Smoking articles

Abstract

The invention relates to a smoking article comprising a part, for example a part in a cigarette filter, which is displaceable longitudinally of the article and is connected to another part thereof by heat-shrinkable film material so arranged that shrinkage of the said material longitudinally of the article caused by heat from the approaching coal when the article is smoked will impart longitudinal displacement to the said displaceable part, for instance for effecting rupture of a capsule containing a smoke-modifying or filtration modifying substance or uncovering perforations in a tipping element so as to allow entry of secondary air.

Description

This invention is concerned with improvements relating to smoking articles, particularly filter and other cigarettes.

An object of the invention is to provide means for modifying the characteristics of the tobacco smoke or controlling its production, especially during the last few puffs of a cigarette or cigar.

According to the invention, a smoking article, such as a cigarette, comprises a part which is displaceable longitudinally of the article and is connected to another part thereof by heat-shrinkable film material so arranged that shrinkage of the said material longitudinally of the article caused by heat from the approaching coal when the article is smoked will impart longitudinal displacement to the said displaceable part.

Preferably, the heat-shrinkable material will take the form of a sleeve or wrapper, but it may be constituted by a partial wrapper or one or more longitudinally extending strips.

Advantageously, the heat shrinkable material is incorporated in a filter, in which case the displaceable part may be a filter section, preferably one section of a dual-section or multiple-section filter. The displaceable section may then be adjacent to either the tobacco end or the mouth end of the filter. However, the shrinkable material may be incorporated in a non-filter mouthpiece or other portion of a smoking article.

The longitudinal displacement of the displaceable part may be utilized to effect rupture of a capsule holding a smoke-modifying or filtration-enhancing substance. Thus, in the case of a filter in which such a capsule is enclosed, the longitudinal displacement of the said part by heat shrinkage of the material due to the near approach of the burning coal may serve to crush and rupture the said capsule, thereby releasing its contents to be absorbed by a filter section or sections.

In one embodiment of the invention, a three-component filter comprising a capsule holding a flavouring agent and located between two filter sections of conventional type, for instance of cellulose acetate, is wrapped in a heat-shrinkable film material. At the tobacco end, the film material is connected by adhesive to the end facing the tobacco rod of the filter section adjacent to the latter and at the mouth end to the end remote from the tobacco rod of the other filter section and to the tipping paper. The circumference of the filter section at the tobacco end may be made slightly less than the internal circumference of the tipping paper by which the filter is joined to the tobacco rod in known manner.

Alternatively or additionally the displacement of the longitudinally displaceable part may be utilized to uncover perforations or porous paper provided in a tipping element, allowing secondary air to enter the smoke stream during the last few puffs. For example, if the said part is a filter section, suitably a section adjacent to the tobacco end of the filter, the tipping may be provided with a ring or rings or a band of perforations which normally overlie that filter section, but will be uncovered by its longitudinal displacement due to shrinkage of the heat-shrinkable material on near approach of the coal.

In another embodiment of the invention, a capsule or pellet located between two filter sections, of which one at least is movable by shrinkage of the heat-shrinkable film material, may contain an adhesive which, when released by crushing of the capsule or pellet, will seal an adjacent face of one or both of the said sections to form a less permeable film, causing an increase in pressure drop of the filter.

Suitable monoaxial film materials which may be used are polyvinylidene chloride, polyvinylchloride and polyester and polystyrene materials, as well as polypropylene and polyethylene materials. However, biaxially shrinkable film prepared from the same materials may be employed in some cases. In such cases, shrinkage of the said material circumferentially of the longitudinally displaceable part, particularly a filter section, may be arranged to effect deformation of that part as well as the displacement. In particular, radial compression of a longitudinally displaceable filter section in this manner may produce or increase clearance between it and the tipping, facilitating longitudinal displacement.

Capsules or pellets may be made of gelatine, wax or a synthetic polymer, depending on their contents. Examples of smoke-modifying substances which can be encapsulated are peppermint oil, spearmint oil and other flavouring agents. Examples of filtration-enhancing substances are sodium carbonate solution, citric acid solution, water and suspensions or emulsions of polyethylene glycol or polyethylene imine.

