Brominated Phosphate Ester Flame Retardants for Engineering

0. 28. 0. 32. 0. 36. 0. 40. 0. TEMPERATUR. E. (°C). 44. 0. 48. 0. 52. 0. 56. 0. Figur e. 1 . Thermogravimetri c. Analysi s. (TGA. ) o f. Brominate d...
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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