FI56616C - TOBAKSROEKFILTER - Google Patents

Description

v! ££>] m / <m ADVERTISEMENT rrr tc ^ 11 UTLÄGGNINGSSKRIFT 566 I 6 • C (45) Pator.ttl rayär.r.etty 10 03 1930

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(41) Made public — Blivit offentlij aL re :. nL

National Board of Patents and Registration Λ *. \ Ο · r * (44) Date of publication and date of publication.

Patent * och registerstyrelsen Anaökan utlagd oeh utl.tkriftan publlcarad jo * 11 * 79 (32) (33) (31) Claim claimed privilege — Begird priorltet England-England (OB) 523W72 (71) Britiah-Aeerican Tobacco Coepany Limited, Westminster House, 7,

Millbank, London S.V.1, England-England (GB) (72) Robin Arthur Crellin, Rcasey, Hampshire, Henry George Horeevell,

Totton, Hampshire, Eagland-Eagland (GB) (7 * 0 Leiteinger Oy (5 * 0 Tobacco smoke filter - Tobaksrökfilter

Several filter forms for tobacco smoke are known which remove the particulate phase of the smoke by mechanical means. However, these filters, which consist of, for example, fibrous or fibrous materials, retain only the volatile constituents of tobacco smoke with poor efficiency. The constituents in vapor form are known to be able to be removed from the smoke to some extent by adsorption on a suitable surface or by a chemical reaction.

For this purpose, the active substance is, for example, carbon, optionally as activated charcoal. The substance may be placed in the form of a granular layer between two filter plugs of fibrous or fibrous filter medium, or they may be placed in or on another filter medium. However, when used in this way, carbon is also known to have a detrimental effect on the taste of tobacco smoke by forming a so-called "off-flavor". The object of the present invention is to provide a carbon-containing filter which removes volatile or vapor phase constituents to an acceptable level, but which has little or no detrimental effect on the taste of the smoke. More specifically, the object is to provide a filter in which the carbon is protected against the settling of smoke particles, but which allows the adsorption of vapors.

2

S661S

To achieve this object, the tobacco smoke filter according to the invention, comprising areas extending mainly in the longitudinal direction of the filter and at least one of which is provided with carbon and at least one forming a smoke passage, is characterized in that each area filled with carbon is closed by smoke flow. through and separated from the smoke passageway by a membrane which is permeable to carbon-adsorbable vapors but impermeable to smoke particles.

Thus, such a filter may comprise two concentric tubes, an inner tube of vapor-permeable material and an outer tube of substantially smoke-impermeable material, the annular space between the tubes being filled with carbon granules or powder and sealed at each end, while the inner tube is free of carbonaceous material. at both ends forming a smoke duct. The ratio of the diameter of the inner tube to the diameter of the outer tube may conveniently be of the order of 1: 4 to 1: 2.

Alternatively, the inner pipe may be filled with carbon and closed in the same way at both ends, the outer pipe being separated from the inner pipe, possibly by means of longitudinal thickenings, forming an open-ended annular smoke duct. The pipe-to-diameter ratio may conveniently be in the order of 5:10 to 9:10.

The carbon particulate filler can be significant in the sense that the larger the usable surface area, the more favorable the conditions for diffusion and thus for the removal of vapor constituents. In terms of weight per unit length of filter, a suitable range 2 2 is 10 to 150 mg / cm, preferably 40 to 100 mg / cm. The particle size is best between 12 and 150 British Standard Specification meshes.

The "porosity" of the porous material, preferably paper, should be at least 32,000 cm / min./10 cm per 10 cm of water column.

Such a filter is best used as a central portion between two end portions of a fibrous material such as cellulose acetate or paper, or in a double filter adjacent to a tobacco rod.

The entire filter may be enclosed in a conventional paper wrapper tube and attached to the cigarette in the usual manner.

3 «616

When a cigarette is burned through such a filter, the cigarette particles pass through the smoke path, the inner tube or the annular gap, as the case may be, without flowing through the carbon. Smoke analysis shows that the amount of volatile constituents, especially aldehydes and hydrogen sulfide, is reduced, although the taste of the smoke remains the same. This reduction is achieved because the volatile constituents diffuse. . ...

through the inner tube to the carbon-filled area to which they are adsorbed. Particulate matter does not diffuse through this tube. Thus, carbon is substantially prevented from being contaminated by smoke particles and no inter-carbon-particle events occur. A further advantage is found in that the ratio of all volatile constituents remains more uniform from blow to blow than in the case where smoke flows through the carbon bed.

