GB2288310A

GB2288310A - Filter for smoking article

Info

Publication number: GB2288310A
Application number: GB9504611A
Authority: GB
Inventors: Edward Dennis John
Original assignee: Rothmans International Services Ltd; Rothmans International Ltd
Current assignee: Rothmans International Services Ltd; Rothmans International Ltd
Priority date: 1994-03-11
Filing date: 1995-03-08
Publication date: 1995-10-18
Also published as: JPH07298866A; GB9504611D0; AU1470695A; CA2144097A1; GB9404707D0; EP0671131A1

Description

2288310 1 FILTER FOR SMOKING ARTICLE AND SMOKING ARTICLE INCORPORATING IT

is This invention relates to a filter for a smoking article such as a cigarette, cigarillo or cigar (hereinafter referred to for brevity as a cigarette), as well as to a.cigarette incorporating it.

The problem faced by the invention is to provide within a given filter the possibility of varying the characteristics of the filter by a mechanical adjustment of its parts.

For this purpose the invention provides a. filter for or in a cigarette which comprises at least two filter portions of different characteristics, which are linked by a wrap which allows a change in the relative longitudinal positions of the two portions, the two portions being constructed such that the total filter characteristics to which smoke passing through the filter is subjected are different in different relative positions of the two portions. One of the two relative positions is preferably of axially abutting contact between ends of the portions.

In a preferred embodiment the two portions each have a plurality of coaxial regions, the regions in respective portions having differing characteristics, such that when the two portions are in one relative 2 is position smoke flow will be through one set of regions at least one member of which set is in one of the portions and another member in the other of the portions, but when the two portions are in the other relative position smoke flow will be preferentially through a second set of regions at least one member of which set is in one of the portions and another member in the other of the portions. The regions in one portion of the filter may be arranged such that an outer annular region has a lower flow resistance than an inner core region, while in another portion an inner core region has a lower flow of resistance than an outer annular region. one or more of the regions may be totally impermeable to.smoke or may be a void. The regions both within each portion and as between portions may vary as to one or more characteristics such as, for example, smoke'permeability; chemical activity; physical materials; content of additives such as perfumes; ventilation.

The portions are joined together by a wrap which is collapsible while maintaining its integrity, so as to allow the portions to alter their relative position, and preferably to be brought into axial abutment; there may be a guide sleeve to guide relative movement of the portions and to assist comparative rigidity of the filter when the portions are in a A is 3 spacedapart condition. The filter portions may move relative to each other by arranging that a wrap of one portion may slide over the other portion. Preferably, however, the wrap will be integral and, in the position of nearer approach of the two portions, in a bellows formation.

Particular embodiments of the inventon will now be described with reference to the accompanying drawings, wherein:

Figure 1 is a diametrical section through a filter end of a cigarette with the filter being in one condition; and Figure 2 is a similar section with the filter in a different condition.

In Figure 1 a tobacco rod 1 is surrounded by paper 2, joined by overwrap 3 to a filter structure 4. The filter structure has two axially aligned filter portions 5 and 6 which are respectively bonded at 7 and 8 to a plug wrap 9.

In the case of the filter portion 5 bonding 7 is via an intermediate sleeve 10 of paper or thin card which extends beyond the end of the portion 5 nearer to the portion 6.

The bonding 8 associated with the filter portion 6 does not extend all along the length of that portion so there is formed outside the periphery of is 4 that portion but inside the wrap 9 a gap 11.

The plug wrap is of a material e.g. plastics, card, tipping paper or stiff plug wrap (porous or nonporous) which can retain its integrity while allowing the two filter portions 5,6 to move relative to each other. In Figure 1 they are shown at a mutually distant relationship; in Figure 2 filter portion 6 has been moved towards filter portion 5 so that their adjacent ends abut, and so that the sleeve 10 has acted as a guide sleeve for that motion while entering into the gap 11 outside the portion 6, and so that also the plug wrap 9 has concertinaed into a bellows formation at 12.

The filter portions-are different from each other.

In this embodiment both of them have an inner cylindrical core region, 13,14 respectively, and an outer annular region 15,16 respectively, but it is not necessary that the physical conformation of the two portions should be similar in-this way. The inner core regions (13,14) of the two filter portions (5,6) are defined by non-permeable plug wrap thus eliminating any flow communication between the inner core region and the outer annulus within the respective filter portions.

