Reactive Oligomers - ACS Publications - American Chemical Society

9 N-Cyanourea-Terminated Resins S.C.LIN

Downloaded by UNIV LAVAL on October 19, 2015 | http://pubs.acs.org Publication Date: July 9, 1985 | doi: 10.1021/bk-1985-0282.ch009

Washington Research Center, W. R. Grace & Company, Columbia, MD 21044

A unique chemistry employing N-cyanourea-terminated reactive oligomers was developed to prepare three different types of polymeric materials. The reactive oligomers were obtained by allowing an isocyanate-terminated polycaprolactone oligomer to react with cyanamide in bulk or in aqueous alkaline solution at room temperature. Upon standing at room temperature, the di-N-cyanourea oligomers underwent homopolymerization to afford linear polymers. The oligomers formed thermosets upon heating above 100°C. When mixed with liquid epoxy resins, the oligomers slowly polymerized to yield linear polymers that were plasticized by the epoxy. These mixtures formed cross-linked thermosets upon heating. The linear polymers synthesized from the oligomers also served as curing agents for epoxy resins. The curing and polymerization mechanisms are discussed in the paper. The oligomers could be used for coatings, adhesives, and other applications needing thermosetting materials. A t h e r m o s e t t i n g r e s i n c o n v e r t s t o an i n f u s i b l e , c r o s s - l i n k e d p l a s t i c which i s i n s o l u b l e i n any s o l v e n t a f t e r c u r i n g . Because of t h i s irreversible cross-linking reaction, excellent physical properties such as heat r e s i s t a n c e , creep r e s i s t a n c e , m e c h a n i c a l s t r e n g t h , e t c . , a r e o b t a i n a b l e through design of the polymer s t r u c t u r e . T h e r m o s e t t i n g r e s i n s have been used e x t e n s i v e l y i n i n d u s t r y f o r a p p l i c a t i o n s such as s t r u c t u r a l a d h e s i v e s , composites, RIM, c o a t i n g s and s e a l a n t s w h i c h need t o r e s i s t s e v e r e s e r v i c e c o n d i t i o n s . T h e r m o s e t t i n g r e s i n s a r e g e n e r a l l y composed o f l o w m o l e c u l a r w e i g h t oligomers which allow f a b r i c a t i o n convenience. T h e s t u d y r e l a t e s t o new c l a s s e s o f t h e r m o s e t t i n g o l i g o m e r s based on N - c y a n o u r e a - t e r m i n a t e d r e s i n s , w h i c h a r e u s e f u l as a monomer, a t h e r m o s e t t i n g r e s i n , a n d a c r o s s - l i n k i n g a g e n t f o r e p o x y resins. R e a c t i v e o l i g o m e r s such as epoxy r e s i n s , i s o c y a n a t e - t e r m i n a t e d compounds, and u r e t h a n e - a c r y l a t e s a r e e x t r e m e l y u s e f u l i n t h e a d h e s i v e , c o a t i n g , r e a c t i o n i n j e c t i o n m o l d i n g (RIM), s e a l a n t and

0097-6156/85/0282-0105$06.00/0 © 1985 American Chemical Society

In Reactive Oligomers; Harris, F., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.


