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b r a n d s that w e r e c o m m o n i n the 1940's a n d 5 0 ! s. The tobacco ... filtration, porous and/or fast-burning papers, filter ventilation, ...
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7 Cytrel® Tobacco Supplement—A New Dimension in Cigarette Design R. W. GODWIN and C. H. KEITH Solvent Spun Rayon, Modified Cellulose Fibers and Derivatives Downloaded from pubs.acs.org by CORNELL UNIV on 06/08/17. For personal use only.

Celanese Fibers Co., Charlotte,N.C.28232

O v e r the p a s t 25 y e a r s t h e r e h a s b e e n a d r a m a t i c d e c r e a s e i n the d e l i v e r y of t a r , nicotine, andother smoke components f r o m cigarettes. This continuing trend has been particularly m a r k e d i n the p a s t f e w y e a r s w i t h the i n t r o d u c t i o n of a l a r g e n u m b e r o f n e w b r a n d s d e l i v e r i n g b e t w e e n 1 a n d 15 m i l l i g r a m s o f tar. T h e s e r e p r e s e n t a l a r g e c h a n g e f r o m t h e 2 5 to 3 0 m i l l i g r a m b r a n d s that w e r e c o m m o n i n the 1940's a n d 5 0 s . T h e tobacco i n d u s t r y h a s b r o u g h t a b o u t t h i s c h a n g e i n r e s p o n s e to c o n s u m e r demand for "lower delivery" cigarettes. n

1 1

!

There a r e a variety of existing techniques which a r e used to d e c r e a s e the s m o k e d e l i v e r y o f c i g a r e t t e s . A m o n g these a r e filtration, porous and/or fast-burning papers, filter ventilation, m o d i f i c a t i o n of the tobacco f i l l e r , a n d changes i n cigarette dimensions. Filtration is most commonly used andgenerally achieves u p to a 5 0 - 6 0 % r e d u c t i o n i n t a r a n d n i c o t i n e d e l i v e r y , b u t i t h a s l i t t l e e f f e c t o n g a s p h a s e c o n s t i t u e n t s {1). Selective filter media s u c h a s c h a r c o a l a r e u s e d i n s o m e b r a n d s to a c h i e v e s i z a b l e r e ductions i n some smoke components, while leaving others relatively unchanged. Porous and/or perforated papers a r e widely used to a c h i e v e 1 0 - 3 0 % r e d u c t i o n s i n b o t h g a s a n d p a r t i c u l a t e p h a s e components. M o r e r e c e n t l y , f i l t e r ventilation b y m e a n s of p e r f o r a t e d t i p p i n g p a p e r s h a s b e e n e m p l o y e d to a c h i e v e a n o t h e r 50 o r m o r e p e r c e n t r e d u c t i o n i n a l l s m o k e c o m p o n e n t s (2). F i n a l l y , changes i n the p a p e r b u r n i n g r a t e , c i g a r e t t e d i m e n s i o n s , a n d the i n c o r p o r a t i o n of expanded tobacco leaf a n d reconstituted tobacco s h e e t h a s b e e n u s e d to c r e a t e f a s t e r b u r n i n g a n d l o w e r p u f f count cigarettes, w h i c h d i r e c t l y translates into l o w e r smoke chemistry.

C y t r e l ® i s a r e g i s t e r e d t r a d e m a r k of the C e l a n e s e C o r p o r a t i o n .

83

84

S O L V E N T SPUN R A Y O N , MODIFIED C E L L U L O S E FIBERS

Solvent Spun Rayon, Modified Cellulose Fibers and Derivatives Downloaded from pubs.acs.org by CORNELL UNIV on 06/08/17. For personal use only.