Embodiments of the invention by way of example will now be more fully described with reference to the accompanying drawings, in which each of

FIGS. 1, 3, 5 and 7 is a diagrammatic longitudinal section of part of a filter cigarette before the approach to the filter of the burning coal on smoking and each of

FIGS. 2, 4, 6 and 8 is a similar section showing the effect of the near approach of the coal.

EXAMPLE 1

In the triple filter shown in FIGS. 1 and 2, a gelatine capsule 1 of about 6-7 mm diameter and holding a peppermint oil is disposed between a 5 mm long cylindrical filter section 2 of cellulose acetate adjacent to the wrapped cigarette-tobacco rod 3 and a 7 mm long cylindrical filter section 4 of cellulose acetate at the mouth end, both of about 25 mm circumference. The sections are wrapped in a band, formed to a sleeve 5, of polyvinylchloride heat-shrinkable film material supplied by Kalle U.K., Hounslow, England, under the trade name "SUPRATHERM-C" (Type CB) which has biaxial shrink properties. The sleeve 5 is adhesively secured at 6 and 7 to the two extreme outer ends of the filter sections 2 and 4. The filter is attached to the tobacco rod 3 by tipping paper 8 which is glued in two narrow bands to the said rod, at 9, and to the sleeve 5 of film material, at 10, at the mouth end only of the filter section 4. When the cigarette was smoked through the filter under standard conditions of 1 puff per minute of 35 ml volume and 2 seconds duration, the heat from the approaching coal 11 (FIG. 2) caused shrinkage of the sleeve 5, forcing the filter section 2 to move longitudinally of the filter away from the tobacco rod 3 at the last two to three puffs only. The sleeve 5 also compressed the section 2 slightly, producing a clearance around the latter. Due to the longitudinal movement, the capsule 1, softened by the heat, was crushed against the filter section 4 and ruptured, so that its contents were released, giving a peppermint flavour to the last two or three puffs. The capsule 1 cannot readily be ruptured prior to smoking of the cigarette, as its gelatine wall is quite strong when cold.

A heat-shrinkable film material of monoaxial type, i.e. which shrinks in the longitudinal direction only, may be similarly used for wrapping a triple filter holding a capsule. In this case, the movable filter section 2 may be of slightly smaller circumference, say 23 mm.

An Example of this kind follows:

EXAMPLE 2

In a triple filter generally similar to that of FIGS. 1 and 2, the polyvinylchloride film used was of a monoaxial type, supplied by W. R. Grace Ltd., London, England under the designation VPMX. The direction which shows shrinkage during manufacture of the film is arranged lengthwise of the filter. The gelatine capsule contained spearmint oil mixed with vegetable oil. On smoking the cigarette through this filter under the standard conditions, no effects were observed until the last 2 or 3 puffs. At this point the heat from the closely approaching coal 11 caused shrinkage of the film and softening of the capsule 1. The capsule was thus compressed by the approaching filter section 2 and ruptured, so that, on the next puff, the smoke was strongly flavoured by spearmint, allowing the smoker to freshen his mouth prior to discarding the cigarette.

EXAMPLE 3

The triple filter shown in FIGS. 3 and 4 differs from that of Example 2 in that the tipping paper 8 is glued at 9 to the tobacco rod 3 and to the sleeve 5 around the filter section 2 at 12 at the tobacco end only. When the cigarette was smoked through the filter, the heat from the approaching coal caused longitudinal shrinkage of the sleeve 5, forcing the filter section 4 to move toward the tobacco end, once again rupturing the capsule 1. In place of conventional tipping paper 8, a stiffer outer wrap or a plastics tube may be used.

EXAMPLE 4

A triple filter of the kind described with reference to FIGS. 1 and 2 comprises an empty gelatine capsule 1 of about 6 to 7 mm diameter, disposed between a 5 mm long cellulose acetate section 2 and a 10 mm long cellulose acetate section 4 wrapped in a sleeve 5 of biaxially heat-shrinkable polyvinylchloride film supplied by Spicer Cowan, Southampton, England, under the designation BS2. The sleeve 5 is secured at 6 and 7 by polyvinyl acetate adhesive.

