CA1065527A - Moldable fire-retardant styrene copolymer compositions - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Disclosed herein are fire retardant polymer compositions based on interpolymers of styrene, maleic anhydride and a brominated monomer such as tribromophenyl acrylate, which have been formulated with various additives. Rubber modifiers may also be added for additional toughness.
These compositions, which have a UL-94 rating of at least V-1, are es-pecially useful for use in radio and T.V. cabinets, furniture, appliance housings and other similar applications.

Description

FIRE RETARDA~T POLYMER COMPOSITIONS
The present invention relates to fire retardant poly-mer compositions comprising an interpolymer of styrene, maleic anhydride and a copolymerizable brominated comonomer such as tribromophenyl acrylate, which have been ormulated with a halogenated fire retardant additive, a metal oxide and a smoke suppressant.
Polystyrene and styrene-maleic anhydride copolymers are well known and are widely used in the prior art. Polymers which are prepared using a comonomer such as acrylonitrile with the styrene and styrene-maleic anhydride polymers are also known in the art. These polymers tend to burn readily and are not generally recommended for use in those applications requir-:;
ing fire retardant polymers.
There exists a need in the art for styrene based molding compositions which can be made fire retardant, and should added toughness be desired, a suitable rubber may be added.
This need is accented by the increasing number of laws and regulations relating to the fire retardant properties of poly-mers used as molding compositions inthemanufacture of furniture, such as radio and television cabinets, tables, chairs, appliance housings, and other related uses.
The above need in the prior art is fulfilled by fire retardant compositions of the present invention which comprise:
(A) from 48 to 94 percent by weight based on the total weight of the molding composition of a polymer or rubber modified polymer which isthe interpolymerization product of:
(1) from 55 to 90 percent by weight of a styrene monomer;

(2) from 5 to 25 percent by weight of a maleic anhydride monomer; and

(3) from 5 to 20 percent by weight of a brominated monomer selected from the group consisting of bromophenyl acrylates, bromophenyl methacrylateS bromophenylneo-pentyl acrylate and bromophenylneopentyl methacrylates, with the proviso that the amount of bromine in the polymer is at least 3 percent, preferably 6 percent, by weight; wherein the amount of rubber in the polymer is in the range of from 0 to 30% by weight of the ; polymer;
~B) from 3 to 12 percent by weight based on the total weight of the molding composition of a metal oxide;
(C) from 3 to 25 percent by weight based on the total weight of the molding composition of a smoke suppressant which is selected from the group consisting of smoke suppressing hydrates, carbonates and borates; and lS (D) from 0 to 15 percent by weight of a brominated aromatic fire retardant additive.
The styrene-type monomers used in the present invention include styrene, alpha-methylstyrene, and halogenated styrenes such as o-, p-, and m-chlorostyrenes, o-, p-, and m-bromostyrenes, etc. The amount of st~rene type monomer used in the present invention is from 55 to 90 percent by weight based on the weight of the total polymer composition. Up to 30 percent by weight of the styrene monomer may be replaced by monomers such as acrylonitrile, me-thacrylonitrile, methyl-methacrylate, etc.
The amount of maleic anhydride used in the present invention is in the range of from 5 to 25 percent by weight, preferably 7 to 20 percent by weight based on the total polymer composition~ The maleic anhydride monomer used may be replaced in whole or in part by monochloromaleic anhydride and bromo-maleic anhydride. The dichloromaleic anhydride was found to be unsuitable because of excessive brittleness in the polymer which s~
also had poor processability. The maleic anhydride monomers used contribute to lower smoke levels for the polymer, raise the heat dlstortion temperature of the polymer and reduce the tendency o~ the polymer to drip during the flame tests.
The brominated comonomers which are copolymerized with styrene and maleic anhydride include brominated phenyl acrylates, brominated phenyl methacrylates, brominated neo-pentyl acrylates and brominated neopentyl methacrylates wherein the monomer contains from 1 to 5 bromine atoms per molecule. The preferred brominated monomers include tribromo-phenyl acryl~te~ tribromophenyl methacrylate, tribromoneopentyl , acrylate and tribromoneopentyl methacrylate.
The amount of brominated monomer used is selected so as to provide an interpolymer with a bromine content of at least 3 percent, preferably 6 percent, by weight. In order to obtain this minimum bromine level, it will be necessary to use brominated monomer in amounts in the range of from 5 to 20 percent, preferably 10 to 20 percent, by weight when using the preferred tribromo monomer. Preferably, the total amount of halogen in molding compositions prepared from the inter-polymers of the present invention is at least 10 percent by weight. This amount of halogen can be due solely to the brominated monomers used. Alternately, at least ~ percent by weight of the halogen can be due to the brominated monomers used and the balance can be contributed by halogenated fire retardant additives or halogenated rubber modifiers as is described in greater detail below.
The use of a brominated comonomer insures dis-persion of the bromine throughout the polymer composition and avoids the problems encountered when trying to obtain a uniform dispersion of fir2 retardant additives into the polymer composi-tion. Moreover, when using the comonomer approach there is ~o~ss~