In g e n e r a l , these techniques a r e u s e d i n c o m b i n a t i o n w i t h e a c h o t h e r to a c h i e v e a l o w e r d e l i v e r y c i g a r e t t e w i t h a d e q u a t e c o n s u m e r a p p e a l . H o w e v e r , e a c h of these e x i s t i n g methods has l i m i t a t i o n s . S o m e w h i c h h a v e b e e n m e n t i o n e d i n c l u d e the a c t i o n of f i l t e r s o n the p a r t i c u l a t e p h a s e of t o b a c c o s m o k e o n l y , a n d the a c r o s s - t h e - b o a r d a c t i o n of v e n t i l a t i o n . B e c a u s e of t h e s e , i t i s d e s i r a b l e to h a v e a d d i t i o n a l t e c h n i q u e s f o r c o n t r o l l i n g t h e d e l i v e r y of v a r i o u s s m o k e c o m p o n e n t s . One s u c h technique, w h i c h has been under development i n o u r l a b o r a t o r i e s f o r a n u m b e r of y e a r s , i s the i n c l u s i o n of t o b a c co s u p p l e m e n t i n a c i g a r e t t e . T h i s m a t e r i a l , w h i c h h a s the t r a d e m a r k e d n a m e C y t r e l , i s a m a n u f a c t u r e d sheet m a t e r i a l of controllable composition w h i c h looks, p r o c e s s e s , and burns like tobacco. It h a s a f u r t h e r d e s i r a b l e p r o p e r t y o f h a v i n g a b l a n d t a s t e u p o n c o m b u s t i o n , so that b l e n d s of C y t r e l w i t h t o b a c c o taste essentially like a m i l d tobacco. I t i s t h e p u r p o s e o f t h i s p a p e r to to d e s c r i b e t h e p h y s i c a l , c h e m i c a l , a n d s o m e o f t h e p e r t i n e n t b i o l o g i c a l p r o p e r t i e s of this m a t e r i a l . T h e effect of C y t r e l i n c l u sion i n tobacco blends is also described. C y t r e l is e s s e n t i a l l y a f i l l e d f i l m m a t e r i a l , f o r m e d by casti n g a n d d r y i n g a s h e e t f r o m a d o u g h - l i k e m i x t u r e of o r g a n i c b i n d e r s a n d a d d i t i v e s w i t h m i n e r a l f i l l e r s (3). A typical compos i t i o n i s g i v e n i n T a b l e I. T h e f i n i s h e d sheet is cut into o n e - i n c h squares w h i c h are subsequently blended with tobacco and m a n u factured into cigarettes by conventional techniques. F o r the p u r p o s e s of t h i s d i s c u s s i o n , c i g a r e t t e s d e s c r i b e d a r e t y p i c a l of the construction commonly utilized in Great Britain. These cigar e t t e s w e r e 7 2 m i l l i m e t e r s l o n g w i t h a c i r c u m f e r e n c e o f 25 m i l l i m e t e r s a n d w e r e e q u i p p e d w i t h a 16 m i l l i m e t e r , d u a l a c e t a t e p a p e r f i l t e r w i t h a t a r r e m o v a l e f f i c i e n c y o f 4 9 % (4). Cigarette w e i g h t s w e r e h e l d c o n s t a n t a t 0 . 98 g r a m , a n d p r e s s u r e d r o p s r a n g e d f r o m 90 m i l l i m e t e r s o f w a t e r a t a n a i r f l o w o f 1 7 . 5 m i l l i l i t e r s p e r s e c o n d f o r t h e a l l - C y t r e l c i g a r e t t e s to 116 m i l l i m e t e r s f o r the a l l - t o b a c c o c i g a r e t t e s . B l e n d e d c i g a r e t t e s c o n t a i n i n g 10, 20, a n d 50% C y t r e l w e r e a l s o p r e p a r e d , a n d puff c o u n t s l i n e a r l y r a n g i n g f r o m 1 0 . 2 to 5 . 8 u n d e r s t a n d a r d s m o k i n g c o n d i t i o n s w e r e o b t a i n e d a s the p e r c e n t a g e of C y t r e l i n c l u s i o n i n c r e a s e d . This c h a n g e i n puff c o u n t o n l y p a r t i a l l y a c c o u n t s f o r the d e c r e a s e s i n deliveries shown later. If i t w e r e t h e o n l y e f f e c t , t h e e x p e c t e d d e l i v e r i e s f r o m a C y t r e l c i g a r e t t e w o u l d be 57% of those of a tobacco cigarette. S i n c e d e l i v e r i e s i n t h e r a n g e o f 0 to 3 8 % a r e f o u n d , i t i s evident that o t h e r f a c t o r s a r e i n v o l v e d . F r o m l o o k i n g at the c o m p o s i t i o n of the m a t e r i a l , i t i s a p p a r e n t that 70% of C y t r e l c o n s i s t s o f i n c o m b u s t i b l e m a t e r i a l , a n d a m a x i m u m o f 30%

7.

