|Publication number||US3716063 A|
|Publication date||Feb 13, 1973|
|Filing date||Sep 25, 1970|
|Priority date||Sep 25, 1970|
|Also published as||CA944249A, CA944249A1, DE2148035A1, DE2148035B2, DE2148035C3|
|Publication number||US 3716063 A, US 3716063A, US-A-3716063, US3716063 A, US3716063A|
|Original Assignee||Brown & Williamson Tobacco|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (25), Classifications (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent 91 Litzinger [451 Feb. 13, 1973 SELECTIVE GAS PHASE FILTER MATERIAL  Inventor: Elmer Francis Litzinger, Louisville,
 Assignee: Brown & Williamson Tobacco Corporation, Louisville, Ky.
[22 Filed: se czs, 1970  Appl. No.1 75,773
 US. Cl ..l31/267  Int. Cl. ..A24b 15/02, A24d 1/06  Field of Search....13l/10 R109, 265, 267, 269
 References Cited UNITED STATES PATENTS 3,434,479 3/1969 Till et a1. ..13'l/10.9
11/1968 Walker etal ..131/267 9/1967 Horsewell et a1 ..131/269 X Primary ExaminerJoseph S. Reich Assistant Examiner-George M. Yahwak Attorney-Kane, Dalsimer, Kane, Sullivan and Kurucz ABSTRACT 9 Claims, No Drawings about 0.1 to 2.0 microns.
SELECTIVE GAS PHASE FILTER MATERIAL This'application is related to co-pending application Ser. No. 75,772, filed Sept. 25, 1970.
BACKGROUND OF THE INVENTION The invention is related to a tobacco smoke filter material. In particular, it is related to a porous particulate material for selectively removing smoke acidsand aldehydes. Hitherto, it has been proposed to disperse 1 various materials, such as amines and/or amine salts, on conventional filter tows (see U.S. Pat. No. 3,410,282) to selectively remove smoke acids from tobacco smoke. Similarly, it has been proposed in US. Pat. No.
3,340,879 to treat conventional filter tow with a poly(alkyleneimine) to selectively removesmoke acids while allowing a major proportion of the flavorants to pass. Additionally, it has been proposed in U.S. Pat.
No. 2,815,760 toadsorb specified amines on certain porous'granules of unspecified pore diameter, surface SUMMARY OF THE INVENTION selected volatile components have been removed, such.
as vapor phase aldehydes, while leaving in the smoke desired flavor or aroma imparting materials.
The above and other beneficial objects and ad vantages are obtained in accordance with the present invention by an improved tobacco smoke filter material which comprises a porous particulate carrier impregnated with an additive having an affinity for volatile smoke acids and aldehydes, wherein each of the said carrier particles has a pore' diameter of from about 0.l to 2.0 microns, a surfacearea offrom about I to square meters per gram and a pore volume no less than -about0.3 cubic'centimeterper gram. It has been should be no less than about 0.3 cubic centimeter per gram (cc/gm). Below this level selective removal of smoke stream acids and, particularly, aldehydes is significantly diminished. While applicant does not wish to be bound to any particular theory, it is nevertheless postulated that as increasing amounts of additive are deposited on the substrate, pore filling occurs. To overcome this defect,it has been found that the porous carrier should have a pore volume of no less than 0.3 cubic centimeter per gram, when sufficient loadings of additive are incorporated on the carrier to effectively reduce smoke acids and aldehydes.
Porous carriers with the above pore sizes and pore volumes have surface areas in the range from about I to 15 square meters per gram (m /gm). This is to be contrasted with conventional commercial adsorbent materials with surface areas of greater than 200 square meters per gram. Such commercial materials have been found to be relatively poor substrates for the additive described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The additive employed should have an affinity for volatile acids and aldehydes entrained in a tobacco smoke stream. The additive may be an amine at least partially buffered by a carboxylic' acid. The carboxylic acid salts are prepared by reacting primary or secondary alkyl and hydroxyalkyl amines with the acid. Some amines which have been found particularly effective include: ethylamine, dibutylamine, ethylenediamine,
I ethanolamine and the like. The acids used in the found that buffered poly(alkylcneimines) supported on i a porous alumina substrate having the aforesaid physical characteristics provide highly efficient filter m' ateri- 'als for the selective removal of volatile aldehydes, such as acetaldehyde and, acrolein, from cigarette smoke.