106

REACTIVE OLIGOMERS

composite i n d u s t r i e s . The a p p l i c a t i o n o f r e a c t i v e o l i g o m e r s depends on t h e i r c h e m i c a l s t r u c t u r e s , w h i c h a f f e c t t h e r h e o l o g y , p h y s i c a l c h a r a c t e r i s t i c s and c u r i n g speed of t h e r e s i n m i x t u r e . Successful p r e p a r a t i o n of a p a r t i c u l a r r e a c t i v e o l i g o m e r which meets a l l the d e s i r e d s p e c i f i c a t i o n s r e q u i r e s an u n d e r s t a n d i n g of t h e s t r u c t u r e p r o p e r t y r e l a t i o n s h i p s o f t h e p o l y m e r i c s y s t e m , as w e l l as t h e c o n t r o l of the chemistry i n v o l v e d . T h i s paper d e a l s w i t h a p a r t i c u l a r c h e m i s t r y based on N - c y a n o u r e a - t e r m i n a t e d o l i g o m e r s , which have been c o n v e r t e d i n t o h i g h m o l e c u l a r w e i g h t p o l y m e r s , f a s t c u r i n g t h e r m o s e t s , ( 1 ) and c u r i n g agents f o r epoxy r e s i n s . ( 2 ) The p r e p a r a t i o n o f N - c y a n o u r e a t e r m i n a t e d o l i g o m e r s i s s i m p l e , and t h e p r o p e r t i e s o f m a t e r i a l s c a n be e a s i l y a d j u s t e d by s t r u c t u r a l change. Therefore, this chemistry i s v e r y v e r s a t i l e f o r many i n d u s t r i a l a p p l i c a t i o n s . The s y n t h e s i s o f t h e o l i g o m e r s i n v o l v e d t h e k n o w n r e a c t i o n o f i s o c y a n a t e s and cyanamide (NH^CN). For example, N-cyano-N -phenyl u r e a has been s y n t h e s i z e d f r o m p h e n y l i s o c y a n a t e and an aqueous a l k a l i n e s o l u t i o n of cyanamide i n h i g h Recently, similar r e a c t i o n s w e r e u s e d t o p r e p a r e v a r i o u s d i - N - c y a n o u r e a compounds f r o m diisocyanates.(1) T h e s e monomers w e r e a l s o s y n t h e s i z e d d i r e c t l y b y r e a c t i n g d i i s o c y a n a t e s w i t h cyanamide at m e l t temperatures. The d i f u n c t i o n a l N - c y a n o u r e a c o m p o u n d s w e r e f o u n d t o p o l y m e r i z e into d i f f e r e n t polymeric materials at d i f f e r e n t temperatures. At r o o m t e m p e r a t u r e , a l i n e a r p o l y m e r was o b t a i n e d e i t h e r f r o m t h e p o l y m e r i z a t i o n o f a d i - N - c y a n o u r e a monomer o r d i r e c t l y f r o m t h e m i x t u r e c o n t a i n i n g a d i i s o c y a n a t e and c y a n a m i d e . At elevated t e m p e r a t u r e ( > 1 0 0 ° C ) , t h e d i - N - c y a n o u r e a monomer, o r t h e m i x t u r e o f a d i i s o c y a n a t e and c y a n a m i d e , c r o s s - l i n k e d t o a r i g i d foam o r f l e x i b l e m a t e r i a l , d e p e n d i n g on t h e s t r u c t u r e o f t h e monomer. Cyanamide and i t s a r o m a t i c d e r i v a t i v e , such as 4 , 4 ' - m e t h y l e n e b i s ( p h e n y l c y a n a m i d e ) , were r e p o r t e d t o c u r e an epoxy r e s i n a t elevated temperatures.(4) I t i s a l s o w e l l known t h a t t h e d i m e r o f cyanamide ( d i c y a n d i a m i d e ) i s t h e most i m p o r t a n t epoxy c u r i n g agent i n one-package epoxy compounding.(5) U n f o r t u n a t e l y , t h i s dimer p r e c i p i t a t e s from the d i s p e r s i o n c a u s i n g uneven m i x i n g upon s t a n d i n g . The g o a l o f t h i s r e s e a r c h was t o d e v e l o p d e r i v a t i v e s c o n t a i n i n g -NHCN g r o u p s , r e t a i n i n g l a t e n c y t o w a r d e p o x i d e s . The d e r i v a t i v e s h o u l d have f l e x i b i l i t y f o r c h e m i c a l s t r u c t u r e change and g i v e homogeneous o n e - p a c k a g e , t h e r m o s e t t i n g epoxy r e s i n f o r m u l a t i o n s . N - c y a n o u r e a compounds and t h e i r p o l y m e r s o r o l i g o m e r s w e r e one o f t h e choice materials f o r study. 1

yield.(2)

