Chapter 17
Brominated Phosphate Ester Flame Retardants for Engineering Thermoplastics Joseph Green FMC Corporation, P.O. Box 8, Princeton, NJ 08543
A brominated triaryl phosphate ester was shown to be a highly efficient flame retardant additive for engineering plastics such as polycarbonate, polybutylene terephthalate, polyethylene terephthalate, and various alloys including polycarbonate/ABS. In some resins antimony oxide or sodium antimonate is not required or desirable. The brominated phosphate has excellent thermal stability and also does not discolor at high processing temperature. Processing studies show the flame retardant disperses readily and aids processability. Flammability data, mechanical properties, impact, and HDT are reported for various resins and compared with resins containing commercial bromine-containing flame retardants.
The combustion o f gaseous f u e l s i s b e l i e v e d t o p r o c e e d v i a a f r e e r a d i c a l mechanism ( 1 , 2 ) . A number o f p r o p a g a t i n g and c h a i n b r a n c h i n g r e a c t i o n s a r e c r i t i c a l f o r m a i n t a i n i n g t h e combustion process. Some o f these r e a c t i o n s a r e i l l u s t r a t e d below: CH
4
+ 0
H + 0
2
CH
3
+ H + 0
OH + 0
2
CH
4
+ OH
CH
CH
3
+ 0
CH 0 + H
3
+ H 0 2
2
CH 0 + OH
CHO + H 0
HCO + 0
H + CO + 0
2
CO + OH
2
2
2
C0
2
2
+ H
0097-6156/90AM25-O253$06.00y0 © 1990 American Chemical Society
254
FIRE AND POLYMERS
Here H, OH and 0 r a d i c a l s a r e c h a i n c a r r i e r s , and the r e a c t i o n o f H r a d i c a l with 0 i s an example o f c h a i n b r a n c h i n g i n which the number o f c a r r i e r s i s i n c r e a s e d . The r e a c t i o n o f CO w i t h OH r a d i c a l c o n v e r t i n g CO t o C 0 i s a p a r t i c u l a r l y exothermic r e a c t i o n . The f u n c t i o n o f h a l o g e n - c o n t a i n i n g compounds as flame r e t a r d a n t s has been e x p l a i n e d by the r a d i c a l t r a p t h e o r y . L i b e r a t e d h a l o g e n a c i d (HX) competes i n the above r e a c t i o n s f o r those r a d i c a l s p e c i e s t h a t a r e c r i t i c a l f o r flame p r o p a g a t i o n . 2
2
CH
^
HX +
H + HX
•
H
OH + HX
^
H0
0 + HX
^
OH + X
4
+ X
2
CH
3
+ X + X
2
The a c t i v e c h a i n c a r r i e r s a r e r e p l a c e d w i t h the much l e s s a c t i v e h a l o g e n r a d i c a l s l o w i n g the r a t e o f energy p r o d u c t i o n and h e l p i n g flame e x t i n g u i s h m e n t . Antimony o x i d e i s known as a flame r e t a r d a n t s y n e r g i s t when u s e d i n c o m b i n a t i o n w i t h h a l o g e n compounds. V o l a t i l e antimony o x y h a l i d e (SbOX) and/or antimony t r i h a l i d e ( S b X ) a r e formed i n the condensed phase and t r a n s p o r t the h a l o g e n i n t o the gas phase ( 3 ) . I t has been s u g g e s t e d t h a t antimony i s a l s o a h i g h l y a c t i v e r a d i c a l t r a p ( 4 ) . The flame r e t a r d a n t mechanism f o r phosphorus compounds v a r i e s w i t h the phosphorus compound, the polymer and the combustion c o n d i t i o n s ( 5 ) . F o r example, some phosphorus compounds decompose t o p h o s p h o r i c a c i d s and p o l y p h o s p h a t e s . A v i s c o u s s u r f a c e g l a s s forms and s h i e l d s the polymer from the flame. I f the p h o s p h o r i c a c i d r e a c t s w i t h the polymer, e.g., t o form a phosphate e s t e r w i t h subsequent d e c o m p o s i t i o n , a dense s u r f a c e c h a r may form. These c o a t i n g s s e r v e as a p h y s i c a l b a r r i e r t o h e a t t r a n s f e r from the flame to the polymer and t o d i f f u s i o n o f gases; i n o t h e r words, f u e l ( t h e polymer) i s i s o l a t e d from h e a t and oxygen. T r i a r y l phosphate e s t e r s a r e t h e r m a l l y s t a b l e , h i g h - b o i l i n g (>350°C) m a t e r i a l s . They can v o l a t i l i z e w i t h o u t s i g n i f i c a n t d e c o m p o s i t i o n i n t o the flame zone, where they decompose. Flame i n h i b i t i o n r e a c t i o n s , s i m i l a r t o the h a l o g e n r a d i c a l t r a p t h e o r y , have been p r o p o s e d ( 6 ) : 3
H P0
^
HP0
H + PO
^
HPO
H + HPO
^
H
OH + PO
•
HPO
3
4
2
2
+
+ PO + e t c .