Such materials also retain their normal affinity forsmoke acids.
Th'ephysical parameters of the substrate material are of critical importance. In order to provide substantial reductions of vapor phase aldehydes, for example, it is necessary that the average pore diameter (assuming cylindrical pores) of the substrate material be from In order to achieve satisfactory loadings of additive on the substrate, the pore volume of the substrate preparation of the amine salts can be aliphatic or aromatic monoor polycarboxylic acids including the following: acetic, itaconic, lactict succinic, benzoic and cinnamic acids. I
Other carbonyl reactive materials which may be employed'as additives include phenylhydrazine, semicarbazide, thiosemicarbaz ide and the like.-
The porous car-rier for the additive can be any solid substrate capable of supporting the additive provided that the carrier has the previously specified dimensionalparameters. In general, organic and inorganic materials may be employed. Typical carriers, also referred toherein as substrates, include: magnesite, zeolites, fullers earth diatomaceous earth, polyethylene granules, silica gel, and the like.
Examplesof the filter material of the invention are produced by at least partially neutralizing each of the following organic bases with any of the following acids and,'thereafter, depositing the buffered additive on any of the following substrates:
Organic Base propylaziridine) diatomaceous earth it is preferred to employ at least partially buffered poly(alkyleneimines) as an additive for the substrate. Preferred poly(alkyleneimines) are disclosed in U.S. Pat. No. 3,340,879 and, accordingly, the disclosure of the aforesaid patent is expressly incorporated herein. The poly(alkyleneimines) are at least partially neutralized or buffered with a carboxylic acid. Generally, alkanoic acids are preferred for this purpose.
. For best results, poly(ethyleneimine), at least partially buffered with acetic acid, is employed.
When acid-buffered filter material is employed, al-
' dehyde filtration efficiency is generally acceptable, as
long as the pH range of the additive is between about 6.0-and 7.6. In the case of the highly preferred additive, poly(ethyleneimine) buffered with acetic acid, it has been found that the optimum pH is 7.4.
Enhanced results are obtained .with'and,'accordingly, it is preferred to employ a particulate porous alumina as the substrate for the additive of the invention. A particularly preferred alumina is produced by calcining the trihydrate at high temperatures (usually between about l,100 to 1,300 Centigrade). v
The particularly preferred filter materials of the invention are formed by buffering to a pH in the range from about 6.0 to 7.6 any of the following poly(alkyleneimines) V having the general formula: NH (CR CRC NH),.l-l where each R is individually selected from the class consisting of hydrogen, lower alkyl radicals free from aliphatic unsaturationand havingfrom one to six carbon atoms and n is a'whole number greater than 12, with any one ofthe following 'alkanoic acids and ,then. combining thebufferedadditive with a porous alumina:
' I Porous Alumina Calcine Temp. Alkanoic (degrees Acid Cent.
Pore Diameter (microns) Pore I Vol.
Surface 'Area mlgm) poly(alkyleneimine) butyric ll 1.5 0.5
valcric l300 l.l 0.4.
caproic glutaric dimethyl- 3-n-pr0- pylaziridine) succinic Generally, for effective selective treatment of tobacco smoke according to the invention, at least about 2 percent by weight of additive based on the weight of the carrier is deposited on the carrier. Usually no more than about 6 percent by weight of additive is employed. Increasing the loading of additive has the effect of filling the pores of the carrier, thereby reducing selective removal of smoke stream components.
In the case of the preferred poly (alkyleneimines) buffered with alkanoic acids to a pH in the range from 6.0 to 7.6 and deposited on a porous alumina substrate of the invention, it has been found that from 4 to 6 percent by weight buffered poly(alkyleneimines) yields enhanced results.
The buffered additives are deposited on the above porous substrates by conventional techniques, for example, by immersing the carrier in the solution in which the additive has been prepared and, thereafter, evaporating the solvent. The substrate is then dried and formed into a filter.
