CA1121535A - Flame retardant phosphorus/nitrogen additives for thermoplastics - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
There are provided flame retardant thermoplastic compositions suitable for molding which comprise, in admixture, a normally flammable thermoplastic resin and a flame retardant amount of a phosphorus/nitrogen (P-N) bond-containing flame retardant agent. Preferred features include a composition of a polyphenylene ether resin and a styrene resin as the normally flammable thermoplastic component, and a reaction product of POC13 and morpholine as a flame retardant agent.

Description

~C~-225 The present invention relates to flame retardant thermoplastic cornpositions comprising a normally ~lammab]e thermoplastic resin or resins and a phosphorus/nitrogen (P-N) bond-containing flame retardant agent.
The compositions possess good flame resistance with superior retention of other physical properties, especially heat distortion tem~
perature, in comparison with similar com-positions wherein a non-nitrogen bond-containing phosphorus material is used to impart flame ; retardancy.
The use of thermop]astic xesins in the Eormation of shaped articles by the use of molding techniques e.g., compression molding, extrusion, blow molding, and the like, is well known to those skilled in the art. Depending on the choice of thermoplastic resins, shaped articles having high impact strength, stiffness, good surface appearance, heat resistance and other desirable properties during or after molding are providedO
By way of illustration, thermoplastic ~3CI~-22 mo]ding resins include polypheny]ene ethers, along or wi-th styrene resins, as we7] as others well kno-~n to those skillecl in the art.
A major shortcoming in the use of such thermoplastic resins is their normal]y flammable nature. Thus, for applications where flame retardancy is desirable, such as in the fields of home construction, automobile and aircraft manufacture, packaging, electrical equipment, furniture, upholstery and the like, flame retardant and/or drip retardant agents are commonly incorporated into the resin or composi-tions containing the resin before molcling.
The flammability of normally flammable thermoplastic polymers has been reduced in the prior art by using antimony-, halogen-, phosphorus-or nitrocJen containing additives, commonly referred to as flame retardant agents, and such compositions are described in various patents and publications. For example, aroma-tic phos-phates, e.g., triphenyl phosphate, either unmodified or synergistically combined with other compounds such as halo-11;~1535 ~C II- 2 2 5 5 1 genated aromatics~ have been added as flame retardant agents

- 2 to polyphenylene ether compositions. See, e.g., Haaf, U.S.

3 3,639,506 and Canadian Application Serial No.291.790 , filed

4 November 25, 1977, and assigned to the same assignee as herein.
These phosphate compounds impart good flame resistance properties 6 to the thermoplastic blend without detracting from physical 7 properties, except for a tendency to reduce heat distortion 8 temperature. Hexaalkylphosphoric triamides are known to stabilize 9 thermoplastics against degradation by heat and oxygen, See Holoch, U.S. 3,414,536 and Holoc~, Raynor and Haaf, U.S. 3,483,271.

12 It has now been surprisingly discovered tha~ com-13 pounds having aromatic or heterocyclic or alicyclic substituents 14 and a phorphorus-nitrogen bond system provide excellent flame retardant properties when added to normally flammable thermo-16 plastic resins or blends of such resins.
17 .
18 In comparison with the phosphate compounds used as 19 flame retardant addltives in~the prior art, the materials of this invention, on a weight for weight basis, have been found 21 to exhibit comparable performance as flame retardant agents.
22 But, unexpected improvements in other properties are obtained, 23 such as a reduced tendency to undergo heat distortion and the 24 capacity for decreased smoke production during burning. For example in a polyphenylene ether/polystyrene composition, tri-26 phenyl phosphate effects a 4.3F./pbw reduction in heat distor-27 tion temperature as compared with only 2.3F./pbw of phosphoryl 2~ trimorpholide.