PO + 0
I n m o d i f i e d p o l y p h e n y l e n e o x i d e , the preponderance o f e v i d e n c e s u g g e s t s t h a t the phosphate e s t e r flame r e t a r d a n t f u n c t i o n s m a i n l y i n the gas phase (2) as a r a d i c a l t r a p to h e l p quench the f l a m e . The p a t e n t l i t e r a t u r e c o n t a i n s many c l a i m s f o r halogen/phosphorus synergy. A c a r e f u l e x a m i n a t i o n o f the d a t a does n o t s u p p o r t t h e s e
17.
GREEN
Brominated Phosphate Ester Flame Retardants
255
claims. N e v e r t h e l e s s , the a d d i t i v e e f f e c t w i t h a l i p h a t i c c h l o r i n e r e s u l t s i n a flame r e t a r d a n t system o f c o n s i d e r a b l e commercial s i g n i f i c a n c e f o r u r e t h a n e polymers. C o m m e r c i a l l y a v a i l a b l e flame r e t a r d a n t s i n c l u d e c h l o r i n e - and b r o m i n e - c o n t a i n i n g compounds, phosphate e s t e r s , and c h l o r o a l k y l phosphates. Recent e n t r y i n t o the market p l a c e i s a b l e n d o f an a r o m a t i c bromine compound and a phosphate e s t e r (DE-60F S p e c i a l ) f o r use i n f l e x i b l e p o l y u r e t h a n e foam ( 8 ) . T h i s paper d e s c r i b e s the use o f a b r o m i n a t e d a r o m a t i c phosphate e s t e r , where the bromine and phosphorus a r e i n the same m o l e c u l e , i n h i g h temperature thermoplastic applications. We p r e v i o u s l y r e p o r t e d t h a t b r o m i n a t e d a r o m a t i c phosphate e s t e r s a r e h i g h l y e f f e c t i v e flame r e t a r d a n t s f o r polymers c o n t a i n i n g oxygen such as p o l y c a r b o n a t e s and p o l y e s t e r s ( 9 ) . Data were r e p o r t e d f o r use o f t h i s phosphate e s t e r i n p o l y c a r b o n a t e s , p o l y e s t e r s and blends. I n some polymer systems, antimony o x i d e o r sodium antimonate c o u l d be d e l e t e d . T h i s paper i s a c o n t i n u a t i o n o f t h a t work and expands i n t o p o l y c a r b o n a t e a l l o y s w i t h p o l y b u t y l e n e t e r e p h t h a l a t e (PBT), p o l y e t h y l e n e t e r e p h t h a l a t e (PET) and a c r y l o n i t r i l e - b u t a d i e n e - s t y r e n e (ABS). D e s c r i p t i o n o f Flame R e t a r d a n t s Three flame r e t a r d a n t s were compared i n t h i s s t u d y , namely, a b r o m i n a t e d p o l y c a r b o n a t e o l i g o m e r (58% b r o m i n e ) , a b r o m i n a t e d p o l y s t y r e n e (68% b r o m i n e ) , and a b r o m i n a t e d t r i a r y l phosphate e s t e r (60% bromine p l u s 4% p h o s p h o r u s ) . These a r e d e s c r i b e d i n T a b l e I . F i g u r e s 1 and 2 compare the t h e r m a l s t a b i l i t y o f the b r o m i n a t e d phosphate w i t h commercial b r o m i