NZ203131A

NZ203131A - Cigarette filter:peripheral ducts and wrapper apertures

Info

Publication number: NZ203131A
Application number: NZ203131A
Authority: NZ
Inventors: J A Luke
Original assignee: Brown & Williamson Tobacco
Priority date: 1982-02-02
Filing date: 1983-01-31
Publication date: 1985-07-31
Also published as: AT384151B; DK158369B; ATA20083A; ES278854Y; BG40312A3; KE3597A; BR8300490A; CS251073B2; AU553753B2; YU42067B; JPS58165780A; TR21762A; SE8300441L; IT8319393A1; SG92285G; IT1163071B; FR2520594A1; IT8319393A0; NO155323B; KR870001748B1

Description

<div class="application article clearfix" id="description"> Dm+a{S). • ' > ^ •••••• Complete Specification Filed: Class: .. BMtS.lfP.'L, Publication Date: IP. 0. Journal, No: .. • *31 JAN 1983 \Ta / NEW ZEALAND N« 36026 THE PATENTS ACT 1953 PATENTS FORM NO. 5 COMPLETE SPECIFICATION "IMPROVEMENTS RELATING TO SMOKE FILTERS" WE, BROWN & WILLIAMSON TOBACCO CORPORATION, a corporation organised under the laws of the State of Delaware, of: 1600 West Hill Street, Louisville, Kentucky 40232, United States of America, hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: Wowed by | A , 203131 DESCRIPTION IMPROVEMENTS RELATING TO SMOKE FILTERS This invention relates to smoke filters for use with smoking articles, cigarettes for example. A number of proposals have heretofore been made for cigarette filters having provision for the ingress of ventilation air into ducts extending at the periphery of the filter to the mouth end thereof and serving to convey the air to the smoker's mouth without any, or substantially any, mixing of the air within the filter with tobacco smoke drawn through the filter. Such mode of filter ventilation may be referred to as "segregated peripheral ventilation". It has been claimed for segregated peripheral ventilation filters that they enhance the quality of the tobacco smoke as perceived by the smoker. The present invention provides a smoke filter compris a rod-like plug of filtration material having at least one groove extending along the peripheral surface of said plug between a first end at the mouth end of said plug to a second end spaced from the first end, and wrapping means enwrapping said plug to form at least one airflow duct and permitting the ingress of a first stream of ambient air into said at least one airflow duct at a location spaced from said first end and permitting the ingress of a second stream of ambient air directly into the interior of said plug. 203131 - 2 - Preferably the ingress of said first stream of ambient air into the duct is independent of the ingress of a second stream of ambient air directly into the interior of said plug. More preferably the at least one airflow duct extends short of the other end of the plug. Advantageously, the wrapping means, or an outer layer thereof underlain by an air-permeable layer, is provided with first and second ventilation perforations for passage therethrough of the first and second streams of air respectively. Suitably, the second ventilation perforations are located over a region of the periphery of the filter plug longitudinally spaced from a region thereof at which extend the airflow ducts. Conveniently, the airflow duct is partly defined by a number of grooves in the peripheral surface of the filter plug, as well as by the wrapping means or inner layer thereof. The grooves may extend parallel to the axis of the filter plug or may be helical. There may be two sets of helical grooves of opposite hand so that the grooves of one set intersect the grooves of the other set. The plug of filtration material may be other than of unitary form. For example, it may comprise two abutting sub-plugs, in which case one sub-plug may be provided with grooves bounding the airflow duct. By use of a filter according to the invention on a cigarette, an unexpected improvement in the taste of the mainstream smoke is obtainable over that perceived when a filter is employed of which the only mode of ventilation is segregated peripheral ventilation. In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawing,in which:- FIGURE 1 shows a part view, in axial section, of a filter-tipped cigarette; FIGURE la shows a cross-sectional view of half of the cigarette of Figure 1 taken along line A-A thereof; FIGURE 2 shows a filter plug of an alternative form from that of the cigarette of Figure 1; and FIGURE 3 shows, partially in axial section, a further alternative form of filter plug. The cigarette of Figure 1 comprises a rod 1 of cut tobacco enwrapped in cigarette paper 2, and a filter 3 comprising a self-sustaining filter plug 4 of fibrous cellulose acetate filtration material. At the periphery of the plug 4 there extend a series of grooves 5 - see also Figure la_. The grooves 5 open at the mouth end of the plug 4 and extend parallel to the plug axis for about half the length of the plug 4. A convenient method of forming the grooves 5 is to subject the plug 4, or preferably a piece of filter rod material from which several of the plugs 4 are to be cut, to a hot moulding process such as, for example, that disclosed in United Kingdom Patent Specification No. 1,507,765. Sealing of the walls of the grooves 5 may be assured by the application thereto of a sealant material, polyethylene for instance. Serving to secure the filter 3 to the cigarette rod 1, 2 is a.tipping 7. In the portions where it overlies the grooves 5, the tipping 7 defines, together with the walls of the grooves 5, airflow ducts 