BACKGROUND OF THE INVENTION It is conventional for cigarette packs, whether soft or rigid, to be overwrapped with a transparent layer of cellophane or similar material. Though this has some protective properties it does not seriously prolong shelf life, especially in adverse conditions such as those of very high or very low humidity. To gain access to the pack the user tears open and discards the transparent layer. EP-A-395249 however shows a transparent overwrap which is not entirely discarded.

The present invention, by contrast, is concerned with providing a barrier material layer, for example of metallized plastics or a plastics/metal laminate, which forms initially a sealed enclosure around the pack but is resealable; thus the protective barrier action remains available even after first use.

In US-A-5333729, Figs 11 and 12, a cuboid cigarette soft pack has a flap in the top face which on lifting tears away part of an overwrap layer. The flap may have permanently tacky adhesive so that it can be flattened down again onto the top face and reclose, to a certain extent, the hole it made in the barrier layer. Leak paths still exist, and it is not clear how the opening gives access to the contents of the pack.

We have previously proposed, in copending WO-A- 9822367 to provide a resealable barrier enclosure for a pack.

SUMMARY OF THE INVENTION In the present invention we are concerned to provide rigid packs, similar for example to the flip- top or shell and slide type, which include or are overwrapped with a sealed, openable and resealable barrier enclosure. We are also concerned to provide a machine adapted to handle such packs and include within them or overwrap them with, the barrier enclosure.

In the present invention, the position of the resealable aperture in relation to the cuboid rigid container is defined. It must extend over at least the top face and part of one major face of the pack. In this way an efficient, proper, access opening is available but is effectively hermetically resealable.

We also disclose in this invention a machine for applying the resealable layers to a barrier web and overwrapping rigid packs with it. A related machine is seen in our co-pending European Application 98306328.0 (EP-A-) where however what is overwrapped is a charge of smoking articles in an incomplete frame.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Figure 1 is a perspective view of a charge of cigarettes; Figures 2-6 show face views of respective carton blanks; Figures 7-10 are perspective views of cartons made up from the blanks and containing a charge of cigarettes; Figure 11 shows an overwrapped rigid pack; Figure 12 shows the pack of Figure 11 in an outer flip-top carton; Figures 13 and 14 are perspective views of a shell and slide carton containing a charge of cigarettes; Figure 15 is a side view of an enclosure- forming machine; and Figure 16 is a face view of a labelled barrier material web.

DESCRIPTION OF PARTICULAR EMBODIMENTS Figure 1 shows a charge of cigarettes 100 assembled in a conventional way and partly wrapped with a conventional foil/paper laminate 102 over approximately half of its length only. The foil having good dead fold characteristics will retain its form and the coherence of the charge of cigarettes in subsequent stages in which it is fed onto the sealer bed of a conventional carton erection packer where it is wrapped in a conventional manner with a carton formed from any of the blanks shown in Figures 2-6.

The blank in Figure 2 is essentially conventional for a rigid pack, with front and rear main panels 201,202 joined by hinge lines to a base panel 203 and a lid top panel 204. Between back panel 202 and top lid panel 204 is a lid back panel 205 and attached to the lid top panel 204 a lid front panel 206 with an extension tongue 207.

Side walls of the carton are to be formed by side panels 208 of the rear panel 201 being adhered or heat-sealed outside respective side panels 210 of the back panels 202 and side wings 211 of the lid being adhered or heat-sealed outside side panels 209 of the lid back panel 205, at cross-hatched areas shown in panels 209 and 210. End flaps 212 and 213 lie in the

erected carton inside base and lid top panels 203 and 204 respectively, and may be adhered or heat-sealed there. The extension tongue 207 is normally turned back and glued inside the lid front panel 206. Thus we get a rigid container.

Blanks giving greater stiffness in the made-up container are shown in Figures 3-6.

All of these allow for access to the cigarettes through a central opening in the lid and front panel, through a resealable barrier layer.

It will be seen in Figure 3 that side walls 215 of the rear panel 202 are continuous over the whole length of that rear panel, with end tabs 213'being abbreviated compared to tabs 213. This is because in lid top panel 204'cuts 216 define side portions 217 and a flap portion 218. The cuts 216 continue into the lid front wall 206, terminating in uncut pips 219 which are joined by U-shaped cut 220 in the material of the flap 206. Figure 4 has a continuation 207'of the front panel, which will overlie the front panel 201.

When these are made up, essentially in the same way as the conventional blank of Figure 2 with 208 and 211 adhered or heat-sealed over the cross-hatched area in the side walls 215, flaps 213'underlie and can be adhered or heat-sealed to side portions 217 of the lid

top panel. The continuity of side walls 215 gives greater rigidity to the carton which has the appearance of a hinged lid carton but which gives access to the cigarettes by opening the flap 218 in the top lid.

This is done after depressing the flap defined by cuts 220 and 216 to break the pips at 219.

The continuous side walls 215 are particularly useful if it is desired to use continuous side-sealing platforms during an overwrap procedure-compare side flaps 209,210 of Figure 2.

Figure 5 is similar to Figure 4 but has a front flap 206''with no side wings so that the appearance of a hingeable opening is not conveyed.

Figure 6 shows a modification of Figure 5 in which flap 218 is omitted, there being a permanent aperture 221 instead.

Figures 7 and 8 show how a pack is made up from the blanks of Figures 3 and 4 respectively, enclosing a charge as seen in Figure 1.

In Figure 7 the side panels 211 and 208, secured together to the continuous side flap 215, give the appearance of a flip-top pack. However, access to the cigarettes is gained by breaking the pips 219 and opening the flap portion 218. The pack in Figure 8 is similar, but shows the extension 207'overlapping part

of the front panel 201.

