US3320961A - Cigarette filters - Google Patents

Description

United States Patent M 3,320,961 CIGARETTE FILTERS Ivor Wallace Hughes, Fareham, Henry George Horsewell,

Totton, and Donal Michael Carroll, Southampton, England, assiguors to Brown and Williamson Tobacco Corporation, Louisville, Ky., a corporation of Delaware No Drawing. Filed July 7, 1964, Ser. No. 380,929 Claims priority, application Great Britain, July 22, 1963, 29,004/ 63 3 Claims. (Cl. 131-267) This invention concerns improvements relating to filters for tobacco smoke.

Filters for tobacco smoke are already known which removes the particulate phase of the smoke by mechanical means. These filters, formed from filamentary or sheet material, have differing capacities for the removal of specific components which it may be desired to remove, and may also adversely afi'ect the taste of the filtered smoke. A large proportion of these components occurs, partially at least, in the form of vapours which cannot be removed by mechanical filtration, but only by absorption or adsorption on a suitable surface, or by chemical reaction.

Of these substances, the more volatile acidic compounds may be those which it is particularly desired to remove, An object of the present invention is to provide simply but eifective means whereby a substantial proportion of these acidic compounds can be removed from the smoke of burning tobacco.

According to the invention, filamentary or sheet tobacco-smoke filter material is treated with an alkaline sodium salt of orthophosphoric acid, i.e. the di-sodium salt or the tri-sodium salt.

The salt may be applied to the supporting material, constituting the bulk of the filter, as a solid in powder form by dusting or as a liquid in solution form by spraying, coating, dipping or the like. The amount of the salt added may be from 5% to 25% weight (calculated as anhydrous material) of the weight of the supporting material) of the weight of the supporting material, i.e. 5-25 gms. of anhydrous salt added to 100 gm. paper, but an addition of from to 20% is preferred.

Examples of ways of carrying out the invention will now be more fully described:

Example 1 1 gm. of trisodium phosphate was dissolved in 47 mls. of water and 4 mls. of this solution was evenly sprayed on to a strip of open-mesh creped wadding (such for example as that known as Myria paper) 90 mm. wide and weighing approximately 0.8 gm. so as to give a final concentration, on a weight basis, of 10% of phosphate. The treated paper was allowed to dry overnight at room temperature (20-25 C.) and was then rolled by hand to form a rod which was 90 mm. long and of cigarette diameter. mm. lengths of the rod were attached as filters to cigarettes and the cigarettes were smoked by machine at l putt per minute, each puff being of 2 sec. duration and a volume of 35 mls. The smoke obtained from the cigarettes was then analyzed in comparison with that from control cigarettes to which untreated filters had been at tached. The untreated filters, in this and the following examples, were prepared exactly as the treated filters,

3,320,961 Patented May 23, 1967 except that water was applied instead of a solution of the sodium salt. The results of the analysis were as follows:

Similar filter paper was treated exactly as in Example 1 except that it was sprayed with 8 mls. of the trisodium phosphate solution, so as to give a final concentration of 20% by weight of the phosphate. Cigarettes with treated and untreated filters were then smoked as previously described. Analysis of the smoke from the treated filters showed that 60% of the acids had been retained.

Example 3 Similar filter paper was treated as in Example 1 except that a solution of disodium hydrogen phosphate was used. Cigarettes with treated and untreated filters were then smoked as described previously. The results obtained are given below:

Percent of smoke Percent constituents retained NazHPOi Pressure drop by filter on paper of 15 mm. tip

Acids Tar Nicotine Example 4 A continuous strip of 11 /2 inch wide open mesh creped wadding (such for example as Schweitzer paper) was passed under a sponge roller and was roller coated with a solution of 2 kgs. of trisodium phosphate in. 20 litres of Water. The rate of travel of the paper was arranged so that the final concentration of phosphate on the paper was 18% by weight. The paper was dried by hot air and formed into a continuous filter rod, using conventional means. 15 mm. lengths of rod were attached to cigarettes and smoked as in Example 1. The smoke analysis results are compared below:

Cellulose acetate tow of total denier of 90,000 and denier per filament of 5 was opened out and sprayed with a solution of trisodium phosphate so as to give a final concentration on the tow of approximately 10%. After drying, the tow was formed into filter rods. Sections of 15 mm. length were cut from the rods, attached to cigarettes and smoked as described in Example 1. Analysis of the smoke from the treated filters showed that 57% of the acids were retained in comparison with only 33% when untreated filters were used.

As may be seen from the results, the addition of the diand tri-sodium salts of ortho-phosphoric acid to conventional filtering materials makes these materials particularly effective in the removal of volatile acids from tobacco smoke without adversely alfecting the removal of other 10 constituents.

Little -or no adverse effect on the taste of the filtered smoke has been observed.

We claim:

1. A tobacco-smoke filter comprising fibrous tobaccosmoke filter material treated with a water soluble alkaline sodium salt of orthophosphoric acid whereby a substantial proportion of acidic compounds are removed from the smoke of burning tobacco without adversely affecting the organoleptic properties of the tobacco after the smoke passes through the filter.

2. A tobacco-smoke filter as claimed in claim 1, wherein the said salt amounts to 10 to 20% by weight of the said filter material.

3. A tobacco smoke filter as claimed in claim 1 wherein the said salt amounts to 5% to 25% by weight of said filter material.

References Cited by the Examiner UNITED STATES PATENTS 2,940,456 6/1960 Touey 131208 FOREIGN PATENTS 287,549 4/ 1953 Switzerland.

SAMUELKOREN, Primary Examiner.

D. J. DONOHUE, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 3,320,961 May 23, 1967 Ivor Wallace Hughes et a1 a It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 37, after "25%" insert by lines 39 and 40, strike out "of the weight of the supporting materialy'o Signed and sealed this 28th day of November 1967c (SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

Claims (1)

1. A TOBACCO-SMOKE FILTER COMPRISING FIBROUS TOBACCOSMOKE FILTER MATERIAL TREATED WITH A WATER SOLUBLE ALKALINE SODIUM SALT OF ORTHOPHOSPHORIC ACID WHEREBY A SUBSTANTIAL PROPORTION OF ACIDIC COMPOUNDS ARE REMOVED FROM THE SMOKE OF BURNING TOBACCO WITHOUT ADVERSELY AFFECTING THE ORGANOLEPTIC PROPERTIES OF THE TOBACCO AFTER THE SMOKE PASSES THROUGH THE FILTER.