Experimental P r e p a r a t i o n of N-Cyanourea-Terminated Oligomers. To 0 . 2 m o l e s o f t o l u e n e d i i s o c y a n a t e was a d d e d d r o p w i s e 0 . 1 m o l e o f a p o l y c a p r o l a c t o n e d i o l o l i g o m e r ( U n i o n C a r b i d e , PCP 2 0 0 ) , h a v i n g a m o l e c u l a r w e i g h t o f 530 g / m o l e , o v e r a p e r i o d o f 4 h o u r s . A f t e r s t i r r i n g at room t e m p e r a t u r e o v e r n i g h t , t h e i s o c y a n a t e - t e r m i n a t e d r e s i n was warmed t o 5 0 ° C , c h a r g e d w i t h 0.2 m o l e s o f c y a n a m i d e , and f i n a l l y , c o o l e d t o room t e m p e r a t u r e as s o o n as a homogeneous l i q u i d had b e e n obtained. P r e p a r a t i o n of One-Package, T h e r m o s e t t i n g Epoxy R e s i n . amounts o f E p o n 828 r e s i n w e r e a d d e d t o d i - N - c y a n o u r e a

Varying r e s i n to form


9.

LIN

Ν-Cyanourea-Terminated

107

Resins

t h e r m o s e t t i n g compounds h a v i n g d i f f e r e n t e q u i v a l e n t r a t i o s ide to N-cyanourea. The IR s p e c t r a w e r e t a k e n r i g h t a f t e r a n d a f t e r a g i n g f o r 5 a n d 13 d a y s t o s t u d y t h e s t a b i l i t y .

of epox mixing

C u r i n g o f O n e - P a c k a g e , T h e r m o s e t t i n g Epoxy Compounds. The t h e r m o s e t t i n g e p o x y r e s i n m i x t u r e was c u r e d a t 160 C f o r 2 h o u r s .


Adhesive A p p l i c a t i o n s . Three s u b s t r a t e s : s t e e l , aluminum and f i b e r r e i n f o r c e d p o l y e s t e r m o l d c o m p o u n d (SMC) w e r e u s e d i n s t u d y . In g e n e r a l , t h e t h e r m o s e t t i n g g p o x y r e s i n was a p p l i e d b e t w e e n t w o p i e c e s o f s u b s t r a t e s h a v i n g 1/2 i n o v e r l a p f o r m e t a l s and 1 i n overlap for SMC. A f t e r c u r i n g , t h e l a p s h e a r s t r e n g t h o f t h e s a m p l e s was o b t a i n e d on an I n s t r o n a t a g e a r r a t e o f 0.2 i n / m i n . The r e s u l t s a r e s u m m a r i z e d i n F i g u r e 1. Coating Applications. The c o m p o s i t i o n s and t h e p e r f o r m a n c e a r e d e s c r i b e d i n T a b l e I. The c o a t i n g s a r e p r e p a r e d by t h e p r o c e d u r e as d e s c r i b e d i n t h e o l i g o m e r p r e p a r a t i o n .

T a b l e I.