more latitude for the use o~ additives in the polymer ~or specific purposes without losing too much of the polymer properti~s.
The polymers of the present invention are pre-pared by conventional mass or solution polymerization tech-niques. Aqueous polymex~zation methods are not used because the water would hydrolyze the anhydride group.
The polymers of the present invention may be further modified with various additives in order to enhance fir~ retardant properties and/or smoke evolution properties.
A description of the preferred additives is set forth below.
HALOGEN ADDITIVES
The polymers of the pxesent invention may be formulated with additives which provide additional halogen content to the polymer composition. These halogenated fire retardant additives are generally well known in the art. The preferred additives are those which contain one or more bromine atoms attached to an aromatic nucleus. One such class of these compounds may be represented by the following general formula:
~ 6 R4 ~ \~ O R

in which Rl is an aromatic group which may be brominated and/or chlorinated or a straight chain or branched alkyl group con-taining from 2 to 12 carbon atoms and may contain an O~ group, and R2 to R6 stand for a member of the group consisting of hydrogen, chlorine and bromine, said ether containing at least three bromine atoms attached to an aromatic group.
Examples of suitable diaromatic ethers containing bromine attached to the nucleus are tribromodiphenylether, tetrabromodiphenylether, pentabromodiphenylether, hexabromodi-phen~lether, tribromochlorodiphenyletherj tribromodichlorodi-~55~7 phenylether, tribromotrichlorodiphenylether, tetrabromodi-chlorodiphenylether and decabromodiphenylether. The halogen atoms of these diaromatic ethers may be distributed in any arrangement on the aromatic rings.
~xamples of suitable aromatic-aliphatic ethers are the 2-ethylhexyl-, n-octyl, nonyl-, butyl-, dodecyl-, and 2,3-dioxopropyl ethers of tribromophenyl, tribromochlorophenyl and tribromodichlorophenyl. The most preferred compound is - decabromodiphenyl ether.
Other aromatic bromine compounds are described in U.S. Patents 3,833,538 issued September 3, 1974; 3,849,369 issued November 19, 1974; British Patent 1,372,120 issued October 30, 1974; West German publications 2,328,517 published January 10, 1974; 2,328,520 published January 10, 1974 and 2,328,535 published December 20, 1973, all issued to Michigan Chemical Corporation. Other suitable aromatic bromine com-pounds are well known to those skilled in the art or will become obvious upon reading the present specification.
The amount of halogenated fire retardant additives is in the range of from 0 to 15 percent by weight, preferably

