WO2003028494A1

WO2003028494A1 - Tobacco smoke filter

Info

Publication number: WO2003028494A1
Application number: PCT/GB2002/004384
Authority: WO
Inventors: Paul Francis Clarke
Original assignee: Filtrona International Limited
Priority date: 2001-10-03
Filing date: 2002-09-27
Publication date: 2003-04-10
Also published as: TWI244383B; GB2380391A; GB0123760D0

Abstract

A tobacco smoke filter element (2) comprising filamentary tow gathered and held in air-permeable rod form with the filaments extending generally longitudinally of the rod, there being at least two groups (6,8) of filaments of respective different colour materials and the filaments being intertwined to provide an end face of the rod element which shows a mixture of the two or more colours (6,8).

Description

TOBACCO SMOKE FILTER

This invention relates to tobacco smoke filters of filamentary tow, and to their production.

Smoking of a cigarette provided with a filter rod of conventional filamentary tow (e.g. cellulose acetate) results in visible staining of the exposed buccal end of the filter due to tar retention. With a ventilated filter the staining may be concentrated centrally of the filter end face, but with or without ventilation the visible staining is frequently irregular and uneven. Such visible staining is undesirable since it may be aesthetically unpleasing to the smoker and can suggest product variability when there is in fact good product uniformity.

The present invention provides a tobacco smoke filter element comprising filamentary tow gathered and held in air- permeable rod form with the filaments extending generally longitudinally of the rod, there being at least two groups of filaments of respective different colour materials and the filaments being intertwined to provide an end face of the rod element which shows a mixture of the two or more colours. The intertwining may be random to give a cross- sectional colour distribution which varies longitudinally of the rod element.

In a preferred type of embodiment, the rod element comprises at least two tows of respective filaments of respective different colour materials, the gathered tows being intertwined to provide an end face of the rod which has a marbled mixture of the two or more colours; in this preferred type of embodiment, at least one of the tows may have respective filaments of respective different colour materials. In all of these preferred types there may be random filament and/or tow intertwining to give a random marbled end appearance - with cross-sectional colour distribution usually varying longitudinally of the rod element.

In an alternative type of embodiment, the rod element may be gathered from a single filamentary tow containing respective filaments of respective different colour materials, in which case the rod element end face may not be marbled but can instead be of uniformly or unevenly mottled bi- or multi-coloured appearance - depending upon the distribution of the different colour materials in the original tow; thus if the tow ^' has just two side-by-side stripes of filaments of two different colour materials, then this might be reflected in the rod element end face having more of the filaments of one colour to one side and more of the . filaments of the other colour to the other side; multiple stripes of filaments of two or more different colour materials in the original tow might be reflected by similar partial concentrations of different colours over the rod element end face, whereas random distribution of respective filaments of two or more different colour materials over the tow could result in a more uniform mottled bi- or multi-coloured rod element end appearance. Random intertwining can again result in cross-sectional colour distribution varying longitudinally of the rod element.

It is important to use filaments of inherently white coloured and/or non-white coloured materials rather than filaments coloured by surface treatment after filament formation. The filaments may thus be made from filament- forming materials which are naturally white or non-white or which are pigmented to be white or non-white. Surprisingly, the bi- or multi-coloured end appearance of filter elements according to the invention significantly masks end staining in use and can do so to the extent that staining and non-uniformity of staining are not noticeable. Elements having a marbled end appearance are currently preferred.

The filter element according to the invention may be provided with a plugwrap (e.g. one having a lapped and stuck seam) to hold it in rod form. Filaments of the element according to the invention may be bonded at points of contact, usually by means of heat-activated adhesive or adhesive/plasticiser for the filaments (e.g. triacetin adhesive/plasticiser for cellulose acetate filaments) ; such bonding may be su ficient to hold the element in rod form in the absence of a plugwrap - as in the case, for example, of conventional N A (non-wrapped acetate) filters; however, a plugwrap may be provided even for a bonded filamentary rod that would be coherent and dimensionally stable without a wrapper.

The elements according to the invention can be made by continuously advancing longitudinally filamentary tow having respective filaments of respective different colour materials to and through a rod-forming tubular garniture, the filaments being intertwined and gathered to rod form as they approach and pass through the garniture so that the exposed end face of the formed rod emerging continuously from the garniture has a mixture of said different colours, optionally continuously wrapping the rod as it is formed in the garniture, and cutting the continuously formed rod transversely into elements of finite length; before the transverse cutting the emerging rod, whether wrapped or non- wrapped, may be subjected to a further step or steps (e.g. application of a - or another - wrapper and/or of a tubular sheath) as part of a continuous in-line process.

