GB2122473A - Improvements relating to smoking articles - Google Patents

Abstract

A smoking article, such as a cigarette, has a filter which incorporates zeolite granules impregnated with a volatile smoke-modifying agent. A cavity-type of filter may contain between 10 and 200mg of metholated zeolite granules. The loading level of a methol on the zeolite granules may be within a range of from 3 to 60 mg/g. The zeolite granules can be mixed with other substances such as smoke filtering materials. Cellulose-acetate plugs may be provided at the ends of the filter cavity. <IMAGE>

Description

SPECIFICATION Improvements relating to smoking articles This invention relates to a smoking article incorporating a smoke-modifying agent. By a smoke-modifying agent in this Specification and the appended claims is meant an agent which imparts a flavour and/or other subjectively appreciated effectto mainstream smoke drawn from the article.

It is a well established practice to incorporated extraneousflavourant materials in smoking articles.

Among flavourants added to cigarettes, one of the most commonly used is menthol. Among ways which have been proposed for incorporating menthol in cigarettes, a method often practiced for producing mentholated cigarettes is to apply menthol to the tobacco priorto cigarette manufacture. Thus, for example, UK Patent Specification No. 1,357,057 describes a method in which an alcoholic solution of menthol is sprayed onto a layer of tobacco formed on a cigarette-ming machine just up-stream of the entry point ofthe layer into the rod-making garniture ofthe machine.However, the spraying of tobacco with a volatile material presents the problem that such a material is liable to contaminate the machine, so that, unless the machine is scrupulously cleaned, cigarettes subsequently made on the machine which were not intended to incorporate the volatile material will in fact be tainted with the material. Another problem that may be encountered when a volatile flavourant is sprayed onto cigarette tobacco is that, during storage of cigarettes manufactured from the tobacco, the flavourant is liable to volatilize and thus be lostfrom the cigarette.

Proposals have been made to ameliorate these problems by incorporating volatileflabour materials in the filters of filter-tipped cigarettes, theflavou r materials being impregnated on granular or particulate carrier materials. In US Patent Specification No.

3,603,319,forexample,there is a disclosure of the concept of absorbing menthol or otherflavourants on organic polymer granules and incorporating the granules in cigarette filters. As is apparent from the examples given in US 3,603,319, a drawback ofthis concept resides in thefactthat, of the flavourant on the polymer granules, only small amounts, typicaly about 11 are transferred to the main-stream smoke.Thisclearly represents an uneconomic use of flavourant material. Asimilar proposal is made in United Kingdom Patent Specification No.2,054,341A, according to which granular magnesium is used as a carrierfor menthol.The same defect, however, is exhibited as with the polymer granules of US 3,603,319, that is to say the menthol is held too retentively by the carrier and only small amounts of menthol aretransferredtothe mainstream smoke.

An object of the present invention is to provide a smoking-article filter in the use of which a flavourant incorporated in the filter is transferred to the mainstream smoke in amounts which are acceptably large as percentages ofthe amount offlavourant added to the filter.

The present invention provides a smoking-article filter comprising zeolite granules impregnated with a volatile smoke-flavouring or modifying agent, menthol for example.

The invention is based on the discovery that zeolite granules possess acceptable retention properties for volatile smoke-modifying agents whilst releasing a higher proportion ofthe agent into the tobacco smoke than is the case with prior proposed granular carrier materials.

Filter cigarettes ofwhich the filters contained magnesium silicate granules impregnated with menthol have been examined. The tobacco rod of each ofthese cigarettes was 63mm long and the filters 20mm long, each filter comprising an 8mm long paperfilter plug abutting the tobacco rod and a 7mm long cellulose acetate filter plug atthe mouth end ofthefilter, the two plugs bounding an intermediate cavity in which magnesium silicate granules were disposed. The loading level of methol on the granules was approximately 56 mg/g.Theweightofthe granules in each filter was about 122mug.

In orderto determinethe degree oftransferof menthol to mainstream smoke, the cigarettes were machine smoked, under standard smoking conditions of one 35cm3 puff of 2 seconds duration each minute, the smoke being discontinued at a tobacco rod butt length of 8mm. The smoke was drawn from the cigarettes through Cambridge filter pads.

Measurements made ofthe amounts of menthol in the total particulate matter (TPM) collected on the filter pads, in the vapour phase ofthe smoke, in the magnesium silicate granules and in the filter plugs indicated that after smoking, 65% of the methol in each cigarette before smoking was still retained by the granules and that 20% resided in the filter plugs.

As to the smoke, 7% transferred to the TPM and no measurable amount was found in the vapour phase.

