WO2009125209A1

WO2009125209A1 - Filter material preparation

Info

Publication number: WO2009125209A1
Application number: PCT/GB2009/050215
Authority: WO
Inventors: Richard Thomas Fiebelkorn; David Dittrich; Matthew Hesford
Original assignee: British American Tobacco (Investments) Limited
Priority date: 2008-04-10
Filing date: 2009-03-04
Publication date: 2009-10-15
Also published as: GB0806455D0

Abstract

One embodiment of the invention provides a method of preparing a filter for use in a smoking article. The method comprises machine-smoking tobacco through a first filter material and then storing the first filter material after machine-smoking in conjunction witha second filter material. The filter for use in a smoking article comprises the second filter material. It has been found that flavour volatiles from the smoked tobacco are retained in the first filter material during the machine-smoking, and then transferred to the second filter material during the storage.

Description

FILTER MATERIAL PREPARATION

FIELD OF THE INVENTION

The invention relates to the production of filter material that may be used in filters or mouthpieces for smoking articles such as cigarettes and cigarette substitutes or in other inhalable devices.

BACKGROUND TO THE INVENTION

Recent years have seen the development of more sophisticated filters (e.g. multi-segmented) for use with smoking articles such as cigarettes, as well as filters or mouthpieces (hereinafter referred to only as filters) for use in corresponding smokeless devices. However, the presence of a filter in a smoking article may have a detrimental impact on certain aspects of product quality for a consumer, for example, a filter may lessen or alter the tobacco smoke flavour experienced by the consumer.

Also, products which can act as a substitute for a smoking article such as a cigarette have been developed that deliver an aerosol or vapour instead of conventional tobacco smoke, but these products may not deliver an acceptable tobacco smoke flavour to smokers.

As used herein, the term "flavour" includes at least one of, and usually the combination of the taste e.g. salt, sweet (within the buccal cavity) and aroma (within the nasal cavity).

SUMMARY OF THE INVENTION

Broadly stated the invention provides a method of preparing a filter, comprising: collecting flavourant components in a first material from a gaseous stream produced from a smokable material; and producing a vapour transfer of volatile flavourant components from the first material into a second material for use as the filter.

One embodiment of the invention provides a method of preparing a filter for use in a smoking article or other device known in the tobacco industry. The method comprises generating smoke aerosol from burning or heating tobacco, e.g. by machine- smoking the smokable material, and collecting that smoke on a first filter material. Flavour components collected on the first filter material are then transferred to a second filter material by vapour transfer techniques. The filter for use in a smoking article or other device comprises the second filter material.

It has been found that volatile and semi- volatile components from the tobacco smoke are retained in the first filter material during the machine smoking. These components then migrate (at least partly) from the smoked (first) filter material to the second filter material during the transfer. The second filter material can then be used in a smoking article to provide additional flavouring during use.

The transfer of these flavour components may be achieved by the simple method of storing both the first and second filter materials within a sealed or contained environment at ambient conditions, and/or with the use of heat, airflow or vacuum to change the rate, number or level of components that are transferred.

In one embodiment, the first filter material is stored in conjunction with the second filter material at ambient conditions (e.g. temperature, pressure and humidity). The first filter material may be stored in conjunction with the second filter material for a period of more than one hour and less than one month, for example, for a period of between four hours and one week. It will be appreciated that other implementations may use a different period of storage.

The duration and conditions of the storage can be used to control the strength and nature of the components transferred from the first filter material to the second filter material. The nature and strength of the flavouring in the second filter material will also depend on factors such as the tobacco(s) used during the machine-smoking phase, the detailed implementation of the machine-smoking, and the substances used for the first and second filter materials.

In one embodiment, the second filter material is formed into individual filters for smoking articles prior to being stored in conjunction with the first filter material. Alternatively, the second filter material may be stored in bulk form in conjunction with the first filter material, and afterwards formed into individual filters. In the latter case, the bulk material should be in a form to facilitate the transfer of the volatiles from the first filter material through the second filter material.

In one embodiment, the first filter material comprises cellulose acetate and the second filter material likewise comprises cellulose acetate. The skilled person will be aware of various other materials that may be used for the first and/or second filter material - e.g. paper. Note that the second filter material may be processed as appropriate during formation of the smoking article. For example, granular carbon may be added into the second filter material (before or after storage with the first filter material) to provide enhanced vapour phase filtration. In one particular embodiment, the filter for use in a smoking article comprises a multi-segment filter. One or more segments of the filter comprise said second filter material. The other segments of the filter may comprise a different filter material (which may or may not have been processed in the same way as the second filter material). In some cases two different segments of the filter may both be made of the second filter material, but processed in a different way - either during the smoke-mediated flavour transfer itself, e.g. by using different tobacco for the machine smoking, and/or during subsequent processing, e.g. with regard to adding granular carbon.