4 to 12 percent by weight in order to provide an additional amount of halogen to the composition.
SYNERGISTS
~i Examples of synergists used in combination with the halogens in order to obtain improved fire retardant proper-ties include metal oxides such as Sb2O3, Bi2O3, MoO3, SnO2, WO3, and the like. The preferred metal oxidè is Sb2O3. These metal oxides (especially antimony oxide) function as synergists in improving the efficiency of the halogen in imparting flame retardancy to the above-mentioned polymers. The amount of metal oxide used with the polymers of this invention will be from 1 to 15 percent by weight, preferably 3 to 12 percent by ~ - 6 -iSS~7 weight, based on the total weight of the formulated composition.
`SMOKE SUPPRESSANTS
The polymers of the present invention may be further modified with smoke suppressants in order to enhance ; 5 fire retardant properties and/or smoke evolution properties.
Examples of smoke suppxessants would include hydrates, carbon-ates and borates such as alumina trihydrate, aluminum hydroxide ` sodium carbonate hydrate, magnesium carbonate, hydrated mag-nesia, hydrated calcium silicate, hydrated calcium borate, calcium carbonate, and magnesium borate. One of the preferred smoke suppressants is dawsonite [Na Al CO3(OH)2] which is available commercially from Alcoa. Mixtures of the above smoke suppressants are also effective. The amount of smoke suppressant used in this invention will be from 3 to 25 percent by weight, preferably from 5 to 20 percent by weight based on the total welght of the formulated composition.
In addition to acting as smoke suppressants, the ~ magnesium carbonate and/or magnesium borate are also believed `l to react with the sodium oxide generated by the dawsonite .
thereby keeping the sodium oxide from reacting with and tying up the fire retarding halogens. Thus, when~using small amounts of the carbonate or borate, e.g., from 3 to 15 percent by welght based on the formulated composition, in combination ~ with the dawsonite, more of the halogen in the composition will i 25 be more readily available to function as a flame retardant.
~ Alternately, when using dawsonite and other such componds, one 'I can increase the amount of halogen used in order to compen-sate for that which may be tied up by the dawsonite.

- 6a -, .

5S~7 C-08-12 032~
The preferred 6moke suppressant system i9 a combination of magnesium carbonate and dawsonite wherein the ratio of magnesium carbonate to dawsonite iB at least 1:1.
RUBBER MODIFIERS
For added toughness, the polyFers of the present invention may contain from O to 30 percent and more preferably rom 5 to 20 percent by weighe of a synthetic or natural rubber component. Examples of the rubber components include polymers and copolymers of butadiene, isoprene, chloroprene, as well as other rubbers such as nitrile r~*bers, epichlorohydrin rubbers, acrylate rubbers, natural rubbers, and'rubbery ethylene-vinyl aceta~e, ethylene-propylene copolymers snd chlorinated polyethylene. The rubber component is used to strengthen or toughen the interpolymer of styrene/maleic anhydride and tXe brominated comonomer. The percent rubber referred to above is that of the rubber substrate based on the total polyme~ composition.
lS The rubbery component may be incorporated into the matrix polymer by any of the methods ~hich are well known to those skilled in the art, e.~., direct polymerization of monomers, graf~ing the styrene, maleic anhydride and brominated monomers and mixtures thereof onto the rubbery backbone, forming a polyblend of a rubber graft polymer with a matrix polymer, etc.
The preferred rubber components are epichlorohydrin rubbers, polychloroprene rubbers and chlorinated polyethylenes.
, The polychloroprene rubber component preferred for use in the pre-sent invention is polychloroprene or a copolymer of-chloroprene and at lesst one other mono~er such as butadlene, acrylonitrile, methacrylonitrile~ styrene, ring substltuted halostyrene, alpha-hal~ostyrene, ring substituted alkyls~yrene,~ alpha-alkylstyrene, vinyl chloride, etc. The amount of comonomer used is in the range of O ~o 20 percent based on the weight of polychloroprene rubber copolymer.
Chloroprene rubbers are commercially available a8 solid rubber~, rubber latices ~also referred to as emulsions) and solutions T~le preferred 5S~7 polychloroprene rubbers used in the present invention are ~hose in solid form or in organic solvent solutions as those in latex form must be recovered from the latex and dried prior to use. The chloroprene rubber used is crosslinked either be~ore or during processing in order to maintain it~ particulate nature.
Chloroprene rubbers are available from the E. I. duPont de Nemours and Company, Wilmlngton, Delaware and from Petro-Tex Chemical Corporation of Houston, Texas.
The preferred epichlorohydrin rubbers are polyepichlorohydrin and copolymers of epichlorohydrin with alkylene oxides such as e~hylene and pro-pylene oxides. These rubbers are available commercially as Hydri* Elastomers from B. F. Goodrich Chemical Company.
The rubber component is selected to provide a balance of good phys-ical properties such as impact and gloss. Ungrafted rubber can be used in the present invention. However, polychloroprene rubber, which has been grafted with a polymer composition similar to that used for the matrix polymer, is preferred because the grafted rubber provides better dispersion of the poly-chloroprene.in the polyblend. This provides better impact strength and fire retardancy properties.
PolychIoroprenes are conventionally grafted by dissolving or dis-persing the rubber in the monomers to be grafted onto the polychloroprene.
The percent of monomer grafted onto the rubber is in the range of from about 10 to 100 percent by weight with 10 to 50 percent being most preferred to insure compatibility and good gloss. The percent graft is defined as the weight percent of monomers grafted onto the rubber particle, based on the weight of the rubber, e.g., 100 grams of rubber grafted with lO0 grams of monomer has 100 percent of grafted monomers. Preferably, t~e grafted rubber - has a particle size in the range of from 0.1 to 20 microns, more preferably, 1 to lO mirrons for optimum gloss and toughness.
~ he type and amount of ~onomers desrribed above in reference to the preparation of the matrix polymer are used in the grafting polymerization of ~: 3a the rubber component. It is desirable to use halogenated comonomers in the *Trade mark i5;2~dJ

