US2881770A - Fibrous tobacco smoke filters - Google Patents

Description

April 14, 1959 G. P. TOUEY 2,881,770

F IBROUS TOBACCO SMOKE FILTERS Filed May 27, 1954 2 Sheets-Sheet l FILAMENTS PA RTICLES OF CARBON POWDER C/GARETTE WRA George I? To uey I N V EN TOR ATTORNEYS April 14, 1959 Filed May 27. 1954 .FIG'. 3

G; P. TOUEY FIBROUS TOBACCO SMOKE FILTERS 2 Shets-Sheet 2 PARTICLES Geo. P. To'ueg INVENTOR.

United States Patent FIBROUS TOBACCO SMOKE FILTERS Georgev P. Touey, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of v New Jersey Application May 27, 1954, Serial No. 432,931 '1 Claims. (Cl. 131-208) The present invention relates to tobacco smoke filtering material and elements thereof suitable for use in cigarettes, pipes, cigarette holders, and cigar holders. More particularly, the invention is concerned with an improvement in filters of the general type disclosed in pending U. S. patent application of Cobb and Hargrave, Serial No. 324,284 filed December 5, 1952, in U. S. Patent No. 2,794,239 issued June 4, 1957 to Crawford and'Stevens, and in U. S. Patent No. 2,794,480 issued June 4, "1957 to Crawford et al.

In theaforementioned applications, newly discovered advantages of a certain type of fibrous tobacco smoke filter are discussed. The preferred type of filter is prepared from a'specially conditioned tow of synthetically spun continuous filaments and comprises a structurally unitary rod-like mass of fibers and a wrapper encircling the'mass, each fiber of the mass being substantially coextensive therewith, the fibers as a whole being in substantial alignment longitudinally of the mass but substantially each of the individual fibers having a plurality of short portions thereof crimped into diverging and converging relationship to the main fiber axis, a plurality of the fibers having surface solvation bonds to contiguous fibers at random points of contact. Very good results have been obtained in the use of such filters for the removal of nicotine and tars from tobacco smoke, especially in view of the fact that the filters supply other requirements equally as necessary to the success of a tobacco smoke filter.

These filters also have a marked processing advantage over other filters known in the art. However, since the fibers in such filters are substantially parallel to each other, some channeling of the smoke through the filter may be possible, resulting in a decreased filtering action.

In other words, while interference with the smooth flow of combustion products through the channels is provided by the random bonds between adjacent fibers, by incompleteness of fiber orientation, and by the short fiber portions which are crimped into diverging and converging relationship to the main fiber axis, yet a certain amount of the smoke in the core of any minute column of smoke passing through the filter apparently may .be exposed to somewhat less than a theoretically maximumamount of contact with the fiber surfaces. Experimental investigations have shown that any attempt to reduce the size of smoke channels through the filters by an increase in filter density either through greater compaction or through the use of finer fibers generally also results in an intolerable increase in pressure drop through the filter. Unfavorable conditions also generally result when an increased amount of fiber crimp is employed in order to increase the relative number of divergent and convergent fiber portions.

I now have found that the eificiency of the filters described may be substantially increased without equivalent increasein pressure drop through the filter by powder to the .fibers electrostatically, .i.e....to.,induce-.

depositing certain finely divided solids in the smoke channels provided by the spacing of adjacent fibers. I further have discovered that when carbon powder, particularly activated carbon powder is employed as the finely divided deposit, unusual eificiency is obtained.

This invention, therefore, has as one object the production of a more efficient cigarette smoke filter consisting of a bundle of substantially longitudinally oriented textile fibers infused with finely divided carbon particles. Another object is to provide means for increasing the efiiciency of a cigarette filter prepared from a textile fiber. A still further object is provision of a filter which is capable of removing nicotine, tars, and other deleterious components of cigarette smoke without causing the smoke to be dry or distasteful. Another object is to increase the efiiciency of tobacco smoke filters of the Crawford and Stevens application without creating a high pressure drop. Other objects will be obvious from the present specification and claims.

Accordingly, the present invention consists, in general, in a tobacco smoke filtering medium comprising a mass of substantially longitudinally aligned fibers, the spacing of substantially all groups of adjacent fibers providing minute passages for smoke therethrough, said mass carrying therein finely divided carbon particles in an amount of 1 to 60% by weight of the mass, said particles occupying positions in and partially blockingsaid passages whereby a substantial portion of the smoke is impinged either on the fibers or on the carbon.

