GB2283401A - Smoking articles and method of making them - Google Patents

Abstract

A smoking article has a pressure drop across it which is in the range 250-700 mmWG at 17.5 cm<3>s<-1>. The purpose is to minimize the volume of smoke drawable by smokers per puff. The pressure drop may be achieved by an essentially impervious portion (4) of a filter (3) and/or by such a portion in the tobacco rod (2). <IMAGE>

Description

SNORING ARTICLES AND METHOD OF MAKING THEM This invention relates to smoking articles such as cigarettes, cigars and cigarillos. They will be referred to, for brevity, as "cigarettes" hereafter.

Conventionally, cigarettes are designed to have a pressure drop usually in the order of 60-150 mmWG measured at the industry standard flow rate of 17.5 cm3s-l. These figures are chosen so that there is some resistance to the draw on the cigarette but not so much that the smoker cannot vary and thereby control the volume taken in per puff. It is a consistent feature of filter and tobacco rod design that resistances must be controlled and kept low. The tobacco rod may, as is conventional, include materials other than cut leaf, such as e.g. reconstituted tobacco, fillers and perfumes.

A construction which does not have a pressure drop of the order of 60-150 mmWG is an unsuccessful one. See for example US-A-3621851 where, in columns 20 and 22, comparative examples giving rise to pressure drops of 473, 566 and 567 mmWG are described as "totally unacceptable", but where in column 24 it is reasserted that a "very low pressure drop" is desirable.

This doctrine however leads to disadvantages.

Smokers of conventional cigarettes having pressure drops of the order of 60-150 mmWG have puff volumes which vary from user to user by a factor of 5.

Low volumes are about 20 cm3 and large volumes about 100 cm3. Low volumes are achieved by the sharp application of a high pressure difference across the cigarette; the larger volumes tend to be achieved by the smoker taking a long draw at comparatively low pressure difference.

The effect is that the amount and even the nature of the smoke generated per puff will vary widely from user to user, leading to radically different perceptions of identical products by different users.

This leads to the marketing difficulty that cigarettes can be identified by brand only rather than by product characteristics.

The present invention turns conventional wisdom on its head. It aims to reduce as far as is feasible the smoker's control over puff volume with the aim of reducing the volume of smoke generated per puff.

To this end we provide a smoking article which has a pressure drop across it which is in the range 250-700 mmWG at the flow rate of 17.5 cm3s-l. This extremely high pressure drop may be achieved by using a high pressure drop filter or a flow impediment in or attached to the tobacco rod, or both. In either case, the flow through the filter or impediment is essentially axial.

We find that a smoking article having this extremely high pressure drop causes a reduction in puff volume to a maximum which is in the range 5-30 cm3.

However it has to be realised that this maximum is now fixed in relation to the article not in the relation to the user, so that smokers who would have drawn volumes at the extreme ends of the ranges indicated at the start will now draw volumes which are very much closer to each other and which are primarily determined by the structure of the smoking article not by the smoker's physique and habit.

In this way several benefits can be achieved.

There is reduced tobacco usage since less tobacco is consumed at low puff volumes. This means that there is reduced visible exhaled smoke. However the primary advantage is that because this will cause greater similarity of experience of a given article amongst users, characteristic identification should be possible in marketing and the problems of achieving standardized testing of the perception of the products can be alleviated.

The reduction in smoke volume per puff can readily be compensated from the point of view of consumer satisfaction by selection blending or formulation of the tobacco rod and/or treatment of the filter, if present, to give more concentrated taste and flavour characteristics so as to provide an acceptable product.

A specific embodiment is seen in Figure 1, which is a partial diametrical section through a cigarette.

A wrapped tobacco rod 1 includes tobacco 2 which is highly flavoured and highly nicotinic, having e.g. a nicotine content of over 3S, and probably about 4W W/W on a dry basis.

A wrapped filter 3, overwrapped to join it to the tobacco rod, has two regions, a high pressure drop portion 4 and a conventional low pressure drop portion 5 at the mouth end of the cigarette. In this example, both are of equal length. The portion 4 is a discrete insert, being a tube 6 of essentially impervious material such as compressed paper, cellophane, closedcell foam or even a plastics material sleeve or ring.

It has a narrow central aperture 7 (not drawn to scale in the Figure). Selection of the diameter of the aperture (and to a minor extent, its length) varies the pressure drop across the region 4; in the present example the aperture has a diameter of 0.8 mm giving a pressure drop of 225 mm WG at the standard flow rate.

The pressure drop across conventional region 5 of e.g.

cellulose acetate tow is of the order of 25 mm WG and across the tobacco rod about 50 mm WG. Thus the cigarette offers a pressure drop of 300 mm WG to the smoker drawing on it. The volume of smoke taken per puff by the smoker will be of the order of 20 + 10 ml.

This means that the very strong tobacco 2 yields a smoke which is perceived as acceptably mild by the smoker: the volume of tobacco burned per puff is reduced and the amount of tobacco in the tobacco rod can be very substantially reduced, e.g. by shortening the tobacco rod, without loss of either perceived yield or of smoking time.

In other embodiments, the region 4 is occupied by a coiled sheet of smooth paper, cellophane or plastic such as polyethylene, polypropylene or nylon.

These elements provide a high pressure drop of 175 mm WG or greater at the standard flow rate but offer relatively low filtration efficiencies at 10 to 30t.

The elements may either replace, or be included with, the flow impediment in region 4 in Figure 1.

Claims (9)

1. A smoking article having a pressure drop across it which is in the range 250-700 mmWG at a flow rate of 17.5 cm3s1.

2. A smoking article according to claim 1 wherein the pressure drop is in the range 250-350 mmWG at said rate.

3. A smoking article according to claim 1 or claim 2 which has a filter (3) which includes a high pressure drop portion (6) and a low pressure drop portion (5).

4. A smoking article according to claim 3 wherein the high pressure drop portion (6) is of essentially impervious material penetrated by at least one axial passage (7).

5. A smoking article according to claim 3 wherein the high pressure drop portion (6) is a high pressure drop low efficiency filter material for conducting smoke axially.

6. A smoking article according to claim 1 or claim 2 wherein there is a high pressure drop portion in a tobacco rod (1) of the article.

7. A smoking article according to any one of claims 3, 4 or 6 wherein the high pressure drop portion is provided by a discrete insert.

8. A smoking article according to any one of claims 3 to 7 wherein the high pressure drop portion provides a pressure drop of at least 175 mmWG at said rate.

9. A method of reducing the maximum volume per puff drawn from a smoking article by a smoker to 5-30 cm3, which consists of forming the smoking article to be as claimed in any one of claims 1 to 5.