4

4 Production of Rayon from Solutions of Cellulose in N O -DMF 2

4

R.B.HAMMER andA.F.TURBAK

Downloaded by CORNELL UNIV on September 26, 2016 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0058.ch004

ITT Rayonier Inc., Eastern Research Div., Whippany,N.J.07981

A wide range o f wood pulps in v a r i o u s p h y s i c a l forms were found t o d i s s o l v e readily in a combination o f DMF/N O . The concentration of pulp d i s s o l v e d was a direct f u n c t i o n o f the degree of p o l y m e r i z a t i o n . Dimethylformamide was compared t o dimethyl s u l f o x i d e and acetonitrile and was found t o be p r e f e r a b l e o v e r a l l w i t h respect t o s o l v e n t power, viscosity of solutions, stability and recovery. The temperature o f N O a d d i t i o n and the r e s u l t a n t time f o r dissolution were found to be critically r e l a t e d t o ultimate fiber p h y s i c a l and analytical p r o p e r t i e s . F i b e r s w i t h a h i g h wet modulus and intermediate t e n a c i t y were readily produced from proton donor systems i n v o l v i n g h y d r o x y l i c c o a g u l a t i o n baths such as water, a l c o h o l s and glycols. A wide variety of fiber cross s e c t i o n s could be produced and proved t o be r e l a t e d t o the nature o f the regenerant employed during s p i n n i n g . 2

2

4

4

Introduction The most w i d e l y used method f o r c o n v e r t i n g wood pulp i n t o regenerated c e l l u l o s e for films and fiber production is the viscose process. However, there a r e s e v e r a l problems a s s o c i a t e d w i t h the v i s c o s e process which do not appear t o be d i m i n i s h i n g even in view o f c u r r e n t developments. There a r e other processes f o r producing regenerated cellulosic products i n c l u d i n g regeneration from cellulose nitrate which is v e r y hazardous, and cuprammonium hydroxide which forms a s o l u b l e c e l l u l o s e complex. However, the p r o d u c t i o n o f cellulosic articles from these processes is minuscule compared t o the v i s c o s e method. There are entirely different c l a s s e s of chemical systems which are non-aqueous which d i s s o l v e cellulose. D i n i t r o g e n tetr o x i d e , N O , has been used as an agent t o make 6-carboxy cellulose in non-polar s o l v e n t s such as chloroform or carbon t e t r a c h l o r i d e . I n 1947-48 W.F. Fowler e t al(1)evaluated the relative s o l v e n t power o f forty-five organic s o l v e n t s w i t h N O , for 2

4

2

4

40

Turbak; Solvent Spun Rayon, Modified Cellulose Fibers and Derivatives ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

4.

H A M M E R A N D TURBAK

41

Production of Rayon

d i s s o l v i n g c e l l u l o s e . In separate p a t e n t s , H.D. W i l l i a m s (2) and H.L. Hergert Q ) et a l r e p o r t e d dimethyl s u l f o x i d e as a s p e c i f i c p o l a r s o l v e n t f o r use w i t h N 0 to d i s s o l v e c e l l u l o s e . In l a t e r work, the s o l u t i o n p r o p e r t i e s of c e l l u l o s e / N 0 / D M F s o l u t i o n s or c e l l u l o s e p l u s other polymer/N 0 /DMF s o l u t i o n s were examined. For example, 0. Nakao r e p o r t e d g r a f t copolymers prepared from c e l l u l o s e / N 0 s o l u t i o n s . ^ ) L.P. Clermont(5) and R.G. Schweiger(6) r e p o r t e d t h a t c e r t a i n c e l l u l o s e d e r i v a t i v e s could be prepared through the use of c e l l u l o s e / N 0 / D M F s o l u t i o n s . B a s i c chemical and p h y s i c a l s t u d i e s on t h i s system have been r e ported by N.J. Chu(j) and M. Pasteka and D. M i s l o v i c o v a . ( 8 ) The experiments to be d e s c r i b e d were intended to e x p l o r e the use of c e l l u l o s e s o l u t i o n s i n N 0 /DMF or DMSO f o r the p r o d u c t i o n of regenerated f i b e r s as a p o t e n t i a l replacement f o r the v i s c o s e process. 2