n e - c o n t a i n i n g flame r e t a r d a n t s by t h e r m o g r a v i m e t r i c a n a l y s i s (TGA) and by d i f f e r e n t i a l s c a n n i n g c a l o r i m e t r y (DSC). The b r o m i n a t e d phosphate m e l t s a t 110°C and shows a 1% weight l o s s a t 300°C. Brominated p o l y c a r b o n a t e and b r o m i n a t e d p o l y s t y r e n e a r e p o l y m e r i c and a r e n o t as v o l a t i l e a t e l e v a t e d temperatures as the monomeric flame r e t a r d a n t s . Brominated phosphate h e a t e d i n a g l a s s tube i n a i r a t 300°C f o r 30 minutes remains a water-white l i q u i d . T h i s was compared w i t h commercial b r o m i n e - c o n t a i n i n g flame r e t a r d a n t s which m e l t ; t h e y a l l turn color. The e x c e l l e n t c o l o r s t a b i l i t y o f t h i s b r o m i n a t e d phosphate e s t e r makes i t s u i t a b l e f o r the h i g h temperature processing of engineering p l a s t i c s . The s o l u b i l i t i e s o f the flame r e t a r d a n t s i n t o l u e n e a r e shown i n T a b l e I . I t i s b e l i e v e d t h a t the h i g h s o l u b i l i t y o f the phosphate i n an a r o m a t i c s o l v e n t a c c o u n t s i n p a r t f o r the ease o f compounding i n t o v a r i o u s aromatic r e s i n s . T h i s i s d i s c u s s e d f u r t h e r i n the s e c t i o n on compounding. Flame R e t a r d a n t P o l y c a r b o n a t e s The b r o m i n a t e d phosphate i s an e f f i c i e n t flame r e t a r d a n t f o r polycarbonate r e s i n . UL-94 r a t i n g s o f V-0 w i t h oxygen i n d e x v a l u e s o f g r e a t e r t h a n 40 a r e o b t a i n e d . P o l y c a r b o n a t e r e s i n c o n t a i n i n g b r o m i n a t e d phosphate p r o c e s s e s w i t h g r e a t e r ease t h a n r e s i n c o n t a i n i n g b r o m i n a t e d p o l y c a r b o n a t e as measured by i n j e c t i o n m o l d i n g s p i r a l f l o w measurements. The h e a t d i s t o r t i o n temperature i s r e d u c e d
FIRE AND POLYMERS
256
and the h i g h Gardner impacts a r e r e t a i n e d . The r e s u l t a n t are t r a n s p a r e n t and w a t e r - w h i t e ( T a b l e I I ) .
Table
Description Brominated polycarbonate oligomer Brominated polystyrene Brominated aromatic phosphate e s t e r
I.
products
Flame R e t a r d a n t D e s c r i p t i o n Toluene Solubility p/100*
Trade Name
% Br
% P
M.P. °C
BC-58
58
-
230-260
68PB
68
-
215-225
PB-460
60
4
110
7
0.2
1
25
Softening Point
Table I I .
Flame R e t a r d i n g P o l y c a r b o n a t e
Polycarbonate Resin Brominated p o l y c a r b o n a t e Brominated phosphate
93 7
Oxygen Index UL-94, r a t i n g (1/16") time, s e c .
32.1 V-0 3.8
Heat D i s t o r t i o n Temp. @ 264 p s i , °F Gardner Impact, i n . l b s . S p i r a l Flow, I n j . Molding, i n .