Alternatively the filter material can be made in situ by at leastpartially neutralizing one of the above compounds with one of the above acids in the presence of a porous carrier.
in general, sufficient quantities of the filter material of the invention are employed in smoking articles to significantly reduce the quantity of volatile components normally present in tobacco smoke and, par
ticularly, hydrogen cyanide, acetaldehyde and acrolein. For this and other purposes,- it is preferred to employ from about to milligrams of filter material in a filter for use in smoking articles, such as cigarettes.
vln one embodiment, a filter is prepared by encasing the filter material of the invention in an outer wrapper. The resulting filter may be employed alone or in combination with conventional cellulose acetate filters. Triple filters employing, sequentially, the following filter sections: cellulose acetate, the filter material of the invention and cellulose acetate, have proven particularly workable. The filter material may be used in conjunction with perforated cigarette paper, if desired, or filter ventilation means may be employed. In another embodiment, the filter material may be dispersed, in granular form, either on paper or cellulose acetate tow and encased in an outer wrapper.
The following examples are provided to further illustrate the nature of the invention and are not limitative of scope. I
EXAMPLE I In order to illustrate the effectiveness of the filter material of the invention, an additive was prepared by buffering poly(ethyleneimine) with acetic acid to pH of 7.4. The amount of aceticacid used for this adjustment was 1.5 milliequivalents of acidv per gram of poly(ethyleneimine). I
The resulting buffered additive was deposited on selected porius aluminas. Their physical charac-. I
teristics are set forth in the following table:
For sample A, percent by weight of the buffered additive was deposited on the porous alumina substrate. Filter material was prepared fromsample B by depositing, respectively, 2 and 5 percent by weight of the additive on the porous alumina. For sample C, 2 percent by weight of additive was deposited on the porous alumina Predetermined quantities of the filter material were packed into 8 millimeter cavities between 7 and 6 millimeter lengths of conventional cellulose acetate filters of 84 millimeter cigarettes (tobacco sections 63 millimeters in length). The resulting cigarettes were smoked to 28 millimeter butt lengths on a constant vacuum smoking machine taking 35 milliliter puffs of 2 seconds duration at one minute intervals.
In the following table, the weight of the, filter 'material is expressed in .milligrams. The filter efficiency represents the weight percent of component trapped by the filter materials based on the total amount of the component enteringthe cigarette filter. I
SELECTIVE FILTRATION EFFICIENCIES The above table illustrates theefficiency with which volatile components, particularly aldehydic components, are removed from tobacco smoke, employing the filter materials of the invention. Similar results are obtained when other additives having an affinity for volatile vapor phase acids and aldehydes are deposited upon porous particulate carriers, wherein the'carrier particleshave a'pore diameter of from about 0.1 to 2.0 microns, a surface area from about 1 to square meters per gram and a pore volume no less than about 0.3 cubic centimeters per gram.
In the following'table any of the additive materials having an affinity for'vapor phase acids and aldehydes may bedeposited upon any of the porous carriers having the aforesaidphysical characteristics to form the filter material of the invention, with similar results.
Additive The effect Qfdifferent loadings of filter material on vapor phase acids and aldehydes was examined by depositing 5 percent by weight, polyethyleneimineacetate buffered, on a porous alumina substrate and diluting the resulting material with untreated alumina in a 13 millimeter filter bed joined with an 8 millimeter cellulose acetate filter. The dual filter was joined to a tobacco cylinder and tested according to the procedure of Example I.
The results set forth in the following table illustrate filter efficiencies of four different'porous aluminas, each deposited with 5 percent by weight of the above additive, wherein the mean pore diameter of the alumina carriers was in the range of from 0.1 to L8 microns. Pore volume and surface area were within the critical ranges.
Effect of Additive Loading on Filter Efficiency Treated Hydrogen alumina-weight Cyanide Acetaldehy de Acrole in (milligrams) removed removed) removed) 50 56-63 0-l5 l6-28 I00 60-7l 21-34 33-38 I50 -77 33-47 41-46 As is evident from the above table, for substantial aldehyde reductions, at least about milligrams of treated carrier per filter are required. Similar results are obtained for other additives deposited on the porous carriers described herein.