4

2

2

2

4

2


4

4

2

4

4

Experimental Experiments were designed to determine the i n f l u e n c e of the form of the pulp and the degree of p o l y m e r i z a t i o n p r i o r t o d i s s o l u t i o n . Although the m a j o r i t y of the s o l u t i o n s were prepared u s i n g Abbe'cut m a t e r i a l , i . e . a h i g h l y powdered, d e f i b e r e d p u l p , the d i s s o l u t i o n process i s not l i m i t e d w i t h r e s p e c t to the degree of p o l y m e r i z a t i o n or the pulp form. A l l s o l u t i o n compositions are g i v e n as weight percents i n the order p u l p / N 0 / s o l v e n t , eg. 8/15/77 r e p r e s e n t s 8$ c e l l u l o s e , 15$ N 0 and 77$ s o l v e n t . A wide v a r i e t y of c e l l u l o s i c pulps were found to d i s s o l v e i n the Ν 0 s o l v e n t system. Both s u l f a t e and s u l f i t e pulps can r e a d i l y be employed and pulps c u r r e n t l y a v a i l a b l e f o r the v i s c o s e process are among those t h a t may be used. In a d d i t i o n , bleached or non-bleached, barked and non-debarked pulp samples a l s o r e a d i l y d i s s o l v e i n t h i s system. These pulps may c o n s i s t of hardwoods, softwoods or mixtures of the two s p e c i e s . A t y p i c a l example of the s o l u t i o n p r e p a r a t i o n procedure i s d e s c r i b e d below. S i l v a n i e r - J , a prehydrolyzed k r a f t pulp of 1050 D.P., a f t e r c o n v e r t i n g t o a l k a l i c e l l u l o s e by methods w e l l known i n the rayon i n d u s t r y , was a l k a l i n e aged t o a D.P. l e v e l of U 5 0 , n e u t r a l i z e d , washed, d r i e d , then e i t h e r f l u f f e d , d i c e d or d e f i b e r e d . An 8/I5/77 c e l l u l o s e / N 0 / D M F s o l u t i o n was prepared by charging I60 p a r t s of t h i s a l k a l i aged p r e h y d r o l y z e d , k r a f t pulp (D.P. U50) and I5U0 p a r t s of dimethylformamide ( DMF) i n t o a twol i t e r f o u r neck r e s i n r e a c t i o n f l a s k equipped w i t h a s t a i n l e s s s t e e l mechanical s t i r r e r , thermometer, and a 250 ml. e q u a l i z i n g pressure a d d i t i o n f u n n e l . The r e s u l t i n g s l u r r y was s t i r r e d and cooled to below +20°C, p r e f e r a b l y between -5°C and +10°C, w h i l e 300 p a r t s of l i q u i d n i t r o g e n t e t r o x i d e ( N 0 ) was added dropwise over ça. 60 minute time p e r i o d . The temperature of the r e s u l t i n g exothermic r e a c t i o n was maintained below 20°C, p r e f e r a b l y i n the range p r e v i o u s l y s p e c i f i e d d u r i n g N 0 a d d i t i o n and f o r the 2

2

4

4

4

2

4

2

2

4

4


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

42

d u r a t i o n o f the remaining d i s s o l u t i o n process. C e l l u l o s e / N 0 / C H C N s o l u t i o n s o f 8 / 2 0 / 7 2 composition were prepared i n a s i m i l a r manner. C e l l u l o s e / N 0 / D M S 0 s o l u t i o n s o f 8 / I 5 / 7 7 composition were prepared under s i m i l a r c o n d i t i o n s except that the l i q u i d N 0 was f i r s t added t o the DMSO c o n t a i n i n g 1 . 5 p a r t s o f water. The c e l l u l o s e was then added t o the cooled (20°C) N 0 / D M S 0 mixture. A l l s o l u t i o n s were observed m i c r o s c o p i c a l l y t o be f r e e o f g e l s and unreacted f i b e r s . The s o l u t i o n s were f i l t e r e d through a 9 0 mm. diameter n y l o n , i n - l i n e f i l t e r d u r i n g s p i n n i n g . The s o l u t i o n s were deaerated p r i o r t o s p i n n i n g and v i s c o s i t i e s measured by a B r o o k f i e l d Viscometer and found t o be i n the range 2

2

4

3

4

2


2

of 8 , 0 0 0 - 1 6 , 0 0 0 cps.