A more specific embodiment of the invention comprises a new tobacco smoke filtering material of synthetically spun continuous filaments and an element made therefrom, the element comprising a structurally unitary rod-like mass of fibers and a wrapper encircling the mass, each fiber of the mass being substantially coextensive therewith, the fibers as a whole being in substantial alignment longitudinally of the mass but substantially each of the individual fibers having a plurality of short portions thereof crimped into diverging and converging relationship to the main fiber axis, a plurality of the fibers having surface solvation bonds to contiguous fibers at random points of contact, the mass carrying substantially uniformly dispersed therein a solidfinely divided carbon in the amount of 1 to 60% by weight of the mass.

Most advantageously, the invention comprises a filter of cellulose acetate fibers having surface solvation bonds achieved through the application of a plasticizer spray, the filter carrying uniformly dispersed carbon particles in the amount of about 10 to 40% by Weight of the filter. By the term surface solvation of the fibers as used herein is meant the creation, by the action of a solvent or plasticizer and/or heat, of an adhesive, tacky or readily bonding condition of the fibers by solution or incipient solution of surface portions of the filament material whereby there is produced a welding and adhesion between adjacent filaments contacting at such portions, and by coalescence we mean the situation caused by partial or incipient solvation of surface portions of the filaments and resulting in a condition within those portions under which the portions will flow into or unite with similar portions of dissolved or plastic Thus, for example, the carbon powder can be blown onto the fibers or it can be applied as a slurry in cold water or in a volatile organic vehicle or a plasticizer for the fibers. Another method is to apply. the carbon 3 a. charge on the fibers by friction or other suitable means and then to run the fibers through a chamber containing highly concentrated carbon dust. Still another method for applying the carbon is to wet the surface of the fibers with an adhesive or a plasticizer before exposing them to a powder spraying device. Preferably, the carbon is continuously applied to an opened and banded moving tow formed as described in the Crawford and Stevens applications. That is to say, tow from a supply roll is opened to debundlize the filaments and provide a larger and more uniform tow cross section, and the opened towis spread uniformly to a much larger width of e.g., 8 times its original width, thereby exposing substantially all of the filaments to material, i.e. plasticizer, issuing from a dispenser adjacent which the tow passes. The carbon may be added before, simultaneously with, or after the plasticizer, preferably with or after.

-' The invention is illustrated in the accompanying drawings in which Fig. 1 represents a magnified view of the interior of a mass of filtering material prepared in accordance with the invention,

Fig. 2 is a view of a cigarette having attached thereto a tip prepared from a filtering material of the invention,

Fig. 3 is a more highly magnified view of a portion of the mass of Fig. I particularly showing surface solvation bonds between adjacent filaments, and

Fig. 4 is a further enlargement of the bonds shown in Fig. 3.

With particular reference to Figs. 3 and 4, the reference numerals 11 and 12 designate surface solvation bonds achieved at random points by the application of a plasticizer spray. The numeral 11 represents a bonding condition or welding as described above which has resulted from the plasticizer rendering the fiber tacky and adhesive by means of solution or incipient solution. As will be seen from the drawing, no foreign material enters into the bonding and the two contacting filaments are more or less held together as one homogeneous body (composition-wise) as the term coalesce implies. The tacky condition of surface portions of the filament material has provided sufiicient cohesiveness to form a bond. The bond 12, on the other hand, has resulted where the solution of surface portions of the filament material has resulted in a condition within these portions, under which the portions have flowed together and united as described above.

The invention is further illustrated in the following examples:

Example 1 A crimped continuous filament tow of yarn type cellulose acetate of 5 denier per filament with a total denier of 100,000, and 9 crimps per inch was used to prepare filters in accordance with the preliminary conditioning procedure of Crawford and Stevens. The tow was pulled froma ball warp over stationary tensioning fingers and into a tensioning device functioning to provide tow opening as the first phase of filament separation. The device employed was of the type employing a pair of driven rolls to place under tension tow positioned in the ratch between the driven rolls and a pair of retarded rolls upstream of the driven rolls. The device was equipped with the improved reciprocating striker as disclosed and claimed in U.S. Patent No. 2,790,208 issued June 30, 1957 to If. W. Smith. Upon being released from the nip of the. positively driven tension rolls into a zone of relative relaxation, i.e. relatively little tension, the tow bloomed through inherent forces manifested upon the return of the tow to its. original position.

The. partially opened tow of cellulose acetate yarn was slowly pulled over a compressed air banding device as disclosed in the aforementioned Crawford and Stevens patents. and in US. Patent No. 2,737,688 issued March 13,, 195.6 to. W. T. Jackson. The banding device momentarily' spread. out. the fibers to a width of six inches.