Resin
261 >320
23.5 transparent,
93
>39.6 V-0 2.4
239 >320
29.5 water-white
Flame r e t a r d a n t s u l f o n a t e s a l t p o l y c a r b o n a t e r e s i n g i v e s a UL-94 r a t i n g o f V-0 a t 1/16 i n c h t h i c k n e s s . A t 1/32 i n c h t h i c k n e s s , however, the p r o d u c t d r i p s t o g i v e a V-2 r a t i n g . The a d d i t i o n o f 3% b r o m i n a t e d phosphate r e n d e r s the p r o d u c t V-0 a t 1/32 i n c h t h i c k (Table I I I ) . Flame R e t a r d a n t
P o l v b u t v l e n e T e r e p h t h a l a t e (PBT)
M i n e r a l f i l l e d PBT p o l y e s t e r r e s i n c o n t a i n i n g 12% b r o m i n a t e d phosphate and 4% antimony o x i d e y i e l d s a V-0 p r o d u c t w i t h a 29.7 oxygen i n d e x . A p r o d u c t c o n t a i n i n g 16% b r o m i n a t e d phosphate and
120
200
240
280
320 360 400 TEMPERATURE (°C)
440
480
F i g u r e 1. T h e r m o g r a v i m e t r i c A n a l y s i s (TGA) o f B r o m i n a t e d Flame R e t a r d a n t s - 10°C/min. under n i t r o g e n 1. b i s - ( t r i b r o m o p h e n o x y ) e t h a n e ; 2. o c t a b r o m o d i p h e n y l o x i d e ; 3. b r o m i n a t e d a r o m a t i c phosphate e s t e r ; 4. b r o m i n a t e d p o l y c a r b o n a t e oligomer
160
520
560
i
r
3
M M
X
O
44
46 -
40
200 240 280 TEMPERATURE (°C)
227.9°C J I L_
320
360
J
L
400
1. o c t a b r o m o d i p h e n y l o x i d e ; 2. b i s - ( t r i b r o m o p h e n o x y ) e t h a n e ; 3. b r o m i n a t e d a r o m a t i c phosphate e s t e r
J
440
F i g u r e 2. D i f f e r e n t i a l S c a n n i n g C a l o r i m e t r y (DSC) o f B r o m i n a t e d Flame R e t a r d a n t s - 10°C/min under n i t r o g e n
80
IIO.I°C 120 _l_ 160
L
480
s
a
17.
GREEN
259
Brominated Phosphate Ester Flame Retardants
no antimony o x i d e i s a l s o V-0 w i t h a 31.2 oxygen i n d e x . The use o f b r o m i n a t e d p o l y c a r b o n a t e r e q u i r e s the use o f antimony o x i d e as a synergist. T h i s shows phosphorus t o be h i g h l y e f f e c t i v e as a flame r e t a r d a n t i n PBT ( T a b l e I V ) . The advantages o f e l i m i n a t i n g antimony o x i d e a r e numerous. The lower oxygen index v a l u e s f o r the systems c o n t a i n i n g b o t h phosphorus and h a l o g e n have been r e p o r t e d ( 9 ) .
Table I I I .
Flame R e t a r d a n t
FR P o l y c a r b o n a t e (sulfonate salt)
Polycarbonate
100
Resin
99
99
1
3
B r o m i n a t e d phosphate
-
Oxygen Index
33.6
34.8
37.5
rating sec.
V-0 1.2
V-0 1.9
V-0 0.9
rating sec.
V-2 4.7
V-2 2.4
V-0 1.4
7.0
-
9.1
UL-94 @ 1/16"
@
1/32"
M e l t Index, g/10 (250°C)
min.
T a b l e IV.
Flame R e t a r d i n g
M i n e r a l - F i l l e d PBT
PBT M i n e r a l F i l l e d Brominated p o l y c a r b o n a t e B r o m i n a t e d phosphate Antimony Oxide
84 12
84
84 16
84
-
-
12 4
-
16
Oxygen Index UL-94, R a t i n g (1/16") Time, s e c .
