WO2013085791A1

WO2013085791A1 - Low antimony flame-retarded styrenic thermoplastic polymer composition

Info

Publication number: WO2013085791A1
Application number: PCT/US2012/067043
Authority: WO
Inventors: Sergei V. Levchik; Yankai YANG; Marc LEIFER; James Innes; Garrett SHAWHAN
Original assignee: ICL IP America Inc
Current assignee: ICL IP America Inc
Priority date: 2011-12-09
Filing date: 2012-11-29
Publication date: 2013-06-13
Anticipated expiration: 2014-06-09

Abstract

There is provided herein a low antimony trioxide flame-retarded styrenic thermoplastic polymer composition comprising: (a) at least one styrenic thermoplastic polymer; (b) at least one brominated flame retardant; (c) at least one antimony trioxide synergist in an amount of less than 5 wt. %; and, (d) at least one calcium borate on an inorganic carrier. There is also provided a method of making said flame retarded styrenic thermoplastic polymer composition and article thereof.

Description

LOW ANTIMONY FLAME-RETARDED STYRENIC

THERMOPLASTIC POLYMER COMPOSITION

This application claims priority to U.S. provisional application 61/568,968 filed on December 9, 201 1.

FIELD OF THE INVENTION

The present invention relates to flame-retarded thermoplastic compositions and more particularly to flame-retarded styrenic thermoplastic polymer compositions and articles containing the same.

BACKGROUND OF THE INVENTION

Styrenic polymers and more specifically high impact polystyrene (HIPS) and

acrylonitrile, butadiene, styrene polymers (ABS) plastics are used for the production of electronic parts such as housings, cases and internal parts, amongst others. In most of these applications, flame retardancy is needed and is usually provided by flame retardant systems based on a combination of brominated flame retardants with antimony trioxide as a synergist. But this type of flame retardant system has limitations, because antimony trioxide, being a very efficient synergist, tends to significantly increase smoke yield, which impairs visibility which could create problems for evacuation of people in the case of a fire. Further, antimony trioxide has a very high bulk density which increases the specific gravity of molded parts containing the same. This is especially undesirable in transportation and aviation applications. Furthermore, antimony trioxide has significantly increased in price in recent years. Still further, some recently introduced ecolabels require elimination of antimony trioxide from thermoplastic parts.

Although there is a clear need for low antimony trioxide or antimony trioxide-free flame retardant plastics, such plastics usually requires a significant increase in the loading of brominated flame retardant which is also undesirable. SUMMARY OF THE INVENTION

It has been unexpectedly discovered by the inventors herein that calcium borate on an inorganic carrier can partially replace antimony trioxide synergist in a brominated flame retardant styrenic composition, more specifically HIPS and ABS thermoplastics, without need of increase amount of brominated flame retardant. Such flame-retardant additive compositions provide flame retardant efficiency adequate to styrenic thermoplastic resins in electrical and electronic applications with significantly reduced loading of antimony trioxide.

The present invention is directed to a low antimony trioxide flame-retarded styrenic thermoplastic polymer composition comprising:

(a) at least one styrenic thermoplastic polymer;

(b) at least one brominated flame retardant;

(c) at least one antimony trioxide synergist in an amount of less than 5 weight percent; and,

(d) at least one calcium borate on an inorganic carrier

Further, the flame-retarded styrenic thermoplastic polymer composition can optionally further comprise antidripping agent, impact modifiers, heat stabilizers, antioxidants, processing aids, and other additives enhancing physical properties of the resin.

It will be understood herein that any reference to a flame-retarded styrenic thermoplastic polymer composition is such that the composition is low antimony trioxide styrenic

thermoplastic composition.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a flame retardant additive composition that comprises a unique and unexpected combination of a bromine compound, an antimony synergist, e.g. , antimony trioxide and calcium borate on an inorganic carrier. Such flame retardant additive compositions can be used in styrenic thermoplastic polymers and compositions containing styrenic thermoplastic polymers, to provide flame retardancy at significantly reduced loading of antimony trioxide.

