Styrenics flame retardants

PVC/Styrenic Flame retardancy, processabihty Business machine housings appliances, construction, electronics, automotive... 

Decabrom has poor uv stabiUty ia styrenic resias and causes significant discoloration. The use of uv stabilizers can minimize, but not eliminate, this effect. For styrenic apphcations that require uv stabiUty, several other brominated flame retardants are more suitable. In polyolefins, the uv stabiUty of decabrom is more easily improved by the use of stabilizers. 

Ethylenebis(tetrabromophthalimide). The additive ethylenebis(tetrabromophthalimide) [41291 -34-3] is prepared from ethylenediamine and tetrabromophthabc anhydride [632-79-1]. It is a specialty product used ia a variety of appHcations. It is used ia engineering thermoplastics and polyolefins because of its thermal stabiUty and resistance to bloom (42). It is used ia styrenic resias because of its uv stabiUty (43). This flame retardant has been shown to be more effective on a contained bromine basis than other brominated flame retardants ia polyolefins (10). 

Brominated Styrene. Dibromostyrene [31780-26 ] is used commercially as a flame retardant in ABS (57). Tribromostyrene [61368-34-1] (TBS) has been proposed as a reactive flame retardant for incorporation either during polymerization or during compounding. In the latter case, the TBS could graft onto the host polymer or homopolymerize to form poly(tribromostyrene) in situ (58). 

In polymers such as polystyrene that do not readily undergo charring, phosphoms-based flame retardants tend to be less effective, and such polymers are often flame retarded by antimony—halogen combinations (see Styrene). However, even in such noncharring polymers, phosphoms additives exhibit some activity that suggests at least one other mode of action. Phosphoms compounds may produce a barrier layer of polyphosphoric acid on the burning polymer (4,5). Phosphoms-based flame retardants are more effective in styrenic polymers blended with a char-forming polymer such as polyphenylene oxide or polycarbonate. 

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

A variety of trichloroethylene copolymers have been reported, none with apparent commercial significance. The alternating copolymer with vinyl acetate has been patented as an adhesive (11) and as a flame retardant (12,13). Copolymerization with 1,3-butadiene and its homologues has been reported (14—16). Other comonomers include acrylonitrile (17), isobutyl vinyl ether (18), maleic anhydride (19), and styrene (20). 

Brandt [200] has extracted tri(nonylphenyl) phosphite (TNPP) from a styrene-butadiene polymer using iso-octane. Brown [211] has reported US extraction of acrylic acid monomer from polyacrylates. Ultrasonication was also shown to be a fast and efficient extraction method for organophosphate ester flame retardants and plasticisers [212]. Greenpeace [213] has recently reported the concentration of phthalate esters in 72 toys (mostly made in China) using shaking and sonication extraction methods. Extraction and analytical procedures were carefully quality controlled. QC procedures and acceptance criteria were based on USEPA method 606 for the analysis of phthalates in water samples [214]. Extraction efficiency was tested by spiking blank matrix and by standard addition to phthalate-containing samples. For removal of fatty acids from the surface of EVA pellets a lmin ultrasonic bath treatment in isopropanol is sufficient [215]. It has been noticed that the experimental ultrasonic extraction conditions are often ill defined and do not allow independent verification. 

Various techniques have been used for the determination of oligomers, including GC [135], HPLC [136-138], TLC for polystyrene and poly a-methyl-styrene [139] and SEC for polyesters [140,141]. GC and PyGC-MS can also profitably be used for the analysis of the compositions of volatile products formed using different flame retardants (FRs). Takeda [142] reported that volumes and compositions of the volatile products and morphology of the char were affected by FRs, polymers (PC, PPE, PBT) and their reactions from 300... 

We previously reported that brominated aromatic phosphate esters are highly effective flame retardants for polymers containing oxygen such as polycarbonates and polyesters (9). Data were reported for use of this phosphate ester in polycarbonates, polyesters and blends. In some polymer systems, antimony oxide or sodium antimonate could be deleted. This paper is a continuation of that work and expands into polycarbonate alloys with polybutylene terephthalate (PBT), polyethylene terephthalate (PET) and acrylonitrile-butadiene-styrene (ABS). 