A p p l i c a t i o n Examples

of N-Cyanourea-Terminated

Example 2 1 D i o l (mole) PPG-725 (b) PCP-200 (a) D i i s o c y a n a t e (mole) 2 χ TDI 2 χ MDI Cyanamide (mole) 2 2 L a p S h e a r f o r SMC ( p s i ) 1070 ( d ) Reverse Impact ( i n - l b ) (c) >160 MEK Rub ( c y c l e ) ( c ) 40 A d h e s i o n (Tap T e s t ) (c) 4 3H P e n c i l Hardness (a) Caprolactone d i o l oligomer TDI = T o l u e n e D i i s o c y a n a t e MDI = D i ( p - i s o c y a n a t o p h e n y l ) m e t h a n e (b) Polypropylene glycol (c) Coating application (d) Substrate f a i l u r e

-

Results

and

-

coatings same

Oligomers

3 PCP-210 2 χ TDI 2

4 PCP-240 2 χ TDI 2

->160

->160

>100 5 3H

>100 5 2B

Discussion

A l t h o u g h N - c y a n o u r e a - t e r m i n a t e d compounds c o u l d be s y n t h e s i z e d d i r e c t l y f r o m t h e r e a c t i o n between i s o c y a n a t e s and cyanamide, t o f u r t h e r m o d i f y t h e p r o p e r t i e s o f an o l i g o m e r , t h e N - c y a n o u r e a t e r m i n a t e d compound h a v i n g t h e d e s i r e d c h a r a c t e r i s t i c s w e r e o b t a i n e d b y f i r s t r e a c t i n g g l y c o l s w i t h two m o l e c u l e s o f a d i i s o c y a n a t e , and t h e n r e a c t i n g t h e d i i s o c y a n a t e o l i g o m e r w i t h two molecules of cyanamide. The p r e p a r a t i o n o f N - c y a n o u r e a o l i g o m e r s i s summarized by t h e f o l l o w i n g r e a c t i o n s :

f? HO-R-OH

+

20CN-R'-NC0

»

*- O C N - R ' - N H C - O - R - O - C - N H - R ' - N C O [I]


(1)


REACTIVE OLIGOMERS

F i g u r e 1. Lap shear s t r e n g t h as of epoxide to N-cyanourea.

a f u n c t i o n of

equivalent


ratio


9.

LIN

109

Ν- Cyanourea- Terminated Resins

c u r i n g a g e n t f o r e p o x y r e s i n s was s y n t h e s i z e d f r o m t o l u e n e d i i s o c y a n a t e ( T D I ) , a c a p r o l a c t o n e d i o l ( P C P ) (MW = 5 3 0 g / m o l e ) a n d cyanamide. T h e o l i g o m e r was m i x e d w i t h E p o n 8 2 8 , a d i g l y c i d y l e t h e r of b i s p h e n o l A, at v a r i o u s c o m p o s i t i o n s . These m i x t u r e s , a f t e r a p p l y i n g as s t r u c t u r a l a d h e s i v e s and c u r i n g a t 160°C f o r 2 h o u r s , p r o v i d e e x c e l l e n t l a p s h e a r s t r e n g t h t o s t e e l , a l u m i n u m a n d SMC ( a f i b e r g l a s s - r e i n f o r c e d p o l y e s t e r m o l d i n g compound), as shown i n F i g u r e 1. Maximum p e r f o r m a n c e c a n b e o b s e r v e d i n t h e c o m p o s i t i o n w h e r e t h e e q u i v a l e n t r a t i o of epoxy t o N-cyanourea i s 2. T h i s i m p l i e s t h a t two e p o x i d e g r o u p s r e a c t w i t h one N - c y a n o u r e a g r o u p , g i v i n g t h e b e s t adhesion to the substrates. The r e a c t i o n b e t w e e n t h e NCNH- o f c y a n a m i d e and e p o x i d e i s reported to give a 1,3-oxazolidine,(4) NH 0 RNHCN