Styrenic thermoplastic polymer (a), as used herein, refers to polymers, and specifically copolymers (including terpolymers), which contain (optionally substituted) a styrenic structural unit, however combined with one or more other structural units. More specific examples of styrenic thermoplastic polymer (a) are styrene-based copolymers belonging to the following classes:

1. HIPS (high impact polystyrene): rubber-modified copolymers of styrenic monomers, obtainable, for example, by mixing an elastomer (butadiene) with the (optionally substituted) styrenic monomer(s) prior to polymerization. The styrenic thermoplastic polymer (a) generally comprise between 40 wt% and 85 wt%, more specifically between 50 wt% and 85 wt% HIPS resins having a melt flow index (MFI) between 1 and 50 g/lOmin (measured according to ISO 1 133; 200°C/5kg).

2. ABS (acrylonitrile butadiene styrene): copolymers and terpolymers that include the structural units corresponding to (optionally substituted) styrene, acrylonitrile and butadiene, regardless of the composition and method of production of said polymers. The styrenic thermoplastic polymer (a) can comprise between 40 wt% and 85 wt%, more specifically between 50 wt% and 83 wt% ABS having an MFI between 1 and 50 g/lOmin (measured according to ISO 1 133 at 220°C/10 kg).

3. SAN (styrene acrylonitrile): copolymer of acrylonitrile and styrene, and SMA (styrene maleic anhydride); copolymer of styrene with maleic anhydride. The styrenic thermoplastic polymer (a) can in one embodiment comprise between 40 wt% and 85 wt% SAN, and in another embodiment can comprise between 40 wt% and 85 wt% SMA. In one embodiment the flame-retarded styrenic thermoplastic polymer composition of the invention can contain as the styrenic thermoplastic polymer (a) an alloy of styrene-containing polymers, namely, a blend of a styrene-containing polymer as set forth above with a second polymer or copolymer (such blends are obtained by extruding pellets of the styrene-containing polymer (a) and pellets of the second polymer in desired proportions). Some non-limiting examples of such blends include a blend of HIPS and polyphenylene oxide or a blend of ABS with polycarbonate. For an HIPS/polyphenylene oxide alloy, such can comprise the styrene- containing polymer (HIPS) at a concentration in the range between 20 wt% and 80 wt%. For an ABS/polycarbonate alloy, such can comprise the styrene-containing polymer (ABS) at a concentration in the range between 5 wt% and 85 wt%.

In one embodiment thermoplastic styrenic polymer (a) is different from any brominated polystyrene flame retardant (b) which is employed. In one embodiment the thermoplastic styrenic polymer (a) is non-halogenated.

Brominated flame retardant (b) includes any flame retardant which contains a bromine atom in its chemical structure. The most specific brominated flame retardant compounds (b) have the following formulae.

Decabromodiphenyl oxide sold under the trade name FR-1210

Tetrabromobisphenol A bis (2,3-dibromopropyl ether) sold under the trade name

Tris(tribromophenoxy)triazine sold under the trade name

Tris(tribromoneopenyl) phosphate sold under the trade name FR-370

CH₂Br O CH₂Br

I II I

BrCII₂— C— CH₂— O— P— O— CH₂— C— CH₂Br

I I I

CH₂Br O CH₂Br

I

CH₂

BrCH₂— C— CH₂Br

CH,Br

(V)

Br minated polyacrylate sold under the trade name FR-1025

Brominated polystyrene sold under the trade name FR-803P

Brominated epoxy polymers sold under the trade name F-2000 series

(VIII)

Brominated end-capped epoxy polymers sold under the trade name F-3000 series

(IX)

Phenoxy-terminated carbonate oligomer of tetrabromobisphenol A

(X)

Tetradecabromodiphenoxybenzene

(XII) Ethylenebistetrabromophthalimide

Tetrabromobisphenol S bis (2,3-dibromopropyl ether)

Poly-dibromophenylene oxide

2-ethylhexyl tetrabromophthalate ester

(XVII)

Preferably, the brominated flame retardant (b) is present in the flame-retarded styrenic thermoplastic polymer composition in the range of from about 2 wt% to about 40 wt% and specifically in the range from about 5 wt% to about 30 wt% based on the total weight of the flame-retarded styrenic thermoplastic polymer composition. Antimony synergist (c) (e.g., antimony trioxide) if used herein shows a synergistic effect with the brominated flame retardant and can serve to further improve the flame retardancy of the styrenic thermoplastic polymer when it is compounded.

