Prospects and Potential for Commercial Production and Utilization of

12 Prospects and Potential for Commercial Production and Utilization of Sucrose Fatty Acid Esters

Downloaded by TUFTS UNIV on October 14, 2014 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0041.ch012

EDWARD G. BOBALEK University of Maine, Orono, Maine 04473

The s t a g e w a s C a s e I n s t i t u t e o f T e c h n o l o g y b e c a u s e i t has very c l o s e r e l a t i o n s t o t h e surface coatings i n dustry; thetime t h e m i d d l e 1950's ; t h e a u t h o r , D r . H e n r y B. H a s s , a g r a n d p r o v o c a t e u r , a n d D r . J o h n L . Hickson, prompter and i n t e r p r e t o r , both o f t h e Sugar R e s e a r c h F o u n a t i o n ; t h e p l o t "what c a n b e done w i t h sugar e s t e r s , e s p e c i a l l y o i l - f a t t y a c i d e s t e r s , u s i n g t h e o i l a c i d s t h a t commonly o c c u r i n s o f t , s e m i - o r hard d r y i n g o i l s ? " . The p l a y e r s i n t h e c a s t i n c l u d e d m y s e l f , D r . Thomas J . Walsh i nChemical E n g i n e e r i n g , and s e v e r a l graduate s t u d e n t s who b r o k e t h e i r t e e t h o n t h e b i t o f s u g a r c h e m i s t r y , p a r t i c u l a r l y D r s . M.T. C h i a n g a n d C.C. L e e , W.J. C o l l i n g s , A l f r e d o C a u s a , A l f r e d o d e M e n d o z a a n d George Kapo. Much o f t h e c o n t r i b u t i o n o f t h e w o r k w h i c h e n s u e d r e a l l y comes f r o m t h e i r e f f o r t s a n d t h e i r a p t i t u d e s a s t h e y grew i n t h i s s c i e n c e . At that p e c u l i a r time, t h ecoatings i n d u s t r y , p a r t i c u l a r l y i n i t s v e h i c l e a s p e c t s , w a s l e s s t h a n 10 y e a r s away f r o m t h e o p e n - f i r e d , v a r n i s h k e t t l e s . I t was s u b s t a n t i a l l y b a s e d o n n a t u r a l d r y i n g o i l s . I t was i n a f e r m e n t o f r e v o l u t i o n t r y i n g t o c o p e w i t h t h e problems o f m a t e r i a l shortages. As i n a l l c o n s e r v a t i v e i n d u s t r i e s , t h e a p p r o a c h t o c o p i n g i s t h e same. That i s , a request t o supply something t h a t i s remarka b l e , b u t t h a t does n o t f o r c e changes which are n o t absolutely necessary. The g o a l s w e r e s i m p l e . That i s , n o t t o begin a t t h e b e g i n n i n g , b u t t o s t u d y what m i g h t be found i n e s t a b l i s h e d markets. T a b l e I i n d i c a t e s some o f t h e p r i m itive targets. f

162

In Sucrochemistry; Hickson, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

12.

BOBALEK

Sucrose Fatty Acid Esters

Table I , P o s s i b l e Sucrose Ester 1. 2. 3.


4.

163

Applications

Printing inks. Wood S e a l e r s Varnishes andPaint V e h i c l e s Oleoresinous Blends Diisocyanate Modifications Emulsion Vehicles

D r y i n g o i l s and d r y i n g o i l p r o d u c t s a l r e a d y were c r i t i cal i nthese p a r t i c u l a r u t i l i z a t i o n s . They r e p r e s e n t ed, a t t h a t t i m e , a l a r g e segment o f t h e consumer p r o ducts market. T h i s r e g i o n a l s o was i n a f e r m e n t o f development. T h e c h e m i c a l p r o c e s s i n d u s t r y h a d come o u t o f W o r l d War I I w i t h a c a p a b i l i t y f o r a m u l t i t u d e of b y - p r o d u c t s f o r w h i c h i t h a d no market. The most r e c e p t i v e domain where t h e y c o u l d g e t a f r i e n d l y t e s t i n g a n d be a c c e p t e d , i f p o s s i b l e , was t h o u g h t t o be i n the p a i n t , v a r n i s h , p r i n t i n g i n k s and r e l a t e d industries. Figure 1 gives something o f t h e scenario.

