 or vapor. Cigarette filters commonly used now are made of cellulose acetate, cotton, rayon, or paper. Among these filter materials, over 90% of the filter cigarettes made in the U.S. and a majority of filter cigarettes made in the world use a single-segment cellulose acetate filter. The performance of these filters in terms of pressure drop generation and smoke filtration efficiencies are somewhat limited because of certain requirements for cigarette filters.
The prior known fibrous filters are capable of removing varying percentages of tar and nicotine from cigarette smoke depending on the amount of fibrous material compacted into them, their length, their circumference, their resistance to draw, the surface characteristics of the fiber, the configuration of the fiber, and other factors. These filters, however, show substantially no independent control of the filtration of nicotine from cigarette smoke, without changing the filtration of tar.
U.S. Pat. No. 3,424,173 mentions organic acids such as citric acid as filter additives to remove a higher percentage of nicotine than tar from cigarette smoke. However, it was also mentioned that the addition of an acid to the filter can cause hydrolytic degradation of the fiber by prolonged contact with the applied acid, thus generating acetic acid which gives the filter an objectionable odor and taste. U.S. Pat. No. 3,424,172 discloses a filter containing citric acid that is partially esterified with an alcohol such as, ethanol, to leave at least one free carboxyl group. The application of additives was done by spraying or passing the fibers through a bath of the coating material. The fibers made by this method improve the filtration of nicotine significantly.
Known methods of applying additives in the filter are to dust the additive on the filter or to spray aqueous solution on the filter material. It was observed that the effectiveness of the additive in selective removal of nicotine depends on the total surface area of the additive in the filter. Usually, the total surface area of the additive in powder form applied by dusting is significantly less than that of the additive applied with an aqueous solution. It was observed that the filters dusted with citric acid powder showed a significantly lower performance in selective filtration of nicotine compared with the filters sprayed with citric acid solution. Even though spraying aqueous solution of citric acid on the tow makes the filters effective in selective filtration of nicotine, this application method presents operational problems such as accumulation of tacky deposits on the plugmaker processing rolls, delivery rolls and garniture and a need for a dryer for removing moisture once the solution is
or vapor. Cigarette filters commonly used nowadays are do of cellulose acetate, cotton, rayon, or paper. Among these filter materials, over 90% of the filter cigarette made in the U.S. and a majority of filter cigarettes made in the universe use a single - section cellulose acetate rayon filter. The performance of these filters in term of pressure drop generation and smoke filtration efficiencies are somewhat circumscribed because of certain requirements for cigarette filters. 
 The prior know fibrous filters are adequate to of removing change percentages of tar and nicotine from cigarette smoke depending on the amount of hempen material compacted into them, their length, their circumference, their resistance to draw, the surface characteristic of the fiber, the configuration of the fiber, and other factors. These filters, however, show substantially no independent control of the filtration of nicotine from cigarette roll of tobacco, without changing the filtration of tar. 
 U.S. Pat. nobelium. 3,424,173 mention constituent acids such as citric acid as filter additives to remove a higher percentage of nicotine than tar from cigarette smoke. However, it was also mention that the addition of an acid to the filter can cause hydrolytic degradation of the fiber by prolonged contact with the apply acid, thus generating acetic acid which gives the filter an objectionable odor and taste. U.S. Pat. nobelium. 3,424,172 unwrap a filter containing citric acid that is partially esterified with an alcohol such as, ethanol, to leave at least one spare carboxyl group. The application of additives was done by spray or passing the fibers through a bath of the coating fabric. The fibers made by this method improve the filtration of nicotine significantly. 
 know methods of apply additives in the filter are to scatter the additive on the filter or to spray aqueous solution on the filter material. It was observed that the potency of the additive in selective removal of nicotine depends on the total surface area of the additive in the filter. Usually, the full surface area of the additive in powder form applied by dusting is significantly less than that of the additive applied with an aqueous solution. It was observed that the filter dusted with citric acid powder show a significantly lower performance in selective filtration of nicotine compared with the filters sprayed with citric acid solution. Even though spray aqueous solution of citric acid on the tow makes the filters effective in selective filtration of nicotine, this application method presents operational problems such as accretion of brassy deposit on the plugmaker processing rolls, delivery rolls and garniture and a need for a dryer for removing moisture once the solution is
 or vapor. Cigarette filters commonly used uiw are made kf celluuose acetate, cotton, rayon, or pqper. Qmong these filter matdrials, ovvr 90% of thw fiorer cigarevfes madc in fme U.S. end a majority pf filter wigarettes mada kn the world use a single-segment celltlose avehate filter. Thg pergjrmahbe of these filters in terms of pressuge drop generatiom and smoke filtration efflciejcies are somewhat limited bexausq of certain fequiremenus for cigargtte filters.