l~lS~S 8CH-2255 In addition to being useful by themselves, the new compositions are useful in compositions with other resins and elastomers to improve flame retardancy.
Description oE the Invention - Accordingly, the present invention, in its broadest aspects, provides a flame retardant thermoplastic composition which comprises, in admixture:
ta) a normally flammable thermoplastic resin or resins; and tb) from greater than 10 to about 30 parts per hundred resin of a phosphorus/nitrogen flame retardant agent seleeted from the formulae t i) [X~

wherein each X is independently seleeted from:
ta) a nitrogen or a nitrogen-oxygen interrupted heterocycloaliphatie ring; and, R2 tb) \ N - , wherein R is an aryl radieal of from 6 to 12 R3~
carbon atoms and R is selected from hydrogen, monovalent lower alkyl radicals, cyeloalkylene diamine, arylene diamine or carbonyl thiocarbonyl; and, O O
tii) [X ~ P ~ Y ~ P ~ [X]2 wherein X is as defined above and Y is seleeted from a divalent dioxyarylene of from 6 to 18 earbon atoms and a eompound of the formula-N\__/N -; and, tiii) including r 7eatlng unlts having the formula ~ P - T -~ O
where Z is selected from ~ and 0 and T is selected from N N - and - NHR NH -4 ~
wherein R is arylene, a earbonyl radical or a thioearbonyl radical.

~ - 4 -~ . 11;~1535 8(:H-2255 1 The term "normally flammable" as used herein, describes c~mpositions which do not meet the V-l requirements 3 of the Unde~riters' Laboratories Bulletin No. 94 test.

. In a preferred embodiment, the P-N flame retardant 6 agent ~r is selected from compounds of the formulae:
'7 8 ~ O

~ ~

2 (ii) 13 ~ ~ ~
14 ~ ~ P - X -- P --t ) 1~;
17 wherein ~ is 18.
19 ~ l~3 ~
~ ~ 0 23 or ~5 ~

. .- 5 - ` .

8CM--225'~
1~ 1535 1~iii) a compound comprising repeating units ~;L
2the formulae:
3 [~3 6 ~ ~ P -- N N

8 or 12 ~ ~N~

14 ¦ ~ r -- . N N

8 ..
19 (iv) 2 3 ( ~ NR7~ P
24 where R7 is H or a (lower) alkyl, e . g . Cl-C6 alkyl; and 2~ . .

~ -6-

5 3S 8C~1-2255 l (v) a compound comprising repeating units of 2 th formul~

6 ~ 3 8 wherein R5 is arylene, - C = O or - C = S.
9 .
Preferably, flame retardant agent 4~ will be comprised ll of the formula:

14 ( O ~ ~ 1l 18 The P-N compounds can be prepared by techniques which 19 are well known in the art and described in the literatu.e.
In general, such materials can be prepared by reacting a P-N
21` ,iprecursor with a mono- or diamine, or a urea or thiourea 22 and, if desired, with a dihydric phenol, e.g., bisphenol A, etc.

24 By way of illustration, the phosphory] trimorpholide can be produced by reacting a phosphous compound, e.g., phos-26 phorus oxychloride with morpholine at an elevated temperature, 27 e.g., from about-100 to about 200C. An acid binding agent 28 can be-employed, too.
2~
Typical pathways to obtain the other compounds of 31 interest a-e as follows: ;

I Ç~Cri--~! 2 '~

o=~_z~o .~, o=~ o ~ z~
(o~ ~z~ 7 o r~
/ \ ~ O~Z_ _ o ~

~ 1 I o ~ û P~ E
~ Z
l ¦ ~ E ~ D

C + ~ + ~ c ., o ,C,~ + a C,~ O

~ __ ~ 535 ~CH-2255 The amount of P~N compound used as flame retardant component is not critical, so long as it is present in a minor, effective amount based on the weight of the resinous components --major proportions may detract from physical properties. In general, amounts of from greater than 10 to about 30 parts by weight, preferably from greater than 10 to 15 parts of the flame retardant per hundred parts resin are employed~
The present invention contemplates compositions wherein the P-N flame retardant agent is used in combination with any normally flammable thermoplastic resins having at least the elements carbon, hydrogen and oxygen in its structure. By way of illustration, with particular reference to preferred thermoplastic materials, these include, but are limited to, polyphenylene ether resins and styrene resins, including mixtures of the foregoing.
The polyphenylene ether resin is preferably of the type having the structural formula:

0 ~ (IV) wherein the oxygen ether atom of one unit is connected to the ben~ene nuc~eus of the next adjoining unit, q is a positive integer and is at least 50, and each Q i~ a monovalent sub-stituent selected from the group consisting of hydrogen, ~ 1535 ~cl-2~5 1 halogen, hydrocarbon radicals free of a tertiary alpha-carbon 2 atom, halohydrocarbon radicals h~ving at least two carbon atoms 3 between the halogen atom and the phenyl nucleus, hydrocarbonoxy radicals and halohydrocarbonoxy radicals having at least two 5 carbon atoms between the halogen atom and the phenyl nucleus.

7 A more preferred class of polyphenylene ether resins

8 for the compositions of this invention includes those of the

9 above formula wherein each Q is alkyl, most preferably, having from 1 to 4 carbon atoms. Illustratively, members of this class 11 include poly~2,6-dimethyl-1,4-phenylene)ether; poly(2,6-diethyl-12 1,4-phenylene)ether; poly(2 methyl-6-ethyl 1,4-phenylene~ether;
13 poly(2-methyl-6-propyl-1,4-phenylene)ether; poly(2,6-dipropyl-14 1,4-phenylene)ether; poly(2-ethyl-6-propyl-1,4-phenylene)eth~r;
and the like.

17 Especially preferred is poly(2,6-dimethyl-1,4-phenyl-18 ene)ether, preferably, having an intrinsic viscosity of about 19 0.45 deciliters per gram (dl./g.) as measured in chloroform at 3QC.

22 The preparation of the polyphenylene ether resins is 23 described in Hay, U.S. 3,306,874 and 3,306,375 and in Stamatoff, 24 U.S. 3 9 257,357 and 3,257,358, dated February 28, 1967 and June 21, 1966, respectively.

27 The preferred styrene resins will be those h~ving at 28 least 25~/~ by weight of ~epeating units derived from a vinyl 29 aromatic ccmpound of the formula:
: 30 ~_ .

~ 535 8CH-2255 R6C = CH2 ~ (Z)p (V) wherein R6 is hydrogen, (lower) alkyl or halogen; Z is vinyl, hydrogen, halogen or (lower) alkyl; and p is O or an integer of from 1 to 5. Herein, the term "(lower) alkyl" means alkyl from 1 to 6 carbon atoms.
The term "styrene resins" is used broadly to define components fully described in Cizek, U.S. 3,383,435.
Merely by way of illustration, such resins include homopolymers, such as polystyrene, polychlorostyrene and polyvinyl toluene, the modified polystyrenes such as rubber modified polystyrene blended or grafted high impact products, e.g., the rubber being a polybutadiene or an elastomeric copoly-mer of styrene and a diene monomer. Also included are styrene containing copolymers, such as styrene-acrylonitrile copolymers (SAN), styrene-butadiene copolymers, styrene-acrylonitrile-butadiene terpolymers (ABS), styrene-maleic anhydride copolymers, polyalpha-methylstyrene, copolymers of ethyl vinyl benzene and divinylbenzene, and the like.
Special mention is made of a preferred class of styrene ~0 containing resins. These are known as "~IPS" resins, for high impact polystyrenes, in which the impact modifier comprises one or more of an ethylene/propylene/diene terpolymer, or a hydro-` I ~ 1535 l genated derivative, a vinylaFomatic/diene block copolymer resin, or a hydrogenated derivative, a hydrogen saturated vinylaromatic/
3 diene random copolymer, a radial teleblock copolymer of a vinyl 4 aromatic compo~ld and a diene, a vinyl aromatic/methacrylic or acrylic acid or ester/diene terpolymer, and the like. These 6 specialty HIPS resins are commercially available or can be pre-7 pared by those skilled in this art.
The compositions of the invention can also further include reinforcing agents, preferably fibrous glass reinforce-11 men~s, alone or in combination with non-glass reinforcing 12 ¦ fillers. The fibrous glass is especially preferably fibrous 13 ¦ glass filaments comprised of lime-aluminum borosilicate glass 14 ¦ which is relatively soda free, known as "E" glass. However, 15 ¦ other glasses are useful where electrical properties are not 16 ¦ so important, e.g., the low soda glass know~ as "C" glass.
17 The filaments are made by standard processes, e.g., by steam 18 or air blowing, f:Lame blowing and mechanical pulling. The 19 preferred filaments for plastics reinforcement are made by mechanical pulling. The filament diameters range from about 21 0.000112 to 0.00075 inch, but this is not critical to the 22 present invention.
23 .
24 In general, bes~ properties will be obtained if the sized filamentous glass rei.nEorcements comprise from about 1 26 to about 80~/o by weight based on the combined weight of glass 27 and pol~mers and prefer2bly, from about 10 to about 50% by weight.
28 Especially preferably, the glass will comprise from about 10 29 to abou~ 40% by weight based on the combine~ weigh~ of giass 3C and resin. Generally, for direct molding ~se, up to about 50%
.