The proportion of antimony synergist (c) which is appropriate is when one antimony atom exists based on every two to five bromine atoms of the brominated flame retardant. When the proportion is smaller than one antimony atom for every five bromine atoms the effect of antimony synergist is negligible. On the other hand, once the proportion is larger than one antimony atom for every two bromine atoms, an increase in the effect can no longer be expected even by further increase of antimony synergist proportion and the obtained flame-retarded styrenic thermoplastic polymer composition is inferior in mechanical properties and moldability such as flowability.

In addition to antimony trioxide, some other examples of antimony syngergist (c) can be antimony pentaoxide or sodium and combinations of any of the noted antimony synergists.

The average particle size of antimony synergist (c) is specifically from 0.5 μηι to 5 μηι. Antimony synergist (c) may be surface-treated with an epoxy compound, silane compound, isocyanate compound, titanate compound, or the like as required. Antimony synergist (c) can be used as a powder or as a masterbatch compounded in a carrier resin. Typically a masterbatch contains 50-80 wt. % pre-dispersed antimony syngerist (c) such as the non-limiting example of antimony trioxide. Use of a masterbach impoves safety of the operation eliminating the handling of hazardous powder and improves dispersion of antimony synergist (c) in the flame-retarded styrenic thermoplastic polymer composition.

In one non-limiting embodiment the antimony synergist (c) can be present in an amount of less than 5 weight percent based on the total weight of the flame-retarded styrenic

thermoplastic polymer composition, and in a further embodiment can have a lower endpoint range amount of zero or a lower endpoint range amount of 0.001 weight percent, more specifically a lower endpoint range amount of 0.01 weight percent, even more specifically a lower endpoint range amount of 0.1 weight percent or a lower endpoint range amount of 0.5 weight percent with said a lower endpoint range amounts being based on the total weight of the flame-retarded styrenic thermoplastic polymer composition.

The calcium borate on an inorganic carrier (d), which is used herein, can in one embodiment be manufactured by the reaction of lime with boric acid in the presence of an inorganic carrier, in a water suspension, with subsequent drying, milling and sieving. The calcium borate on an inorganic carrier can in addition to the calcium borate comprise any known inorganic filler material as the inorganic carrier. Some non-limiting examples of inorganic filler material which may function as the inorganic carrier are aluminum hydroxide, boehmite, natural calcium carbonate, precipitated calcium carbonate, calcium sulphate, carbon black, carbon fibers, clay, cristobalite, diatomaceous earth, dolomite, feldspar, graphite, glass beads, glass fibers, kaolin, magnesium carbonate, magnesium hydroxide, metal powders or fibers, mica muscouite, mica phlogopite, natural silica, synthetic silica, nepheline-syenite, talc, whiskers, natural wollastonite or synthetic calcium silicate, and combinations thereof.

In one non-limiting embodiment the inorganic carrier for the calcium borate on an inorganic carrier is wollastonite. More specifically, the calcium borate on an inorganic carrier (e.g. wherein the inorganic carrier is wollastonite) is such that the particles of calcium borate on the inorganic carrier (e.g wollastonite) have a mean particle size (d₅o) of from about 1 micron to about 15 microns and 99 weight percent of the total amount of particles of calcium borate on an inorganic carrier have a diameter (d₉₉) of less than about 50 microns, and more specifically, a d₅o of from about 2 microns to about 10 microns and a d₉₉ of less than about 25 microns. In one embodiment, the calcium borate on an inorganic carrier contains from about 20 to about 80 weight percent of wollastonite and from about 20 to about 80 weight percent of calcium borate, provided that the total weight percent of calcium borate and the total amount of inorganic carrier is equal to 100 weight percent.

In another embodiment the inorganic carrier is synthetic calcium silicate having a d₅o of from about 0.5 microns to about 3 microns. Such calcium silicates are available for example from Evonik, Europe or Shreji, China. In one embodiment herein the calcium borate on any inorganic carrier (d) herein can be present in an amount of from about 1 to about 10 weight percent based on the total weight of the flame-retarded styrenic thermoplastic polymer composition.

In one embodiment herein the antidripping agent is used in order to further improve efficiency of the flame-retarded styrenic thermoplastic polymer composition. The antidripping agent is generally a fluoropolymer or copolymer containing a fluoro-ethylenic structure.