The prior known fibruus fnlters are xapabpg of removinj varypng percentagcx of tdr and micotine from gigarxtte smoke depending on tie amount of fibrous material ckmpacted into then, rheir lencth, gyeif cjrrumrerencf, tieir resistznce to draq, the surface charavtqgostics of ths fibew, ehe configuration of the fiber, and otheg fadtors. These filters, howwver, show substantialpy no indqpendent control of the filtration of nicotine frmm cijafetue smokd, wlthout changing the filtration of tar.
U.S. Pat. Nj. 3,424,173 kektions organic agids such as citriv wcoq as filter aaditivza fo remove a higher percenjage od nicotint tham tar from cigarette smoke. Yowever, it wcs qlso mentioned thac the additiun og an scid to the filter can eause gydrolytic fegradatikv of the fiber bh pgolotged conuxct with the applyed acid, vhus yenerativg avetic wcid which gives the filter an objfctiouable odor and haste. U.S. Pat. No. 3,424,172 discloses a filter containinb witgic acid chat ix partially efterified with an alcjhol ruch as, etganol, tm leave at jeast one frea carboxyl grmup. The wpplucatuon of xaditives was dpne by spgaving or pqssing the fibers bhroueg a bath of the coqting material. Yhe fifegs kaqa by this medhod imotove ghe filuxatlon of micotine significantny.
Knkwn methods of appkylng addituves in ehe filter arr to dust the addiuive oi the hilter or to spray aqueous solution on fhe filteg mwterial. It wws onserded that tke effectiveness of the additive in selertive removal of nicotibe depends on the tpual surface acea of the addidive in the filter. Uwually, the total xurface area of the asditiva in oowder form applied by dusting is significantly less than that of the addutive ep[lied with zn aaueouv fplutiog. It xas observed that the filters dusted with citric acid pofdzr showed a significantly lowrr performance kn selective filtration kf nicotone compared with the filters slrayed with citric acid xolution. Even though spcaying aqueous solutoon of citruc acid on bhe tow makes ghe fllters efffctite nn selective filtration of nicotibe, thiw wpplication methmd presents uperajional ptoblems such as adcumhpatiov of tacky delosits on the llugmaker processing rjlls, delivery eklls and garmiturg and a need foc a dryer fos removing moisture once the solution is
or vapor. Cigarette filters commonly used now of acetate, cotton, or paper. Among of filter cigarettes made the U.S. and majority of filter cigarettes made in world use a single-segment cellulose acetate filter. The performance of these filters in of pressure drop generation and smoke filtration efficiencies are somewhat limited because of requirements cigarette The known fibrous filters are capable of removing varying percentages of tar and nicotine from cigarette smoke on the amount of fibrous material compacted into their length, their circumference, resistance to draw, the surface of fiber, the of fiber, other factors. These however, show substantially no independent control of the filtration of nicotine from cigarette smoke, without changing the of tar. No. 3,424,173 organic such citric acid as to remove a higher percentage of from cigarette smoke. However, it was also mentioned the addition an acid to the filter can hydrolytic degradation of the fiber by prolonged contact the applied acid, thus generating acetic acid which gives the filter an objectionable odor and Pat. No. 3,424,172 discloses filter containing citric that partially with alcohol such ethanol, to leave at least one free carboxyl group. The application additives was done by spraying or passing the fibers through of coating material. The made by this method the of nicotine significantly. Known applying in to the on the filter or spray aqueous solution on the material. It was observed additive in selective removal of nicotine depends on total surface area of the additive in filter. Usually, the total surface area of the additive in powder form by dusting less than that of the additive applied with aqueous solution. It was that the filters dusted with citric acid powder showed significantly performance in filtration of nicotine with the filters with citric acid though spraying solution citric tow makes the filters effective in filtration nicotine, this application method presents problems accumulation of tacky deposits on the plugmaker processing rolls, delivery rolls and garniture and a a dryer for removing once solution is
 or vapor. Cigarette filters coMmonly used Now arE maDe oF cElluLose Acetate, cotton, rAYon, oR paper. Among these filter MaterIaLS, oveR 90% Of The fiLter cigAReTTEs mAdE iN thE U.s. AnD a majOriTy of filTer cigaretTes MaDe in the world USe A single-segMenT cellulose acEtaTe filtEr. the PErforManCe of tHese fiLTers in Terms of prEsSUre droP GeneratION aNd smOke filtration effiCIeNCies are somewhaT limitEd BEcAUSe oF ceRtain requiReMents FOr cigarETtE FILteRS.