4

4

at 2 2 ° C

The m a j o r i t y o f the s p i n n i n g t r i a l s were performed on a bench-scale v e r t i c a l s p i n n i n g u n i t . The s o l u t i o n s were spun i n t o the a p p r o p r i a t e primary r e g e n e r a t i o n bath and the r e s u l t i n g f i b e r s passed v e r t i c a l l y t o a primary godet, then through a secondary bath t o a secondary godet, whose speed could be a l t e r e d t o produce d e s i r e d s t r e t c h c o n d i t i o n s . S e v e r a l types o f s p i n n e r e t t e s have been used s u c c e s s f u l l y t o s p i n f i b e r s from these s o l v e n t systems. For example, g o l d - p l a t i num, t y p i c a l f o r the v i s c o s e p r o c e s s , s t a i n l e s s - s t e e l , t y p i c a l f o r c e l l u l o s e acetate s p i n n i n g , and g l a s s . The g l a s s spinner e t t e s have a f f o r d e d the best r e s u l t s and are thus p r e f e r r e d s i n c e they are both inexpensive and o f f e r the advantage o f l a r g e r h o l e length/diameter r a t i o s . R e s u l t s and D i s c u s s i o n The d i s s o l u t i o n o f c e l l u l o s e i n N 0 / s o l v e n t systems i s b e l i e v e d t o r e s u l t from the formation o f a c e l l u l o s e n i t r i t e e s t e r and n i t r i c a c i d . (2) Consequently, the r e g e n e r a t i o n o f c e l l u l o s e d u r i n g s p i n n i n g from a true c e l l u l o s e n i t r i t e e s t e r would r e q u i r e a t r a n s n i t r o s a t i o n r e a c t i o n by some agent t o remove the n i t r i t e and provide a hydrogen i o n t o c e l l u l o s e . These r e quirements are met by p r o t o n i c n u c l e o p h i l i c species such as water, a l c o h o l , and o t h e r s . I f the régénérant-coagulant were water o r a l c o h o l then the spent r e g e n e r a t i o n bath would c o n t a i n n i t r o u s a c i d , H N 0 , and/or the a l k y l n i t r i t e , R0N0, i n a d d i t i o n t o the DMF and HNO3 introduced by the c e l l u l o s e s o l u t i o n . Any unreacted N 0 i n the c e l l u l o s e s o l u t i o n would r e s u l t i n the formation o f a d d i t i o n a l H N 0 (or RONO) and H N 0 . Because o f the r a p i d i t y of c o a g u l a t i o n and r e g e n e r a t i o n o f the c e l l u l o s e from the N 0 s o l u t i o n s , b a s i c f i b e r p r o p e r t i e s a r e determined t o a l a r g e extent by the composition o f the regenerat i o n bath and the s p i n n i n g c o n d i t i o n s employed immediately d u r i n g and a f t e r e x t r u s i o n . Therefore, i n i t i a l j e t s t r e t c h i s important i n determining the o v e r a l l f i b e r p h y s i c a l p r o p e r t i e s . As regene r a t i o n i s r e t a r d e d , godet t o godet s t r e t c h becomes more import a n t and more e f f e c t i v e but i s s t i l l l i m i t e d by the i n i t i a l j e t s t r e t c h . For example, r e g e n e r a t i o n can be r e t a r d e d by the 2

4

2

2

4

2

3

2

4



4.