The filter characteristics of the various 1 1 Y W regions (13-16) are such that the total or preferential smoke paths through the filter when the portions 5,6 are in one relative position (Figure 1) is different from that when they are in another relative position (Figure 2).

In this particular embodiment the core region 13 of the portion 5 is an impermeable plug, surrounded by conventional material such as cellulose acetate tow in the annular region 15.

In portion 6 the core region 14 is in contrast a void of somewhat lesser diameter than region 13, while annular region 16 is a conventional filter material such as, again, cellulose acetate.

The permutations available between the different regions of the different portions is obviously very great, bearing in mind that there is a great range of known materials or admixtures available giving a wide range of permeabilities, pressure drops, chemical or physical actions or the possibilities of addition of perfuming or flavouring to the smoke.

In the situation seen in Figure 1 the preferential smoke flow is illustrated by arrows 17, namely through the annular region 15 at filter portion 5 but then preferentially through the void central core region 14 of the filter portion 6. A certain minor amount of smoke will follow the path 18 through the 6 annular region 16.

In Figure 2 the two portions have been brought into abutment so there is almost no possibility for flow through the region 14 and almost all smoke flow will be through both of the filter regions 15 and 16 of the portions 5 and 6, as shown by arrows 18.

In this way the smoker can select either at the beginning of the smoking of a cigarette or during it to have a different filtration efficiency applied to the smoke.

For example, this configuration would be useful to increase early puff yield, the filter being open for the first puffs thus increasing yield, and closed during the latter puffs to decrease delivery.

In other examples the outer annular region (such as 16) and inner core region (such as 14) of the filter portion 6 both have permeable materials and one has the following specific possibilities, amongst many others.

1. Selected Carbon Filtration CONFIGURATION OF THE FILTER PORTION 6 outer annular region: Cellulose Acetate (CA) filter, normal efficiency Inner core region: Activated carbon segment FILTER CLOSED (as in Fig 2): Non carbon-filtered smoke produced 7 FILTER OPEN (as in Fig l): A combination of carbonfiltered and non carbon- filtered smoke results 2. Selected Flavour Filtration CONFIGURATION OF THE FILTER PORTION 6 Outer Annular region: CA filter, normal efficiency Inner core region: Flavoured thread CA filter, normal efficiency FILTER CLOSED:

FILTER OPEN:

is CA filtered smoke produced A combination of CA filtered and flavoured smoke from the flavoured thread Inner Core results.

1 1 8

Claims

1. A filter for a smoking article, the filter having at least two filter portions which are of different characteristics and which are linked by a link which allows a change in the relative longitudinal positions of the portions, the portions being constructed such that the total filter characteristics to which smoke passing through the filter is subjected are different in different relative positions of the portions.

2. A filter according to claim 1 wherein one of the relative positions is of axially abutting contact between ends of adjacent portions.

3. A filter according to claim 1 or claim 2 wherein regions in respective portions have differing characteristics, such that when the portions are in one relative position smoke flow will be through one set of regions at least one member of which set is in one of the portions and another member in another of the portions, but when the portions are in another relative position smoke flow will be preferentially through a second set of regions at least one member of which set is in one of the portions and another member in another of the portions.

4. A filter according to claim 3 wherein the is 1 % 9 regions in one portion of the filter are arranged such that an outer annular region has a lower flow resistance than an inner core region, while in another portion an inner core region has a lower flow of resistance than an outer annular region.

5. A filter according to claim 3 or claim 4 wherein at least one of the regions is impermeable to smoke.

6. A filter according to claim 3, claim 4 or claim wherein at least one of the regions is a void.

7. A filter according to any one of the preceding claims wherein the link is a wrap which is an integral whole joined to each of the portions.

8. A filter according to claim 7 wherein when the is portions are in a position of nearer approach the wrap adopts a bellows formation.

9. A filter according to any one of the preceding claims wherein at least one of said portions has a sleeve projecting therefrom, another of said portions being received in the sleeve at least in a position of nearer approach of the portions.

10. A filter substantially as herein described with reference to and as illustrated in the accompanying drawings.

11. A smoking article incorporating a filter according to any one of the preceding claims.