The following is a more complete description of examples of the practice of the invention and the results obtained therefrom with reference to the accompanying schematic drawings, in which:

Figure 1 is a longitudinal section of a cigarette filter with an annular, carbon-filled region.

Figure 2 is a similar view of a filter with a central carbon filled region.

Figure 3 is a similar view of a filter with a bag-like carbon-filled area.

Figures 3a and 3b show the filter from opposite ends.

Figure * + graphically shows the filter efficiency results obtained.

Figure 5 is a perspective view of a carbon filled bag.

Figure 6 is a perspective view of a filter section comprising three such bags.

Figures 7 and 8 are cross-sectional and longitudinal sections taken along line VIII-VIII of Figure 7 of a filter with a wrapped carbon-filled bag.

“56616

In all of the following examples, cigarettes with an outer tube diameter of 8 mm were burned under standard conditions, i. one minute blowing for 2 seconds and a volume of 35 ml. The measured filtration efficiency of all volatile aldehydes was considered an indication of the efficiency with which the carbon removed the constituents of the vapor phase from the cigarette smoke.

Example 1

The triple filter shown in Figure 1 comprises a part 1 according to the present invention interposed between cellulose acetate filter plug parts 2 and 3 and adjacent to a tobacco rod 4, respectively, all of which are enclosed in a smoke-impermeable wrapper tube 5. Part 1 includes very vapor permeable paper an inner tube 6 running coaxially with the tube 5 and delimiting a central channel 7, the annular gap 7 'between the tubes being filled with carbon particles and closed at both ends by impermeable annular partitions 8. These partitions may be made of plastic, for example polyvinyl is used as a sealing compound, or in plates made of smoke-impermeable material with a central hole which mates with the pipe 6.

In a special case, the total length of the filter was 71 mm.

Pipe 5 was made of smoke-impermeable paper and pipe 5 was made of paper with a porosity of 34,000 cm / min./10 cm per 10 cm of water column. The tube 6 was 58 mm long and 4.5 mm in diameter. The gap 7 'between tubes 5 and 6 contained 720 mg of granular carbon, grade "203B" (available from Sutcliffe Speakman Ltd.). The total pressure drop of the filter was 7.1 cm from the water column. The filter removed 45% of the total volatile aldehydes from the smoke. For comparison, cigarettes were prepared equipped with filters containing a 50 mg layer of carbon granules between two portions of cellulose acetate and designed to remove the same amount of volatile aldehydes from the smoke.

Cigarettes with both types of filter were offered to a test group of smokers with specific experience in evaluating the taste characteristics of carbon filter cigarettes. The evaluation team found that a reference filter with a granular layer of $ 5 to 616 caused a lot of undesirable side taste properties of carbon filter cigarettes, while another filter with a porous inner tube 6 did not produce this taste.

Example 2

The filter structure according to Fig. 2 differs from the structure according to Fig. 1 in that the granular carbon is placed in the space 9 'inside the pipe 6. This space is closed at both ends, at point 10, while the annular smoke duct 9 is open at both ends. In a filter of this type, which was 53 mm long, the outer tube 5 was made of plastic. The inner tube was made of paper with a porosity of 200,000 cm / min./10 cm per 10 cm of water column. It was 40 mm long and 4.5 mm in diameter and was filled with 282 mg of the same granular carbon as in Example 1. A filter with a pressure drop of 3.2 cm from the water column removed 48% of the total volatile aldehydes from the smoke. A reference filter was prepared in the same manner as in Example 1, but using a 55 mg carbon layer. This cigarette was assumed to have the same aldehyde filtration efficiency. The smoking test group again found a lot of characteristic off-flavors in the control cigarettes, but not in cigarettes with carbon inside the porous tube.

Example 3

In the filter according to Figure 3, the granular carbon is located in a porous bag 11 placed inside the tube 5. Both ends of the bag 11 are closed along lines 12, 13 at right angles to each other, as shown in Figures 3a and 3b, forming fin-like formations 14 which support the bag 11 inside the tube 5 and help to ensure a favorable flow of smoke around the bag.

In a stand of this type, which was 53 mm long, the tube 5 was made of air-impermeable paper. The bag 11, which was made of paper with a porosity of 200,000 cm / person / 10 cm per 10 cm of water column, was 40 mm long and 4 mm in diameter. .5 mm. It was filled with 235 mg of granular carbon, grade "BPL", available from Pittsburgh Activated Carbon Co. The pressure drop of the filter was 4.5 cm from the water column.

6 56616

When burned under standard conditions, the total amount of volatile aldehydes was reduced by 40%. When the evaluation team compared cigarettes equipped with a particulate filter with 70 mg of carbon and the same filtration efficiency, cigarettes with the filters shown in Figure 3 did not produce the off-flavor caused by the carbon layer filter.