+

CH -CH-R

(3)

f

0

which f u r t h e r r e a c t s w i t h d i g l y c i d y l e t h e r of b i s p h e n o l A to form a cross-linked resin. T h i s m e c h a n i s m seems t o a g r e e w i t h t h e c o n c l u s i o n t h a t t h e maximum a d h e s i o n p e r f o r m a n c e o c c u r s a t t h e e q u i v a l e n t r a t i o of e p o x i d e t o N-cyanourea e q u a l t o 2. However, t h i s mechanism c o u l d n o t be used t o e x p l a i n f a c t s o b t a i n e d i n t h e following studies. To u n d e r s t a n d t h e r e a c t i o n m e c h a n i s m a n d t o s t u d y t h e s t a b i l i t y o f t h e t h e r m o s e t t i n g s y s t e m , t h e m i x t u r e o f E p o n 828 a n d N - c y a n o u r e a o l i g o m e r , s y n t h e s i z e d f r o m TDI, p o l y c a p r o l a c t o n e d i o l and c y a n a m i d e , was s t o r e d a t r o o m t e m p e r a t u r e . I t was f o u n d t h a t t h e v i s c o s i t y o f t h e m i x t u r e i n c r e a s e d w i t h s t o r a g e t i m e and f i n a l l y became a g l a s s y s o l i d a f t e r two m o n t h s . F i g u r e 2 shows t h e IR s p e c t r a o f t h i s mixture taken at d i f f e r e n t storage periods. A strong a b s o r p t i o n of - C H N g r o u p a t 2 2 7 0 cm can be observed i n F i g u r e 2a. The N-cyanourea a b s o r p t i o n i n t h e r e s i n m i x t u r e g r a d u a l l y weakens upon a g i n g a t r o o m t e m p e r a t u r e , a s s h o w n j n F i g u r e s 2b a n d 2 c . In Figure 2 , t h e e p o x i d e a b s o r p t i o n a t 915 cm shows no d e t e c t a b l e c h a n g e i n intensity. T h i s s u g g e s t s t h a t e p o x i d e a n d N C N H - do n o t u n d e r g o a n y a p p r e c i a b l e r e a c t i o n upon s t a n d i n g a t room t e m p e r a t u r e . R e c e n t l y , t h e d i f u n c t i o n a l N - c y a n o u r e a compound was d i s c o v e r e d t o p o l y m e r i z e i n t o a h i g h m o l e c u l a r w e i g h t p o l y m e r a t room t e m p e r a ture. A t e n t a t i v e p o l y m e r i z a t i o n m e c h a n i s m was p r o p o s e d i n t h e r e p o r t , ( 1 ) b a s e d o n I R a n d NMR s t u d i e s . This polymerization i s

OCN-R-NCO

+

H NCN 2

NCNHCNH-R-NHCNHCN


(4)


REACTIVE OLIGOMERS

F i g u r e 2. IR s p e c t r a o f Epon 8 2 8 - d i ( N - c y a n o u r e a ) m i x t u r e a t d i f f e r e n t a g i n g p e r i o d s , ( a ) 0 d a y s ; ( b ) 5 d a y s ; ( c ) 13 d a y s .


9.

LIN

111

Ν- Cyanourea- Terminated Resins

Room T e m p e r a t u r e

^

I

CHN 0 II / R-NHC-N,

(5)

^C-NHC-NH[III]

NH

s

^


R-NHC-N

(6)

Ν

/ H N 2

[IV] w e l l s u i t e d f o r i l l u s t r a t i n g t h e v i s c o s i t y i n c r e a s e and t h e d i s a p p e a r a n c e o f -CEN a b s o r p t i o n i n t h e IR s p e c t r a o f Epon 8 2 8 - d i - N cyanourea mixture. (Figure 2). Upon s t a n d i n g , t h e d i - N - c y a n o u r e a oligomer slowly polymerized i n t o a high molecular weight l i n e a r p o l y m e r w h i c h was p l a s t i c i z e d by t h e l i q u i d e p o x y r e s i n . Upon h e a t i n g , t h e l i n e a r p o l y m e r s y n t h e s i z e d f r o m a d i - N c y a n o u r e a compound was c o n c l u d e d t o u n d e r g o a t h e r m a l d e g r a d a t i o n o f t h e u r e a l i n k a g e , as shown i n E q u a t i o n 7. NH [Ill]

on

[IV]