Figure 1



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SUCROCHEMISTRY

At t h a t time the D i v i s i o n of P a i n t , V a r n i s h , P r i n t i n g i n k s and P l a s t i c s p r o b a b l y e n r o l l e d a b o u t 15-20 percent of the American Chemical S o c i e t y d i r e c t l y or i n d i r e c t l y a f f i l i a t e d as p r o v i d e r s o f t h e f i n a l p r o ducts, or vendors of intermediates. In a d d i t i o n , a b o u t 80 p e r c e n t o f t h e m w e r e s h o w i n g up a t t h e n a t i o n a l meetings. The p o i n t t o be made i s t h a t t h e S u g a r R e s e a r c h F o u n d a t i o n had h o u s e d i t s e l f m a i n l y i n t h e b a s e o f t h e pyramid, i n basic organic chemistry. Much o f t h e work i t h a d b e e n s u p p o r t i n g h a d b e e n down i n t h i s d o m a i n . W h e r e t h e y w a n t e d t o g e t was up i n t h e m a r k e t s a t t h e peak of the p y r a m i d . A t t h a t t i m e i n p a r t i c u l a r , and s t i l l t o d a y , t h e r e was a l o t o f b r i l l i a n t r e s e a r c h i n t h e t e c h n o l o g y of the products mentioned. B u t , t h e k e y f i g u r e was the " f o r m u l a t o r " , who c o n s t i t u t e d t h e i m a g e o f t h e c o m p a n y making the p l a s t i c s , p r i n t i n g i n k s , p a i n t s , e t c . The formulator o c c a s i o n a l l y could transcend the research to s o l i d i f y an i n v e n t i o n . Needless to mention very litt l e r e s e a r c h from s a t e l l i t e s u p p l i e r s or the users could enter the system except through h i s c o o r d i n a t i n g position. I f s o m e t h i n g was g o i n g t o be p r o o f - t e s t e d and b r o u g h t f r o m t h e r e s e a r c h b a s e up t o t h e p r o d u c t i o n p e a k , i t w o u l d h a v e t o go t h r o u g h t h e formulator i n s u c h a c o n d i t i o n t h a t he c o u l d a d a p t i t q u i c k l y w i t h a m i n i m u m o f p a i n , make h i s e v a l u a t i o n a n d , h o p e f u l l y , p u s h i t f u r t h e r up t h e p y r a m i d . The d o m a i n t h a t C a s e was s u p p o s e d t o t a k e c a r e o f was t o e s c o r t some e s t e r s f r o m b a s i c r e s e a r c h t o t h e s e c o n d s t a g e , by a p p l y i n g i n d u s t r i a l p r o c e s s c h e m i s t r y . F i g u r e 2, p r e s e n t s o u r t a r g e t . Structure

of

Hexalinoleate Ester of

Sucrose.

H C-0-C-(CH )7-CH=CH-CH2-CH=CH-(CH )^-CH 2

2

2

3

0 -C-R

H

Reaction C

| 2

0„H

Stoichiometry 2 2

R-C-0 ii 0

OH

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Figure 2



12.

BOBALEK


165

T h e r e was r e l a t i v e l y l i t t l e u s e f u l s u c r o c h e m i c a l l i t e r a t u r e t o go on a t t h a t time. The c h e m i c a l l i t e r a t u r e i t s e l f was e x t e n s i v e , b u t n o t t o o a d a p t a b l e t o the l i m i t e d s k i l l s o f chemical engineers. The o n l y s u g a r e s t e r p r o c e s s t h a t we r e a l l y c o u l d g e t o f f t h e b e n c h w a s t h e t r a n s e s t e r i f i c a t i o n p r o c e s s i n a homogeneous s o l v e n t medium, w h i c h t h e n was i n a p e n d i n g p a t e n t by Dr. Hass a n d Dr. L l o y d Osipow. We came c l o s e s t , a c t u a l l y , t o accomplishing t h egoal w i t h t h i s p a r t i c u lar reaction. We d o n o t c l a i m t h a t t h i s r e a c t i o n , a s f i r s t s t u d i e d , w i l l t u r n o u t t o be t h e u l t i m a t e , t h e b e s t , a n d t h e f i n a l one. S i n c e t h a t t i m e , an e x t e n s i v e monograph h a s been p u t t o g e t h e r on t h e p a t e n t l i t e r a t u r e e m e r g i n g s i n c e t h e m i d - ' 5 0 s w h i c h g i v e s many alternatives. We h a v e l e a r n e d , o n e c a n g e t away f r o m solvents by going through heterophase p o l y m e r i z a t i o n , mass t r a n s f e r e x c h a n g e s b e t w e e n p h a s e s , u s e o f d i f f e r ent kinds o f s o l v e n t s , s o l i d suspensions, l i q u i d media, etc. Y e t those i n v o l v e d p r o c e d u r e s , i n s o f a r a s I have b e e n a b l e t o d e t e r m i n e , a n d t h e r e h a s b e e n n o new d i s c l o s u r e i n t h i s Symposium, have never been p u t t o t h e c r i t i c a l t e s t by t h e chemical e n g i n e e r s , even on a bench s c a l e . Figure 2 i l l u s t r a t e s t h ep o i n t . Before the react i o n s e l e c t e d c o u l d g e t o f f t h e b e n c h , i t was n e c e s s a r y to c l o s e the m a t e r i a l balance. T h i s means t h a t r e p e t i t i v e l y , i n a t l e a s t a dozen t r i e s , one measures t h e p e r c e n t a g e s coming o u t i n t h ep r o d u c t s , what i s g o i n g up t h e s t a c k , a n d w h a t i s b e i n g d i s c a r d e d i n t a r s , a n d whether t h i s d i s t r i b u t i o n i s c o n s i s t e n t . The f i r s t r e p o r t e d o b j e c t i v e t h e n w a s t h a t we s h o u l d come c l o s e t o m a k i n g a c o n s i s t e n t m a t e r i a l b a l ance a t a l a b o r a t o r y bench. This i s a precursor step on t h e way t o a p i l o t p l a n t . I w i l l summarize h a s t i l y some o f t h e n e c e s s a r y , e v e n i f n o t e n t i r e l y s u f f i c i e n t , conditions. F i r s t , t h e system has t o be v e r y anhydrous, thus a feed stock preparation i s e s s e n t i a l . Secondly, one must a c h i e v e a t o t a l l y homogeneous r e a c t i o n . The c a t a l y s t must be i n s o l u t i o n o r seeming so. The sugar must be t o t a l l y i n s o l u t i o n . A l l o f theintermediate prod u c t s and f i n a l p r o d u c t s must remain i n s o l u t i o n . I f t h e y do n o t , one r u n s i n t o t r o u b l e s w i t h r e a c t o r p r o blems. A l l r e a c t o r s foam, s p a t t e r , m i s t a n d s o f o r t h . They have h o t zones a n d c o l d zones, c r y s t a l l i z a t i o n areas and c h a r i n g areas. Maintaining beneficial color and a v o i d i n g b y - p r o d u c t s u s u a l l y i s v e r y d i f f i c u l t i f one m u s t t r y t o m a n i p u l a t e h e t e r o p h a s e , s u s p e n s i o n r e actions. One demand i s t h a t t h e r e b e n o p r e p e r o x i d a t i o n o r o x i d a t i o n o f the methyl e s t e r s . However,