31.8 V-0 0
4
29.7 V-0 3.7
29.1 B
-
31.2 V-0 3.1
W i t h 30% g l a s s f i l l e d PBT, b r o m i n a t e d phosphate r e q u i r e s the use of antimony o x i d e . A d r i p i n h i b i t o r was used i n t h e s e s t u d i e s and as l i t t l e as 0.3% T e f l o n 6C f i b r o u s powder i s adequate t o i n h i b i t dripping. As l i t t l e as 10% b r o m i n a t e d phosphate w i l l g i v e a V-0 product (Table V). The t h r e e flame r e t a r d a n t s are compared i n T a b l e V I . Brominated phosphate d i s p e r s e s r e a d i l y i n the r e s i n presumably due t o i t s h i g h s o l u b i l i t y i n aromatics. R e s i n c o n t a i n i n g brominated polycarbonate i s r e l a t i v e l y d i f f i c u l t t o p r o c e s s as measured by i n j e c t i o n m o l d i n g s p i r a l f l o w measurements. P r o p e r t i e s o f the r e s i n s a r e s i m i l a r w i t h the b r o m i n a t e d phosphate c o n t a i n i n g r e s i n showing a s l i g h t l y lower h e a t d i s t o r t i o n
FIRE AND POLYMERS
260
temperature and a s l i g h t l y h i g h e r I z o d impact. The f l e x modulus i s l o w e s t f o r the b r o m i n a t e d phosphate c o n t a i n i n g r e s i n . Flame R e t a r d a n t
Polyethylene Terephthalate
(PET)
T a b l e V I I shows t h a t sodium antimonate i s a n t a g o n i s t i c w i t h the phosphorus/bromine compound i n 30% g l a s s f i l l e d PET p o l y e s t e r r e s i n .
T a b l e V.
Flame R e t a r d i n g G l a s s F i l l e d
PBT/30% G l a s s Brominated P o l y s t y r e n e Brominated Phosphate Antimony Oxide T e f l o n 6C
86.,5 10
Oxygen Index UL-94, R a t i n g Sec.
-
3..5 0..5
264
3.,5 0..5
28,.2
30..6
27.,9
30..0
(1/16")
V-•0 1..4
V-•0 0..2
V-•0 2.,4
V-•0 1..6
Table VI.
Flame R e t a r d a n t 82.5 3.5 0.3 14 -
(1/16")
(1/8")
M e l t Index, g/10 (250°C)
82.5 3.5 0.3 14 -
82.5 3.5 0.3
14
V-0 0
V-0 0.1
29.7
32.7
33.0
1.3
204 1.0
200 1.1
47
46
37
13.6
13.0
12.5
min.
Flex Strength, p s i F l e x Modulus x 1 0 p s i
24,600 0.83
6
(no FR)
PBT/30% G l a s s
V-0 0.9
197
S p i r a l Flow, i n . *
^Control
14 3..5 0..5
p s i , °C
I z o d Impact
82. 5
10 3.,5 0..5
Oxygen Index HDT,
86. 5
82. 5 14
-
PBT/30% G l a s s Antimony Oxide T e f l o n 6C Brominated Phosphate Brominated P o l y s t y r e n e Brominated P o l y c a r b o n a t e UL-94, r a t i n g sec.
PBT
g i v e s 48
inches
flow
22,800 1.13
26,500 1.15
17.