R-NCO

+

Hîf W ΗΝ

ÎÎ N -

(7)

0

H

[V]

NH R-NCO

+

Ν

0

N-

[VI] E q u a t i o n s ( 5 ) , ( 6 ) , and (7) e x p l a i n t h e c u r i n g o f t h e aged Epon 828-di-N-cyanourea mixture. F i g u r e 3 shows t h e e p o x i d e a b s o r p t i o n o f t h e m i x t u r e d i s a p p e a r a n c e upon h e a t i n g a t 165°C f o r 2 h o u r s . At e l e v a t e d t e m p e r a t u r e s t h e e p o x i d e group s h o u l d r e a c t w i t h -NHCN, E q u a t i o n 3, as w e l l as f u n c t i o n g r o u p s



112

REACTIVE O L I G O M E R S

i n c h e m i c a l s t r u c t u r e s I I , IV, V and V I , t o form a t h e r m o s e t . The i s o c y a n a t e groups shown i n E q u a t i o n (7) s h o u l d r e a c t r a p i d l y w i t h -OH groups g e n e r a t e d from the epoxy c u r i n g r e a c t i o n s , g i v i n g a h i g h l y cross-linked material. I n o r d e r t o c o n f i r m t h a t the polymer s y n t h e s i z e d from a d i - N c y a n o u r e a compound was an epoxy c u r i n g a g e n t , the polymer p r e p a r e d f o r TDI, PCP (MW = 530 g/mole) and cyanamide was d i s s o l v e d i n a c e t o n e w i t h Epon 828, c a s t i n t o f i l m , and t h e n h e a t e d a t 165°C f o r 2 hours. S i m i l a r r e s u l t s were o b t a i n e d .

N-Cyanourea O l i g o m e r s as C o a t i n g M a t e r i a l s . P r e v i o u s l y , the d i f u n c t i o n a l N - c y a n o u r e a - t e r m i n a t e d o l i g o m e r s were used t o p r e p a r e thermoset p l a s t i c s a t a temperature h i g h e r t h a n 100°C.ÇL) I t was r e p o r t e d t h a t t h e o l i g o m e r s , upon h e a t i n g , underwent t h e same major p o l y m e r i z a t i o n as e q u a t i o n s (5) and (6) i n l i n e a r polymer p r e p a r a tion. Some s i d e r e a c t i o n s , based on IR, NMR and mass s p e c t r o s c o p i c s t u d i e s were p r o p o s e d t o i l l u s t r a t e t h e f o r m a t i o n o f c r o s s - l i n k s , as shown i n F i g u r e 4. Based on t h e s e r e s u l t s , a p p l i c a t i o n r e s e a r c h was c o n d u c t e d t o e v a l u a t e the f e a s i b i l i t y of t h i s c h e m i s t r y i n c o a t i n g s u t i l i z a t i o n . T a b l e I shows t h e s t r u c t u r e s o f N - c y a n o u r e a - t e r m i n a t e d o l i g o m e r s s y n t h e s i z e d from d i o l s , d i i s o c y a n a t e s , and cyanamide, and t h e use o f t h e s e o l i g o m e r s as c o r r o s i o n p r o t e c t i o n c o a t i n g s f o r s t e e l s u b s t r a t e . The o l i g o m e r s e x h i b i t e x c e l l e n t a d h e s i o n , s o l v e n t r e s i s t a n c e , f l e x i b i l i t y and h a r d n e s s , depending on the s t r u c t u r e of the polymer backbone. I n a d d i t i o n t o c o a t i n g a p p l i c a t i o n s , the o l i g o m e r s a l s o p r o v i d e a s u b s t r a t e f a i l u r e when t h e y a r e used as SMC a d h e s i v e s .