166

SUCBOCHEMISTRY

t h e r e were t e c h n i q u e s o f s t o c k p r e p a r a t i o n w h i c h n e g a t e d any o x i d a t i o n t h a t h a d o c c u r r e d . One w a n t s a l s o a s o l v e n t w h i c h , i n a d d i t i o n t o b e i n g a good s o l v e n t f o r t h e w h o l e r e a c t i o n s y s t e m , has a n i c e c l e a v a g e p o s s i b i l i t y under d i s t i l l a t i o n c o n d i t i o n s f o r methanol. T h e r e was some t i m e b e f o r e t h e s o p h i s t i c a t e d s o l u b i l i t y p a r a m e t e r c o n c e p t s e m e r g e d , s o t h a t t h e r e was much t r i a l and e r r o r . A g o o d d e a l m o r e c a n be d o n e now on a scientific basis. The r e a c t i o n r a t e h a s t o be b r o u g h t t o r e a s o n a b l e l e v e l s , h o p e f u l l y t o be a c h i e v e d i n 3-4 h . Obviously, t h i s m e a n t t h a t t h e m e t h y l e s t e r s h a d t o be i n s u r p l u s . S o m e t i m e s a t a r a t i o a s h i g h a s 4, 6, o r e v e n 8 t o 1 d e p e n d i n g on w h a t s p e e d i s w a n t e d i n o r d e r t o p r o d u c e the d e s i r e d higher e s t e r s . T h a t p u t demands on an e x t r a c t i o n , s e p a r a t i o n and r e c y l e p r o c e s s . The one i n h e r i t e d from the Hass-Osipow p a t e n t , a s i l i c a g e l a b s o r p t i o n t e c h n i c , was n o t s u i t a b l e b e c a u s e o f i t s i n c o n v e n i e n c e and t h e r e s u l t i n g s i d e r e a c t i o n s w h i c h n u l l i f i e d some o f t h e b e n e f i t s a t t a i n a b l e b y c a r e i n managing the r e a c t i o n . F o r t u n a t e l y , i t was f o u n d t h a t t h e s p e c t r u m o f sucrose e s t e r s d i f f e r e d q u i t e sharply i n t h e i r temperature c o e f f i c i e n t s of s o l u b i l i t y i n methanol. A simple methanol e x t r a c t i o n at v a r i e d temperatures could e f f e c t r e a s o n a b l y good f r a c t i o n a t i o n s w i t h o u t d e g r a d i n g t h e product. L a s t , b u t n o t l e a s t , t h e r e c o u l d be t r a n s l a t e d a c l o s e d m a t e r i a l balance from the bench t o the p i l o t p l a n t where c h e m i c a l a n a l y s e s of the p r o g r e s s of the r e a c t i o n seemed t o c o i n c i d e w i t h t h e y i e l d s o f t h e methanol s t r i p p e d o f f . I f one p r o c e e d e d a t l o w e n o u g h t e m p e r a t u r e s , a t h i g h e n o u g h r a t e s , one c o u l d m i n i m i z e decomposition of the s o l v e n t . T h i s was a b e t t e d p a r t i c u l a r l y by s p a r g i n g an i n e r t a t m o s p h e r e u n d e r r e d u c e d pressures. The r e a c t o r s y s t e m i s shown i n F i g u r e 3. The p r o c e s s s t a r t s w i t h a s t i r r e d tank r e a c t o r w i t h a good r e f l e x c o n d e n s e r and a good s t r i p p i n g s t i l l f o r t h e methanol. The d i s c h a r g e w o u l d go i n t o a s t i l l f o r s t r i p p i n g o f f t h e DMF. The D M F - f r e e r e a c t i o n m i x , h i g h i n m e t h y l e s t e r s w o u l d go o v e r t o a s o l v e n t e x t r a c t i o n column. E a c h e x t r a c t , t h e n w o u l d be p u r g e d a g a i n o f m e t h a n o l , and s e n t b a c k f o r r e c y c l e t h r o u g h t h e system. Figure 4 i n d i c a t e s something of the complexity of t h e e x t r a c t i o n s y s t e m , w h i c h t h e n was t h o u g h t t o be a complex t h i n g . B u t , i t was v e r y p r i m i t i v e c o m p a r e d t o modern t e c h n o l o g y as i t has emerged i n t h e p e t r o l e u m industry.