GREEN
Brominated Phosphate Ester Flame Retardants
261
V-0 p r o d u c t s w i t h h i g h oxygen index v a l u e s a r e o b t a i n a b l e u s i n g b r o m i n a t e d phosphate a l o n e . PET f i b e r s can be r e a d i l y spun and the r e s u l t i n g f i b e r i s white. Flame R e t a r d a n t P o l v c a r b o n a t e / P B T P o l y e s t e r B l e n d A 50/50 b l e n d o f p o l y c a r b o n a t e r e s i n and PBT p o l y e s t e r c o n t a i n i n g 13.5% b r o m i n a t e d phosphate and no antimony o x i d e r e s u l t s i n a p r o d u c t w i t h a V-0 r a t i n g and an oxygen index o f 33. An e q u i v a l e n t p r o d u c t c o n t a i n i n g b r o m i n a t e d p o l y c a r b o n a t e has a low oxygen i n d e x and burns i n the UL-94 t e s t ( T a b l e V I I I ) . V a r i o u s b l e n d r a t i o s o f p o l y c a r b o n a t e and PBT p o l y e s t e r were flame r e t a r d e d w i t h the t h r e e flame r e t a r d a n t s . These d a t a a r e shown g r a p h i c a l l y i n F i g u r e 3. Brominated phosphate i s the most e f f i c i e n t and b r o m i n a t e d p o l y c a r b o n a t e the l e a s t e f f i c i e n t flame retardant. At a 50/50 r a t i o o f p o l y c a r b o n a t e / P B T , b r o m i n a t e d phosphate i s s i g n i f i c a n t l y more e f f e c t i v e than b r o m i n a t e d polystyrene. Flame R e t a r d a n t P o l v c a r b o n a t e / P E T P o l y e s t e r
Alloy
The flame r e t a r d a n t performance o f the t h r e e flame r e t a r d a n t s i n a commercial p o l y c a r b o n a t e / P E T p o l y e s t e r a l l o y were compared. Brominated phosphate i s a v e r y e f f i c i e n t flame r e t a r d a n t as measured by oxygen index and UL-94 ( T a b l e IX and F i g u r e 4 ) . The m e l t index o f the r e s i n does n o t change w i t h the a d d i t i o n o f b r o m i n a t e d p o l y c a r b o n a t e , d o u b l e s w i t h b r o m i n a t e d p o l y s t y r e n e , and d o u b l e s a g a i n w i t h b r o m i n a t e d phosphate ( T a b l e I X ) . Brominated phosphate was a l s o e v a l u a t e d i n a commercial g l a s s f i l l e d polycarbonate/PET p o l y e s t e r a l l o y . A c o n c e n t r a t i o n o f 10% g i v e s a V-0 r a t i n g w i t h an oxygen i n d e x v a l u e o f about 35 ( T a b l e X ) . Flame R e t a r d a n t Polvcarbonate/ABS
Alloy
The flame r e t a r d a n t performance o f v a r i o u s flame r e t a r d a n t a d d i t i v e s i n a commercial p o l y c a r b o n a t e / A B S a l l o y were compared. No antimony o x i d e was r e q u i r e d . The d a t a shows b r o m i n a t e d phosphate t o be a h i g h l y e f f i c i e n t flame r e t a r d a n t i n t h i s a l l o y ( T a b l e X I ) . An a l l o y c o m p o s i t i o n c o n t a i n i n g 14% b r o m i n a t e d phosphate and no antimony o x i d e g i v e s a V-0 r a t i n g ( T a b l e X I I ) . The melt i n d e x o f t h i s a l l o y c o n t a i n i n g 12% b r o m i n a t e d p o l y s t y r e n e was 7.6 g/10 min. ( a t 2 5 0 ° C ) ; the e q u i v a l e n t r e s i n c o n t a i n i n g b r o m i n a t e d phosphate had a m e l t i n d e x o f 13.3 g/10 min. Compounding
Characteristics
I t was o b s e r v e d t h a t b r o m i n a t e d phosphate b l e n d s e a s i l y i n t o v a r i o u s r e s i n s i n a s i n g l e o r t w i n screw e x t r u d e r . Compounding r a t e s a l s o are increased. I t has been assumed t h a t t h i s i s p a r t l y due t o i t s h i g h degree o f s o l u b i l i t y i n a r o m a t i c s o l v e n t . This i s i n contrast w i t h the p o l y m e r i c flame r e t a r d a n t s which a r e more d i f f i c u l t t o i n c o r p o r a t e o r compound i n t o v a r i o u s r e s i n s . A s t u d y was conducted i n a Brabender P l a s t i c - C o r d e r . Brominated phosphate was compared w i t h the p o l y m e r i c flame r e t a r d a n t s b r o m i n a t e d
262
FIRE AND POLYMERS
p o l y c a r b o n a t e and b r o m i n a t e d p o l y s t y r e n e . V a r i o u s r e s i n s w i t h and w i t h o u t g l a s s were used and t h e temperature a d j u s t e d f o r t h e r e s i n . When t h e p o l y m e r i c flame r e t a r d a n t s a r e added i n i n c r e m e n t s , t h e v i s c o s i t y i n c r e a s e s t o a p o i n t and then d e c r e a s e s and p l a t e a u s as the o r i g i n a l v i s c o s i t y o r a t a h i g h e r v i s c o s i t y . When b r o m i n a t e d phosphate i s added i n i n c r e m e n t s , the v i s c o s i t y d e c r e a s e s immediately and then p l a t e a u s , a t a lower v i s c o s i t y t h a n t h e starting viscosity.