Sketch 4

Additional filters described in Example 3 were prepared, but now a 30 mm bag containing 150 mg of the same carbon was used. The total pressure drop was 3.0 cm from the water column. The filtration efficiency of all volatile aldehydes was determined by blow-by-blow for these filters (A) and a conventional filter (B) containing 50 mg of carbon and removing essentially the same average percentage (29%) of volatile aldehydes. The blow-by-blow results given in the following table are shown in Fig. 4 as the efficiency n, which is shown against the number of blows PN.

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8 56616

Filter A removed an equal proportion of all volatile aldehydes with each blow. In contrast, filter B removed a very large portion of the aldehydes with the first blow, but its efficiency decreased rapidly and did not remove any aldehydes from the last three blows.

Example 5

Filters as described in Example 3 were prepared, but bag 11 was made of porous paper perforated so that the total porosity increased to 600,000 cm / min./10 cm per 10 cm of water column. The 30 mm long bag contained 161 mg of carbon of the same quality. The total pressure drop of the filter was 2.9 cm from the water column and removed 31% of the total volatile aldehydes. Compared to the reference filter containing 50 mg of carbon and having similar filtration efficiency, the former filters did not cause the off-flavor observed as the latter filter.

Example 6

The filters described in Example 3 were prepared, but the bag 11 was 30 mm long and 6 mm in diameter and filled with 259 mg of carbon of the same quality. The pressure drop of the filter was 3.1 cm from the water column. These filters removed 32% of the total volatile aldehydes without causing the off-flavor observed with reference filters with granular carbon layers weighing 54 mg.

Example 7

Filters according to Example 3 were prepared, but containing 3 bags, each 2.75 mm in diameter and 30 mm in length, all filled with 51 mg of the same quality of carbon. These filters, with a pressure drop of 3.3 cm from the water column, removed 34% of the total volatile aldehydes. The evaluation team was unable to detect the off-flavor observed with filters with 59 mg granular carbon layers.

9 SI6I6

Example 8

Filters according to Example 3 were further prepared. The gap between bag 11 and tube 5 was filled as follows: (a) 1700 mg of inert, unglazed porcelain granules known as anti-bumping granules, or (b) open cell polyethylene foam, manufactured by Monsanto Chemicals Ltd., or (c) molten ^ bloomed) cellulose acetate rope. The length of the bag 11 was 30 mm and it contained 155 mg of carbon of the same quality. The pressure losses of the finished filters were 3.5, 5.7, and 4.8 cm from the water column, and the filtration efficiencies of all volatile aldehydes, 46%, 32%, and 43%, respectively.

The granular filters, which had similar efficiencies and contained 82 mg, 51 mg, and 74 mg of carbon, respectively, produced a much characteristic carbon taste that the previous filters did not have.

Example 9

The filters described in Example 3 were prepared. The bags 11, which were 30 mm long and 4.5 mm in diameter, contained other types of carbon, i.e. (a) 140 mg of "MF3" carbon, produced by Chemviron Ltd, and (b) 114 mg of "AC45 carbon, produced by The British CECA Co.Ltd, with pressure losses of 2.8 and 3.0 cm of water column and total aldehydes, respectively. filtration efficiencies of 30% and 33¾.These filters had no off-flavors.Comparable granular layer filters containing 36 mg of "MF3" and 40 mg of "AC45" carbon, respectively, produced a high amount of off-flavors.

Example 10

Additional filters as described in Example 3 were prepared, but polyethylene was used for the outer tube 5. The tubes were aerated near the cellulose acetate portion 2 at the mouth end by making holes in the tube 5 and then wrapping the entire filter in a porous cover paper, produced by Papeteries de Malaucene.

Aeration reduced the cigarette pressure drop by 55%. The porous bag, 30 mm long and 4.5 mm in diameter, contained 149 mg of carbon of the same quality as in Example 3. The combination of aeration and porous bag 10 sete reduced the permeation of all volatile aldehydes by 73%. Comparable carbon-kennel, unventilated filters containing 183 mg of the same carbon produced a lot of off-flavors that were not present in previous filters.

Example 11

To make the filter shown in Figures 5 and 6, "AC45" carbon powder of the above type (52-100 British Standard Specification mesh) was placed on a sheet of paper having a porosity of 200,000 cm / min./10 cm per 10 cm of water column. The sheet was folded to form a bag 15, and closed down at the longitudinal edge 16 and at both ends 16 '. Three such bags, 30 mm long and about 7 mm wide, each contained 40 mg of carbon. Three bags 15 were assembled triangularly (Figure 6) between two cellulose acetate sections (not shown) inside an impermeable paper tube 5. The filter, with a pressure drop of 2.7 cm from the water column, removed 55% of the total volatile aldehydes from the smoke. In the evaluation experiments, a comparable cigarette equipped with a granular layer filter containing 79 mg of the same carbon was found to produce a lot of characteristic off-flavors that was not present in cigarettes with filters prepared as described above.