On smoking the cigarette through this filter, the heat from the approaching coal softened the capsule 1 and longitudinal shrinkage of the sleeve 5 caused the capsule to be compressed. The smoke path through the filter was partially obstructed and the pressure drop substantially increased. The pressure drop observed, puff by puff, was as follows:

Puff No. Pressure drop cm Water Gauge ______________________________________ 0 10.9 1 17.1 2 16.6 3 18.9 4 15.3 5 14.2 6 14.4 7 14.1 8 14.1 9 13.4 10 10.0 11 34 approximately 12 90 approximately ______________________________________

The length of the tobacco rod which remained after the 10th puff was approximately 20 mm.

EXAMPLE 5

The filter of FIGS. 5 and 6 is composed of two cellulose acetate sections 2 and 4, of 5 mm and 10 mm length respectively, spaced from each other at a distance of 7 mm and wrapped in a sleeve 5 of the biaxially heat-shrinkable polyvinylchloride film material referred to in Example 4. The sleeve 5 and tipping 8 are secured at 6,7 and 9,10 as in FIGS. 1 and 2. The tipping 8 is provided with a ring of perforations 13, affording 6.5 mm.sup.2 total area of opening, which are initially located over and closed by the filter section 2 (FIG. 5). On smoking the cigarette through this filter under the standard conditions and to a butt length of 8 mm, the filter section 2 was compressed radially and drawn longitudinally towards the section 4, by shrinkage of the sleeve 5 due to the heat of the approaching coal, thereby uncovering the perforations 13 (FIG. 6) to admit secondary air at the last few puffs. This resulted in a decrease in the delivery of total particulate matter (TPM). The delivery per puff was as follows:

Puff No. Weight of TPM (mg) ______________________________________ 1 1.0 2 1.3 3 1.5 4 2.1 5 1.9 6 1.6 7 2.3 8 2.0 9 2.7 10 2.5 11 2.9 12 3.9 13 5.1 14 0.2 15 0.4 ______________________________________

EXAMPLE 6

The filter of FIGS. 7 and 8 is similar to that of FIGS. 5 and 6 except that the sleeve 5 is of monoaxial heat-shrinkable film material, so that the filter section 2 simply moves longitudinally towards the section 4 without being compressed. Two rings of perforations 14, each ring affording 2.25 mm.sup.2 of opening, in the tipping 8 are thereby uncovered to admit secondary air with an effect similar to that obtained in Example 5.

Claims

We claim:

1. A smoking article comprising an elongated filling of smokable material burnable progressively, with formation of a coal at one end, when said article is smoked, said article including a first part which is displaceable longitudinally of the article and means for imparting longitudinal displacement of said first part in response to heat from the approaching coal when said article is smoked, said means comprising a heat shrinkable film connecting said first part to a second part of said article.

2. An article according to claim 1, wherein the heat-shrinkable film is in the form of a sleeve extending longitudinally between the two connected parts.

3. An article according to claim 1 and comprising a filter, wherein the heat-shrinkable film is incorporated in the said filter.

4. An article according to claim 1 and comprising a dual-section or multiple-section filter, wherein the displaceable part is constituted by one section of the filter.

5. An article according to claim 1 and comprising a tipping element provided with perforations, wherein the longitudinal displacement of the displaceable part is arranged to effect uncovering of the said perforations, thereby allowing entry of secondary air.

6. An article according to claim 1 and comprising a tipping element provided with perforations which normally overlie and are closed by the longitudinally displaceable section, but will be uncovered upon its displacement by shrinkage of the heat-shrinkable film.

7. A mouthpiece device for a smoking article comprising a first part which is displaceable longitudinally of the mouthpiece device and means for imparting longitudinal displacement of said first part in response to heat, said means comprising a heat shrinkable film connecting said first part to a second part of said mouthpiece device.