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LIMITED BROWN & WILLIAMSON TOBACCO CORPORATION RESEARCH DEVELOPMENT & ENGINEERING MEETING REPORT EfiBJECT : LOCATION : PRESENT : DATE : CO: SCHWEITZER PAPERS FOR CIGARETTES WHICH SELF-EXTINGUISR OR HAVE REDUCED IGNITION PROCLIVITY/32~ RD~E J. G. Bsterle, T. F. Riehl, M. C. Bryant, R. R. Johnson~ g. K. gt.Charles, L. C. Chao, R. F. Langford, J. P. Banks, d. K. Wells: From Schweltzer: Don Duroeher~ John Carter, Dick Grau, Vladlmlr Hampl August 22, 1983 R. A. Sanford~ E. E. Kohnhorst~ M. L. Reynolds, J. G. Esterle, J. K. Wells On Tuesday~ August 16tht representatlves from Schweltzer visited to demonstrate two new types of elgare£te papers. One type causes a cigarette to self-extingulsh in -3 mln. The other reduces the ig- nition procllvi£y of a cigarette. Bo~h papers were made by a varla£ion of the same basic theme. They start with a paper which does not support cigarette combustion and force the cigarette to burn by adding high levels of potassium citrate. The self-extin~ulshin@ paper has alternating bands of high and low Citrate levels. The high citrate regions will smoulder, but the low citrate hands do not support eomhustlon unless puffed. The citrate, dn the low citrate regions, ~s added only for ash appearance. The low ignition proclivity paper is made by adding eltra£e to the paper until it is just past the threshold where a cigarette will smoulder normally when surrounded by air. When the cigarette is dropped onto some substrata, oxygen supply to the coal is reduced causing the coal to shrink. This gives an insulating sheath of tobacco around the coal. The insulating layer of tobacco reduces the Ignition proellv~ty and if the coal shrinks enongh, the clgarette goes our. 6; 034S647

The appearance and opacity of these papers is equivalent to normal papers. Their tensile strengths are higher than normal and bobbin lengths are -1.5 times that of a normal paper. Because of the mechanism Involved~ cigarette deliveries are increased by -30%. If tar is adjusted by ventflatfon to the amounts obtained uslng a normal paper, CO deliveries are stfll 10-15% higher. No ~jor taste dffferences were noted by Schweltzerls in-house taste panel. The cost for these papers was estimated to be 2-3 times that of a normal paper. The reduced ignition proclivity paper should cost less : than the self-extlnguishlng paper because citrate bands have to be' gravure printed onto the self-extinguishing paper. The lead time for production of the self-extingulshlng paper was estimated to be h-8 months. The reduced ignition proclivity paper could be produced sooner. Schweitzer left One small bobbin of each of the two types of papers for our evaluation. In the near future~ they will provide bohbln quantities for further testing, Basic Mechanism A very "tight" paper Is made by reducing the paper pore sizes. This is accomplished by enhanced flax refining, by using less CaC03~ and/or coating the paper with starch. With these "tight" papers, very little oxygen diffuses in through the paper. Most of the oxygen dlf- fusion occurs at the paper burn llne (PBL) where the cellulose struc- ture is degrading. Therefore, oxygen d~ffusion, and subsequently cig- arette smoulder, is controlled by the width of the paper burn llne. When citrate is added to the paper, the cellulose structure begins to degrade at lower temperature. A higher citrate level gives a lower degradation temperature. This in turn increases the width of the PBL allowing more oxygen to the coal. These papers were characterized by defining a Burn Mode Index. This fs essentially a measure of the diffusion coefficient of oxygen through the paper. The procedure for obtaining the BMI was also dis- cussed. A paper with a BMI > 2.0 requires no citrate for freehurn while a paper with a BMI < 0.5 cannot be made to freeburn at any citrate level. Self-Extinguishlng Paper This paper was made by gravure printing a "tight" paper with high ci- trate bands i0 ~ wide separated by low citrate (<1%) bands 4 mm wide. When the cigarette is llt, a wide PBL is establlshed on the h~gh citrate band allowing the cigarette to smoulder. When the low citrate band is reached, the PBL narrows which decreases the coal diameter as ft burns hock |nto the rogaceo column. The paper is now insulated from the coal by an annular ring of tobacco so that, even df the coal burns past the low nitrate bandI the paper temperature is too low for cellulose decomposition. The coal then burns back Into the cigarette until it extinguishes. A puff re-establlshes the PRL and the cigarette will smoulder untll another low citrate band is reached. 2 - 62034S64S

w m Schwei£zer feels that prlnting technology is good enough to allow adequate control of the hand widths. The only problems noted Occurred along the glue llne of a few cigarettes where cltra£e was smeared across the ba~ds. Low Ignlt~on Proclivity Paper Whe~ a clgaret£c made wlth this paper ls dropped onto some substra£e~ ft may not go ou£ in all cases, but Schweltzer Btates that it will not Ignlte the substrate. The low iRnltleu proclivity ls achieved by adding c~trate to a "tlght" base paper until it is just past the "threshold where a cigarette will smoulder in air. When the cigarette is dropped on a substra~e~ air flow into the coal ~s partially disropted~ starviog the coal of oxygen. The coal then shrinks and an insolatlng layer of tobacco surrounds it. In ~80X of the cases tested~ the cigarette wen~ out. Cigarettes made with this paper were tested on various suhstrates. The most ~ensltlve test was flannel stretched over a hoop which allowed very little air flow restriction. These clgaret~e would no~ always pass this test. The next mos~ sensitive gest was flaonel over urethane foam in a "mlnl-couch" arrangement~ The clgarettes did not ignlte the substrata with thls arrangement. OthErs less sensitive te~t substrates were label paper stretched over a hoop and cardboard. The papers were also characterized u~ing a more controllable test method which dfdn't Involve layfng a clgare~te On a substrata. This test ~uvolvcd oxygen deprlvatfou where air was diluted wlth nitrogen ont~l the cigarette went out. The higher the oxygen content needed to freeburn. £he lower the ~gnftlon proclivlty of the clgarette. For example, a normal elgarette will freeburQ down to ~IIZ oxygen. Tight papers with hlgh eltrate content were made whlch needed from 15-19~ oxygen to freehurn. It should be noted that ~f ~he oxygen Content needed to freeburn i~ too close £o atmospherle conditions, then the c~arette may not stay llt at higher alti£udes. F. K. St. Charles FKS/jmu 02651 6Z034 649