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Figure 3

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Now i t b e c o m e s n e c e s s a r y t o d e v e l o p t h e a m m u n i t i o n t o c o r n e r t h e f o r m u l a t o r a n d show h i m t h a t u s e o f t h e new v e h i c l e w o u l d l e a d t o r e l a t i v e l y f e w h a z a r d s when a p p l i e d i n t h e p r a c t i c e s , a s he c o u l d u n d e r s t a n d them, t o c o n v e r t t h i s i n t e r m e d i a t e i n t o some o f h i s r e g u l a r coatings products. Some o f t h e s e d a t a a r e t a b u l a t e d in Table I I , which a l s o i l l u s t r a t e s a f a i l u r e . The t a r g e t , h a d b e e n a d e g r e e o f e s t e r i f i c a t i o n (D.E.) o f 8 or close t o i t . I t n e v e r was a c h i e v e d ; t h e h i g h e s t l e v e l achieved under t h ebest c o n d i t i o n s , keeping w i t h i n t h e r e s t r i c t i o n s o f p l a n n e d p r a c t i c a l i t y , was a b o u t 7.5 D.E. F o r t u n a t e l y , i t was d i s c o v e r e d t h a t , t o g e t a d e q u a t e d r y i n g o i l p r o d u c t s , s u c h a h i g h DE i s unnecessary. A n a p p r o x i m a t e 5.5 D.E. was a d e q u a t e . Any f u r t h e r g a i n i n D.E. i n t e r m s o f c o a t i n g s b e n e f i t s a t t a i n e d , was n o t t h a t g r e a t . P o s s i b l y t h i s was b e c a u s e t h e D.E. b e g a n t o b e o v e r w h e l m e d b y t h e i o d i n e v a l u e (the degree o f u n s a t u r a t i o n ) o f t h e f a t t y a c i d s chosen. Table I I . EFFECT

OF

DEGREE

OF

E S T E R IFI CAT ION

ON DEGREE

OF

ESTERIFICATION

IODINE

DRYING DRY TO

VALUE

ANO

IODINE

VALUE

RATE

TOUCH(HR)

DRIED

HARD(HR)

TACK FREE(HR)

6.1

19 I

2

S

10

6.1

175

2

10

14

6.1

148

3

16

20

6.3

152

3

14

20

6.1

I 48

3

16

2 0

3

16

22

5.6 FILM

»53 THICKNESS - I MIL -

CAST

ON T I N AT 100 % S O L I D S

I n t h i s l i g h t , t h e g o a l o f a D.E. o f 8, w h i c h may be i m p o r t a n t f o r some e s t e r s , was a b a n d o n e d f o r t h e drying o i l s . As a m a t t e r o f f a c t , t h e r e e v o l v e d l a t e r r e a s o n s t o b e l i e v e t h a t some r e s i d u a l h y d r o x y l f u n c t i o n a l i t y i s a n i m p o r t a n t a d v a n t a g e t o t h e s e p r o d u c t s , when used i nc o n v e n t i o n a l d r y i n g o i l type a p p l i c a t i o n s . Table I I I b r i e f l y places t h e s i t u a t i o n i n t o a context o f where t h e s u c r o s e e s t e r s s t a n d compared t o t h e conventional products. These a r e t h e p h y s i c a l p r o p e r t i e s of t h e f i l m s . G e n e r a l l y , t h e h i g h e r t h e number, t h e


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169

better i sthe property, except f o r drying rates. The d a t a compared here a r e f o r a s u c r o s e h e x a l i n o l e a t e ; a s u c r o s e e s t e r made b y t h e m o s t a d v a n c e d t e c h n i q u e s o f the time, u s i n g e n t i r e l y t h e methyl e s t e r f r a c t i o n from t a l l o i l t h a t c o r r e s p o n d e d i n i o d i n e number t o p u r e l i n o l e i c a c i d , b u t i t was n o t p u r e l i n o l e i c a c i d . Table I I I . COMPARISON