Examples of the antidripping agent include difluoroethylene polymers, tetrafluoroethylene polymers, tetrafluoroethylene-hexafluoropropylene copolymers, and copolymers of

tetrafluoroethylene with fluorine-free ethylenic monomers. More specifically the antidripping agent (d) is polytetrafluoroethylene (PTFE). Any and every type of polytetrafluoroethylene known at present in the art is usable for antidripping agent.

Among polytetrafluoroethylenes, the use of those which are capable of forming fibrils can impart especially high melt-dripping preventing ability. The fibril-forming

polytetrafluoroethylene used herein is not specifically limited. Specific examples of the polytetrafluoroethylene capable of forming fibrils include Teflon 6C (registered trademark of DuPont) or Hostaflon 2071 (registered trademark of Dynon).

The content of the antidripping agent in the flame-retarded styrenic thermoplastic polymer composition is generally from 0.05 percent by weight to 2 percent by weight, specifically between 0.1 percent by weight to 0.5 percent by weight. The amount of the fluororesin may be suitably determined depending on the required flame retardancy of the article formed from the flame-retarded styrenic thermoplastic polymer composition, for example, based on V-0, V-l or V-2 in UL-94 in consideration with the amount of the other components.

Other ingredients that can be employed in amounts less than 10 percent by weight of the low antimony trioxide flame-retarded styrenic thermoplastic polymer composition, specifically less than 5 percent by weight, include the non-limiting examples of lubricants, heat stabilizers, light stabilizers and other additives used to enhance the properties of the resin. Such other ingredients may be specifically utilized in amounts from 0.01 to 5 percent by weight of the total weight of the low antimony trioxide or antimony free flame-retarded styrenic thermoplastic polymer composition and include specific examples such as hindered phenols and phosphites. In one embodiment herein, the low antimony trioxide flame-retarded styrenic thermoplastic polymer composition comprises styrenic thermoplastic polymer (a), e.g., HIPS, ABS, SAN or SMA resin in an amount of from about 40 wt% to about 85 wt%; brominated flame retardant (b) in an amount of from about 2 wt% to about 40 wt%; antimony trioxide (c) in an amount of from about 0.001 wt% to about 5 wt% and an calcium borate on an inorganic carrier (d), in an amount of from about 1 wt% to about 10 wt% all based on the total weight of the low antimony trioxide flame-retarded styrenic thermoplastic polymer composition.

In a more specific embodiment, the low antimony trioxide flame-retarded styrenic thermoplastic polymer composition comprises styrenic thermoplastic polymer (a), e.g., HIPS, ABS, SAN or SMA resin in an amount of from about 50 wt% to about 85 wt%; brominated flame retardant (b) in an amount of from about 5 wt% to about 30 wt%; antimony trioxide (c) in an amount of from about 0.5 wt% to about 5 wt% weight percent and calcium borate on a silicate carrier (d), in an amount of from about 1 wt% to about 10 wt% all based on the total weight of the low antimony trioxide flame retarded styrenic thermoplastic polymer composition.

These amounts of flame retardant additives (b), (c) and (d) in the low antimony trioxide flame-retarded styrenic thermoplastic polymer composition or articles made therefrom are flame- retardant effective amounts thereof.

The low antimony trioxide flame-retarded styrenic thermoplastic polymer composition or articles made therefrom herein can have a flame retardancy classification of one or more of HB, V-2, V-l, V-0 and 5VA according to UL-94 protocol. In one embodiment, the low antimony trioxide flame-retarded styrenic thermoplastic polymer composition can have a flame retardancy of at least V-l or V-0.

There is also provided herein a method of making a low antimony flame-retarded styrenic thermoplastic polymer composition or articles made therefrom comprising blending the styrenic polymer (a) and other ingredients (b), (c) and (d) in powder or granular form, extruding the blend and comminuting the blend into pellets or other suitable shapes. Blending and compounding of the low antimony flame-retarded styrenic thermoplastic polymer compositions of this invention, can be carried out by any other conventional techniques. Although it is not essential, the best results are obtained if the ingredients (a), (b), (c) and (d) are compounded, pelletized and then molded into a desirable article. Compounding can be carried out in conventional equipment. For example, the styrenic polymer (a), other ingredients (b), (c) and (d), and, optionally, other additives are fed into a twin screw extruder in the form of a dry blend of the composition, the screw employed having a long transition section to insure proper melting.