In order to determine the sources of contamination, some water samples, including wastewaters and effluents from different industries were also sampled. Along the Cinca River and in the industrial area of Monzon, industrial effluents from two different industries were selected the first one produced EPS (Expandable polystyrene) treated with flame retardants and ABS (Acrylonitrile-butadiene-styrene), and the second one produced PVC (Polyvinyl chloride). As regards the Vero River, three industries were sampled the first one, a textile industry which produced polyester fibers treated with flame retardants, the second one produced epoxy... 

The replacement of established chemistries with newer ones is one of the classic drivers of change in the chemical industry. One of the current hotbeds of this kind of change is the replacement of brominated flame retardants in polymer formulations. The brominated flame retardants under the most scrutiny have been polybrominated diphenyl ethers, particularly penta- and octabromodiphenyl ether, which have been shown to be persistent in the environment and to bioaccumulate. Great Lakes Chemical is voluntarily phasing out penta- and octa-BDEs by the end of next year. The phaseout is made possible by the clean bill of health granted by EPA for Firemaster 550, a replacement for penta-BDE in flexible PU applications. BRG Townsend claims the phaseout of penta-BDE and octa-BDE is not as earth shattering as would be an exit from deca-BDE, a styrenics additive that is produced in the highest volume of the PBDEs. 

A range of reactions of 2-chlorocyclohexyl(dichloro)phosphine (60) with alcohols and epoxides has been described, largely with a view to the synthesis of polymer intermediates and flame-retardants.50 The copolymerization of dichloro(phenyl)-phosphine with styrene and vinyl butyl ether in the presence of maleic anhydride has been studied.61... 

A few comments on dibromostyrene Known also as brominated styrene, it has been used as a flame retardant in the manufacture of thermoplastics. Although it does not seem to be toxic for the amounts present in the environment, it might have a teratogenic potential if large amounts of it are orally administered, as developmental studies in rats and rabbits have shown. 

Polymer mixtures of aromatic PC, ABS graft polymer and styrene-containing copolymers and monophosphates are described as flameproofing additives (20). It has been claimed that phosphonate amines are superior flame retardants for PC/ABS molding compositions (21). 

T. Bhaskar, K. Murai, T. Matsui, M.A. Brebu, M.A. Uddin, A. Muto, Y. Sakata, and K. Murata, Studies on thermal degradation of acrylonitrile-butadiene-styrene copolymer (ABS-br) containing brominated flame retardant, J. Anal. Appl. Pyrolysis, 70(2) 369-381, December 2003. 

In order to rescue the amounts necessary to be added, PS-encapsulated Mg(OH)2 has been prepared. In a high speed mixer Mg(OH)2 was dispersed together with 3-(methacryloxy)propyltri-methoxysilane in acetone solution. After drying, the powder was encapsulated with PS by polymerizing styrene in the mixer. It is believed that the thus modified Mg(OH)2 can be more finely divided in the HIPS matrix an in this way better flame retardancy at lower levels of Mg(OH)2 is achieved (22). 

Methyl methacrylate is often used in combination with styrene to improve light transmission and uv stability in flame-retardant glazing applications. Phosphate ester (triethyl phosphate) additives are also included to supplement flame-retardant efficiency benzophenone uv stabilizers are required to prevent yellowing of these uv-sensitive resins. 

Fe203 and Fe304 in presence of a chloride source act as flame retardants for nitrile-containing plastics and rubbers such as acrylonitrile-butadiene-styrene copolymers.52 The activity appears to be connected with the formation of FeCl3 on combustion, but other properties of FeCl3 itself make it unsuitable for direct use. If an alkyl chloride is present iron(II) citrate may be used, and for halogen-containing nitrile polymers acetates, stearates, sulfates and carbonates are effective. 

---