graft polymerization of the rubbers when these are used to prepare the matrlx polymer.
TEST PEl~OCEDURF.S
Underwriter's Labora~ UL-94 Test tl~
Fire retardant properties are measured using the "Test for Flamm-ability for Plastlc Materials - U~-g4", September :L7, 1973. The test is carried out on test specimens 15.2 x 1.3 x 0.32 ~n. ~en other sample thicknesses are used the stated thickness is given.
The te6t specimen is supported from the upper end, wi~h longest dimension vertical, by a clamp on a ring stand so that the lower end of the ~pecimen i5 1 c~. above the top of the burner tube. The burner is then placed remote from sample, ignited, and ad~usted to produce a blue flame, 1.9 cm. in height.
The test flame is placed centrally under the lower end of the test specimen and allowed to remain for 10 seconds. The test flame is then with-drawn, and the duration of flaming or glowing combustion of the specimen noted.
If flaming or glowing combustion of the specimen ceases wi~hin 30 seconds after removal of the test flame, the test flame is again placed under the speclmen for 10 seconds immediately after flaming combustion of the specimen stops. The test flame is again withdrawn, and the duration of flaming com-bustion of the specimen noted.
If the specimen drops flaming particles or droplets while burning in this test, these drippings shall be allowed to fall onto a horlzontal layer of cotton fibers (untreated ~urgical cotton) placed one foot below the test specin~en. Significantly flaming particles are considared to be those capable of igniting the cotton fibers.

~1) The numerical flame spread ratings reported herein are not intended to reflect hazards presented by the presently claimed polyblends or any other materials under actual fire conditions.

~LO~iS5;~7 C-08-1~-0329 The duration of flaming or glowing combustion of vertical specimens after application of the test flame, average of five specimens (10 fla~e applications) shall not exceed 25 seconds (maximum not more than 30 seconds), and the portion of the specimen outside the clamp shall not be completely burned in the test.
~aterials ~hich comply with the above requiremen~s and do not drip any flaming particles or droplets during the burnin~ test will classify as V-l according to the nomenclature used in the UL-94 test.
Materials which comply with the above requirements, but drip flaming particle3 or droplets ~hich ignite cotton fibers will classlfy as V-2 accord-ing to the nomenclature used in the UL-94 test.
Class V-O i9 given to materials wherein the duration of flaming averages less than 5 seconds under the conditions sbove with no ignition burning more than la seconds.
SMOKE EVOLUTIO~ TESTS
The method used for measuring smoke evolution is that describ~d in D. Gross, J. J. Loftus, and A. F. Robertson, "Method for Measuring Smokè from Burning Materials'7, Symposium on Fire Test Nethods - Restraint and Smoke, 1966, ASTM STP 422, Am. Soc. Testing Mats., 1967, p. 166.
The follo~ing examples are set forth in illustration of the present invention and are not to be construed as a limitation thereof. Unless other~
wise indicated all parts and percentages are by weight.
EX~PLES 1 to 4 ~Control) Examples 1 to 4 illustrate the effect of various amounts of maleic an~ydride on the smoke evolution in styrene-maleic anhydride copolymers during fire xetardant tests. The polystyrene and styrene-maleic anhydride (SMA) co-polymers testsd are prepared by conventional ~echniques. These polymers are then formulated as follows:

~ssz~

`- Polymer 77 parts Antimony Oxide 4 part~
Decabromodiphenyl Oxide 9 parts Dawsonite 5 parts Magnesium Carbonate 5 parts 100 parts total The decabromodiphenyl oxide is a conventional fire retardant addi-tive, which is available commercially as Dow FR-30~ rom the Dow Chemical Company. The antimony oxide is a synergist for the decabromodiphenyl oxide.
The dawsonite and magnesium carbonate are smoke suppressants.
The ingredients are compounded on a mill roll at temperatures in the range of 160 to 195C. and then compression molded into test specimens using temperatures in the range of 175 to 195~C. and pressures of about 4000 ; to 5000 p9i (281 to 351 kg/sq.cm.). The molded-specimens are then tested for flame and smoke properties using the tests described above. The results o$
these tests are tabulated ln Table I below.
TABLE I
SUMMARY OF CONTROL EXAMPLES 1 to 4 % Maleic Anhydride UL-94 Dripping Example in Polymer Dm (1~ RatinR Behavior AFOT (2) 1 Poly- 0 550(284~ Fail Drips 35 styrene ~eavily 2 SMA 7 518(226) Fail Drips 35 Slightly 3 SMA 14 472(213) V-O None 2 4 SMA 21 330(162) V-O None 2 - (1) The first number is under flaming while the second number in parenthesis is under non-flam~ng (smoldering~ conditions.
(2) Approximate flame out times.
Referring to Table I above, as the amount of ~aleic anhydride i~-creases from 0 to 14 percent, the UL rating and approximate flame out times *Trade mark iSSZ7 (AFOT) become significantly better. In this regarcl the polystyrene of Example 1 and the styrene-maleic anhydride copolymer of Example 2 which only contain 7 percent by weight of maleic anhydride should be compared with Examples 3 and 4 which contain 14 and 21 percent of maleic anhydride. In S addltion, there is less smoke evolved and less tendency for the polymer to drlp when using increasing amounts of maleic anhydride.
~ 11 of the above samples contain 9 parts of a decabromodiphenyl oxide fire retardant additive9 which provides 7.4 percent bromine to the com-position. Even at these bromine levels Examples 1 and 2 f~l the UL-94 test.
However, it should be noted that when Example l was repeated without the dawsonite it passed the UL-94 test but dripped heavily and gave off greater amounts of smoke. Moreover, the use of halogenated fire retardant additives instead of halogenated monomers may result in non-uniform properties because of the problem of obtaining a uniform dispersion of the additives in the polymer.

Thi8 example illustrates a method for the preparation of the inter-polymers of the present invention wherein a brominated monomer is inter-polymeri~ed with the styrene (S) and maleic anhydride (MA). A mixture of 71 parts of styrene, 14 parts o maleic anhydride and 15 parts of 2,4,6-tribromo-phenyl acrylate are stirred gently under a nitrogen blanket until the maleic &nhydride and ~ribromophenyl acrylate are dissolved in the styrene monomer.
The resulting solution is transferred to pyre~ test tubes which are stoppered and placed in an oil bath. The solutions are polymerized for 48 hours at 2S 80C. followed by polymerization at 105C. for 72 hours. It should be noted ~hat when using larger amounts of maleic anhydride, lower polymerizatlon temperatures are used in order to obtain better control of the reaction. The polymer is then ground, soaked in methanol for 24 hours, Piltered and dried.