- 4 While the tow was in this spread condition it was sprayed with a highly agitated slurry of one part activated bone charcoal powder in five parts dimethoxyethylphthalate plasticizer.

After this spreading and spraying treatment the tow was uniformly collected and fed to a garniture, i.e. a cigarette making machine. The tow was fed into the garniture through a shaping horn which served to condense the conditioned tow back into its original shape of a cord. The cigarette-making machine wrapped the tour with paper and cut it into rods similar in size to a standard size cigarette. The rods contained 1 part carbon powder, 5 parts plasticizer and 20 parts cellulose acetate by weight. After the filter rods were given a short heat treatment to cause partial solvation of the acetate fibers by the plasticizer they were readily cut into 12 mm. filter tip lengths. These tips were attached to a standard brand of cigarettes available on, the retail market in. the by means of an adhesive tape. The cigarettes were. smoked on a smoking machine similar in design and, openation to the smoking machine described by I. A. Bradford, W. R. Harlan and H. R. Hanmer in Industrial and Engineering Chemistry, vol. 28-, pp. 8369 (1936) The collected smoke was analyzed for nicotine. and tars. The results of the smoking experiment were compared with those obtained from smoking the same brand of cigarettes. containing 12 mm. filter tips, made from the same tow of cellulose acetate fibers plasticized with dimethoxyethylphthalate without the addition of carbon.

Moisture of the tobacco in each of the cigarettes,=12.2%. 1 Obtained from the collected smokeof ten filtered cigarettes.

The cigarettes containing the acetate tow filters had; an average pressure drop of 27%; the cigarettes containing the filters of cellulose acetate tow and bone charcoal powder had an average pressure drop of 28%, where pressure drop is measured as the per cent addi--.

tional time required for a standard tube of water to drain when the cigarette to be measured is inserted intothe vent of this tube, compared to the draining time of the same apparatus when this vent is unobstructed with any cigarette to be measured.

Example 2 A loose, i.e. partially opened crimpedcontinuous fil'a ment tow of cellulose acetate yarn containing approximately 10,000 fibers of 8 denier per filament was pulled through a bath containing a highly agitated slurry of commercially available activated wood charcoal in water.

When dried, the tow contained 10% of charcoal powder. The carbon: impregnated tow was processed into filter rods in a garniby weight uniformly dispersed throughout.

ture as described in Example 1 and the resulting rods were cut into 12 mm. lengths. The filter tips so produced were attached to standard brand cigarettes and ten of thesev filter tipped cigarettes were smoked on the smoking machine. The collected smokewas analyzed for nicotine and tars. A control, consisting of the same brand of cigarettes tipped with filters made from the 8 denier per filament-towcontaining no carbon was also smoked on the smoking;

machine and the collected smoke was analyzed in the same:

manner for nicotine and tars.

msof. ment tars. nicotine Acetate tow filter 1,52, 21 Acetate tow filter containing 10% wood charcoal- 122' 14 Moisture of the tobacco-in each of the eigarettee=l2i3%.

a ix The cigarettes containing the acetate tow filters had an average pressure drop of 22%; the cigarettes containing the filters of cellulose acetate tow and wood charcoal powder had an average pressure drop of 30%, where pressure drop is measured as explained in Example 1 above.

Example 3 A tow of cellulose acetate yarn containing approximately 40,000 fibers of 3 denier per filament was spread out to a width of six inches and sprayed with a solution of a water-base adhesive. While the tow was still spread out and wet with the adhesive it was sprayed with a commercially available finely divided lampblack powder and then rolled into its original form. The impregnated tow was processed into filter rods and the rods were cut into 12 mm. lengths. The filter tips, containing 9% carbon based on the weight of the acetate fibers, were attached to standard brand cigarettes and ten of these cigarettes were smoked on the smoking machine. The collected smoke was analyzed for nicotine and tars. A control consisting of the same brand of cigarettes tipped with a filter of the 3 denier per filament tow containing the adhesive but no lampblack carbon powder was also smoked on the smoking machine and the collected smoke was analyzed in the same manner for nicotine and tars.

Moisture o! the tobacco in each of the cigarettes=12.0%.

The cigarettes containing the acetate tow filters had an average pressure drop of 33%; the cigarettes containing the filters of cellulose acetate tow and lampblack powder had an average pressure drop of 34%, where pressure drop is measured as explained in Example 1 above.

