GB2139869A

GB2139869A - Improvements relating to smoking articles

Info

Publication number: GB2139869A
Application number: GB08411170A
Authority: GB
Inventors: Richard Roland Baker; Frederick Joseph Dashley; Anthony Denis Mccormack; Colin Campbell Greig
Original assignee: British American Tobacco Co Ltd
Current assignee: British American Tobacco Investments Ltd
Priority date: 1983-05-17
Filing date: 1984-05-01
Publication date: 1984-11-21
Also published as: GB2139869B; GB8411170D0

Abstract

In a smoking article such as a cigarette comprising a smoking-material rod enwrapped in a wrapper paper comprising at least one compound of the group or a plurality of such compounds comprising lithium hydroxide, aluminium hydroxide, calcium hydroxide, potassium formate, sodium formate and sodium acetate, the loading level of the compound or total loading level of the compounds is not less than two g/m<2> and the total particular matter (TPM) in the sidestream-smoke emanating from the lit end of said article during the smoking thereof being reduced by at least 30% in relation to the TPM which emanates from the lit end of an otherwise identical smoking article comprising conventional wrapper paper and smoked under the same smoking conditions. Advantageously the reduction in sidestream TPM is at least 50%. The invention may reside in a wrapper paper comprising at least one compound of the group comprising lithium hydroxide, aluminum hydroxide, calcium hydroxide, potassium formate, sodium formate and sodium acetate at a loading level of the compound, or a total loading level of the compounds, of not less than two g/m<2>. The invention may also reside in cigarette paper, treated as described in any of Examples 1-5.

Description

SPECIFICATION Improvements relating to smoking articles This invention relates to wrapped smoking articles, particularly cigarettes.

Various proposals have been made for cigarettes which, when smoked, emit reduced amounts of sidestream-smoke constituents, sidestream smoke being the smoke which emanates from the lit end of the cigarette. Thus, for example, in United Kingdom Patent Specification No. 2,094,1 30A there is disclosed a cigarette of reduced sidestream emission which comprises a rod of smoking material wrapped in a cigarette paper of which the air permeability due to viscous flow is not more than about 3 CORESTA units of which the ratio of the coefficient of diffusion of oxygen through nitrogen in the paper to the thickness of the paper is in the range of 0.08 to 0.65 cm sec-1.

In United States Patent Specification No.

4,231,377, it is proposed to reduce sidestream smoke by incorporating a combination of magnesium oxide and an adjuvant salt in cigarette paper.

Conventional cigarette paper comprises cellulose fibres and an inorganic filler, most commonly chalk.

A burn-controlling compound is also often included.

The present invention provides a cigarette or the like of which the smoking-material rod is enwrapped in a cigarette paper comprising one or more compounds of the group comprising lithium hydroxide, aluminium hydroxide, calcium hydroxide, potassium formate, sodium formate and sodium acetate, whereby the total particulate matter in the sidestream smoke emanating from the lit end of said cigarette during the smoking thereof can be reduced by at least 30% compared with tht which emanates from the lit end of a comparable cigarette, smoked under comparable smoking conditions, comprising conventional cigarette pauper.

The inherent air permeability of the paper, i.e. that due to viscous flow, should in a range of 3 to 45 CORESTA units but preferably within a range of 3 to 20 CORESTA units and more preferably within a range of 3 to 10 CORESTA units. the air permeability of a paper as expressed in CORESTA units is the amount of air in cubic centimetres which passes through one square centimetre of the paper in one minute at a constant pressure difference of 1.0 kilopascal. For details as to the concept of viscous flow in relation to cigarette-paper permeability, reference is made to the aforesaid Specification No.

2,094,1 30A.

Preferably, the cigarette paper comprises a plurality of compounds of said group, advantageously at least three.

The present invention also provides smokingarticle wrapper paper comprising one or more compounds of the group comprising lithium hydroxide, aluminium hydroxide, calcium hydroxide, potasium formate, sodium formate and sodium acetate.

The invention further provides features of method of production of cigarette paper, cigarettes and/or smoking-material rod substantially as hereinafter described in the accompanying Specification, and/or the appended Experiments.