~6S5Z7 C-08-1~-0329 EXAMPLE ~
Example 5 i8 repeated here except that trlbromoneopentyl meth-acryla~e i9 used in place o the tribromophenyl acrylate used in ~xample 5.
Th~ polymers prepared ln Examples 5 and 6 above, whlch have halogen

5 contents o about 7.9 percent by weight and t~ree di~ferent polymers used as control sample~, are formulated as follows:
Polymer 86 parts Antimony Oxide 4 parts Da~sonite 5 parts ~agnesium Carbonate 5 parts lQ0 parts total The first control sample is the polystyrene homopolymer o~ Example 1. The secont control sample is a copolymer of styrene and tribromophenyl acrylate (S/TBPA) and the thlrd sample is a copolymer of styrene and tribromo-neopentyl methacrylate (S/TBNPA~, each containing 75 percent by weight ofstyrene and 25 percent ~y weight of the brominated monomer. The second and . ~
third control sample~ have bromine contents of about 13 percent by weight.

Th~ samples are formulated and tested as outlined above. The results of these tests are tabulated in Table II belo~.

TEST II

SUMMARY OF TESTS ON EXAMPLES S and 6 .
UL-94 Dripping D~
Example (1) Ratln~ AFOT (2) Behavior Flaming Non-Flamin~

1st control FailBurns Drips 462 255 Heavily 2nd con~rol V-2 2 Drips 445 20S

253rd control V-2 2 Drips 505 225 ~-0 2-3 None 464 178

6 ~-0 2-2.5 None 509 177 (1) ls~ control - polystyrene; 2nd contrQl - S/TBPA 75/25;
3rd control - S/T~NPA 75/25.
~2) Approximate flame out tlmes.

~ ;
~0~

Referring to Table II above, Examples 5 and 6 have a higher UL-94 rating (V-0~ than the second and thlrd control sa~ples (V-2)~ notwithstanding the fact that the control samples contain 25 perclent by weight of the bro~i-nated monomer as compared to the 15 percent by ~eight in ExampleR 5 and 6.
Moreover, ~xamples 5 and 6 do not drip whereas th~e control samples do. Note further that the samples listed in Table II above, do not contaln any addi-tlonal fire retardant additive. This illustrates the improved properties which are obtained with the interpolymers of the present invention.
EXA~LES 7 and 8 These examples illustrate the use of a chlorinated rubber with the interpolymers of the present invention. A high impact polystyrene (HIPS) sample is included for control purposes. The interpolymers used in Examples

7 and 8 are the same as those used in Examples 5 and 6, respectively.
Seventy-six parts of these polymers are compounded with 10 parts of Hydrin*100, a polyepichlorohydrin homopolymer which is available commercially from B. F~ Goodrich Company. The rubber component is shredded and mill rolled with ~ the matrix at temperatures in the range of from 160C. to 195C. The mill - rolled samples are ground and formulated with 4 parts of antimony oxide, 5 parts of dawsonite and 5 parts of magnesiu~ carbonate. The rubber modified compositions of Examples 7 and 8 contain 7.9 percent bromine and 3.8 percent chlorine for a total halogen content of 11.7 percentr The formulated samples are then compression molded and tested for flame and smoke properties. The results of these tests are tabulated in Table III below.

*Trad~ mark 106~i527 C-08~ 0329 ~ABLE III
SUMMARY OF EXAMPL~S 7 and 8 HIPS
Polymer (1) Control Example 7 Exam~le 8 UL-94 Test Fails V-O V~O
S AFOT (seconds~ Burns Dm (Flaming) 600 420 460 (~on-flaming) ~0 191 181 Dripping Drips None None (1) XIPS - polystyrene contains about 9 percent by weight of a grafted bu~adiene styrene rubber.
Ex mple 7 - S/MA/tribromophenyl acrylate 71/14/15 pexcen~ by weight.
Example 8 - S/MA/tribromoneopentyl methacxylate 71¦14/15 percent by weight.
The data in Table III above indicate that the terpolymers of the present invention, which are compounded with a chlorinated rubber and other additives, have a UL-94 rating of V-O and an approximate flame out time of 1 second. In additlon, these samples have better impact properties than com-parable non-rubber modified polymers.
29 EXAMPLES 9 to 11 A matrix polymer ls prepared which contains 78 percent by weight o styrene, 7 percent by weight of maleic anhydride and 15 percent by weight of tribromophenyl acrylate using ~he general procedures outlined above. This matrix polymer is then for~ulated and tested for fire and smoke properties.
The formulations and test result~ are tabulated in Table IV below.