The amount of menthol on the granules after smoking was 86% ofthe amount of menthol on the granules before smoking.

Itwas thus clearly demonstrated that although magnesium silicate possesses a good retention property with respect to menthol, the degree of transfer of menthol from the granules to the mainstream smoke was very low. This means that to ensure the attainment of a desired level of smoke mentholation, a large excess menthol loading on the magnesium silicate granules is necessitated.

In the accompanying drawings, figure 1 shows a graph which illustrates menthol present in the mainstream TPM per mg/puff plotted against puff numbers forthe above described examination of filter cigarettes whose filters contained mentholimpregnated magnesium silicate granules.

Figure 2 ofthe drawings shows a graph for puff-by-puff levels of menthol in the mainstream smoke of filter cigarettes, produced in accordance with a preferred embodiment ofthe present invention, as described with reference to Figure 3 of the accompanying drawings.

As may be seen, the menthol delivery per puff in Fig. 1 increases very rapidly, especially overthe last few puffs.

In orderto investigate the suitability of zeolites as carriers for menthol in cigarettefilters, a construction of filter cigarettes (Figure 3) was used having, within a wrapping a, a 64mm long tobacco rod band a further element ccomprising a 1 sum iong cavity d contai n- ing specified mentholated zeolite granules, and bounded by 5mm long cellulose-acetate plugs, e1 and e2 respectively, atthe mouth and tobacco ends.

The zeolites employed, in each case with 100 mg of selected mentholated zeolite granules in the cavity, were obtained from Anaconda Copper Co Ltd under the designations 101 0A(i), 101 0A(ii), 2020A and 5050L,the respective initial loading levels of menthol on these zeolites being 4.7,36.4,91.6 and 48.2 mg/g of zeolite.

Determinations were made of the total amount of menthol in samples ofthezeolite-containing cigarettes just before others ofthese cigarettes were smoked. The results are shown in Table 1.

TABLE 1

Zeolite Menthol (Mg/cigarette) 1010A (i) 0.21 1010A (iij 1.55 2020A 6.37 5050L 1.74 The zeolite-containing cigarettes were machine smoked underthe aforesaid standard conditions and measurments were made ofthe menthol transferred tothemainstreamTPM.The results are shown in Table 2.

TABLE 2

Zeolite . Menthol in TPM (r of menthovoigarette before smoking) 1010A (ij 37 1010A (iij 29 2020A 24 5050L 36 The levels of menthol transfer to mainstream smoke which are indicated in Table 2 are substantially in advance ofthe 7% transfer obtained when magnesium silicate granules were employed as the carrierfor menthol.

Figure 2 shows the graph for puff-by-puff levels of menthol determined forthe cigarettes containing the 101 0A (ii) zeolite. As is evident from Figure 2, the menthol delivery per puff increases in a proportionate manner, there is no accelerated build-up of TPM menthol in the last few puffs as was the case, (Figure 1) with the cigarettes containing magnesium silicate.

Itwill be understood that the invention is not to be construed as limitedtothedesribed embodiments: For example, thefilter may contain between 18 and 200 mg of mentholated zeolite granules per cavity of a cavity-type filter. Furthermore, the loading level of menthol on the zeolite granules may be within a range of from 3to 60 mg/g. Moreover, the zeolite granules may be admixed with material of a different composition, which mayalso bein granularform. For exampie,the material of a different composition may comprise a smoke filtration material.

Claims (10)

1. Asmoking article having afilterwhich incorporates a volatile smoke-modifying agent, wherein the filter comprises zeolite granules impregnated with the volatile agent.

2. A smoking-article filter comprising zeolite granules impregnated with a volatile smoke-modifying agent.

3. Afilter according to Claim 2, wherein the smoke-modifying agent comprises menthol.

4. Afilter according to Claim 3, wherein the filter contains between 10 and 200mg of mentholated zeolite granules per cavity of a cavity4ypefilter.

5. Afilteraccording to Claim 2 or3 wherein the loading level of menthol on the zeolite granules is within a range offrom 3to 60 mg/g.

6. Afilter according to Claim 4 or 5, wherein cellulose-acetate plugs are provided at the ends ofthe filter cavity.

7. Afilter according to any one of Claims 2 to 6 wherein the zeolite granules are admixed with materials of a different composition.

8. Afilter according to Claim7wherein said material of a different composition comprises a smoke filtration material.

9. Asmoking article provided with afilteraccording to any one of Claims 2 to 8.

10. Asmoking article orfilter substantially as hereinbefore described with reference to the accompanying drawings.