COMPARATIVE EXAMPLE I Effect of Pore Size on Filtration Efficiency PORE DIAMETER Weight of Additive on Pore Volume Pore Diameter Acetaldehyde Alumina (cc/gm) (microns) removed From this table, it is seen that removal of vapor phase aldehydes is reduced when the pore diameter of the porous carrier is less than 0.1 microns and more than 2.0 microns.
PORE VOLUME Weight of Surface Pore Pore Acetal- Acrolcin Additive Area Volume Diameter dehyde reon alumina (mi/gm) (cc/gm) (microns) removed moved 5% LI 0.2 0.8 56 48 5% 1.1 0.4 l.] 67 78 As is seen from the results of the above tests, when pore volume is reduced below about 0.3 cc per gram then filtration efficiency for vapor phase aldehydes is undesirably reduced. Note that during the above tests,
both the surface area and pore diameter of the substrate were maintained within permissible limits.
SURFACE AREA Weight of Surface Pore Hydrogen Acctal- Additive on Area Volume Cyanide dehyde I Alumina (m /gm) (cc/gm) rcmoved% removed From theabove, it is seen that when the surface area of the porous carrier is greater than about 15 square meters per gram, then vapor phase filtration is advcrsely affected. Similar results are obtained below about i m /gm.
Similar filtration effects with respect to vapor phase components are noted when other porous carriers described herein are employed with the aforesaid physical characteristics.
COMPARATIVE EXAMPLE II In order to further illustrate the enhanced selective filtration results obtained, aporous alumina, calcined at a temperature of 1300Centigrade having a surface area of 1.1 square meters per gram, a pore volume of 0.4 cubic centimeters per gram and a pore diameter of 1.1 microns was employed. To a portion of the porous alumina was added 5 percent by weight poly(ethyleneimine), unbuffered. To another portion of the porous alumina was added 5% by weight poly- (ethyleneimine) buffered with acetic acid to a pH of 7.4. Another portion of the calcined alumina was treated with percent by weight poly(ethyleneimine) buffered with acetic acid. The resulting filter materials wereformed into filters and testedfor vapor phase efficiency :according to Example l. The following results were obtained:
Acrolein 10% acetatc buffcred 3i v additive From the above table, it is seen that untreated porous alumina had no measurable effect on vapor phase, deliveries. With unbuffered poly(ethyleneimine) (PEI') there is some reduction in vapor phase aldehydes. A
' substantial reduction in vapor phase aldehydes is obtained when a poly( alkyleneimine), buffered to a pH of from about 6 to 7.6 with an alkanoic acid, is employed on porous alumina substrate.
Filter material prepared from buffered PEI and deposited on conventional paper, sections ofqdual paper-cellulose acetate filters was also tested for vapor phase component removal. It was found that only about 25 percent acetaldehyde was selectively removedfrom cigarette smoke employing the dispersed additive.
The synergism observed between the additive and the porous carrier illustrated hereinabove is obtained when other additives and porous substrates of the invention are employed in place of the buffered poly(ethyleneimine) additive deposited on the porous alumina substrate. As shown above, when the quantity of additive deposited on the porous carrier is adjusted above about 6 percent by'weight, aldehydic reductions in tobacco smoke significantly decrease. It is postulated that the pores of the substrate become filled by the excess additive, thereby reducing the affinity of the filter material for the vapor. phase components in tobacco smoke.
This invention is not to be limited except as set forth in the following claims. Having thus described my invention, what is claimed 1. An improved tobacco smoke filter material comprising at least mg. of a porous particulate carrier impregnated with a poly(alkyleneimine) alkanoate, wherein from about 2 to 6 percent by weight alkanoate is deposited on the carrier based on the total weight-of the alkanoate and carrier, said poly(alkyleneimine) alkanoate having a pH from about 6.0 to 7.6, and wherein each of said carrier particles has a pore diameter of from about 0.1 to 2.0 microns, a surface area of from about 1 to 15 square meters per gram and a pore volume no less than about 0.3 cubic centimeter per' gram.