Example 12

For the filter shown in Figures 7 and 8, 115 mg of "AC45" carbon powder of the above quality (100-150 British-Standard Specification mesh) was placed between two 100 mm x 25 mm sheets of well 3 porous paper (porosity 200,000 cm / 2 min./ 10 cm per 10 cm of water column). All edges of both sheets were glued together to form a sealed bag 17 containing carbon 18. The bag 17 was wrapped from its flat shape to the spiral shape shown in Figure 7. As in the previous examples, it was placed between two cellulose acetate portions 2, 3 so as to form a 25 mm long filter enclosed in an impermeable paper tube 5 with a pressure drop of 3.5 cm from the water column. The filter removed 57% of the total volatile aldehydes from the smoke. A reference cigarette equipped with a granular filter containing 84 mg of carbon of the same quality produced a lot of characteristic off-flavors that were not present in the filter of the example.

The bag 17 is best wrapped with a longitudinally corrugated sheet of paper between turns of the bag wrapped in a spiral space 19. This ensures that the different parts of the bag do not come into contact with each other, so that the effective surface area of the bag through which the smoke components can diffuse increases, as does the number of smoke passages.

The same can be achieved by making the bag 17 itself from corrugated porous paper. The contact between the different gaps of the paper is then limited to the branches. The corrugations also increase the surface area of a bag of a certain length.

The bag or bags made in one of the ways described in Example 12 may be placed in the filter in a manner other than in a single helical shape as seen in cross-section. For example, such a bag can be C-shaped, with both free ends further wrapped inwards. In fact, the bag can be placed in the filter so that the cross section is arbitrary.

The bag or bags need not fill the entire cross-section inside the tube. The bag can be wrapped or folded into the filter along with a longitudinally flowing filter media, such as a piece of cellulose acetate or paper.

In fact, in all cases, the smoke duct or ducts, whether in the middle and / or in the circumference, can be filled with a particulate removal filter (not carbon), for example fibrous or filamentous cellulose acetate, paper or the like.

Alternatively, the flue may be filled with an inert granular material, as described in Example 8, or with glass spheres or shavings. Such a filler forms a more effective contact between the smoke and the porous paper, thus promoting the diffusion of the volatile constituents of the smoke into the carbon. The filtration efficiency of the filter's volatile components can thus be improved above the above value obtained for a filter without such a filling, again without adversely affecting the taste.

Preferably, and as described above, the carbon is in the form of loose granules or powder. Alternatively, it could be used in the form of a rod or tube of charcoal carbon or other carbon positioned as described above. The carbon may be bonded with a resin such as polyethylene, an organic substance such as paraffin wax or an inorganic substance such as trisodium phosphate.

Claims (6)

13 S6616 A tobacco smoke filter (1, 2, 3) comprising regions extending mainly in the longitudinal direction of the filter and at least one (7 ', 9') of which carbon is arranged and at least one of which forms a smoke passage (7, 9), characterized in that that each area (7 ', 9') filled with carbon is closed from the flow of smoke through it and separated from the smoke passage duct (7, 9) by a membrane (6, 11, 15, 17) permeable to the vapors adsorbed by the carbon, but does not pass through smoke particles. Filter according to claim 1, characterized in that the membrane (6) is tubular and in that said regions (7 ', 9'; 7, 9) are located inside each other, preferably consisting of two concentric tubes, of porous material, impermeable to smoke particles. an inner membrane tube (6) and an essentially smoke-impermeable outer tube (5). Filter according to Claim 1 or 2, characterized in that the carbon is contained in one or more closed bags (11, 15) or shells (17) of porous material, which are enclosed inside an outer pipe (5) delimiting the smoke passage. A filter according to claim 3, characterized in that said bags (15) or shells are arranged triangularly inside the outer tube, or the bag or shell (17) is wrapped or folded inside the outer tube (5) in its longitudinal direction. Filter according to one of Claims 1 to 4, characterized in that the film or films (6, 11, 15, 17) are made of highly porous paper with a porosity of at least 32,000 cm / min / 2 10 cm per 10 cm of water column. Filter according to one of Claims 2 to 5, characterized in that the outer tube (5) is aerated close to the mouth end of the filter.