The low antimony trioxide flame-retarded styrenic thermoplastic polymer composition can be molded in any equipment conventionally used for thermoplastic compositions. If necessary, depending on the molding properties of the styrenic polymer (a), the amount of additives, resin flow and the rate of solidification of the styrenic polymer (a), those skilled in the art will be able to make the conventional adjustments in molding cycles to accommodate the composition.

The following examples are used to illustrate the present invention.

EXAMPLES

Example 1

285 gallons of cold city water (about 50 - 70 degrees F) were added to a 1000 gallon stainless steel reactor. This was followed by addition of 262 lbs of hydrated lime, Ca(OH)₂, 1000 lbs of wollastonite (calcium metasilica, NYAD M1250, ex. Nyco) and 430 lbs of boric acid. The mixture was suspended and mixed for at least 10 minutes to complete the reaction. The temperature in the reactor increased to about 90-120 degrees F. The slurry of the product was then pumped to a surge tank and then it was pumped through a wet milling system 35 U Palla followed by M60 Sweco vibrating mills (1/2 inch ceramic cylindrical media). The wet- milled product was pumped into a steam heated drum dryer operating at 190 - 240 degrees F and was then conveyed by a hot air line with the end temperature setup at about 310 degrees F. At the final stage the dried product went through a ACM60 grinding mill further decreasing the particle size to d₅o < 7 micron and d₉₉ < 25 micron. The final product was packaged into bags. Examples 2-14.

In order to prepare samples of flame-retarded HIPS and ABS that illustrate some embodiments of the invention, the following procedures have been used.

1. Materials.

The materials used in this study are presented in Table 1.

2. Compounding

The polymers pellets, brominated flame retardants, antimony trioxide, calcium borate on a silicate carrier, PTFE and stabilizers were weighted on semi analytical scales with consequent manual mixing in plastic bags. The mixtures were introduced into the main feeding port of the extruder. The compounding was performed in a twin screw co-rotating L/D=32 Brabender Plasti- Corder twin screw extruder at 200°-235°C and 100 rpm. The obtained pellets of compounded mixtures were dried in a circulating air oven instruments at 80°C for overnight.

3. Injection molding.

Test specimens were prepared by injection molding the pellets of compounded mixtures on Arburg All-Rounder Injection Molding machine at 220-250°C.

4. Flammability test and physical properties tests

Flammability and physical properties tests are listed in Table 2.

5. Results

Composition and tests results for HIPS are presented in Table 3. Comparative examples 2 and 5 (C2 and C5) show standard formulations recommended in technical literature for V-0 rated HIPS using FR-245 or FR-1410 respectively. Replacement of about 1/2 of the antimony trioxide with FR-1120 in both example 3 which contains FR-245 and in example 6 which contains FR- 1410 allowed the preservation of the V-0 rating and the comparable physical properties to the standard formulation. Replacement of about 2/3 of the antimony trioxide in C2 and C5 with FR- 1 120 (in examples 4 and 7 respectively) resulted in decreasing UL-94 rating from V-0 to V-l, which is still acceptable for many parts of electronic equipment and keeping good physical properties. Thus, the formulations of examples 3,4,6 and 7 represent low antimony trioxide HIPS thermoplastic polymers. Composition and tests results for ABS are presented in Table 4. Comparative examples 8 and 1 1 show standard formulations recommended in technical literature for V-0 rated ABS using FR-245 or FR-1524 respectively. Replacement of about 1/2 of the antimony trioxide with FR- 1 120 in example 9 which contains FR-245 allowed the preservation of the V-0 rating and comparable physical properties to the standard formulation. Replacement of about 2/3 of the antimony trioxide with F-l 120 in example 10 resulted in a decrease in the UL-94 rating from V- 0 to V-1. In the case of the FR-1524 containing formulations, FR-1120 was able to replace only 1/3 of antimony trioxide in CI 1 and still preserve a V-0 rating in example 12. Replacement of 1/2 of the antimony trioxide in comparative example 11 (CI 1) with Fr-1120 lead to the failure of UL-94 vertical test in comparative example 13 (C I 3). Thus, the formulations of examples 9,10 and 19 represent low antimony trioxide ABS thermoplastic polymers.

TABLE 1 Materials

TABLE 2. Flammability and physical properties tests

TABLE 3 Flammability performance and physical properties of flame retarded HIPS

While the above description comprises many specifics, these specifics should not be construed as limitations, but merely as exemplifications of specific embodiments thereof. Those skilled in the art will envision many other embodiments within the scope and spirit of the description as defined by the claims appended hereto.