H A M M E R AND

43

Production of RdyOU

TURBAK

a d d i t i o n of bases such as p y r i d i n e to the c e l l u l o s e s o l u t i o n to n e u t r a l i z e the n i t r i c a c i d present. I n t h i s manner, a c e l l u l o s e n i t r i t e f i b e r can be obtained which i n i t i a l l y was observed to r e d i s s o l v e i n dimethylformamide. A wide range of s o l v e n t s may be used to regenerate the s o l u t i o n emerging from the s p i n n e r e t t e . V i r t u a l l y any l i q u i d which i s compatible w i t h and causes e x t r a c t i o n of the organic s o l v e n t and f u r t h e r d e - e s t e r i f i e s the c e l l u l o s e may be employed. A few of the s o l v e n t s which are a p p l i c a b l e to c o a g u l a t i o n i n c l u d e water, a wide range of a l c o h o l s , ethylene g l y c o l and mixtures of these or other p r o t i c s o l v e n t s w i t h dimethylformamide. In some cases, s p i n n i n g and the r e s u l t i n g f i b e r p h y s i c a l p r o p e r t i e s may be aided or improved by the presence of s o l u b l e s a l t s or bases i n the c o a g u l a t i o n bath. However, f o r such a process t o be commercially f e a s i b l e , such compositions would have to be balanced between f i b e r p r o p e r t i e s and the economy of the recovery and r e c y c l e process f o r the chemicals i n v o l v e d . By v a r y i n g the composition of the r e g e n e r a t i o n or s p i n b a t h , i t i s p o s s i b l e to o b t a i n a wide v a r i e t y of f i b e r p r o p e r t i e s , from those of r e g u l a r rayon s t a p l e to medium-high performance rayon. For example, use of lower molecular weight a l c o h o l s such as methanol or ethanol a f f o r d s f i b e r s w i t h good t e n s i l e p r o p e r t i e s i n c l u d i n g wet modulus. The a d d i t i o n of s o l u b l e bases to such régénérants appears to improve wet s t r e n g t h w h i l e lowering Sg.^ and water r e t e n t i o n v a l u e s . The S g ^ values are an i n d i c a t i o n of a regenerated c e l l u l o s i c f i b e r ' s s o l u b i l i t y i n 6 . 5 $ sodium hydroxide at 20°C. This i s a u s e f u l t e s t f o r determining the p o t e n t i a l r e s i s t a n c e of such f i b e r s or r e s u l t a n t f a b r i c s to a l k a l i n e t r e a t ment such as a l k a l i n e l a u n d e r i n g or m e r c e r i z a t i o n . A c c o r d i n g l y , r e g u l a r v i s c o s e rayon which cannot be mercerized and i s not r e s i s t a n t to a l k a l i n e washing, unless c r o s s l i n k e d , has a r e l a t i v e l y high of from 2 5 - 3 5 $ . On the other hand, the h i g h p e r f o r mance and p o l y n o s i c rayons have s u p e r i o r r e s i s t a n c e to c a u s t i c soda as evidenced by S g ^ values of from 5 - 1 5 $ . We have r e c e n t l y found that i n a d d i t i o n to u s i n g s o l u b l e bases i n the primary r e g e n e r a t i o n b a t h , that t h i s important f i b e r p r o p e r t y can be obtained by c a r e f u l c o n t r o l of the c o n d i t i o n s employed d u r i n g s o l u t i o n p r e p a r a t i o n j l e , the temperature during N 0 a d d i t i o n and the r e s u l t a n t time and temperature f o r t o t a l d i s s o l u t i o n . Our s t u d i e s have d e f i n i t e l y e s t a b l i s h e d t h a t N0 o x i d a t i o n should be minimized so t h a t low temperatures of N 0 a d d i t i o n (below 10°C f o r example w i t h DMF) and short d i s s o l u t i o n times (k hours at l e s s than 20°C) are mandatory i f S g ^ l e v e l s are to be maintained i n a reasonable range ( 1 0 - 3 0 $ ) f o r commerc i a l u s e f u l n e s s of the r e s u l t i n g rayon f i b e r s . I t should be noted f u r t h e r t h a t i n t h i s s p i n n i n g system i t i s r e a d i l y p o s s i b l e to o b t a i n f i b e r s w i t h h i g h wet modulus w i t h out the use of z i n c or other a d d i t i v e s which are r e q u i r e d i n a v i s c o s e s p i n n i n g o p e r a t i o n . In a d d i t i o n , f i b e r s w i t h v e r y f i n e deniers can be r e a d i l y produced, eg. 0 . 5 d e n i e r , w h i l e m a i n t a i n #

e

2

4

2

2

e


4

S O L V E N T SPUN R A Y O N , MODIFIED C E L L U L O S E FD3ERS


44

Figure 1.