Preferably the procedure involves continuously and simultaneously advancing longitudinally at least two 5 filamentary tows of respective different colour materials to and through a rod-forming tubular garniture, the tows being intertwined and gathered to rod form as they approach and pass through the garniture so that the exposed end face of the formed rod emerging continuously from the garniture has 10 a marbled mixture of said different colours; as indicated above, at least one of the tows may itself have respective filaments of respective different colour materials.

A filter wrapper may be fed into and through the garniture simultaneously with the filaments/tows to be 15 wrapped and secured around the continuously formed rod in conventional fashion, and/or adhesive or adhesive/plasticiser may be pre-applied to the filaments and activated during rod formation to bond filaments together at points of contact.

2.0 These general manufacturing procedures, apart from the use of filaments of coloured material, are well known and widely used in the tobacco smoke filter industry.

The intertwining of the filaments and/or tows of different colour can result in the colour combination

25 varying continuously longitudinally of the continuously formed rod, so that each ^'transverse cut to form finite rod lengths will give a different end appearance, this being especially so with filament and/or tow intertwining to given marbled end appearance. Whilst the individual finite length 0 elements cut from the continuously produced rod preferably vary subtly in (e.g. marbled) end appearance, they will all have a common and distinctive general appearance to distinguish them from conventional filamentary tow elements and from other elements according to the invention made using different filament and/or tow combinations. The invention can thus provide security and brand identity by the subtle combination of two or more randomly intertwined filaments and/or tows of two or more respective different colour materials. The subtly and continuously varying but distinct end appearance of the rods of a given production format according to the invention thus offers a strong branding opportunity with protection against counterfeiting.

The colours from which the tows used according to the invention may be selected include, for example, white, black, red, green, yellow, orange, and blue etc. Tow colour combinations which can be employed according to the invention include, for example, black and white, red and white, green and white, red and yellow, orange and red, orange and white, blue and white, blue and yellow, orange and green, and green and yellow, etc. Three or more respective filaments and/or tows of respective different colour materials may be employed, but the use of two colours is satisfactory and may be preferred for economy and for clarity and distinctiveness of end appearance. The filaments/tows of different colours for a product may be of the same or similar filament denier and cross-section (e.g. Y-section) , or may differ in one or both of these features . At least some (e.g. all) of the filaments (or at least one - e.g. all - of the tows) may be crimped. The respective proportions of the different colours may be varied as desired, but would normally remain substantially constant at the chosen values for a given product run in order to maintain distinctive product identity. The filter rod element according to the invention, which may have its own plugwrap, may be employed alone as the filter for a filter cigarette e.g. attached to a wrapped tobacco rod by a conventional tipping overwrap which extends along and around the whole of the filter and the adjacent end of the wrapped tobacco rod; where the filter rod element has its own plugwrap, it could instead be attached to a wrapped tobacco rod by ring tipping which extends around only the adjacent ends of the filter and tobacco rod.

In other embodiments, the filter rod element according to the invention may form part of a composite filter structure. An example of such a composite structure has a filter rod element according to the invention (with or without its own plugwrap) held in longitudinally abutting or spaced alignment with another rod by a common overwrap; the manufacture of such composite filters of abutting or spaced plugs is well known throughout the filter and filter cigarette manufacturing industries.

In such a composite of two rods, said other rod combined with the element according to the invention could be an open-ended tubular body the bore of which is circular or non-circular (e.g. star-shaped, triangular, cruciform, crescent-shaped, polygonal, or heart-shaped etc.) in end appearance; such tubular bodies can be formed by extrusion of plastics material (solid or cellular) over a suitably shaped mandrel or by gathering fibrous or filamentary material around a suitably shaped mandrel in a rod-making garniture as well known in the cigarette filter industry. Where said other rod is tubular, the bi- or multi-coloured element according to the invention is usually and preferably visible through the bore of the tubular portion. In other such composites of two rods, said other rod (whether a tubular body or a cylindrical plug) may incorporate activated carbon and/or other particulate sorbent; in a filter cigarette including such a composite filter, said other rod would normally be at the upstream end of the composite filter, i.e. between the rod element according to the invention and the wrapped tobacco rod.

The filter rod element according to the invention can also be employed as the or a rod portion of any known other type of tobacco smoke filter which incorporates a filter rod. For example a filter rod element according to the invention could be the core around which is wrapped a wrapper having particulate sorbent adhered to its radially inner face, as described for example in GB-A-9124535 and GB- A-9221545, to which attention is directed for more information; the wrapper may be applied as part of the initial continuous production of the rod element, or it could be applied continuously to the initial continuously produced rod element before transverse cutting to finite lengths .