GODWIN AND KEITH

T a b l e I:

85

Cytrel Tobacco Supplement

C o m p o s i t i o n of C y t r e l Amount

Material Binder (sodium carboxymethyl Inorganic fillers/combustion Humectant/plasticizer

19% 71%

cellulose)

modifiers

5%

(glycerol)

3% 2%

Solvent Spun Rayon, Modified Cellulose Fibers and Derivatives Downloaded from pubs.acs.org by CORNELL UNIV on 06/08/17. For personal use only.

Colorants F l a v o r additives

can burn during smoking.

T a k i n g 30% of 57% g i v e s

17%,

which

s h o u l d b e the d e l i v e r y of a n y g i v e n c o m p o n e n t i f no c h a n g e i n combustion

occurs.

B e f o r e e x a m i n i n g the r e l a t i v e d e l i v e r i e s of v a r i o u s ponents f r o m C y t r e l and tobacco,

com-

i t i s n e c e s s a r y to r e f e r t o

methods

e m p l o y e d a n d the g e n e r a l p a t t e r n of d e l i v e r i e s .

methods

u t i l i z e d a n d the d e l i v e r i e s of 250

the

The

c o m p o u n d s a n d 75

ele-

ments f r o m these cigarettes have been reported i n a s e r i e s papers by V i c k r o y , Mauldin, f o r s c h u n g (4, j>,

6).

a n d A l l e n i n the B e i t r a g e

Briefly recapitulating,

zur

the v o l a t i l e

collection trap,

graphic techniques

w e r e m e a s u r e d by either gas

or specific tests for individual

(e. g . , h y d r o g e n c y a n i d e , ponents are

components

The semi volatile

of 1 3 0 ° C .

These were analyzed by a

chromatography and mass spectrometry.

densed phase components

(i. e.,

specific techniques.

mass spectography

except for m e r c u r y , spectroscopy.

M

tar

1,

and

a substantial l i n e a r d e c r e a s e i n d e l i v e r y as M

Figure 1

w h i c h i s defined as total p a r t i c u l a t e

c o l l e c t e d o n the f i l t e r p a d m i n u s w a t e r a n d n i c o t i n e . f r o m 15.8

to 3 . 6

milligrams/cigarette.

is a s i m i l a r graph for another important smoke tine i s absent f r o m the C y t r e l f o r m u l a t i o n .

shows matter

It i s

evi-

mixture

Figure 2

component,

I n t h i s c a s e t h e l i n e g o e s to z e r o f o r 1 0 0 % C y t r e l ,

characteristic

mea-

2,

almost

dent that t h e r e i s m o r e t h a n a f o u r f o l d d e c r e a s e i n this of m a t e r i a l s

and

spark

which was

Figures

the a m o u n t o f C y t r e l i n the b l e n d i s i n c r e a s e d . the d e c l i n e i n

con-

collection

chromatographic

3 i l l u s t r a t e the g e n e r a l d e l i v e r y p a t t e r n o b s e r v e d f o r every component,

combina-

The elements were measured by

s u r e d by a t o m i c f l o u r e s c e n c e

tine.

com-

The

those r e m a i n i n g o n the

pad) w e r e m e a s u r e d b y a v a r i e t y of gas source

fiber

chromato-

t h o s e w h i c h c a n b e d i s t i l l e d f r o m the c o l l e c t i o n p a d

at a t e m p e r a t u r e t i o n of gas

nitric oxide).

Tabak-

smoke

c o m p o n e n t s , w h i c h a r e t h o s e w h i c h p a s s t h r o u g h the g l a s s smoke

of

This pattern

of a n u m b e r of n i t r o g e n - c o n t a i n i n g

smoke

t u e n t s b e c a u s e of the r a t h e r l o w n i t r o g e n c o n t e n t of

as

niconico-

is consti-

Cytrel.

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S O L V E N T SPUN R A Y O N , MODIFIED

0 100 50 50

Figure 1. Tar delivery

Φ

Figure 2. Nicotine delivery

CELLULOSE

100 % C y t r e l 0 % Tobacco

FIBERS

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7.