Fiber cross sections resulting from various coaguhnts (430X)


4.

H A M M E R AND TURBAK

45

Production of Rayon

i n g reasonable t e n s i l e s t r e n g t h . Although optimum c o n d i t i o n s were not e s t a b l i s h e d , s u c c e s s f u l s p i n n i n g t r i a l s were e a s i l y performed at 115 meters/minute; f a s t e r speeds apparently being l i m i t e d o n l y by equipment and p o s s i b l y by l i q u i d f l o w c h a r a c t e r i s t i c s , but not by k i n e t i c s of r e g e n e r a t i o n . V a r i a t i o n s i n the type of régénérants r e s u l t s i n f i b e r s w i t h d i f f e r e n t c r o s s - s e c t i o n s . Water f o r example gives a s e r r a t e d , gear-shaped c r o s s - s e c t i o n ; methanol y i e l d s a c i r c u l a r c r o s s s e c t i o n ; isopropanol a f f o r d s i r r e g u l a r shapes; isoamyl a l c o h o l g i v e s a t r i l o b a l c r o s s - s e c t i o n ; b e n z y l a l c o h o l gives x-shaped s t r u c t u r e s and o c t a n o l a f f o r d s h o l l o w f i b e r s . S e v e r a l examples of these t y p i c a l c r o s s - s e c t i o n s obtained from c e l l u l o s e / N 0 / D M F s o l u t i o n s are i l l u s t r a t e d i n F i g u r e s 1 and 2 along w i t h those of F i b e r kO and r e g u l a r rayon. S i m i l a r f i b e r c r o s s - s e c t i o n s r e s u l t from c e l l u l o s e / ( N 0 ) / D M S O s o l u t i o n s . Even the type of h o l l o w f i l a m e n t s obtained from an o c t a n o l r e g e n e r a t i o n bath appears to be c o n t r o l l a b l e . Filaments w i t h segments resembling bamboo are o b t a i n a b l e as w e l l as those w i t h v a r i o u s lengths of h o l l o w lumens i n the center of the f i b e r . The frequency of the segmentation appears c o n t r o l l a b l e , w i t h segments occurring 5 P i n c h or 25 per i n c h depending upon the combinat i o n of c o n d i t i o n s employed. In Figure h s t r e s s - s t r a i n curves [^conditioned ( c ) and wet f o r an a l k a l i n e methanol-spun f i b e r are shown f o r comparison w i t h r e g u l a r and high-wet modulus rayon. The shape of the wet curve i s of p a r t i c u l a r importance s i n c e the y i e l d i n g p o r t i o n s i s d i f f e r e n t from that of other rayons. Low e l o n g a t i o n i n the f i b e r r e s u l t s i n the steep slope of the c o n d i t i o n e d s t r e s s - s t r a i n curve f o r these f i b e r s and i s an i n d i c a t i o n of s t i f f n e s s . I f the cond i t i o n e d e l o n g a t i o n could be increased to 1 0 - 1 2 $ or the slope manipulated to f a l l between t h a t of high-wet modulus rayon and c o t t o n f o r example, a s u p e r i o r c e l l u l o s e f i b e r may be o b t a i n a b l e . In f a c t , e l o n g a t i o n s approaching 10$ were observed f o r f i b e r s spun from p y r i d i n e - s t a b i l i z e d c e l l u l o s e / N 0 / D M F s o l u t i o n and from runs employing low j e t s t r e t c h . Some t y p i c a l p h y s i c a l p r o p e r t y data are shown i n Table I emp l o y i n g a v a r i e t y of primary bath coagulants f o r the p r o d u c t i o n of rayon f i b e r s from s p i n n i n g s o l u t i o n s of 8/I5/77 c e l l u l o s e / N 0 / D M F composition. The wide range of p r o p e r t i e s obtained by v a r y i n g the chemical composition of the r e g e n e r a t i o n bath a f f o r d s an a p p r e c i a t i o n of the v e r s a t i l i t y of the system. Some p h y s i c a l property data are shown i n Table I I comparing some commercial rayons w i t h those produced from s p i n n i n g 8/15/77 c e l l u l o s e / N 0 / D M F s o l u t i o n s i n t o an isopropanol primary regenera t i o n bath.