, . . - - ~
., ` 8C~-2255 1 of glass can be present without causing flow problems. However, 2 it is useful also to prepare the compositions containing sub-3 s'antially greater quantities, e.g~ up to 70 to 80% by weight 4 of glass. These concentrates can then be custom blended with blends of resins that are not glass reinforced to provide any 6 desired glass content of a lower value.

8 Other ingredients, such as stabilizers, pigments, 9 plasticizers, antioxidants, and the like, can be added for their conventionally employed purposes.

12 The manner in which the present compositions are 13 prepared is not critical and conventional methods can be employed.
14 Preferably, however, each of the ingredients is added as part of a blend premix, and the latter is passed through an extruder, e.g.
16 e.g., a 28 mm. Werner Pfleiderer twin screw extruder, at an 17 extrusion temperature of from about 500 to about 600~F., depen-18 dent on the needs of the particular composition. The strands 19 emerging from the extruder may be cooled, chopped into pellets and molded to any desired shape.

22 Description of the Preferred Embodiments. - The 23 following examples are illustrative of the compositions of 24 this invention. They are not intended to limit the invention in any manner. In the Examples, the compositions are made by 26 extrusion in a 28 mm. Werner Pfleiderer twin screw extruder, set 27 at the temperature and vacuum venting conditions specified. Mold-28 ing is done on a 3 oz. NewburyTM machine set at the cylinder and 29 mold temperatures specified. The heat deflection temperature (~F) is determined under 264 psi fiber stress on a 1/8" x 1/2i' x 31 2-1/2" specimen. The notched Izod impact strength ~ft.-lbs./in.

, , ~ ~

: llZ1535 1 notch) is determined on a 1/8" x 1/2" x 2-1/2" specimen. The 2 percent elongation, tensile strength at yield (psi) and tensile 3 strength at bxeak ~psi) are determined in 1/8" x 2-1/2" L-type 4 specimens. The self-extinguishing -- i.e., burning -- times for specimens (dimensions indicated in Tables~ are determined-in fi accordance with Underwriters Laborabories' Bulletin 94 procedures.
7 Gardner (i.e., drop-dart~ impact resistance (in.-lbs.) is deter-8 mined on specimens of the size indicated. The poly (2,6-dimethyl-1,4-phenylene)ether has an intrinsic viscosity of 0.48 dl./g. as measured in chloroform at 30C.
1~ .

13 The following compositions are prepared in the extruder 14 at 575F with 25 in.-Hg vacuum venti~g. Molding is done at 530F (cylinder) and 190F. (mold). The molded pieces are tested 16 for physical properties and flame retardancy with results s~t 17 forth in Table 1:

21 .

