Smoking Articles

Abstract

The invention relates to a smoking article comprising a rod of smoking material having two or more channels, for instance tubes, of small cross section extending substantially longitudinally of the rod from near the mouthend to points short of the other end, at least two of the said channels being of different lengths. The smoking article may have a smoke filter against which the channels substantially abut.

Description

The invention concerns improvements relating to smoking articles, particularly but not exclusively cigarettes. It seeks to obtain, by simple means, a reduction in the total delivery, and/or a more uniform delivery, of particulate matter.

According to the invention, a smoking article comprises a rod of smoking material having two or more channels of small cross section extending substantially longitudinally of the rod from near the mouthend to points short of the other end, at least two of the said channels being of different lengths. Generally the smoking material will comprise natural or reconstituted tobacco, but it may comprise a tobacco substitute. A tobacco rod may be wrapped in paper in conventional manner. The article may be provided with a smoke filter in known manner.

The channels of different lengths may be provided by tubes. The tubes may be of the same or different diameters, the internal diameter being within the range of 0.1 to 4 mm. The tubes may be made of a combustible non-toxic material such as paper, a cellulosic material, tobacco sheet or the like, or of a synthetic smokable composition such as is referred to below.

A cigarette in accordance with the invention may be produced on a conventional cigarette-making machine which has been modified for inserting the tubes or assembly of tubes in the tobacco rod.

One embodiment of the invention by way of example and possible modifications are illustrated in the accompanying diagrammatic drawing, in which:

FIG. 1 is a longitudinal section through a cigarette provided with longitudinal tubes,

FIG. 2 is a cross section on the line II--II in FIG. 1, and

FIGS. 3 to 5 are similar cross sections illustrating alternative dispositions of the tubes.

The cigarette illustrated comprises, in a conventional arrangement, a tobacco rod 1 in a paper wrapper 2 and a cellulose-acetate filter plug 3. Open-ended tubes 4 of the same diameter, but different lengths extend longitudinally through the tobacco rod 1. At their inner ends, they abut or substantially abut against the inner end of the filter plug 3. Their outer ends are located short of the outer end of the tobacco rod 1.

Instead of being disposed closely side by side near to or at the central axis of the tobacco rod 1 as shown in FIG. 2, the two tubes 4 may be located at or near the circumference, for example either closely side by side as shown in FIG. 3 or at diametrically remote points as shown in FIG. 4, or one near the central axis and the other near the circumference as shown in FIG. 5.

More than two tubes 4 may be employed, provided that at least two of them are of different lengths. Closely disposed tubes 4 may form an assembly, of substantially circular or oblong section, which is wrapped or bonded by adhesive.

The tubes 4 may be made from a strip of cigarette-paper material with a sealed longitudinal seam produced with a composition which is itself an acceptable smokable composition consisting of 76 percent chalk, 15 percent tobacco extract, 2 percent glycerol and 7 percent sodium carboxymethyl cellulose, by weight. This composition, prepared in sheet form, may be made into a paste by dissolving it in a little water.

The cigarettes used for the following Examples were substantially as shown in FIGS. 1 and 2, the tubes 4 themselves being made in the manner just described.

EXAMPLE 1

Two tubes of 40 mm and 30 mm length respectively and 1.3 mm diameter were incorporated in the tobacco rod, of 65 mm length, of a cigarette. On smoking the cigarette to a butt length of 23 mm under standard conditions of one puff per minute of 35 ml volume and 2 seconds duration the following yields of total particulate matter (TPM) per puff were obtained.

__________________________________________________________________________ Puff No. 1 2 3 4 5 6 7 8 Sum Yield (mg) 2.9 2.5 3.0 3.3 3.7 3.1 3.1 2.6 24.2 __________________________________________________________________________

A comparable normal filter cigarette when smoked to a butt length of 23 mm in eight puffs gave yields of TPM which increased with successive puffs, the sum of the yields being about 35 mg. The sum of 24.2 represents a reduction of about 31 percent.

EXAMPLE 2

One of the two tubes was of 40 mm length and 1.3 mm diameter and the other of 30 mm length and 0.5 mm diameter. On smoking the cigarette under the standard conditions, the following yield of TPM per puff were obtained.

__________________________________________________________________________ Puff No. 1 2 3 4 5 6 7 8 9 10 Sum Yield (mg) 1.6 1.6 1.8 1.6 2.2 2.2 2.4 2.2 2.2 2.2 20.0 __________________________________________________________________________

In this case, the TPM yields levelled out with increasing puff number. As compared with a sum yield of about 40 mg in 10 puffs for a comparable normal filter cigarette, a reduction in the sum TPM of 50 percent was obtained.

EXAMPLE 3

Two tubes, of 40 mm and 30 mm length and 1.3 mm diameter were used. The per-puff yields of TPM were as follows:

Puff No. 1 2 3 4 5 6 7 8 9 10 Sum Yield (mg) 2.2 2.0 1.8 2.0 2.2 2.2 2.2 2.4 2.4 2.2 21.6

The reduction in the sum TPM was 46 percent in comparison with a normal filter cigarette. Even with 10 puffs, there was no material increase in the yield per puff for the later puffs.

The results obtained in these Examples and other tests confirm that relatively uniform or level yields of TPM per puff are obtained as well as a reduction in the sum of such yields. The pressure drop of cigarettes in which the tubes are incorporated is not materially affected. For the cigarettes of the above Examples, the pressure drop was about 10.5 cm water gauge as against 12.9 cm for a comparable normal filter cigarette. The presence of the tubes reduces the volume of tobacco or other smoking material required to produce cigarettes of given external dimensions. In the case of the above Examples, the tobacco reduction amounted to about 3 percent.

A possible explanation of the effect achieved by the provision of the tubes as described above is as follows:

It is known that part of the condensate from each puff of a cigarette is retained by the remaining tobacco through which it passes, producing an uneven yield of condensate per puff over the 10 puffs normally obtained per cigarette. If, however, a part of the condensate from the first two or three puffs passes through tubes directly to the cigarette filter, two results follow:

a. As this part passes directly to the filter and is not retained by the tobacco, the yield of condensate from the early puffs will be slightly higher than from a comparable filter cigarette without the tubes.

b. The remaining tobacco thereafter burnt will be less highly contaminated with condensate and a lower sum yield of condensate will be obtained.

Claims

I claim:

1. A smoking article comprising a rod of smoking material and a filter at one end of said rod, at least two combustible tubes of small cross section, open at each end, and extending longitudinally through the rod of smoking material from points closely adjacent the filter to points short of the end of the rod of smoking material opposite the filter, said tubes being of different lengths, the ends of said tubes located at the end of the rod opposite said filter being positioned at such different distances from said rod end so that a programmed air ventilation effect is achieved whereby during the initial puffs a mixture of air and tobacco smoke is delivered through the tubes providing a delivery of a higher TPM smoke to the filter than that which would be delivered in the initial puffs during smoking of the same tobacco column without inclusion of the tubes, and during successive puffs, the ratio of air to tobacco smoke in said mixture is increased as the fire cone moves through the tobacco rod to the ends of the tubes.

2. A smoking article as claimed in claim 1, wherein at least one of the tubes is disposed near the central axis of the rod.

3. A smoking article as claimed in claim 1, wherein at least one of the tubes is disposed near the circumference of the rod.

4. A smoking article as claimed in claim 1, wherein the tubes have a longitudinal seam sealed by a combustible material.