2

2

4

4

e r

2

4

2

2

4


4

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

CELLULOSE

FIBERS


46

Figure 2. Fiber cross sections resulting from various coagulants compared to viscose rayon (430X)


Production of RdiJOn



Figure S. Segmented hollow fiber IC

j i /

STRESS-STRAIN CURVES

I

N 0 /DMF

1

/ / / // // // //

2

4

R E G . RAYON

r

COM.HWM

t

\\ A If• / «

w 1

Ο

/

/

/

' W

•

f

10

20 30 E L O N G A T I O N (%)

Figure 4. Stress-strain curves of regular rayon, commercial high wet modulus rayon and rayon produced by régénérâting cellulose-N 0 -DMF solutions from alkaline methanol t

4

American Chemical Society Library 1155 16th St. N. W. Turbak; Solvent Spun Rayon, Modified Cellulose Fibers and Derivatives Washington, D. C. Society: 20036Washington, DC, 1977. ACS Symposium Series; American Chemical


13.2

9Λ

I.30 I.23 I.51

2.hk 2.29 2Λ8

3.^7 3.29

3.5

1.6

1.25

0.87

1.8

Water

Octanol

Methanol/1.5$ A l k o x i d e

Isopropanol/l.5$ Alkoxide

Methanol/10$ A l k o x i d e

1.90

2.13

11.7

1.U6

3.55

0.81

Methanol

8Λ

6-3

6.7

13.0

11.9

18.9

19.9

15.5

13.5

12.9

6.7

O.80

Isopropanol

2.26

3.58

Denier

Coagulant

Elongation, $ Cond. Wet

4

T e n a c i t y , g/d Cond. Wet

2

PROPERTIES OF FIBERS PREPARED FROM AN 8/I5/77 CELLULOSE/N 0 /DMF SOLUTION

TABLE I


1.19

0.98

0Λ9

0.37

0.51

0.73

0.8U

Wet Modulus,

I

i

Ο


3.5-8.Ο

2.0-3.6

High Wet Modulus Rayon

8/15/77 C e l l u l o s e / N 0 /DMF F i b e r

4

3.5-5.0

Intermediate Wet Modulus Rayon

2

1.5-2.8

1.5-2Λ

2.5-6.0

2.5-3.5

1.0-1.8

T e n a c i t y , g/d Cond. Wet

Regular Rayon

Staple Type

6-19

6-ik

12-19

lU-25

10-15

9-18

18-2U

18-35

Elongation, $ Cond. Wet

FIBER PHYSICAL PROPERTIES

TABLE I I

0.7-1.7

0.7-3.0

ΟΛ5-Ο.60

0.18-0.28

&M

Wet Modulus


20-80

5-10

15-20

20-35

50

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

Conclusions A wide range of pulps have been found t o r e a d i l y d i s s o l v e i n the N 0 /DMF system i n c l u d i n g non-debarked experimental samples. However, groundwood f u r n i s h , such as i s employed f o r news p r i n t w i l l not d i s s o l v e i n t h i s system. The pulps may be used i n e i t h e r a f l u f f e d , Abbe^cut, shredded or d i c e d sheet form without encountering d i s s o l u t i o n problems. The c o n c e n t r a t i o n of pulp which can be used depends upon the degree of p o l y m e r i z a t i o n . At 1000 D.P., c o n c e n t r a t i o n s up to 3$ can be spun w h i l e a t U00~500 D.P. up t o 8$ s o l u t i o n s were f e a s i b l e , w h i l e a t 300 D.P. up t o 10$ c e l l u l o s e s o l u t i o n s could be r e a d i l y processed. Dimethyl formamide was found t o be p r e f e r a b l e to d i m e t h y l s u l f o x i d e or a c e t o n i t r i l e as the s o l v e n t system based upon overa l l s o l u t i o n p r o p e r t i e s . The DMF/N 0 s o l u t i o n s were c l e a r and e s s e n t i a l l y f r e e from g e l s or f i b e r s t h e r e f o r e r e q u i r i n g o n l y a s i n g l e stage p o l i s h i n g f i l t r a t i o n p r i o r t o s p i n n i n g . The temperature of the N 0 a d d i t i o n and the