PROPERTY TENSILE

OF

FILM

PROPERTIES

LONG OIL ALKYD RESIN

STRENGTH (PSI)

SUCROSE HEXALINOLEATE

1450

LINSEED OIL

730

180

80

95

ELONGATION (%)

1 1 0

MICROKNIFE

HARDNESS

3 50

325

27 5

MICROKNIFE

ADHESION

J 76

1 64

166

0.8 1 .0 3.0

1 .0 1 .5 2 .0

1. 5 2 .5 4. 0

DRY 1 NG ( HR S) - 40 V . SOLIDS DRY TO TOUCH DRIED HARO TACK FREE I V . ALKALI

RESISTANCE

BLISTER - 3 HR

BLI S TER - 2 HR

FAIL-IOMIN

One c a n n o t i c e t h a t t h e s u g a r e s t e r i s c l o s e r i n properties t o the architectural,long o i l alkyds,at that t i m e , t h e most commonly u s e d e x t e r i o r p a i n t s i n h a r d f i n i s h e s , t h a n t o l i n s e e d o i l i t s e l f , w h i c h w a s t h e common h o u s e p a i n t b a s e . However, i n most f l u i d i t y p r o p e r t i e s and otherwise, i t resembled a l i n s e e d o i l . So one c o n c l u d e s t h e h e x a l i n o l e a t e l o o k s e s s e n t i a l l y a t tractive. Table IV. OIL

ABSORPTION

RATIO

PIGMENT

DIOXIDE

PHTHALOCYANINE MILORI

BLUE

TOLUIOINE LAMPBLACK

VARIOUS

OIL ABSORPTION SUCROSE

TITANIUM

FOR

RED

GREEN

HEXALINOLEATE

PIGMENTS

RATIO / LINSEED

0.37 0.8 I I .0 8 0.80 0.9 3


OIL


170

SUCROCHEMISTRY

T a b l e IV i l l u s t r a t e s a f e a t u r e t h a t perhaps i s the most i m p o r t a n t p r o p e r t y of a l l . I t t e n d s t o be i g n o r e d m o s t o f t e n b y p e o p l e who h a v e n o t h a d t o l i v e w i t h f o r m u l a t o r s o f compounded p r o d u c t s . These m a t e r i a l s h a v e t o be b l e n d e d w i t h a v a r i e t y o f m i n e r a l s , p i g m e n t s , f i l l e r s , and a d d i t i v e s o f a l l s o r t s . U s u a l l y the i n dex o f q u a l i t y i s t h e minimum amount o f o i l t h a t c a n disperse, or turn i n t o putty, a standardized quantity of pigment. This i s t r u e across the whole spectrum of such formulated products from p r i n t i n g i n k s to mastics. I n o n l y one i n s t a n c e , w i t h one p i g m e n t , M i l o r i b l u e , w h i c h p e o p l e who know t h e a r t r e c o g n i z e a s a v e r y miserable customer, d i d the sucrose e s t e r appear a l i t t l e worse than l i n s e e d o i l . I n most c a s e s , i t t o o k l e s s of the sucrose e s t e r t o e f f e c t t h i s compositing t h a n o f t h e l i n s e e d o i l , t h e common g r i n d i n g m e d i u m f o r these d i s p e r s i o n s . These t a b l e s summarize o n l y the main p o i n t s . T h e r e a r e w e a t h e r i n g a n d many o t h e r t e s t s t h a t show t h e sucrose esters i n general are equal or superior to t r a d i t i o n a l oleoresinous v e h i c l e s with which sucrose e s t e r s hoped most t o compete. A m i d s t t h e c o u r s e o f t h i s w o r k an u n u s u a l o b s e r v a t i o n was made d u r i n g some p r e c i s i o n s t u d i e s o n o x y g e n absorption (Figure 5). Those f a m i l i a r w i t h d r y i n g o i l s c i e n c e know t h a t many s i d e r e a c t i o n s o c c u r i n t h e h a r d e n i n g o f an o i l i n a n o x i d i z i n g e n v i r o n m e n t . Some o f t h e r e a c t i o n s add o x y g e n , u t i l i z i n g i t i n e f f e c t t o p o l y m e r i z e t h e o i l , o t h e r s decompose t h e o i l . There a l w a y s a r e w e i g h t l o s s e s b e i n g o f f s e t by w e i g h t g a i n s and t h e r e a l i n d e x o f q u a l i t y i s t h e n e t c h a n g e .

-I

o

2

3

4

5

6

7

TIME (HOURS)

Figure 5.

Oxidation rate of sucrose heptalinoleate vs. bodied linseed oil



12.