One embodiment of the present invention provides a filter produced in accordance with the above method. Such a filter generally comprises a substrate, such as cellulose acetate, impregnated with volatiles and/or semi-volatiles from tobacco smoke.

One embodiment of the present invention provides a smoking article including a filter such as described above. The smoking article may comprise an otherwise conventional cigarette. Another possibility is that the smoking article is a smokeless device (various smokeless devices are known in the art). In the latter case, the pre- smoked second filter material can provide the user with flavourings from smoke, but without the user receiving any smoke itself.

BRIEF DESCRIPTION OF THE DRAWING

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawing in which: Figure 1 depicts overlaid chromatograms for control filter material and for smoke- flavoured filter material in accordance with one embodiment of the invention.

DETAILED DESCRIPTION

In accordance with one embodiment of the invention, a method for the transfer of smoke flavour to new filter material is implemented as follows, a) tobacco, plus any casing and/or flavouring as required, is pre-smoked through a first material that may act as a filter medium. Examples of a suitable filter medium are conventional cellulose acetate (with triacetin), a Cambridge filter pad (a glass filter), and so on. One possibility is to collect material on the filter medium via smoke impaction onto the medium. The filter medium may be formed as individual filters, such as might be used directly in smoking articles, or in larger blocks of material (but not too large to prevent smoke penetration). During the pre-smoking, the filter medium retains some or all of the particulate phase of smoke, and some of the volatile and non- volatile components too. b) the pre-smoked filter medium is stored in a sealed or contained environment with a second material that may comprise new (unflavoured or unsmoked) filter material. The new filter material may comprise cellulose acetate or some other appropriate substance. The new filter material may again be formed as individual filter rods or plugs, such as might be used directly to produce smoking articles or other inhalable devices, or in larger blocks of material (but not too large to prevent flavour penetration). The storage may be for a period ranging from about 1 hour to several days or more, depending on the amount of transfer required. During storage, it has been found that volatile and semi- volatile flavouring components migrate from the smoked filter material to the new (non-smoked) filter material without requiring any direct contact between the smoked filter material and the non-smoked filter material, or transfer of particulate material.

Sensory evaluation of the smoke-flavoured filters over a period of a week, with the smoke-flavoured filters being maintained in an open ambient environment, has confirmed that a transfer of flavour components from the pre-smoked filter material to the new filter material does indeed occur. Moreover, this transfer has been found to be reasonably stable over the observation timescale (good initial smoke flavour, decreasing slowly with aging).

The tobacco smoke generated may come from machine smoking standard cigarettes, although the method of generating smoke can be any of the known burning or heating methods e.g. burning tobacco within a furnace, or a heat-not-burn technique, thereby producing a gaseous stream containing flavourants that are collected in the first material.

Different tobacco blends can be used to provide a range of different flavours, ranging from light and aromatic to dark and cigar-like. Single grades or styles of tobacco may be used to create unique flavours, and tobacco additives in the form of casings and/or flavours may also be used to create additional flavour notes. The transfer of flavour components from the first to the second material may be accomplished with the aid of heat, airflow or vacuum. These methods alter the rate of transfer and the selectivity of the transfer. For example, applying heat to the first filter will enable the transfer of different (type and level) flavour components to the second filter.

Also, the smoke generated can be modified before being captured on the first filter in order to achieve the desired flavour and/or remove any unwanted components. This can be achieved by selection of the phase that is to be captured on the first filter, i.e. particulate phase only, vapour phase only or both phases, or by treating the smoke generated to interim filtration and/or chemical or physical processes, e.g. modification of Ph .

Furthermore, the first material can be chosen (e.g. paper fibres rather than acetate) or treated (e.g. with triethly citrate rather than triacetin) so as to be more selective in capture and release of flavour components.

The outcome of the above processing is to provide the second material for use in a smoking article, which is able to deliver a significant amount of cigarette smoke taste and aroma when air is drawn through it, but without actually providing any smoke to the user. In other words, the flavour from the second, filter material is accessible to a user even in an unburnt smoking article, without having to light the smoking article.

Note that the smoking article itself does not come into contact itself with smoke during pre-smoking, nor is there any specific addition of flavouring to the smoking article, other than indirectly via the pre-smoked filter material. Rather, the new (fresh) filters made of the second material, which can be otherwise standard, may be impregnated with at least some of the smoke flavour components that are known to be present within the volatile and semi- volatile portion of smoke. The new filter material can be packed and used as an alternative to smoking, i.e. in a smokeless tobacco (dry-draw) product. Alternatively, the new filter material can be used as part of a conventionally smoked product to enhance the taste, especially the initial taste at the start of smoking.