time of d i s s o l u t i o n were found t o be c r i t i c a l l y r e l a t e d t o the f i n a l Sg c f i b e r l e v e l s . For example, by m a i n t a i n i n g the temperature below 20°C, the S6.5 l e v e l can be h e l d i n the 2 7 - 3 0 $ range which i s s i m i l a r t o t h a t of r e g u l a r rayon. C o a g u l a t i o n and r e g e n e r a t i o n of the c e l l u l o s e / N 0 / D M F s o l u t i o n s i s extremely r a p i d i n the presence of proton donor systems. F i b e r s of e x c e l l e n t h i g h wet modulus eg. up to 1 . 7 g/d can be spun w i t h o u t the need f o r s p i n - b a t h a d d i t i v e s . Spinning speeds of 115 meters per minute were achieved employing o n l y a 3 i n c h primary bath c o a g u l a t i o n t r a v e l l e n g t h . No attempts were made t o o p t i m i z e f i b e r p h y s i c a l p r o p e r t i e s a t t h i s h i g h e r s p i n n i n g speed, which was the maximum speed o b t a i n a b l e and was l i m i t e d by the godet s i z e and motor d r i v e u n i t s . Conditioned f i b e r s t r e t c h g e n e r a l l y was between 7 $ and 10$ which i s n o r m a l l y too low f o r p r o c e s s i n g . However, t h i s l e v e l c o u l d be improved by proper c o n t r o l of j e t s t r e t c h t o godet s t r e t c h r a t i o s . F i b e r cross s e c t i o n a l shapes can be c o n t r o l l e d by the use of v a r i o u s molecular weight a l c o h o l s t o g i v e e i t h e r round, s e r r a t e d , "X" or "Y" shapes or even segmented h o l l o w f i b e r s . These f i b e r s d i s p l a y e x c e l l e n t cover power as compared to r e g u l a r HWM rayon i n k n i t s .


2

4

2

2

4

4

2

4

Acknowledgements We are g r a t e f u l t o Dr. A r t h u r C. West* who performed much of the i n i t i a l b a s i c r e s e a r c h and e x p e r i m e n t a t i o n i n v o l v e d i n this investigation. * Present Address - 3-M Company, S t . P a u l , Minnesota


4.


Literature

Cited

1.

Fowler, W. F. and Kenyon, W. O., J. Amer. Chem. Soc., 69

2. 3.

W i l l i a m s , H. D., U.S. Patent No. 3 , 2 3 6 , 6 6 9 ( 1 9 6 6 ) . H e r g e r t , H. L. and Z o p o l i s , P. N., French Patent No.

4.

a)

5. Downloaded by CORNELL UNIV on September 26, 2016 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0058.ch004

51

Production of Rayon

6.

1636

(1947).

1,469,890

(1967).

Nakao, O. et. al Canadian Patent No. 8 7 6 , 1 4 8

b ) U.S. Patent No. 3 , 6 6 9 , 9 1 6

(1971),

(1972).

Clermont, L. P., (a) Canadian Patent No. 8 9 9 , 5 5 9 ( 1 9 7 2 ) ; (b) Monthly Research Notes, Dept. o f F i s h e r y and F o r e s t r y , Canada 2 6 , No. 6, 58 (1970); ( c )J.P o l y . Sci., 1 0 , 1669 ( 1 9 7 2 ) ; (d) J. Appl. Poly. Sci., 1 8 , 133 (1974). Schweiger, R. G., (a) Chemistry and Industry 296 ( 1 9 6 9 ) ; (b) U.S. Patent No. 3 , 7 0 2 , 8 4 3 ( 1 9 7 2 ) ; (c) German Patent No.

2,120,964 (1971).

7. 8. 9·

Chu, Ν. J., Pulp and Paper Research I n s t i t u t e o f Canada, Report No. 42 ( 1 9 7 0 ) . Pasteka, M. and M i s l o v i c o v a , D., C e l l u l o s e Chemistry and Technology 8 , 107 (1974). Portnoy, Ν. Α., Unpublished R e s u l t s .


4

Recommend Documents