GODWIN A N D K E I T H

Cytrel Tobacco Supplement

87

F i g u r e 3 shows a s i m i l a r d e l i v e r y p a t t e r n f o r a n i m p o r t a n t gas phase constituent, carbon monoxide. In F i g u r e 4 w e h a v e a n e x a m p l e of o n e of the r a r e i n s t a n c e s where a different pattern is o b s e r v e d . In this case, g l y c e r o l i n c r e a s e s l i n e a r l y a s the a m o u n t of C y t r e l i n the b l e n d i s i n c r e a s e d , g o i n g f r o m z e r o i n t h e u n c a s e d t o b a c c o c i g a r e t t e to 2 . 1 m i l l i g r a m s i n the 100% C y t r e l c i g a r e t t e . In c a s e d cigarettes (such as those u s e d i n the U n i t e d States) w h e r e g l y c e r o l i s c o m m o n l y a d d e d a s a h u m e c t a n t , t h i s c h a n g e i s n o t n e a r l y s o m a r k e d . It i s k n o w n that g l y c e r o l i s d i s t i l l e d i n t o the s m o k e s t r e a m a s a C y t r e l c i g a r e t t e c o m b u s t s , a n d c o m p r i s e s a b o u t 58% of the t a r c o l l e c t e d . O n l y two o t h e r c o m p o u n d s of the 250 e x a m i n e d s h o w a n i n c r e a s e i n d e l i v e r y a s the C y t r e l content i n the b l e n d i s i n c r e a s e d . These a r e : (1) h y d r o g e n s u l f i d e , w h i c h m o d e s t l y i n c r e a s e s f r o m 4 6 to 55 m i c r o g r a m s / c i g a r e t t e , a n d (2) a m m o n i a , w h i c h r e m a i n s c o n s t a n t a t 2 0 - 2 2 m i c r o g r a m s / c i g a r e t t e u p to a 5 0 % b l e n d i n c l u s i o n o f C y t r e l , b u t t h e n i n c r e a s e s to 50 m i c r o g r a m s / c i g a r e t t e f o r a n a l l - C y t r e l cigarette. T h e s e m a t e r i a l s a r e k n o w n to b e d e r i v e d f r o m r e s i d u a l s u l f u r i n the c o l o r a n t u s e d a n d d e c o m p o s i t i o n of a n i t r o g e n e o u s f l a v o r a d d i t i v e , r e s p e c t i v e l y . A m o n g the e l e m e n t s , a l l b u t s o d i u m m a r k e d l y d e c r e a s e a s the C y t r e l c o n t e n t of the b l e n d i s i n c r e a s e d . S o d i u m , w h i c h c a n be d e r i v e d f r o m the s o d i u m c a r b o x y m e t h y l c e l l u l o s e b i n d e r , shows as e r r a t i c i n c r e a s e w i t h i n c r e a s i n g C y t r e l content; but this i s not n e a r l y as m a r k e d as the d e c r e a s e i n p o t a s s i u m , w h i c h i s a m a j o r e l e m e n t i n t o b a c co. A s i n d i c a t e d i n the p r e v i o u s d i s c u s s i o n , a c o m p a r i s o n o f s m o k e c o m p o n e n t d e l i v e r i e s c a n b e s t be done c o n s i d e r i n g the c o m p o s i t i o n s of C y t r e l a n d t o b a c c o . It t h e r e f o r e i s o f i n t e r e s t to e x a m i n e the r e l a t i v e d e l i v e r i e s of a n u m b e r of s m o k e c o m p o n e n t s to s e e i f t h e o v e r a l l c o m b u s t i o n p r o c e s s c a n b e b e t t e r u n d e r s t o o d . F r o m the d i f f e r e n c e s i n p u f f c o u n t s a n d the i n o r g a n i c c o n t e n t of C y t r e l , i t i s e x p e c t e d that the C y t r e l c i g a r e t t e s h o u l d d e l i v e r 17% of the a m o u n t of a n y c o m p o n e n t i n t o b a c c o s m o k e i f a l l o t h e r f a c t o r s w e r e e q u a l . I n T a b l e II the r e l a t i v e d e l i v e r i e s of g a s e s a n d v a p o r p h a s e c o m p o n e n t s a r e l i s t e d a s c a l c u l a t e d f r o m the V i c k r o y d a t a (4). F o r m o s t of t h e s e c o m p o n e n t s , the d e l i v e r i e s a r e n e a r o r b e l o w the e x p e c t e d 17% d e l i v e r y ( w i t h the e x c e p t i o n s p r e viously noted for a m m o n i a and hydrogen sulfide). The l o w levels of a l k a n e s , a l k e n e s , b e n z e n e , and toluene i n C y t r e l s m o k e r e f l e c t the a b s e n c e o f s a t u r a t e d h y d r o c a r b o n s s u c h a s t o b a c c o waxes in Cytrel. T h e r e l a t i v e l y h i g h e r l e v e l s of a l k y n e s , p r i n c i p a l l y a c e t y l e n e , suggest that f r e e r a d i c a l r e a c t i o n s a r e o c c u r r i n g i n the p y r o l y s i s p r o c e s s . The v e r y l o w l e v e l s of a l c o h o l s , f u r a n s ,

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88 S O L V E N T SPUN R A Y O N , MODIFIED C E L L U L O S E FIBERS

Figurée. Glycerol delivery

7.