In carrying out the operation of this invention the type of carbon employed is not a critical factor. Rather, the form of the carbon is more important. The carbon should be in a powdered form so that it can be readily slurried in a liquid or passed through a spraying nozzle. Any source of carbon which passes this requirement can, therefore, be employed. Such commercial carbon powders as bone charcoal, coconut charcoal, wood charcoal, or lampblack carbon may be employed. Also, the various types of aqueous emulsions of carbon or graphite may be employed.

While unusually good results have been obtained with filters prepared from a crimped continuous filament tow of cellulose acetate fibers sprayed with a plasticizer, e.g. dimethoxyethylphthalate or methylphthalylethylglycollate, it will be recognized by those skilled in the art that the usefulness of the invention extends to other fibrous filters, including those prepared from fibers of viscose, cotton, nylon, polyamides, polyesters, etc., particularly where the fibers are in substantial longitudinal alignment and are coextensive with the body of the filter.

I claim:

1. A tobacco smoke filter adapted to be held in a smokers mouth and adapted to remove certain undesirable components from tobacco smoke, said filter being comprised of a bundle of continuous, longitudinally aligned crimped filaments in which substantially all of the filaments extend through the full length of the filter from end to end, said filaments being essentially comprised of cellulose acetate and a plasticizer therefor, solid finely divided carbon power, carried on the surface of the filaments and a paper wrapper around the circumference of said bundle.

2. A filter in accordance with claim 1 wherein the bundle of filaments is comprised of several thousand filaments of a denier per filament not greater than 3.

3. A filter in accordance with claim 1 wherein the amount of plasticizer by weight is at least twice greater than the weight of the carbon powder which is dispersed on the surface of the filaments.

4. A filter in accordance with claim 1 wherein the plasticizer is an ester.

5. A filter in accordance with claim 1 wherein the percentage by weight of the carbon powder with respect to the weight of the filaments is from about 5 to 10%.

6. A filter in accordance with claim 1 wherein the carbon powder is from the group consisting of bone charcoal, coconut charcoal, wood charcoal and lampblack carbon.

7. A tobacco smoke filter adapted to be held in a smokers mouth and to remove certain undesirable components from tobacco smoke, said filter consisting essentially of a bundle of at least several thousand longitudinally aligned synthetic thermoplastic filaments of a denier per filament not greater than 8 and in which substantially all the filaments extend through the full length of the filter from end to end, said filaments being crimped at least 9 crimps per inch, said filaments carrying a content of a material that will facilitate the bonding of a powdered solid to the filaments, a content of finely powdered carbon material dispersed on the surface of the filaments, and a paper wrapper around the circumference of said bundle.

References Cited in the file of this patent UNITED STATES PATENTS 959,649 Thomson May 31, 1910 964,589 Campo July 19, 1910 1,808,707 Wiggings June 2, 1931 1,868,469 Broadway July 19, 1932 2,085,293 Buflington June 29, 1937 2,126,422 Tarrant Aug. 9, 1938 2,128,432 Ramage Aug. 30, 1938 2,228,383 Berl Jan. 14, 1941 2,476,582 Browne et al. July 19, 1949 2,483,406 Francis Oct. 4, 1949 2,688,380 MacHenry Sept. 7, 1954 2,707,308 Taylor et al. May 3, 1955 2,739,913 Lieser Mar. 27, 1956 2,761,798 Knudson Sept. 4, 1956 2,774,680 Hackney et al. Dec. 18, 1956 2,789,563 Taylor et al. Apr. 23, 1957 FOREIGN PATENTS 290 Great Britain 1863 9,826 Great Britain 1899 121,414 Australia Mar. 30, 1944 538,529 Great Britain Aug. 7, 1941 665,278 Great Britain J an. 23, 1952 813,324

France Feb. 22, 1937

Claims (1)

1. A TOBACCO SMOKE FILTER ADAPTED TO BE HELD IN A SMOKER''S MOUTH AND ADAPTED TO REMOVE CERTAIN UNDESIRABLE COMPONENTS FROM TOBACCO SMOKE, SAID FILTER BEING COMPRISED OF A BUNDLE OF CONTINUOUS, LONGITUDINALLY ALIGNED CRIMPED FILAMENTS IN WHICH SUBSTANTIALLY ALL OF THE FILAMENTS EXTEND THROUGH THE FULL LENGTH OF THE FILTER FROM END TO END, SAID FILAMENTS BEING ESSENTIALY COMPRISED OF CELLULOSE ACETATE AND A PLASTICIZER THEREFOR, SOLID FINELY DIVIDED CARBON POWER, CARRIED ON THE SURFACE OF THE

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