~L06SSZ7 C-0~-12-0329 TABLE IV
SUMMARY OF EXAMPLES g to ll COMPOSITIONS
Parts of Example 9 E~ample 10 Exam~le 11 S Matrix Polymer 65 53.9 53.9 Hydrin 100 16 16 13.5 : Butadiene Rubber (1) ~ 13.2 13.2 Sb23 4 4 4 MgCO3 10 lQ 7.5 . ~
' ~ 10 Dawsonite 5 0 5 , .~ Decabromodiphenyl oxide 0 2.9 2.9 Bromine Content ~% by weight) 6.1 7.4 7.4 Chlorine Co~tent ~ 9' 6.1 6.1 5.1 , Total Halogen content C% by 12.2 13.5 12.5 `: weight) ~; ; 15 (1) Gra~ted with about 100 percent by weight of styrene.
******
TEST RESULTS

AFOT (seconds) ; Dm (Flaming)435 452 469 ~Non-flaming) 253 345 281 Referring to Table IV above, ~xamples 10 and 11 illustrate the use f~a butadiene-styrene type rubber in combinat~on with a chlorinated rubber without adversely effecting the flame retardant properties of these 8y8tem8.

: The general procedure of Example 5 is repeated here to prepare an i~terpolymer which contain~ 70 percent by wei~ht of styrene~ 10 percent by weight of maleic anhydride and 20 percent by weight of tribromophenyl acrylate.

.

~; ' '' ' ' ~36SSZ'7 EXAMPL~S 13 to 17 The interpolymer prepared in Exa~ple 12 above i8 ~ormulated and tested for fire retardan~ properties. The formulation and test results are tabulated in Table V below.
TABLE V
SUMMARY OF FORMULATIONS AND TEST RESULTS
_ _ FOR EXAMPLES 13 to 17 Ex~m~le (1) 13 14 15 16 17 Polymer 68 63 68 63 $~
Epichlorohydrin rubber 1,6 16 0 0 Chloroprene rubber 0 0 16 16 16 Antimony oxide 6 6 6 6 6 Magnesium carbonate 5 10 5 10 15 DawsonitP 5 5 5 5 5 X Bromine 8.43 7.81 8.437.81 7.19 % Chlorine 6.13 6.13 6.406.40 6.40 UL-94 V-O V-O V-~ V-O V-O
AFOT (seconds) ~ 1 C 1 ~ 1 C 1 G 1 Dm (Flaming) 407 397 399 403 388 (Non-flaming) 200 290 250 370 288 Drlpping Behavior None None None None None ~1) Numerical values for co~ponents of ~he formulations are parts by weight.
Referrlng to Table V above, the epichlorohydrin rubber used ln Examples 13 and 14 i8 the Hydrin 100 reerred ~o above~ The polychloroprene rubber used is a solid neoprene rubber obtained from E. I. duPont de Nemours and Comp2ny. The UL-94 tes~s indicate ~he good flame retardant properties ehat are obtained with the compositions oF the present invention.