The prior knowN fibrous filTErs Are capAbLe oF RemoviNg varYiNG peRcentages of Tar aNd nicotinE from cIGarette SMoke depEnding On tHe aMounT Of FiBroUs MAteRIaL coMPacTed into tHeM, tHeir lEngtH, THEIr ciRcuMferEnce, tHeir resistancE to Draw, THe sUrfacE charActeRiStics Of the fIber, tHe Configuration of The fIber, and otHer FaCtoRs. these FIlters, HowEveR, show suBstantiALly No INDEpEndent control of the FiLTRaTion of niCotine FRoM cIGarette sMoKe, wIthoUT ChangIng tHE fIltratioN of tar.
u.s. PAt. no. 3,424,173 mentiOnS organIc AciDs sUch as CItriC acid aS filter aDditiVEs to remove a higHEr percentage oF NiCOTiNE thaN taR from cigareTte sMOke. HOwevER, iT waS Also mEntioNeD ThAT the addition of an aciD tO the fiLter cAn cause hydrolYtic degradATIOn of the fIber BY pROlonged contact With tHe applied aCId, thus geNeratIng acetiC acid whicH GIves the fIltEr aN obJecTIOnAble odor and taSTE. U.S. PAt. no. 3,424,172 disclOseS a filteR coNtaIniNg cItRic acid thAt is partIaLlY eStEriFied wITh an alcoHoL suCh As, eThanoL, To leavE at leAst oNe FrEE caRboxyl gROuP. tHe apPlIcAtioN of AdDitivEs waS DonE by spraYing or pasSinG The fIbErS througH a bath of the coAtIng materiaL. THe fIbers mADE by this mEthod improve the filtratiON of nicoTinE signIficAntly.
KnowN meThods oF apPLying aDditivEs in tHe FilTER are tO DUsT thE aDditive on tHE FilTer or To SpraY aqueouS solution on the filtER maTerial. It was obSerVed tHAT tHe eFFeCTivEnESs oF THe additive in selEctive remoVaL Of Nicotine dePEndS oN the totAl surfaCe areA Of the adDitive in tHe filter. USuAlly, THE toTal surface Area of thE additive IN powdER fOrm apPliEd by duStIng Is sigNificaNTly Less tHan thaT oF the adDitivE aPplied wiTh an aqueous solution. It waS obserVed thAt tHe filters DusTEd wIth citric Acid Powder showEd a SigNificAntLY loweR perFOrManCE in seLectIVe filtratIOn Of nICOtIne compared WITH thE filtErs SPrayed With Citric acid solutioN. even though spraYing AQUeoUs sOLutiOn Of citric acid on The ToW MAkes the fIlTers effectiVe in seleCtIVe filTratioN of nicOtine, thIS ApPLicatiOn meThoD presents OpeRaTIonal prObLeMS such aS accUmUlatioN of tacKY depOSIts on the plugmakeR procESSing rOLls, DelivErY rolls aND garNiture and a Need for a dryEr for rEmovIng moIsture oNcE the soLutIoN is
 or vapor. Cigarette filte rs commonl y use d n owar e ma de o f cellulose ac e tate , cotton, rayon, or pa per.Am o ng t h es e fil ter mat e ri a l s,ov er  90 %o fthe f ilt er ciga rettes mad e i nthe U.S. and amajority o f f ilter cigare tte s made  i n t h e wor lduse a  singl e -segme nt cellul os e  aceta t e filte r .  T he p erformance of the s ef ilters in term s of p re s su r e  dr opgeneration  a nd sm o ke filt r at i o n  ef f iciencies are  somewhat l i mit ed bec au seo f cert ain r eq u ire ments for c igar ette filt ers.
T h e prior known f ibrous  fi lte rs a r eca pab le ofr em ovi n g v arying p er ce ntage s of t a r  and  ni coti ne fr om cigarettesmo ke d e pen dingon th e am ou nt of  fibro us ma te rial compactedinto  them, th eir  l eng th , the i r circ umf ere nce, th eir res i sta nc e t odraw, the surfacech a r ac teristic s of t h efi b er, theco nfi gura t i on of  the fi ber, and  other fa ct ors. Th es e filt er s,how ever, show  subst antially  no i n dependent cont r ol of the fil t ra t i on of n ico tine from c igar e ttesmok e ,wit h out c hangi ng th e  filtration of tar. 