BOBALEK


171

N e a r l y a l w a y s t h e s u c r o s e e s t e r s , a t D.E.'s o f 5 o r b e t t e r seem t o h a v e a u n i q u e b e h a v i o r , e v e n a t comparable iodine values. I t seemed t h a t t h e y p e r o x i d i z ed and g a i n e d w e i g h t w i t h m i n i m a l d e c o m p o s i t i o n , comp a r e d t o most n a t u r a l o i l s . W h e t h e r t h i s was a c o n d i t i o n e n t i r e l y due t o t h e g r e a t e r p u r i t y o f t h i s e s t e r c o m p a r e d t o n a t u r a l o i l s , o r w h e t h e r some f e a t u r e s o f s t r u c t u r a l c h e m i s t r y were i n v o l v e d i n i t , must be l e f t to f u t u r e i n v e s t i g a t o r s . T h i s o b s e r v a t i o n d i d promote g r e a t i n t e r e s t . Two b i g c o m p e t i t i v e systems a t t h a t t i m e were e s s e n t i a l l y , vinylated oleoresinous materials, l i k e styrenated a l kyds and o i l s , and t h e emerging, e m u l s i o n v e h i c l e s l i k e SBR l a t i c e s . The s u c r o s e e s t e r s c o u l d b e o x y g e n a t e d a n d t h e oxygenated p r o d u c t s were e s s e n t i a l l y s t a b l e p e r o x i d e s . The p e r o x i d e s w e r e s t a b l e e v e n i f d i s p e r s e d i n w a t e r a n d c o u l d b e d i s p e r s e d w i t h t h e h e l p o f t h e i r own, l o w er esters. One c o u l d p o l y m e r i z e t h e m w i t h s t y r e n e , styrene-butadiene, or v i n y l acetate. We d i d n o t t r y hard t o a c h i e v e a l l t h e p o s s i b i l i t i e s , b u t t h e r e were some i n d i c a t i o n s t h a t t h r o u g h t h i s p o s t - o x i d a t i o n r o u t e ,

Figure 6.

Flow sheet from process to products


172

SUCROCHEMISTRY

t h e s u c r o s e e s t e r s c o u l d be e n t e r e d d i r e c t l y e i t h e r i n to styrenated solvent resins(which dry i n seconds,or i n m i n u t e s , compared t o h o u r s — r e a l l y s p e c i a l k i n d s of l a tex) or even i n t o emulsion t e c h n o l o g i e s . F i g u r e 6 i s a summary o f w h e r e t h e s t u d y seems t o h a v e l e f t t h e p r o s p e c t s i n a b o u t 1960. A p r o c e s s was d e s i r e d t h a t was c l e a n , e n v i r o n m e n t a l l y c l o s e d , and w h i c h c o u l d be o p e r a t e d i n c o m m o d i t y q u a n t i t i e s , t o provide v a r i o u s degrees of e s t e r i f i c a t i o n of the sucrose esters. These were the o u t l e t s t h a t were t e s t e d and p r o v e n f e a s i b l e t o some d e g r e e , b u t f o r w h i c h t h e r e was no e x t e n s i v e d e v e l o p m e n t t o p l a n t processes. I t was b e l i e v e d t h a t t h e p r o c e s s w o u l d r e q u i r e such heavy c a p i t a l investment i n whatever p l a n t was n e c e s s a r y , t h a t i t w o u l d h a v e t o make l a r g e v o l u m e s o f p r o d u c t s , and s h o u l d be f l e x i b l e e n o u g h t o p r o d u c e t h e v a r i e t y o f p r o d u c t l i n e s t h a t , a t t h a t t i m e , were emerging i n competition w i t h the n a t u r a l products. T a b l e V l i s t s t h e o b v i o u s p o t e n t i a l s as o f 1960 when e v e r y t h i n g l o o k e d v e r y g o o d . H e r e i t i s 1976, and n o t h i n g h a s h a p p e n e d . Perhaps a word i s i n o r d e r o n w h a t , i n r e t r o s p e c t , I t h i n k w e r e some o f t h e p r o blems.


f

T a b l e V. 1. 2. 3. 4. 5.

1960

Potentials for

Commercialization

Chemical research data e x i s t P i l o t process design v a l i d a t e d Product q u a l i t y i s e x c e l l e n t Raw m a t e r i a l c o s t s f a v o r a b l e Marketing targets i d e n t i f i e d

I n 1 9 6 6 , t h e p r o c e s s we p r o p o s e d ( T a b l e V I ) was too complex t o f i t the t e c h n o l o g y of the v a r n i s h p l a n t s of t h a t era; r e c y c l e , r e f l u x , e x t r a c t i o n , f r a c t i o n a t i o n , etc. The p r o c e s s c o s t s w e r e u n c e r t a i n . The m a r k e t i n g f u t u r e s were u n c e r t a i n . The o n l y t h i n g t h a t was c e r t a i n was t h a t t h e u s e o f t h e t r a d i t i o n a l n a t u r a l a n d r e f i n e d d r y i n g o i l s was w a n i n g . New m a t e r i a l s w e r e c o m i n g up. The new m a t e r i a l s w e r e c o m i n g l e s s and l e s s out of the v a r n i s h p l a n t s of the formulator i n d u s t r y , and m o r e and m o r e o u t o f t h e c h e m i c a l p r o c e s s i n d u s t r y . I t was n o t a t a l l c e r t a i n w h e t h e r , i f t h e c h e m i c a l p r o c e s s i n d u s t r i e s , who w e r e now v e n d o r s , s h o u l d c a p t u r e a l l the v e h i c l e manufactures, would expand a l s o i n t o the f i n a l products.