Conclusion Novel chemistry regarding N-cyanourea-terminated r e a c t i v e oligomers can be summarized as Scheme 1, when the p r e v i o u s p u b l i c a t i o n i s combined w i t h t h i s r e p o r t . The o l i g o m e r can be p r e p a r e d from a d i i s o c y a n a t e and cyanamide e i t h e r i n b u l k or i n an a l k a l i n e aqueous solution. The o l i g o m e r undergoes h o m o p o l y m e r i z a t i o n (Route a) t o form h i g h m o l e c u l a r w e i g h t , l i n e a r polymer a t room temperature and c r o s s - l i n k i n g r e a c t i o n (Route b) t o g e n e r a t e a thermoset upon heating. The m i x t u r e o f epoxy r e s i n and the o l i g o m e r q u i c k l y forms a network p l a s t i c i z e d by epoxy r e s i n upon c u r i n g , and t h e n , a t o t a l l y c r o s s - l i n k e d thermoset a f t e r f i n a l c u r e (Route e ) . The l i n e a r polymer d e r i v e d from t h e o l i g o m e r a l s o s e r v e s as c r o s s l i n k i n g agent f o r epoxy r e s i n (Route d ) . The o l i g o m e r s a r e , t h e r e f o r e , a p p l i c a b l e t o c o a t i n g s , a d h e s i v e s , and o t h e r u s e s n e e d i n g t h e r m o s e t t i n g m a t e r i a l s .



9. L I N

4000

Ν-Cyanourea- Terminated Resins

3000

2000

113

1500

1000

500

F i g u r e 3 . I R s p e c t r u m o f Epon 8 2 8 - d i ( N - c y a n o u r e a ) m i x t u r e a f t e r b e i n g a g e d f o r 13 d a y s , a n d t h e n c u r e d a t 1 6 5 ° C f o r 2 h o u r s .

Major Reaction 0 2 -NHO-NHCN •

η

f=N

-Ν HON

-NH£-N

A

.

yNHCNHHN

N-

.

H N^N^0 o 2

l

Minor Reactions 0 •I

-HNC-N

X

2

NH

A.

> -NCO

Η Ν*Ν^*0

N^N-Ô

2

-

0 —NHC-NHCN

CO2 N

»

=

C-N—

O -NHC-NH-f

N

ù \ NHC-NH-

NHC-NH-

11

0 Figure

4.

Possible

cross-linking

reactions.


-1


Pofymer I

Scheme 1 .

Cyanourea

chemistry.

Crosslinked Polymer *-gEpoxy*Po1ymer I ond/brll

Room Τj&

s

Crosslinked Polymer

s

£j \ e^

RtNt$NHCNki+ Epoxy

C Epoxy

R4NC0)n + IÇNCN

Crosslinked Polymer

—RfNH^NHCNh «

f Q P" Jlfi-NHON

%NCN+ NaOH+NoNHCN ^^RtN^NNoCHh

HoN^NÔ

NH Polymer IIIÎR^N^NX^

CYANOUREA CHEMISTRY II


9.

LIN

N-Cyanourea-Terminated Resins

115

Literature Cited


1. Lin, S. C., "New Polymers Prepared from N-Cyanourea Compounds," in "New Monomers and Polymers," Polymer Science and Technology, 1984, 25, 103. 2. Lin, S. C., "Novel Cross-linking System - N-Cyanourea and Its Adducts as Latent Curing Agent for Epoxy Resins," U.S. Patent 4 379 728, 1983. 3. Kurzer, F. and Powell, J . R., "Organic Syntheses," 1963, Coll. Vol. IV, p. 213. 4. Costsiff, Ε. H . ; Dee, H. B.; Diprima, J . F . ; and Seltzer, R.; ACS Polymer Preprints, 1981, 22 (2), 111. 5. Skeist, I . , "Handbook of Adhesives," Van Nostrand Reinhold Company, New York, 1977, 2nd Ed. RECEIVED March 12, 1985


Reactive Oligomers - ACS Publications - American Chemical Society

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