~3 225 . ' . ' 535 ~3CII- 2 2 5 5 I

U~ o U~ U~ . . .. I , , I
U~ o O
.
-o ~ o) S~ C) o ~ ~ ~o ~3~
a~ u u) O ~ ~ ' '~
~:: t~ Lr~ "-, . . . . , I ~ _ U
o a~ ¢ u~ 1~1 o o I I ~v ~
:~ ~ ~ . ~
P~
. ~ ~ o ~ ~ ~
G ,~: ~ h t~

` P~
U~ ~ o . u~ O
-~ ~ 1 u~ ~~i ~ o o cJ
~a O ~~d n E~ c) ~ :~
~ ~ ô ~

` u E
I .~ a :~ ~ ~ ~ a~ I o . ~ c~ ~ ~ x&. ~ r~

U~ ~ ~4 U ~ ~1 ;-' .~ u~
h u o 1--~ tll ,1~ 1 F. ~ p.~ O F-~
e~ & ~ U3 _ r~ a.) ;~ ~_ a) J U C~ O ~--/ ,.
~, ~ U ~1 ~ iJ V ~ h -J `1-~C ~ ~ O ~ ~ r~) O
~ ~-.; I S~ U ~ I _ U
'D ~ ~ O C~
-~ ~ X O F. S~ C~ L~ X
~n c~J ~ JJ u U u~ o o ~ C~
~ ~ CJ
a .~ O ,, O O ~ O 0 1~ 1 .~ O h C~ L ~ N `~ u I :~ ~ u ~:' .. ~
. - 15 -I .
.

I 1~1535 8CH~2255 C~
J o o h s~ o . ~

, a' C~
o . o -r_ ^o a~
o~ `~
I ~D ~ ~ r~ ~ t~ O O
O O o _ ......... c~J C~ GO ~ 00 o ~1 ~ ~,~, o ~ . C~l ~, , .

. ~ ~ .~
.
_ J~ CS~.
.` ~:
~_ ~ ' -~13 U~
~ I
O
.: ~ ,~ ~ o s~ o C~ ' O O' I~
.. . ~ ~ r~
`_ ,1 `
G
C'~l~ , C~l~ , .

,~
' .C
U~
.,~
.1 ~ tq .
bO tO L~ -,~ ' _ ~ o ~ .. _ V
X .~
~ ~ I n.CO
~
.
tO a~ - ~ JJ ~
tl~t.q : C~ O ~ ~
a~c) _ ~ ., .,1~ . ~. ~ -~ ~ ~ O t~
~~ ~n X ~ p,, ~ ~n o o~ ~ tn ~ "~
~ a~
P~ ~ C~
:
d ~ ~
~ u ~ 1535 8c~1-225s 2 The foliowing compositions are prepared in the extruder 3 at 570F. with 25 in.-Hg vacuum venting. Molding is done at 500F. (cylinder) and 190F. ~mold). The molded pieces are tested for physic~l properties and flame retardancy, with

10 result set forth in Table 2:

2:1 .
26 ~ .

28 .
301 , '"

~ - 17 - I

~1~1535 :~3"T~1- 2 2 ~, C~ ~ .~1 1 0 V~ ¢ U~ U~ .. . . ~ .
~ C~ ~ o o o C~
~ . . .
.~

~ ~ o I
O
~ c~ O O O r~
. ~
.
.
.
~ ~ ' :. . C .~

O ~C ~
.b~

~ ra ~
E~ ~ ~ O O ~:
~d ,r - ~, ~ P.
. ~ _ ~
_l ~ ~ ~ ~ ~ .n Q t~
~: r~ I ~ ~ ~ E~

.~ ^ ?~ X O 1: J~
tq ~ J ~ ~ o~ O ~ ~ 0 ~3 o ~ c~ u~
C~
~ ~ ~ ~ ~ ~ ~ o ~
O O O O
U ~ P.- ~ ~ N N 1::~, ~ t~l ~ 8CII--2255