2. The invention in accordance with claim 1 in which the carrier is a porous alumina.
3. The tobacco smoke filter of claim 1 wherein the pH of the poly(alkyleneimine) is buffered to about 7.4 with acetic acid. I
4. An improved filter adapted to be affixed to a cigarette and comprising, in combination: a filter outer wrap having a tubular configuration and an inner filler formed from a .plurality of particles formed from a porous particulate carrier impregnated with an alkanoic acid buffered poly(alkyleneimine) additive, said additive buffered to a pH from about 6.0 to 7.6, from about 2 to 6 percent by weightadditive deposited on the 'carrier based on the total weight of carrier and additive, wherein from about 100 to milligrams of filler are employed in said filter and wherein the carrier particles each'have a pore diameter fromabout 0.1 to 2.0 microns, a surface area of from about 1 to 15 square meters per gram and a pore volume no less than about 0.3 cubic centimeter per gram.
5. An improved tobacco smoke filter material'comprising at least 100 mg. of a porous particulate carrier impregnated-with a poly(alkyleneimine) buffered with an alkanoic acid to a pH from about 6.0 to 7.6, wherein from about 2 m6 percent by weight buffered poly(alkyleneimine) is deposited on the carrier based on the total weight of the buffered poly(alkyleneimine) and carrier and wherein the carrier particles each have a pore diameter from about 0.1 to 2.0 microns, a surface area of from about 1 to 15 square meters per gram and a pore volume no less than about 0.3 cubic centimeter per gram.
6. An improved tobacco smoke filter material adapted to be affixed to a cigarette and comprising: at least 100 milligrams of a porous alumina impregnated with poly(ethyleneimine) buffered to a pH of 7.4 with acetic acid, wherein the porous alumina has a pore diameter of from about 0.1 to 2.0 microns, a surface area of from about 1 to square meters per gram, a pore volume of from 0.3 to 0.8 cubic centimeter per gram and wherein from about 4 to 6 percent by weight buffered poly(ethyleneimine) is deposited on the porous alumina.
7. An improved filter adapted to be affixed to a cigarette and comprising, in combination: a filter outer wrap having a tubular configuration and an inner filler formed from a plurality of particles formed from at least 100 milligrams of a porous particulate carrier impregnated with a poly(alkyleneimine) buffered with an alkanoic acid wherein from about 2 to 6 percent by weight acid buffered poly(alkyleneimine) is deposited on the carrier base on the total weight of the poly(alkyleneimine) and carrier, said poly(alkyleneimine) being buffered to a pH from about 6.0 to 7.6 and having an affinity for volatile smoke aldehydes and acids, wherein the carrier particles each have a pore diameter from about 0.1 to 2.0 microns, a surface area of from about 1 to 15 square meters per gram and a pore volume no less than about 0.3 cubic centimeter per gram.
8. The invention in accordance with claim 7 in which the carrier is a porous alumina.
9. The invention in accordance with claim 8 wherein the additive is poly(ethyleneimine) buffered to a pH of about 7.4 with acetic acid and wherein from 4 to 6 percent by weight of poly(ethyleneimine) is deposited on the porous alumina.
UNITED STATES PATENT @FFKCE 1110-2 14A QERTWMATE GE RWTHN Patent No. 3 716 O63 Dated February 13 1973 I t Elmer Francis Litzinger It is certified that 'error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
At Col. 3, line 40, "NI-I (CR CRC NH) H" should be --NH (CR CR NH) H7 Col. 5, second chart, there should be a space between the third and fourth lines and a space between the fifth and sixth lines;
Col. 7, line 54, after "buffered" add--additiVe---; and
line 56, delete "additive".
Signed and sealed this 3rd day of July 1973.
EDWARD M.FLETCHERI,JR. v Rene Tegtmeyer Attesting Officer Acting Commissioner of Patents FORM PO-1050 (10-69) -oc 375.p 9
- u S. GOVERNMENT PRINTING OFFICE: I969 o356-334
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|EP1594376A2 *||Feb 18, 2004||Nov 16, 2005||Filligent Limited||Filter containing a metal phthalocyanine and a polycationic polymer|
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|WO2007121439A2 *||Apr 17, 2007||Oct 25, 2007||Filligent Limited||Method and device for making tobacco smoke filters|
|WO2007121439A3 *||Apr 17, 2007||Oct 23, 2008||Filligent Ltd||Method and device for making tobacco smoke filters|
|U.S. Classification||131/334, 131/342|
|International Classification||A24D3/14, A24D3/00|