Likewise a filter rod element according to the invention could be the core of a composite filter in which said core is engaged with and surrounded by a coaxial tubular body of air-permeable filtering material, e.g. as disclosed in GB-A-8308216, to which attention is directed for further information. In production of the latter composite filter, the core element emerging continuously from the garniture as described above can be led directly to a further garniture simultaneously with a further supply of filter material to continuously form a tubular sheath engaged coaxially around the core, the transverse cutting to finite lengths occurring only after composite formation by this continuous in-line procedure. Whether the filter element according to the invention is employed alone as a filter or forms part of a composite filter, it may be of plain circular section, or formed with surface grooves or flutes extending ail or part of its length - e.g. extending from one end only partially towards the other - as described for example in FR-A-7737449, to which attention is directed for more information.

Whether the plain or surface-grooved/fluted element according to the invention is employed alone as a filter or forms part of a composite filter structure, it may in use be ventilated or non-ventilated.

The filamentary tows employed according to the invention may be, for example, of cellulose acetate, polyester, polyolefin (e.g. polypropylene) or any other material suitable for filamentary filter rod manufacture. The tows making up the element are preferably of the same material, differing only in colour, or of different materials of the same class (e.g. different types of cellulose acetate) ; they may instead be of different material types, e.g. cellulose acetate and polyolefin.

In the accompanying drawing, Fig.l is an end view of a filter rod according to the invention having a conventional plugwrap 2 around a permeable filter core 4 of two filamentary tows intertwined and gathered to rod form with • filaments extending generally longitudinally of the core and bonded at points of contact. Both tows are of crimped

' cellulose acetate Y-section filaments plasticised with triacetin and having a filament denier of 2.1; the filaments of one tow are of yellow pigmented cellulose acetate and those of the other tow are of dark blue pigmented cellulose acetate; the yellow tow is of total denier 32,000 and the dark blue tow is of total denier 32,000. The two tows intertwine randomly to give a cross-sectional colour distribution which varies longitudinally of the rod and which at the illustrated exposed end has the illustrated marbled appearance of yellow 6 and dark blue 8 areas. Different elements cut transversely from the rod will have ends which differ slightly from each other but which share a common distinctive yellow/dark blue marbled appearance.

It will be appreciated that, although the lines in the drawing have clear boundaries, in reality the boundaries may be fuzzy in appearance.

Claims

C L A I M S :

1. A tobacco smoke filter element comprising filamentary tow gathered and held in air-permeable rod form with the filaments extending generally longitudinally of the rod, there being at least two groups of filaments of respective different colour materials and the filaments being intertwined to provide an end face of the rod element which shows a mixture of the two or more colours.

2. An element according to claim 1 wherein the rod is gathered from a single tow of respective filaments of respective different colour materials .

3. An element according to claim 1 comprising at least two tows of respective filaments of respective different colour materials gathered and held in rod form with the filaments extending generally longitudinally of the rod, the gathered tows being intertwined to provide an end face of the rod which has a marbled mixture of the two or more colours.

4. An element according to any preceding claim wrapped in a plugwra .

5. An element according to any preceding claim wherein gathered filaments are bonded at points of contact.

6. An element according to any preceding claim wherein the rod has surface grooves or flutes extending the whole or part of its length.

7. A tobacco smoke filter which comprises an element according to any preceding claim within a wrapper having particulate sorbent adhered to its radially inner face.

8. A tobacco smoke filter comprising an element according to any of claims 1 to 6 surrounded and engaged by a coaxial tubular body of air-permeable filtering material.

9. A tobacco smoke filter comprising an element according to any of claims 1 to 6 held in longitudinally spaced or abutting alignment with another rod.

10. A filter according to claim 9 wherein said other rod is an open-ended tubular body.

11. A filter element or filter according to any preceding claim having a ventilated wrapper.

12. A method of manufacturing a tobacco smoke filter element which comprises continuously longitudinally advancing filamentary tow having respective filaments of respective different colour materials to and through a rσd- forming tubular garniture, the filaments being intertwined and gathered to rod form as they approach and pass through the garniture so that the exposed end face of the formed rod emerging continuously from the garniture has a mixture of said different colours, and cutting the continuously formed rod transversely into elements of finite length.

13. A method according to claim 12 wherein at least two filamentary tows of respective different colour materials are continuously and simultaneously advanced to and through the rod-forming tubular garniture, the tows being intertwined and gathered to rod form as they approach and pass through the garniture so that the exposed end face of the formed rod emerging continuously from the garniture has a marbled mixture of said different colours.

14. A smoking article comprising a filter according to any preceding claim.

15. A smoking article according to claim 14 in which the article is a cigarette.

IS. A tobacco smoke filter element substantially as herein described with reference to the drawing.