GODWIN A N D KEITH

Table

89

Cytrel Tobacco Supplement

II: R e l a t i v e D e l i v e r i e s o f V a p o r P h a s e Number

Delivery

Delivery

f r o m Tobacco f r o m C y t r e l

of Material

Components

Compounds

(pg/cig)

(ug/cig)

Relat i v e (%)

Solvent Spun Rayon, Modified Cellulose Fibers and Derivatives Downloaded from pubs.acs.org by CORNELL UNIV on 06/08/17. For personal use only.

Hydrocarbons Cj-C^

alkanes

6

2165

312

C i - C

alkenes

10

1106

alkynes

2

48 104

169 18

D

C1-C5

14.4 15.3 37. 5 12. 5 7.4

13

Benzene

1

Toluene

1 2 4

8. 0

7.8

13. 1

W i t h t h i s e x t e n s i v e b a c k g r o u n d of i m p r o v e m e n t s i n the chemic a l and b i o l o g i c a l p r o p e r t i e s of C y t r e l s m o k e , i t i s of i n t e r e s t to e s t i m a t e what C y t r e l i n c l u s i o n c o u l d do f o r e x i s t i n g types of c i g a -

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94

SOLVENT SPUN RAYON, MODIFIED CELLULOSE FIBERS

rettes. In this country the most popular brands of cigarettes have a tar delivery of around 17 m i l l i g r a m s , a nicotine delivery of about 1. 2 m i l l i g r a m s , and a carbon monoxide delivery of 15 m i l l i g r a m s per cigarette. Replacing 30% of the tobacco with C y t r e l should reduce these deliveries to 13. 1, 0. 8, and 13 m i l l i grams per cigarette, respectively. Thus, a medium tar brand can be changed to a lower tar brand by inclusion of 30% C y t r e l . S i m i l a r l y , a ventilated low tar brand might have tar, nicotine, and CO deliveries of 8. 0, 0. 6, and 9. 9 m i l l i g r a m s per cigarette. Inclusion of 30% C y t r e l i n the blend could further reduce these to 6 . 5 , 0.4, and 8. 6 m i l l i g r a m s per cigarette, respectively. In conclusion, we have shown that C y t r e l tobacco supplement offers a means to reduce deliveries of virtually a l l smoke c o m ponents of a cigarette. These reductions are for the most part greater than would be expected on the basis of the burning rate of the m a t e r i a l and its composition. The s i m p l e r smoke composition and the reduced deliveries of Cytrel-containing cigarettes a p p e a r to translate into a reduction i n biological response i n animal test systems. Inclusion of C y t r e l i n cigarettes can be readily utilized with other existing techniques to provide lower delivery cigarettes. Abstract C y t r e l i s a tobacco supplement consisting of m i n e r a l components, combustion modifiers, and organoleptic-active materials bound together by a film-forming cellulose ether. C y t r e l i s being used i n several brands of cigarettes on the European market at a 20-25% level blended with tobacco. The amount of "tar" c o n t r i buted to the "mainstream" smoke by C y t r e l i s one-fourth to one-seventh of that from tobacco. There are s i m i l a r reductions for other non-nitrogeneous smoke constituents relative to tobacco. Neither C y t r e l nor C y t r e l smoke contains nicotine, and the number and amount of nitrogen-containing compounds i n C y t r e l smoke are d r a s t i c a l l y reduced. S i m i l a r l y , the amount and complexity of the combustion products i n C y t r e l "sidestream" smoke are significantly reduced. It has been shown that the delivery of smoke components from blends of C y t r e l and tobacco is reduced in direct proportion to the level of C y t r e l i n the blend with tobacco. This relationship has been demonstrated for virtually all the components of smoke studied to date. C y t r e l can be readily blended with tobacco i n conventional cigarette making equipment. F u r t h e r , Cytrel/tobacco blend technology is fully compatible with other means currently being used to modify cigarette smoke, such as various cigarette filters and high porosity cigarette papers.

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7.

GODWIN AND KEITH

Cytrel Tobacco Supplement

95

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