endless rod of web material and to be wrapped in a wrapper segment 601.

[0065] FIG. 5 shows a measurement set-up for measuring an anchoring of a PLA rod 1 in its plug wrapper 6. For this measurement the wrapped PLA plug is pierced onto a pin 18 provided with an extended base. An adhesive tape 18 is attached to the wrapper 6. Preferably, the adhesive force between adhesive tape 18 and wrapper 6 is stronger than an adhesive force between wrapper 6 and PLA plug 1. Pin 1 and adhesive tape 18 are each fixedly held in a force measurement device 16, for example, dynamometer grip cells. The two dynamometers pull at the tape and the plug in opposite directions as indicated by arrows 17.

[0066] In FIG. 6 results of PLA anchoring measurements performed with the set-up as shown in FIG. 5 are depicted. FIG. 6 shows that the anchoring strength can be improved by the corona treatment, when comparing samples of non-corona treated PLA foil 15 and corona treated PLA foil 65. Routinely, a doubling or tripling of the anchoring strength may be achieved by the corona treatment of the PLA foil. An additional effect is apparent between different glue patterns 631 provided on the paper wrapper 6. Random spiral, double longitudinal strips and square or transverse strips show enhanced anchoring compared to the commonly used single longitudinal strip 170. If corona treatment is combined with a dedicated glue pattern, anchoring strength may significantly be enhanced and a number of defective products may significantly be reduced.

[0067] The amount of defective semi-finished products (as shown in FIG. 2) comprising non-corona treated polylactic acid foil glued to a paper wrapper provided with one longitudinal glue line along the central axis of the wrapper have been compared with the amount of defective semi-finished products comprising corona treated polylactic acid foil glued to a paper wrapper provided with glue strips extending transverse to the wrapper. Products were identified as defective if the shift distance 12 between PLA plug 1 and wrapper 6 amounted to more than 1 millimeter. Comparison showed that the number of defective products could be reduced by about 120 times (29 defective semi-finished products per one tray 91 compared to one defective semi-finished product per four trays 91).