The or each component may be applied, together with a suitable binder or solvent, as a coating on the cigarette paper to either one or the other side thereof. Alternatively, it may be included in the paper at the paper-making stage. The compound(s) and loading level thereof are preferably selected so as to result in a reduction in sidesteam smoke-total particulate matter (TPM) of at least 50% and preferably at least 60%.

The rate of production of sidestream TPM, i.e. the sidestream TPM delivery per cigarette divided by the time over which the cigarette is smoked, correlates with the amount of visible sidestream smoke which is observed issuing from the cigarette. By use of the present invention, it is possible to achieve rates of production of sidestream TPM considerably less than the typical value of three mg min-1 encountered with conventional cigarettes. Advantageously, the rate of sidestream TPM should be less than two mg min-1 when measured according to a procedure described for Experiment 1 hereinbelow.

Some of the compounds which in accordance with the present invention bring about a reduction in sidestream smoke TPM exhibit adverse properties if they are present at too high a loading level. Thus, for example, lithium hydroxide can cause a breakdown of the paper structure and therefore the loading level of this compound should be limited to a level below which this breakdown phenomenon does n6t occur.

A loaing level limit should also be observed for potassium formate, because higher loading levels have been found to result in an unacceptable, coke-like ash formation in the smoking of test cigarettes. An advantage of using a plurality, especially three or more, sidestream-smoke reducing compounds is that a requisite total loading level can be obtained without exceeding an upper loading level limit of any one of the compounds.

Suitably, of the above-mentioned compounds, the wrapper paper comprises at least calcium hydroxide.

It was determined by smoking test cigarettes that no reduction, or only a negligible reduction, in visible sidestream smoke resulted from using cigarette papers treated respectively with magnesium oxide, calcium carbonate, lithium carbonate, potassium sodium tartrate, aliminium ammonium sulphate, magnesium citrate, magnesium oxalate, triammonium citrate, citric acid and heavy magnesium carbonate.

Examples of the invention will now be further described, by way of example, by reference to a number of experiments.

Experiment 1 Plain, 70mm long cigarettes were made using a flue-cured tobacco and a single-layer wrapper of cigarette paper having an initial air permeability of 26 CORESTA units and a weight of 23 g/m2. the cigarette paper had, before cigarette manufacture, been coated, on the side inended to be the inner side in the manufactured cigarettes, with a coating comprised of starch (6%), aluminium hydroxide (12%), magnesium hydroxide (12%), calcium hydro xide (12%), sodium formate (3%) and sodium acetate (3%). The percentage figures are the loading levels for the respective compounds based on the weight of the coated pauper. Thus the total coating level was 48%, that is 21.2 g/m2. The starch was used as a binder. The air permeability of the coated paper was 22 CORESTA units.

Each of these cigarettes was smoked under standard smoking conditions, i.e. a 35 cc.puff of 2 seconds duration every minute, while extending into a vertical flask through an aperture in the wall thereof which was fitted with a cigarette contacting seal. across the upper opening of the flask was fitted an 82 mm diameter Cambridge filter pad. Air and sidestream smoke were drawn upwardly under the action of an air pump, the flow of air into a lower opening of the flask, which flow was induced by the pump, being maintained at 1 litre/minute. The sidestream smoke TPM was collected on the filter pad.

By weighing the filter pad before the commencement of the smoking of a cigarette and after the completion of the smoking cycle, a determination was made for each cigarette of the total amount of reduction in sidestream TPM is obtained. The rate of production of sidestream-TPM for the test cigarettes was 2.0 mg min-1.

When conrol cigarettes, having uncoated cigarette paper, were smoked in the same manner, it was found that the total sidestream-smoke TPM was 23.2 mg. Thus the application to the cigarette paper of the test cigarettes of the above detailed coating brought about a 39% reduction in sidestream-smoke TPM.

Experiment 2 The procedure of Experiment 1 was followed except that the coating applied to the cigarette paper comprised starch (9%), aluminium hydroxide (18%), calcium hydroxide (18%), sodium formate (2.7%) and sodium acetate (2.7%). Thus the loading level, excluding the starch, was 17.3 g/m2. the air permeabilty of the paper after the coating had been applied was 18 CORESTA units. The total sidestream smoke TPM for uncoated control cigarettes was 23.9 mg, whereas tht for the test cigarettes was 13.9 mg.

Therefore the coating brought about a 42% reduced tion.