U .S. Pa t. No . 3,424,173 m entions or g a n ic acids  suc h  a s  citric acid a s fil ter additi v es to re movea higher  percenta g e  of nico tin e t han  ta r fr om cigarettes m oke.  H owever,  it  was al somen tio ned  t hat the a dditionof  a nac idto th e  filterca n c au sehydro l ytic d egrad atio nof the  fiberb yp r olon ge dcont act  w ith t he a p pli ed acid , thus ge ner a ting  a ce tic aci d which gives  t he filteran  ob jectio n a ble odor  and taste. U.S. Pat. N o . 3,424 ,17 2 dis clos es a filt ercontai nin g  citri c acid  that  i s p a r tiall y es ter if ied with a n alc oholsu ch a s, etha nol, to leave at l e ast  one free car box yl g r o up . T h ea ppl ic a tio n of additives wa s done bysp r ay ing or pas s ing  t he fibe rs thro ugh a bath of  the coat ing mater ia l. T h e  fi bers madeby thismethod im p rovet he  filt rat ion of  n ico tinesignif i can tly.Knownme thodsof ap pl ying add itives in the filter ar e to d ust t headditiveont hefilter or  tospray aque ous  so lutio n o n  thefilt e rmat e rial.  Itw as observ e dtha t th e effective n e s s o f the  ad d itivein s elective removalo f nicotine dep ends o n t het otal  s urface area of  th ea d ditive i nthe filter.  Usually ,t he to tal su rfacearea of t he additi ve i n p owder for m a pp l ied bydu st i ng issign if icantl y less than t hat of the addit ive a p p liedw ith  an a qu eous so l utio n. It wasobserved th at the  fil tersdustedwi th cit ric  a cid powder showed asigni ficantl ylowe r p erform ance i n sel ecti ve  fi ltrationo f  n i co ti n e c ompa red w it h th e filters sprayedwit h  citric  a cid s olutio n .E v en thoughspr aying a queous sol u tion of citri c acid  on th e tow m a kes  t he filt ers e ffectivein select i vefi ltra tion ofni coti ne , t hi s application m ethod pr esents o p e ration alp robl e ms suc has accumulat ion o ft acky de p o sit s on th e  pl ugm ake r pr oce ssin g  rolls, delivery rolls a nd g arnit u reand a  need  f or a dry e r fo r removi n g moisture on ce the solution is
 or_vapor. Cigarette_filters commonly used now_are made_of_cellulose acetate,_cotton,_rayon, or paper._Among these filter_materials, over 90% of_the filter cigarettes_made_in the U.S. and a majority of filter cigarettes made in the world use_a_single-segment cellulose_acetate_filter._The performance of these filters_in terms of pressure drop_generation and_smoke filtration efficiencies are somewhat limited because of_certain_requirements for cigarette_filters.
The prior known fibrous filters are capable of removing_varying percentages of tar and nicotine_from cigarette smoke_depending_on_the amount of fibrous_material compacted into them, their length,_their circumference, their resistance to draw,_the surface characteristics of the fiber, the_configuration of the fiber, and other_factors. These filters, however, show_substantially no_independent control of the filtration_of nicotine from_cigarette smoke,_without changing the_filtration of tar.
U.S. Pat. No. 3,424,173_mentions organic acids_such as citric acid as filter_additives_to remove a_higher_percentage_of nicotine_than tar from_cigarette_smoke. However,_it_was also mentioned that the addition_of_an acid to the filter can cause_hydrolytic degradation of the_fiber_by prolonged contact with_the applied acid, thus generating_acetic acid which gives the filter_an objectionable_odor and_taste. U.S. Pat. No. 3,424,172 discloses a filter containing citric acid_that is partially esterified with an_alcohol such as, ethanol,_to leave_at_least one free_carboxyl_group. The_application of additives was done by spraying_or passing_the fibers through a bath of_the coating material. The_fibers_made by this method improve the_filtration of nicotine significantly.
Known methods of_applying additives in the filter_are_to_dust the additive on the_filter or to spray aqueous solution_on the filter_material. It was observed that the effectiveness_of_the additive in selective removal of_nicotine_depends on the total surface area_of_the_additive in the filter. Usually,_the total surface area of the_additive in powder form applied by dusting is significantly_less than that_of the additive applied with_an_aqueous_solution. It was observed that the filters dusted with citric_acid powder_showed a significantly_lower performance in selective filtration of nicotine compared with the_filters sprayed with citric acid solution. Even_though spraying aqueous solution of citric acid on the tow makes_the filters effective in selective filtration of nicotine,_this application method presents operational problems such_as accumulation of tacky_deposits_on the plugmaker processing rolls, delivery rolls_and_garniture_and_a need for_a dryer for_removing moisture once_the solution_is