11~1535 ~ ' . , U~o r~
. ~
o o o C:~
~ 3 u~
¢ ~ ~1 0 c~ ~ ~ ~ ~ ~ r~

. I~
^r~ o o .a~ o o ~1 C~ ~D O ~ 1--' c~J ~ . U"~ ^ ^ ~D
~ C`~

CJ
. .
. . "
C~l ~ .
a) ,~
C ~
,~ ~ p ,~ ta X
a) I C~ E~ P
~ c~
,~
' G~
0 4~ JJ bO I
~ ~ X r~
a) E3 ~1 P ~ ~ ~ O
E~ O ~ H U~ O
~ ~ U~
X
pl ~
O ~ c~ ~d O ~ ~ O
S I ~ a~ N t~
p ~
. I

l - 19 - I

11~15 35 8CH- 2 2 5 5 .' . ~_ 2 The following compositions are prepared in the 3 extruder at 580F. with 15 in.-Hg vacuum venting. Molding is 4 done at 550F. (cylinder) and 200F. (mold). The molded pieces are tested for physical properties and flame retardancy, with results se forth in Table ~:

. I

~C11-2255 1~1535 ~ .
o E~' a~ o U~ U~
o U~ U~
. ~o ~ ~ oc~
P~C~ ~ . o Q~ ~
~ ~, .aJ
a) o a~ ~
P.~ ~ ~

g; ~ ~: o h ''~:. S Sa, ~ ' a~

~ ,a r~
~ ~1 ~ h O ~ ~
E~ ~ ~ 3S '~

. ~ g ~ O
~ I ~ a ~ ~ ~ ~
t~ ~~D h ~ ~ J-X ,~~ X O ~:: ~ a U~ ~ ~ ~ ~J U~ O ~ ~ ~ ,-. O ~ 0~ C~ V~
~ ,~ ~
t:t,~ O~1 . O O O O Or~
C~ ~ P. ~ ~ N NP~ J-\ t~l ~

. , ~.
.
. '.

21 - .
_--, - . , , ~

C!I- 2 2 5 5 `;~ O O
o~ ~ o o ¢ I ~ ~ oo I ~ O
C~
C`l~

. ~
~ o o C~ ~ O O
~1 u C`'t ` ' oo ~` Lt~
V~
. C~ . I
. . I
, . .
. ., ~1 ~
.~
E~ oo ' J- V ~ d X
a~
I .
u a~
.
~q ~ g ~ hO
. ~ V ~
~3 ~ ~ : V 0 _ q,~
~d u, ~ ~ Cl. V h ~ a~ 4~ ~ ~v , ~ g ~ t~
~C I
cr~
ai ,~ - v r~ bO
' P~ . L~ ~ V ~
O ,~ I td O ~ . O
O~ N Q) r-l . ~ -~ X W~

I

llZ:~535 1 It is no~eworthy that the composition eontaining 2 the phosphorus/ni~rogen bonded flame retardant agents, ~xamples 3 1 - 3 cause a smaller reduc~ion in heat distortion tempertures, 4 and generally superior retention of important physical proper-ties, in eomparison with the conventional triphenyl phosphate-6 containing composition lA 3A.

9 The relative smoke-producing characteristics of phosphoruslnitrogen bonded flame retardants are compared ~ith 11 a conventional flame retardan~.

12

13 Two to three grams o triphenyl phosphate are placed

14 in an aluminum weighing dish. The dish is then placed under a radiant panel such that the triphenyl phosphate is exposed 16 to the heat radiation. The temperature at the surface of the 17 triphenyl phosphate is estimated to about 300C. A lit Bunsen 18 burner is placed horizontally above and to ~he side of tne dish, 19 thus serving as an ignition source of whatever flammable vapors will be évolved by the heating of the triphenyl phosphate.

22 After a matter of seconds, the triphenyl phosphate 23 melts, ignites1 and burns vigorously accompanied by ~he 24 evolution of copious quantities of black smoke.
26 The above experiment is repeated with tris (2-27 carbamoyl ethyl) phosphine oxide and with pllosphoryl trimorpho-28 lide. In both cases, as compared to that of triphenyl phosphate, 29 ignition requires a measurably greater amount of time, and practically no smoke is evolved.