The smoke- flavoured filter elements produced as described herein can be combined with other materials to form multi-component filters e.g. paper and cellulose acetate, or cellulose acetate and cellulose acetate plus carbon. These different mediums can then be used to provide different tastes.

In one embodiment, the multi-segment filters are formed prior to storage with the pre-smoked filters for flavour transfer. In another embodiment, the filter material for each segment of the multi-segment filter is stored separately from the filter material for the other segments during the flavour transfer phase. This then provides more flexibility in terms of the processing e.g. different storage times might be used for different filter materials to control the degree of flavour transfer.

A Solid Phase Micro -Extraction (SPME) analysis has been carried out on a filter provided with smoke- flavouring in accordance with the method described above. In this analysis, the smoke- flavoured filter was compared against a non-flavoured control filter. The tobacco style used to generate the flavour was a standard modified Flue cured blend and the first filter material was a cellulose acetate filter. The transfer of flavour from the first pre-smoked filter material to the second new filter material was accomplished under ambient conditions in a sealed unit for a period of two days.

The SPME analysis involved heating a small amount of the (new) material and using gas chromatography and mass spectrometry to measure and identify individual compounds that were present. ChemStation software using Wiley libraries was used to identify the peaks. Figure 1 depicts the overlaid chromatograms for the smoke- flavoured filter material and for the control (blank) filter material obtained as a result of this analysis.

The chromatograms are broadly similar, indicating that a number of compounds were present in both the control and the smoke- flavoured filter material. In many cases, the levels of these compounds were similar, which indicates that they arise from the intrinsic filter material itself, not from the smoke flavouring. Nevertheless, in some cases, e.g. nicotine, the level of compound found in the smoke- flavoured filter material was considerably higher than the level of compound found in the control filter. In other cases, certain compounds were only found in the smoke- flavoured filter material, but not at all in the control filter.

Table 1 below provides the results of this analysis for the compounds identified as being present in the smoke-flavoured filter, but not in the control filter. The first column of Table 1 gives the name of the relevant compound. The second column of Table 1 gives the area under the peak, which is indicative of the amount of the compound present in the filter material. The third column of Table 1 gives a percentage certainty, which provides a measure of how closely the observed mass spectrum matches the library spectrum. Overall, a total of 59 identified compounds and several unidentified compounds were transferred from the pre-smoked filter into the new filter material.

Table 1

The skilled person will be aware of various modifications that may be made to the embodiments described above within the scope of the present invention defined by the appended claims.

Claims

1. A method of preparing a filter, comprising: collecting flavourant components in a first material from a gaseous stream produced from a smokable material ; and producing a vapour transfer of volatile flavourant components from the first material into a second material for use as the filter.

2. The method of claim 1 including producing the gaseous stream by heating the smokable material.

3. The method of claim 1 or 2 including producing the gaseous stream by burning the smokable material to produce smoke.

4. The method of claim 2 or 3 wherein the smokable material at least in part comprises tobacco.

5. The method of any preceding claim wherein the first material comprises a filter material.

6. The method of any preceding claim including storing the first material in conjunction with the second material to produce said vapour transfer.

7. The method of claim 6, wherein the first material is stored in conjunction with the second material for a period of more than one hour and less than one month.

8. The method of claim 7, wherein the first filter material is stored in conjunction with the second material for a period of more than four hours and less than one week.

9. The method of any preceding claim, wherein the second material is formed into individual filters for smoking articles prior to being stored in conjunction with the first material.

10. The method of any preceding claim including storing the first and second materials under ambient conditions in a container.

11. The method of any preceding claim wherein the vapour transfer is performed utilising heat, airflow or a vacuum to facilitate the transfer of volatile flavourant components from the first material to the second material.

12. The method of any preceding claim including chemically or physically modifying the composition of the gaseous stream supplied to the first material.

13. The method of any preceding claim, wherein the first material comprises cellulose acetate.

14. The method of any preceding claim, wherein the second material comprises cellulose acetate.

15. The method of any preceding claim, wherein the filter for use in a smoking article comprises a multi-segment filter, and one or more segments of the filter comprise said second material.

16. A filter prepared in accordance with the method of any preceding claim.

17. A filter comprising a substrate impregnated with volatiles but not particulate matter from tobacco smoke.

18. A smoking article including the filter of claim 16 or 17.

19. The smoking article of claim 18 that comprises a smokeless device.