Claims

CLAIMS:

1. A low antimony trioxide flame-retarded styrenic thermoplastic polymer composition comprising:

(a) at least one styrenic thermoplastic polymer;

(b) at least one brominated flame retardant;

(d) at least one calcium borate on an inorganic carrier.

2. The low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1 , wherein styrenic thermoplastic polymer (a) is at least one selected from the group consisting of high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS), styrene- acrylonitrile copolymer (SAN) and styrene-maleic anhydride copolymer (SMA).

3. The low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1, wherein styrenic thermoplastic polymer (a) is at least one selected from the group consisting of high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS), styrene- acrylonitrile copolymer (SAN) and acrylonitrile-styrene-acrylate (ASA).

4. The low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1 , wherein brominated flame retardant (b) is at least one compound selected from the group consisting of decabromodiphenyl oxide, tetrabromobisphenol A, tetrabromobisphenol A bis (2,3- dibromopropyl ether), tris(tribromophenoxy)triazine, tris(tribromoneopenyl) phosphate, brominated polyacrylate, brominated polystyrene, brominated epoxy polymers, brominated end- capped epoxy polymers, phenoxy-terminated carbonate oligomer of tetrabromobisphenol A, decabromodiphenylethane, tetradecabromodiphenoxybenzene,

ethylenebistetrabromophthalimide, tetrabromobisphenol S bis (2,3-dibromopropyl ether), poly- dibromophenylene oxide, 2-ethylhexyl tetrabromophthalate ester and bis (tribromophenoxy) ethane.

5. The low antimony flame-retarded thermoplastic composition of Claim 1 , wherein the antimony synergist (c) is antimony trioxide

6. The low antimony flame-retarded thermoplastic composition of Claim 1, wherein the inorganic carrier is wollastonite.

7. The low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1 , further comprising an antidripping agent (e) which is polytetrafluoroethylene.

8. The low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1 further comprising a lubricant.

9. The low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1 further comprising a heat stabilizer and/or an antioxidant.

10. The low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1 wherein the styrenic polymer (a) is present in an amount from about 40 wt% to about 85 wt%; brominated flame retardant (b) in an amount of from about 2 wt% to about 40 wt%; antimony trioxide (c) in an amount of from about 0.001 wt% to about 5 wt% and calcium borate on inorganic carrier (d), in an amount of from about 1 wt% to about 10 wt% all based on the total weight of the low antimony trioxide flame retarded styrenic thermoplastic polymer composition.

1 1. The low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1 wherein the styrenic polymer (a) is present in an amount of from about 50 wt% to about 85 wt%; brominated flame retardant (b) in an amount of from about 5 wt% to about 30 wt%; antimony trioxide (c) in an amount of from about 0.5 wt% to about 5 wt% weight percent and calcium borate on silicate carrier (d), in an amount of from about 1 wt% to about 10 wt% all based on the total weight of the low antimony trioxide flame retarded styrenic thermoplastic polymer composition.

12. An article comprising the low antimony flame-retarded styrenic thermoplastic polymer composition of Claim 1.

13. The article of Claim 12 wherein the article is an electronic part.

14. The article of Claim 13 wherein the electronic part is selected from the group consisting of an electronic housing, an electronic case, an electronic internal component and combinations thereof.

15. A method of making a low antimony flame-retarded thermoplastic article comprising (1) blending:

(a) at least one styrenic thermoplastic polymer;

(b) at least one brominated flame retardant;

(c) at least one antimony synergist in an amount of less than 5 wt.%;

(d) at least one calcium borate on an inorganic carrier;

and, optionally, at least one of an antidripping agent, an antioxidant, a heat stabilizer and a lubricant, to provide a low antimony flame retarded thermoplastic composition; and,

(2) shaping the low antimony flame retarded thermoplastic composition into a low antimony flame-retarded thermoplastic article.

16. A low antimony flame retarded thermoplastic article made by the method of Claim 15.

17. The low antimony flame retarded thermoplastic article of Claim 16 wherein the article is an electronic part.

18. The low antimony flame retarded thermoplastic article of Claim 17 wherein the electronic part is selected from the group consisting of an electronic housing, an electronic case, an internal electronic part and combinations thereof.