, i . . ~ .~ , ~ _ ~

~ llZ1535 RC~1-72SS

1 The results indicate that the non-aromatic natures of 2 the 2-carbomoylethyl and morpholide groups are highly beneficial 3 wlth respect to smoke reduction. 5uch non-aromatic compounds thus provide a ~eans of formulating PPO/polystyrene/impact-modifiers with fire-resistant and low-smoke characteristics.
It is to be understood, therefore, that these and 8 other modifications may be made in the particular embodiments 9 disclosed herein without departing from the scope o~ the inven-13 tio R defined in ~hc appended cl~

7 . . .

~0 2~!

Claims (15)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A flame retardant thermoplastic polyphenylene ether resin alone or in combination with a styrene resin including from greater than 10 to about 30 parts per hundred resin of a phosphorous-nitrogen flame retardant agent selected from at least one compound:
(i) having the formula, wherein each X is independently selected from:
a) a nitrogen or a nitrogen-oxygen interrupted heterocycloaliphatic ring; and, b) , wherein R2 is an aryl radical of from 6 to 12 carbon atoms and R3 is selected from hydrogen, monovalent lower alkyl radicals, cycloalkylene diamine, arylene diamine or carbonyl thiocarbonyl; and, (ii) having the formula wherein X is as defined above and Y is selected from a divalent dioxyarylene of from 6 to 18 carbon atoms and a compound of the formula ; and, (iii) including repeating units having the formula wherein Z is selected from and and T is se]ected from and - NHR4NH -wherein R4 is arylene, a carbonyl radical or a thiocarbonyl radical.

2. The thermoplastic resin of claim 1 wherein said at least one compound is .

3. The thermoplastic resin of claim 1 wherein said at least one compound is .

4. The thermoplastic resin of claim 1 wherein said at least one compound is .

5. The thermoplastic resin of claim 1 wherein said at least one compound includes repeating units having the formula .

6. The thermoplastic resin of claim 1 wherein said at least one compound includes repeating units having the formula .

7. The thermoplastic resin of claim 1 wherein said at least one compound includes repeating units of the formula and R4 is as defined above.

8. A composition as defined in claim 1 wherein the polyphenylene ether resin (a) has the formula:

wherein the oxygen ether atom of one unit is connected to the benzene nucleus of the next adjoining unit, q is a positive integer and is at least 50, and each Q is a monovalent substituent selected from the group consisting of hydrogen, halogen, hydrocarbon radicals free of a tertiary alpha-carbon atom, halohydrocarbon radicals having at least two carbon atoms between the halogen atom and the phenyl nucleus, hydrocarbonoxy radicals and halohydrocarbonoxy radicals having at least two carbon atoms between the halogen atom and the phenyl nucleus.

9. A composition as defined in claim 1 wherein at least 25% of the units of said styrene resin have the formula:

wherein R6 is hydrogen, (lower) alkyl of from 1 to 6 carbon atoms or halogen; Z is vinyl, halogen or (lower) alkyl; and p is 0 or an integer of from 1 to 5.

10. A composition as defined in claim 1 wherein the styrene resin is a rubber modified high impact polystyrene.

11. A composition as defined in claim 8 wherein the polyphenylene ether resin is poly(2,6-dimethyl-1,4-phenylene) ether.

12. A composition as defined in claim 10 wherein said styrene resin comprises a styrene resin modified with one or more of an ethylene/propylene/diene terpolymer or a hydrogenated derivative thereof; a vinylaromatic/diene block copolymer resin or a hydrogenated derivative thereof; a hydrogen saturated vinyl aromatic/diene random copolymer, a radial teleblock copolymer of a vinyl aromatic compound and a diene, or a vinyl aromatic/acrylic acid or ester/diene terpolymer.

13. A composition as defined in claim 1 wherein the flame retardant is present in an amount of from greater than 10 to about 15 parts per hundred resin.

14. A composition as defined in claim 1 which further includes a reinforcing amount of a reinforcing filler.

15. A composition as defined in claim 14 wherein said reinforcing filler comprises fibrous glass.