The general procedure of Example S is repeated here to prepare an in~erpolymer which contains 90 percent by welght of styrene, 5 percent by ~5S~7 C-0~ 0329 weight of maleic ~nhydride and S percent by weight of trlbromophenyl acrylate.
EXAMPLES 19 ~o 22 The polymer prepared in Example 18 above is formulated and tes~ed for fire retardant properties. The formulations and test results are tabu-lated in Table Vl below.
TABLE V~
_ .
SUMMARY OF FORMULATIO~S AND TEST RESULTS
FOR EXAMPLES 19 to 22 ~ . .
Example (l?` 19 20 21 22 Polymer . 69 69 62 62 Epichlorohydrin rubber 16 O 16 0 Chloroprene rubber O 16 O 16 ; Antimony oxide 5 5 5 5 Magnesiu~ carbonate S 5 5 5 Dawsonite 5 5 5 5 Decabromodlphenyl oxide a o 7 7 ~ Bro~ine 2.142.14 7.737.73 X Chlorine - 6.1~6.4 6.13 6.4 UL-94 Fails Pails V-O V-O

AFOT (seconds) ~ 30 ~ 30 Dm ~Flaming) 546 429 443 458 (Non-flaming) 362 361 372 383 Dripping Behavior None None None None ~l) Numerical values for components of the ~ormulation are parts by weight, ~xamples 19 and 20 in Table Vl ~bove show the need for having at - least 3 and preferably 6 percen~ by weight bromlne in the lnterpolymers of the present invention. ~hen using the lower level of 5 percent by weight of a ~rominated monomer, the pa~ti~ular monomer used should have a bro~l~e content which would supply the minimum requirement. Alt~rnately, an external source of bro=ine must be u~ed.
' ' ~6iSS~

The polymers of the present invention are useful :~ for preparing a wide variety of molded objects such as radio and television cabinets, applianca housings~ parts and components for vehicles, furniture and other related items.
S Polymers of the present invention may be further modified with conventional additives and adjuvants such as fillers, plasticizers, U.V. stabilizers, heat stabilizers, antioxidants, etc. Care should be taken when formulating or compounding the polymers of the present invention so as not to adversely effect the flammability and/or smoke evolution propertles of th polymers of the present invention.

Claims (9)

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

1. A fire retardant polymer composition comprising:
(A) from 48 to 94% by weight based on the total weight of said polymer composition of a polymer or rubber modified polymer which is the interpolymerization product of:
(1) from 55 to 90% by weight of a styrene monomer;
(2) from 5 to 25% by weight of a maleic anhydride monomer; and (3) from 5 to 50% by weight of a brominated monomer of bromophenyl acrylates, bromophenyl methacrylates, bromophenyl-neopentyl acrylate and bromophenylneopentyl methacrylates, provided that the amount of bromine in the polymer is at least 3% by weight of said polymer;
wherein the amount of rubber in the polymer is from 0 to 30% by weight based upon the weight of said polymer;
(B) from 3 to 12% by weight based on the total weight of the polymer composition of a metal oxide; and (C) from 3 to 25% by weight based upon the total weight of the polymer composition of a smoke suppressant of smoke suppressing inorganic metal hydrates, carbonates or borates.

2. A fire retardant polymer composition as in claim 1 additionally comprising up to 15% by weight based on the total weight of the polymer composition of a brominated aroma-tic fire retardant additive.

3. A fire retardant polymer composition as in claim 1 or 2 characterized wherein said styrene monomer is styrene, alpha-methyl styrene or chlorostyrene.

4. A fire retardant polymer composition as in claim 1 or 2 characterized wherein said brominated monomer contains three bromine atoms.

5. A fire retardant polymer composition as in claim 1 or 2 characterized wherein said brominated monomer is tribromo-phenyl acrylate or tribromoneopentyl methacrylate.

6. A fire retardant polymer composition as in claim 1 or 2 characterized wherein said metal oxide is antimony oxide.

7. A fire retardant polymer composition as in claim 1 or 2 characterized wherein said smoke suppressant is magnesium carbonate, dawsonite or mixtures thereof wherein the ratio of magnesium carbonate to dawsonite is at least 1:1.

8. A fire retardant polymer composition as in claim 1 or 2 characterized in that there is added from 3 to 12% by weight of a brominated aromatic fire retardant additive.

9. A fire retardant composition as in claim 1 or 2 characterized wherein said rubber component is a chlorinated rubber of polyepichlorohydrin, polychloroprene or chlorinated polyethylene rubbers.