12.

BOBALEK

Table VI.


1. 2. 3. 4. 5.


1966 R e s i s t a n c e s

173

t o Commercialization

Process complexity unacceptable Process costs uncertain Marketing futures uncertain B i o d e g r a d a t i o n p o t e n t i a l unwanted R & D s h i f t s t o defensive posture

B i o d e g r a d a t i o n was a c u r s e a t t h a t t i m e . Anyt h i n g t h a t b i o d e g r a d e d was r e g a r d e d a s n o t d u r a b l e . M e r c u r y and o t h e r f u n g i s t a t s were b e i n g f o r b i d d e n , a n o t h e r d i r e c t i o n t h a t seemed l i k e l y t o l e a d t o a b a n donment o f a l l o l e o r e s i n o u s p r o d u c t s . On t o p o f t h a t , R & D s h i f t e d t o a d e f e n s i v e p o s ture. A l l t h eChairmen o f the Board and Boards o f D i r e c t o r s o f vendors and s u r f a c e c o a t i n g s companies a l i k e , c o n c l u d e d t h e r e w a s t o o much s p e n d i n g o n r e s e a r c h . The r e s u l t s w e r e n o t b e i n g u s e d . The e m p h a s i s was o n quick s o l u t i o n s t o production problems. Ina period of l e s s than t h r e e o r f o u r y e a r s , a combined r e s e a r c h s t a f f o f 4,000 o r s o , p r o d u c t i v e s c i e n t i s t s d w i n d l e d t o 600 o r 700, o r l e s s o v e r t h i s w h o l e i n d u s t r y . P e r h a p s I am i n c l i n e d t o p u t r e a s o n n u m b e r f i v e a s t h e m a i n f a c t o r why t h e r e m a i n i n g p r o b l e m s w e r e n o t s o l v e d , a n d s u g a r e s t e r s w e r e u n a b l e t o b e moved f r o m the f o r m u l a t o r s c o r n e r up i n t o c o m m e r c i a l i z a t i o n . 1

Table

VII. 1. 2. 3. 4. 5. 6.

1976 P o t e n t i a l s f o r

Commercialization

B e t t e r c h e m i c a l r e s e a r c h d a t a added E n g i n e e r i n g advances f a c i l i t a t e process design EPA/OSHA e t c . make c l o s e d p r o c e s s s y s t e m s necessary M a t e r i a l / e n e r g y needs f a v o r renewable resources New i n d u s t r i a l s t r u c t u r e s o p e n new m a r k e t s Renaissance o f R & D

I n 1976, one c a n s e e c e r t a i n t h i n g s t h a t d i d n o t e x i s t , a s shown i n T a b l e V I I . Generally speaking, some e x c e l l e n t c h e m i c a l r e s e a r c h h a s c o n t i n u e d a n d b e t t e r c h e m i c a l r e s e a r c h data on t h e s y n t h e s i s o f t h e e s t e r s has been a c q u i r e d . Infact, i t i s possible t h a t t h e c h e m i s t o f 1976 i s becoming even s l i g h t l y aware o f m a t e r i a l a n d e n e r g y b a l a n c e s . Thus, t h e r e i s l e s s chance he w i l l be d e l i v e r i n g h a l f - f r i e d r e a c t i o n s to t h echemical engineer. One c a n h o p e t h i s now w i l l become h a b i t u a l .