Table VII.
Flame R e t a r d a n t
PET/30% G l a s s Brominated Phosphate Sodium Antimonate T e f l o n 6C Oxygen Index UL-94, r a t i n g (1/16") sec.
Table V I I I .
IX.
resin
80 15 5 0.5 29.4 V-2 5.1
-
0.5 36.0 V-0 0.1
0. 5 30. 6 V-•2 1. 2
Flame R e t a r d i n g P o l y c a rbonate/PBT (No Antimony)
- 24 g/10 min.
Blends
43 43 0.5 13.5
43 43 0.5
-
13.5 33.0 V-0 0.9
-
24.8 Burn
Flame R e t a r d i n g P o l y c a r b o n a t e / P E T
Polycarbonate/PET A l l o y Brominated P o l y c a r b o n a t e Brominated P o l y s t y r e n e Brominated Phosphate T e f l o n 6C Oxygen Index UL-94, R a t i n g (1/16") sec. M e l t Index, g/10 min.* (275°C) *Virgin
Resin
80 20
82 18
Polycarbonate PBT P o l y e s t e r T e f l o n Powder Brominated P o l y s t y r e n e Brominated Phosphate Oxygen Index UL-94, r a t i n g (1/16") time, s e c .
Table
PET/30% G l a s s
90 10
86 12
90
-
-
10
0.5 27.3 V-l 11.3
-
0.5 27.9 V-l 6.1 20
Polyester Alloy 86
90
86
12
-
-
0.5 30.6 V-0 1.0
0.5 30.9 V-0 2.7 37
10 0. 5 31. 2 V-•0 4..9
-
12 0.5 35.4 V-0 2.3 71
17.
GREEN
Brominated Phosphate Ester Flame Retardants
20
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
10 2 0 30 4 0 5 0 6 0 70 8 0 9 0 100 CONCENTRATION OF POLYCARBONATE (%)
F i g u r e 3. Flame R e t a r d i n g P o l y c a r b o n a t e / P B T P o l y e s t e r B l e n d s (12% Flame R e t a r d a n t ) 1. b r o m i n a t e d p o l y c a r b o n a t e o l i g o m e r ; 2. b r o m i n a t e d p o l y s t y r e n e 3. b r o m i n a t e d a r o m a t i c phosphate e s t e r
F i g u r e 4.
Flame R e t a r d i n g P o l y c a r b o n a t e / P E T P o l y e s t e r
1. b r o m i n a t e d p o l y c a r b o n a t e o l i g o m e r ; 2. b r o m i n a t e d 3. b r o m i n a t e d a r o m a t i c phosphate e s t e r
Alloy
polystyrene;
FIRE AND POLYMERS
264 Conclusions
A b r o m i n a t e d t r i a r y l phosphate e s t e r was shown t o have e x c e l l e n t t h e r m a l s t a b i l i t y and e x c e l l e n t r e t e n t i o n o f c o l o r a f t e r h i g h temperature p r o c e s s i n g . I t i s a h i g h l y e f f i c i e n t flame r e t a r d a n t i n e n g i n e e r i n g t h e r m o p l a s t i c s and a l l o y s such as p o l y c a r b o n a t e s , PBT p o l y e s t e r , PET p o l y e s t e r , and p o l y c a r b o n a t e a l l o y s w i t h PBT, PET, and ABS. W i t h many polymers antimony o x i d e o r sodium antimonate i s n o t needed presumably due to the p r e s e n c e o f the h i g h l y e f f e c t i v e phosphorus. Brabender P l a s t i - C o r d e r s t u d i e s show the b r o m i n a t e d t r i a r y l phosphate e s t e r to b l e n d e a s i l y i n t o the a r o m a t i c r e s i n s , presumably due t o i t s h i g h s o l u b i l i t y i n a r o m a t i c s o l v e n t , u n l i k e p o l y m e r i c flame r e t a r d a n t s which can be d i f f i c u l t t o b l e n d i n t o the e n g i n e e r i n g t h e r m o p l a s t i c s . T h i s c o n f i r m s the ease o f compounding o b s e r v e d i n a s i n g l e o r twin screw e x t r u d e r . Increased melt index and g r e a t e r s p i r a l f l o w when b r o m i n a t e d t r i a r y l phosphate e s t e r i s used c o n f i r m s the ease o f i n j e c t i o n m o l d i n g o b s e r v e d .