8. In the tipping 7 are two rows of ventilation perforations 9 and 10. As is indicated in Figure 1, the row of perforations 9 encircles the plug 4 at that portion thereof at which the grooves 5 extend, the arrangement being such that at least one of the perforations 9 is in communication with each of the airflow ducts 8. The row of perforations 10 encircles a portion of the plug k into which the grooves 5 do not extend. The perforations 9 and 10 may, if desired, be formed as micro-perforated regions of the tipping 7. It is also possible for the tipping 7 to overlie a plug wrapper of air-pervious quality in which case the tipping serves as an outer layer in which the ventilation perforations are provided. - 5 - A further alternative is for the tipping 7 to overlie an impervious plug wrapper, in which case the wrapper would be provided with perforations in-register with the perforations 10 in the tipping 7. Suitably 5 in such latter case the plug wrapper perforations would be formed at the same time as the perforations 10, mechanically or by laser drilling. When the cigarette of Figure 1 is smoked, ambient air is drawn in through the perforations 10 10 directly into the filter plug b and mixes with tobacco smoke passing through the latter. Ambient air is also drawn in separately through the perforations 9 into the airflow ducts 8 and passes along the ducts to the outlet ends thereof unmixed, or substantially unmixed, with 15 smoke. The filter plug shown in Figure 2 and generally designated 11 is one which may be used in place of the plug h of Figure 1. The plug 11 is provided with a number of equally-spaced longitudinal grooves 12 which 2q open at the mouth end of the plug and extend therefrom for substantially less than the full length of the plug# In a portion of the plug 11 clear of the longitudinal grooves 12 the plug is provided with a deep annular circumferential channel 13. The longitudinal grooves 25 12 and circumferential channel 13 may conveniently be formed by a hot moulding process. When the plug 11 is incorporated in a filter-tipped cigarette, it is enwrapped in a wrapping which is constructed to permit the ingress of a first stream of air directly into airflow ducts bounded by the walls of the longitudinal grooves 12 and by the inwardly facing surface of the wrapping, and a second, separate stream of air into the circumferential channel 13. The second stream of air directly enters the interior of the plug 11, mainly through the downstream side wall of the circumferential channel 13. If a tipping wrapper surrounding the filter plug 11 is provided with a row of perforations (like the perforations 9 of Figure 1) in register with the portion of the plug in which the longitudinal grooves 12 extend and if some intermediate ones of the perforations in that row are disposed between the longitudinal grooves, air may be prevented from entering the interior of the plug 11 through such intermediate perforations by applying a sealant to the peripheral surface of the plug 11. Alternatively, the plug 11, or a piece of filter rod of which the plug 11 initially formed part, may be enwrapped in a non-permeable wrapper of thermoplastic character prior to being hot-moulded to provide the longitudinal grooves 12 and the circumferential channel 13. In the latter case the hot-moulding of the comparatively shallow longitudinal grooves 12 leaves the non-permeable wrapper substantially intact, whereas little or no remnant of 1 3 1 - 7 - the wrapper is observable in the deep circumferential channel 13. Thus the walls of the longitudinal grooves 12 are air-impermeable and at least the side walls of the circumferential channel 13 are air-permeable. 5 Figure 3 shows another form of filter plug, generally designated 14, which may be used in place of the plug b of Figure 1. Plug lb is provided with a number of equally-spaced, helical grooves 15 which extend from the mouth end of the plug lb and may be 10 formed by a hot-moulding process. Plug lb is also provided, clear of the grooves 15, with a number of holes 16 extending radially inwardly from the peripheral surface of the plug. The holes 16 may be formed mechanically or by a laser, formation of the holes 25 conveniently taking place after assembly of the plug 14 with a cigarette rod so that the step of forming the holes 16 also results in the perforation of the wrapper. Although the above described filter plugs are of 20 a unitary nature, dual element plugs could be used, such that a first element has grooves formed in it extending from the mouth end of the first element, and the second element has means for permitting the ingress of air into the interior of the second element. The grooves in the 25 first element could extend for the full length of the first element. If such dual element plugs are wrapped 2031 - 8 - in respective plug wrappers, conveniently the wrapper of the first element is air-impervious and that of the second element is air-pervious. The air/smoke regime issuing from each of the above 5 described filters, as far as it is due to the segregated peripheral ventilation, is modified by the establishment within the filter of an air/smoke flow by virtue of the direct ventilation air flow into the interior of the filter plug. This modification effect 10 results in an unexpected improvement in the taste of the mainstream smoke. The various perforations 9, 10 and 11 shown in the drawing are not to scale and are exaggerated for ease of illustration. </div>