Experiment 3 The procedure for Experiment 1 was followed except that the coating comprised starch (9%), calcium hydroxide (35%), sodium formate (2.8%) and sodium acetate (2.8%), giving a loading level, excluding starch, of 15.7 g/m2. The total sidestreamsmoke TPM was reduced from 27.0 mg for conrol cigarettes to 14.5 mg for the test cigarettes, this representing a 46% reduction. Experiment 3 shows the ability of calcium hydroxide to effect a good sidestream reduction when it predominates in a coating mixture.

Experiment 4 The procedure of Experiment 1 was folowed except that the coating comprised starch (8%), aluminium hydroxide (16%), magnesium hydroxide (16%) and calcium hydroxide (16%), giving a loading level, excluding starch, of 21.2 g/m2. The coating reduced the air permeability of the paper to 10 CORESTA units. Total sidestream-smoke TPM for control cigarettes was found to be 25.8 mg and for the test cigarettes 16.9 mg, this representing a reduction of 34%.

Experiment 5 The procedure of Experiment 1 was again repeated except that a cigarette paper was used which had an initiai air permeability of 5.2 CORESTA units and tht the coating comprised only sodium formate (5%) and sodium acetate (5%), giving a loading level of 2.6 g/m2. The air permeability of the paper after coating was 5.1 CORESTA units. total sidestreamsmoke TPM was found to be 28.8 mg for control cigarettes having the same cigarette paper as for the control cigarettes of Experiment 1 and 19.8 mg for the present test cigarettes, this representing a reduction of 31%. This experiment shows that, by use of a comparatively low level (10%) of loading of sidestream-reducing compounds in combination with the use of a low permeability paper, a significant reduction in sidestream-TPM for the test cigarettes was 2.0 mg min-1.

Claims

1. A smoking article comprising a smokingmaterial rod enwrapped in a wrapper paper comprising at least one compound of the group comprising lithium hydroxide, aluminium hydroxide, calcium hydroxide, potassium formate, sodium formate and sodium acetate, at a loading level of the compound or a total loading level of the compounds, of not less thant two g/m2, whereby the total particulate matter (TPM) in the sidestream-smoke emanating from the lit end of said article during the smoking thereof is reduced by at last 30% in relation to the TPM which emanates from the lit end of an otherwise identical smoking article comprising conventional wrapper paper and smoked under the same smoking conditions.

2. A smoking article as claimed in Claim 1, wherein the reduction in sidestream TPM is at least 50%.

3. A smoking article as claimed in Claim 1 or 2, wherein the inherent air permeability of said wrapper paper is within a range of 3 to 45 Coresta units.

4. A smoking article as claimed in Claim 3, wherein said permeability of said wrapper is within a range of 3 to 20 Coresta units.

5. A smoking article as claimed in Claim 4, wherein said permeability of said wrapper is within a range of 3 to 10 Coresta units.

6. A smoking article as claimed in any one of the preceding claims, wherein said wrapper paper comprises a plurality of said compounds of said group.

7. A smoking article claimed in Claim 6, wherein said wrapper paper comprises at least two hydroxide compounds of said group.

8. A smoking article as claimed in Claim 6, wherein said wrapper paper comprises at least two organic compounds of said group.

9. A smoking article as claimed in Claim 6, wherein said wrapper paper comprises at least one hydroxide compound of said group and at least one organic compound of said group.

10. A smoking article as claimed in any one of the preceding claims, wherein the loading level of any one of the organic compounds of said compounds does not exceed three g/m2.

11. A smoking article as claimed in any one of the preceding claims, wherein the loading level of any one of the hydroxide compounds of said compounds is at least two g/m2.

12. A smoking article as claimed in any one of the preceding claims, wherein the rate of production of sidestream TPM does not exceed about two mg min-l.

13. A smoking article as claimed in any one of the preceding claims, wherein said wrapper paper comprises calcium hydroxide.

14. Smoking article wrapper paper comprising at least one compound of the group comprising lithium hydroxide, aluminium hydroxide, calcium hydroxide, potassium formate, sodium formate and sodium acetate at a loading level of the compound, or a total loading level of the compounds, of not less than two g/m2.

15. A cigarette, comprising coated cigarette paper, as described hereinabove in any one of Examples 1-5.