Figures 9 and 10 show a pack made up from the charge of Figure 1 and respectively the blank of Figure 6 and the blank of Figure 5.

The carton assembled from the blank of any of Figures 2 to 6 is now passed through a pre-severed and labelled barrier material seen in Figure 16, on a machine seen in Figure 15, both described more fully below. The result is a resealable rigid pack 225 of Figure 11, the barrier material 226 having been conventionally folded and secured by heat-sealing, such that its opening 227 resealable by permanently-tacky overlapping boundary portions of a label 228 overlies the access opening 221 or is adhered or heat sealed to the flap 218 which then opens with it.

Figure 12 shows how the overwrapped rigid pack of Figure 11 may if desired be further enclosed in a conventional"flip-top"outer container 229 which may have an inner frame 230. Before insertion of the overwrapped pack into the outer carton 229 or erection of that outer carton around it, a lift tab 231 of the resealable label, free from adhesion or heat-sealing, is lifted so as to present itself to the user when the flip-top lid 232 is opened, as shown in Figure 12.

Figures 13 and 14 show how an otherwise

conventional shell and slide carton 233 can be modified by cutting away part of the top front flap 234 in the slide and cutting a U portion 235 out of the shell, and then overwrapping as before to yield the pack 236 of Figure 14, analogous to pack 225. If the carton is to be erected on conventional machinery, the charge should be as in Figure 1.

As was disclosed in our WO-A-9822367, a hermetically resealable barrier enclosure can be provided by the application of a label 228 (Figure 16) on a web 226 of barrier material such as a plastics/foil laminate or metallized film, with permanently tacky adhesive on a margin 237 of the label around a potential opening through the barrier, defined by line of weakening 238. This line of weakening must correspond with the potential or actual aperture 218,221 in the rigid pack which the web 226 will overwrap. A foil cut pitch 239 is illustrated. Tab 231 is non-adhesive and is to assist the eventual user in lifting the label. The label guides the user when resealing the opening so that the barrier material re- fills that opening and only a cut line remains as a potential leak path. This is covered by the label and it permanently tacky adhesive region beyond the line effectively completely reseals the enclosure.

The cut pitch is provided by a main knife in the machine of Figure 15. A reel of foil 401 (preferably laminated foil) carried on a bobbin is mounted on a spindle. The foil is led over two rollers 402 and 403, one or both of which is held on the end of a pivoted spring loaded arm so as to be of the nature of a dance roller. One of the arms is fitted with a braking arrangement which, in the event of the foil becoming too slack as it is pulled off by pulling rollers, causes the brake to act against the spindle to restore the desired level of tension. Other methods of tension control can be used including electrical speed matching of a motor used to drive the reel compared to desired foil velocity determined by the pulling rollers.

The foil is led to the pulling rollers 405 via a series of idler rollers 404 which guide it clear of obstructions and across a table 406 which forms a platform for manual or an automatic splicing system (not shown), which is required to join the start of a new reel of foil to the end of a previous reel.

Should the foil used have a printed pattern on it the foil will have to be registered correctly to the pattern on the cutting roller 407 which forms the line of weakening 238 and the main cutting knife 408. To

achieve this, an encoder is used to determine the position of the cutting roller 407. The signal from this is compared to a registration mark on the foil which is detected before the pulling rollers. Any deviation from the desired comparison results in the speed of the pulling rollers being increased or decreased at a programmable rate to restore the desired comparison.

To ensure the foil is cut in the right position its length between the cutting roller 407 and the main knife 408 can be adjusted by moving the position of idler rollers 409 between them.

Soon after the cutting roller the label 228 is applied to the foil 226 by a conventional applicator 410. The label overlaps all sides of the line 238 defined by the rotary cutter. Both the tongue defined by the line of weakening or cut and the label pull tag 231 are best arranged to pass in the trailing rather than leading direction.

The foil with labels 228 on it is pulled through a further pair of drive rollers 411 and guided to the rotary main knife cutter 408 where it is cut to length immediately after it is impacted by a pack driven in the direction of arrow A. The pack, which continues to be moved forward by a pusher, has the ends

of the foil lap folded and its sides envelope-folded by an arrangement of tuckers and ploughs 414.

From this point on the foil-overwrapped packs are pushed one against another through a series of side, top and end heaters which seal the foil to itself and the foil to tongue shaped"notched"openings in the pack to enable it to be lifted when the label is lifted.

Typically, the side 412 and top heaters 413 may be of the reciprocating type as shown or may be belt or tractor heaters.

To enable lap end sealing, the wrapped packs are preferably elevated one at a time by a reciprocating lifting mechanism 415 to pass in front of a reciprocating heater 416.

They can then be taken in turn from the top of the four high stack to the next process which could be, for example, film overwrapping or card overwrapping.

The latter, if required, could take the form of a hinge lid box. If so the inner frame in the hinge lid box would be styled to accommodate the opening of the label in such a way that the tab of the label overlapped the inner frame to make it stand up to be easier to get hold of.

Before application to the film or before the

final overwrapping step, it may be desired to fold the pull tab 231 of the label back to enable its easier opening. If this is required the packs are pushed forward by a reciprocating pusher (into the paper) (not shown) and under a vacuum nozzle 417 which lifts the label tab and leads it under a plough (not shown) which it is pushed through by subsequent packs. The plough turns the tab right back on itself. The tab is then creased/tacked into position as it passes under a heater which presses down on it.

The process and equipment described above can be easily modified to provide for the manufacture of a resealable shell and slide arrangement of rigid pack.