Claims

- 9 - 2C3131 WHAT WE CLAIM IS:

1. A smoke filter comprising a rod-like plug of filtration material having at least one groove extending along the peripheral surface of said plug between a first end at the mouth end of said plug to a second end spaced from the first end, and wrapping means enwrapping said plug to form at least one airflow duct and permitting the ingress of a first stream of ambient air into said at least one airflow duct at a location spaced from said first end and permitting the ingress of a second stream of ambient air directly into the interior of said plug.

2. A filter according to claim 1, wherein that the ingress of said second stream of ambient air is independent of the ingress of said first stream of ambient air.

3. A filter according to either preceding claim, wherein said second end of the at least one airflow duct is between and spaced from the ends of the plug.

4. A filter according to any one of the preceding claims, wherein said wrapping means is provided with first and second ventilation perforations to pass the respective first and second streams of ambient air. 2C3131 -10 -

5. A filter according to any one of claims 1 to 3, wherein said wrapping means is substantially air-permeable but has a less permeable outer layer provided with first and second ventilation 5 perforations to pass the respective first and second streams of ambient air.

6. A filter according to claim 4 or claim 5, wherein the at least one airflow duct extends over a first region of the plug and the second ventilation 10 perforations are located over a second region of the periphery of the plug which is spaced longitudinally from said first region.

7. A filter according to claim 6, and including a circumferentially 15 extending channel in the plug at said second region; said channel being in register with the permitted ingress of the second stream of ambient air, and being effective to admit the second stream directly into the interior of the plug. 20

8. A filter according to any one of claims 4 to 7, wherein said ventilation perforations comprise micro-perforated regions of the wrapping means to permit the ingress of at least one of said first and second streams of ambient air through the wrapping 25 means. - 11 - 2C3131

9. A filter according to any one of the preceding claims, wherein there is plurality of said airflow ducts equiangularly spaced around the periphery of said plug.

10. A filter according to any one of the preceding claims, wherein said plug comprises two abutting sub-plugs, one of said sub-plugs being provided with said at least one groove, and the other being devoid of such grooves.

11. A filter according to any one of claims 1 to 11, wherein said at least one airflow duct extends helically of said filter starting from the mouth end of the filter.

12. A filter plug according to any one of the preceding claims wherein said location is at said second end of said at least one airflow duct.

13. A filter plug substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and la, or Figure 2, or Figure 3, of the accompanying drawings.

14. A smoking article including a tobacco rod and a filter according to any one of the preceding claims.