T a b l e X.
Flame R e t a r d i n g P o l y c a r b o n a t e / P E T A l l o y - Glass F i l l e d
Polycarbonate/PET (20% G l a s s )
90
86
82
Brominated Phosphate T e f l o n 6C
10 0.5
14 0.5
18 0. 5
Oxygen Index
34.8
36.6
>39. 6
V-0 1.9
V-0 2.5
V- 0 0
UL-94, r a t i n g sec.
Alloy
Polyester
(1/16")
44/44 PC/30% g l a s s f i l l e d PET V-0/0.9 sec.and 36.9 0.1.
Table XI.
p l u s 12%
Brominated Phosphate g i v e s
Flame R e t a r d i n g Polycarbonate/ABS
Polycarbonate/ABS A l l o y T e f l o n 6C Brominated P o l y c a r b o n a t e bis-(tribromophenoxy)ethane Brominated P o l y s t y r e n e Brominated Phosphate
82..5 0..5 17.,5
Oxygen Index UL-94, R a t i n g (1/16") sec.
Alloy
82.5 0.5
82.5 0.5
-
-
17.5
82 .5 0 .5
-
-
17.5
-
17 .5
26.,4
27.0
27.0
28 .2
V-•1 22
V-0 2.0
V-0 2.6
V--0 1 .4
17.
GREEN
Brominated Phosphate Ester Flame Retardants
Table XII. Polycarbonate/ABS
Flame R e t a r d i n g Polycarbonate/ABS Alloy
Brominated
Polystyrene
Brominated
Phosphate
Antimony Oxygen
Oxide Index
UL-94, R a t i n g sec.
(1/16")
265
Alloy
86
86
86
10
-
-
-
10
14
4
4
-
27.0
26.1
25.8
V-0 0.8
V-0 0.1
V-0 1.3
Acknowledgments I w i s h t o acknowledge the e x c e l l e n t c o n t r i b u t i o n s o f C h a r l e s A. Tennesen f o r compounding and t e s t i n g , Ray Skok f o r f l a m m a b i l i t y t e s t i n g , and John J e s s u p f o r m e c h a n i c a l p r o p e r t y t e s t i n g .
Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9.
Avondo, G.; Vorelle, C.; Debourgo, R. Combust. Flame, 1978; 31, 7. Williams, F. A. Encyclopedia of Physical Science and Tech., 1987, 3, 211. Pitts, J . J.; Scott, P. H.; Powell, D. G. J . Cell Plastics, 1970, 6, 35. Brauman, S. K.; Brolly, A.S. J . Fire Retardation Chem., 1976, 3, 66. Green, J . Plastics Cpding, 1987, 10, No. 3, 57. Hastie, J . W. J . Res. NBS, 1973, No. 6, 733. Carnahan, J.; Haaf, W.; Nelson, G.; Lee, G.; Abolins, V.; Shank, R. Fourth Int. Conf. on Flammability and Safety, San Francisco, Jan. 1979. Green, J . U.S. Patent 4 746 682, 1988. Green, J . Proc. Fire Retardant Chemicals Assoc. Mtg., Grenelefe, F l . March, 1988.
RECEIVED November20,1989