174

SUCROCHEMISTRY

S e c o n d l y , e n g i n e e r i n g d e s i g n has jumped eons i n t e r m s o f new p r o c e s s e s , p a r t i c u l a r l y e x t r a c t i o n , d i s t i l l a t i o n , f r a c t i o n a t i o n , stock preparation, etc. T h a t i s , p r o c e s s e s t h a t u s e d t o be c u m b e r s o m e s t i l l may be c a p i t a l i n t e n s i v e , b u t t h e y c a n be f a s t . On t o p o f t h a t , EPA, OSHA, e t c . , p r o b a b l y w i l l never t o l e r a t e again the appearance of the k i n d of v a r n i s h p l a n t s t h a t p r o v i d e d the low c o s t c o m p e t i t i o n w h i c h c o n s t i t u t e d t h e b a r r i e r t o s e t t i n g up t h i s new k i n d o f s y s t e m i n 1960. The i n d u s t r y w i l l be f o r c e d t o go t o c l o s e d s y s t e m s . T h i s sugar e s t e r process i s , s h o u l d b e , a n d c a n be an e f f l u e n t c l o s e d s y s t e m , p a r t i c u l a r l y i f one e m p l o y s m o d e r n c h e m i c a l e n g i n e e r i n g equipment, such as c o n t i n u o u s r e a c t o r s , f i l m r e a c t o r s , e t c . , f o r which t h i s batch data i s adequate t o j u s t i f y the f i r s t l e v e l s of design. The raw m a t e r i a l p i c t u r e i s i m p r o v i n g . F o r examp l e , i n t h e p a p e r i n d u s t r y k r a f t p u l p i n g now h a s d i s placed v i r t u a l l y a l l except mechanical pulping. The product stream of f a t t y a c i d by-products of k r a f t pulpi n g t o d a y i s a b o u t 6 o r 7 t i m e s w h a t i t was i n 1 9 6 0 . Astoundingly, the f r a c t i o n t h a t would best f i t o l e o r e s i n o u s v e h i c l e s a n d s u c r o s e e s t e r s i s t h e one i n l e a s t demand f o r c o m p e t i t i v e p u r p o s e s . Best of a l l , these kinds of f a t t y a c i d wastes are being generated e i t h e r f r o m wood p r o c e s s i n g o r f o o d p r o c e s s i n g . One a l s o g e t s c l o s e t o many c o m p o s i t e m a t e r i a l s t e c h n o l o g i e s l i k e p r e s s e d - w o o d , f i b e r b o a r d , and p l y w o o d , where a l l o f t h e s e c o u l d f e e d b a c k t h e i r own s u g a r e s t e r s a s necessary intermediates. In a d d i t i o n , these n a t u r a l products i n d u s t r i e s ; p u l p , f o o d p r o c e s s i n g a n d t h e l i k e , come t h e c l o s e s t t h a t e x i s t t o d a y t o b e i n g s e l f - s u f f i c i e n t i n e n e r g y , on t h e b a s i s o f t h e i r own wastes. One a n t i c i p a t e s t h e o v e r a l l g e n e r a t i o n o f new p r o d u c t l i n e s from n a t u r a l p r o d u c t s i n d u s t r i e s as closed situations. H e r e , many o f t h e d i s a d v a n t a g e s now e n c o u n t e r e d w i t h p e t r o c h e m i c a l s , a n d a n t i c i p a t e d d e l a y s i n t h e e v o l u t i o n o f c o a l c h e m i c a l s , may provide a f a v o r a b l e new o p p o r t u n i t y f o r s u c r o c h e m i c a l s t h a t d i d not e x i s t before 1970. F i n a l l y , i t seems i m p o r t a n t t o p o i n t t o t h e r e n a i s sance of R & D . T h i s S u c r o c h e m i c a l Symposium i s n o t o n l y a symptom, b u t a s y m b o l t h a t f i n a l l y t h e R&D s i t u a t i o n has been t u r n e d around. Once a g a i n we may h a v e t o do some h a r d t e c h n o l o g i c a l d e v e l o p m e n t f o r t h e f u n d i n g i s b e g i n n i n g a g a i n t o emerge. We may a g a i n s e e an e r a when t h e r e s e a r c h l a b o r a t o r i e s o f t h e *60s w i l l r e a p p e a r i n t h e c o a t i n g s p r o d u c t s i n d u s t r y .



12. BOBALEK


175

Abstract Laboratory and pilot plant data are reviewed c r i t i cally to establish design guidelines for production of sucrose ester drying oils using process systems which are environmentally acceptable and can be economically feasible, providing that a limited number of standard products can be marketed in sufficient volume to offset high capital equipment costs needed to assure reliable product quality and efficient energy utilizaiton. Raw material supply and costs are very favorable. Sucrose esters of unsaturated fatty acids can be used d i rectly to replace natural drying oils in traditional paints and varnishes, and also as major intermediates for a variety of copolymers or of heterophase emulsoid or organosol compositions that are potentially useful in design of coatings, plastics, adhesives or sealants. Increasing costs of competitive materials of petrochemical origin, and intensification of environmental and toxicity standards for consumer products, can make both direct and intermediate usages of selected sucrose esters more attractive today than seemed probable about 20 years ago. Some possible directions where product design research should be renewed are discussed. Professor Edward G. Bobalek, Ph.D., Chairman, Chem. Eng. Dept. Educated at St. Mary's Coll. (Minnesota), the Creighton Univ. and Indiana Univ. Industrial chem. eng. at Dow Chemical Co., and Dir. Polymer Res. & Production, the Arco Co.; Case Institute of Technology 1948-1963, leaving as Prof, of Chem. Eng. to become Gottesman Research Prof, and Chairman of the Chem. Eng. Dept. Univ. of Maine at Orono. About 120 research papers. Dept. of Chem. Eng., Univ. of Maine, Jenness Hall, Orono, Maine 04472 U.S.A.


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