Other Flame Retardants

Flame retardants Reactive, additive, other systems Prevent ignition of polymer, promote extinguishing types not producing smoke or fumes 

Antistatics, Antistatic/conductive Increase electrical conductivity. 

Curing systems for Accelerators, curing agents. Initiate and control the cure of 

Cross-linking, Forming cross-links between Cross-linking agents for 

Plasticizers Mainly phthalates. but many systems are used Improvement in processability, flexibility used mainly in PVC. but limited use in other plastics 

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Reactive Flame Retardants. Reactive flame retardants become a part of the polymer by either becoming a part of the backbone or by grafting onto the backbone. Choice of reactive flame retardant is more complex than choice of an additive type. The reactive flame retardant can exert an enormous effect on the final properties of the polymer. There are also reactive halogenated compounds used as iatermediates to other flame retardants. Tables 8 and 9 Hst the commercially avaHable reactive flame retardants and iatermediates. 

Brominated Phenols. Tribromophenol [75-80-9] and dibromophenol [615-58-7] are both prepared through bromination of phenol. These are not actually used as reactive flame retardants, but rather as starting materials for other flame retardants such as BTBPE [37853-59-1] and epoxy oligomers. 

FWWMR Finish. The abbreviation for fire, water, weather, and mildew resistance, FWWMR, has been used to describe treatment with a chlorinated organic metal oxide. Plasticizers, coloring pigments, fiUers, stabilizers, or fungicides usuaUy are added. However, hand, drape, flexibUity, and color of the fabric are more affected by this type of finish than by other flame retardants. Add-ons of up to 60% are required in many cases to obtain... 

This provides a durable finish which, unlike many other flame retardants, can withstand repeated (50—100) launderiags without a loss of efficiency. An added advantage is that the feel of the cloth (hand) is Htde effected. Principal markets are ia the treatment of iadustrial protective clothing, military uniforms, and, ia Europe, for furnishings. These products are available from Albright Wilson Ltd. and Cytec Industries Inc. 

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). 

Injection-Molded Products. Numerous housings, electrical enclosures, and cabinets are injection-molded from rigid PVC. These take advantage of PVC s outstanding UL flammabiUty ratings and easy mol ding into thin-waHed parts. PVC has developed melt flow capabiUties to the point where it competes with essentially any other flame-retarded engineering thermoplastic and molds easier than most. 

Other flame retardants and/or smoke suppressants can also be used such as magnesium hydroxide, magnesium carbonate, magnesium-zinc complexes and some tin-zinc compositions. Zinc oxide is a common ingredient in many rubber base formulations used as part of the curing system. At the same time, the action of zinc oxide is similar to that of antimony trioxide, but less effective. 

Blends of flame retardant additives have been advocated as an approach to an optimum balance of properties in the finished products. For example, blends of tetrabromophthalate esters with de-cabromodiphenyl oxide or other flame retardants are reported to yield a V-0 rating in modified PPO and in polycarbonate resins without compromising melt processability or performance properties (23a-b). 

Phosphorus flame retardants, 77 484-510 additive organic, 77 488-489 commercial, 77 487-499 economic aspects of, 11 503 in epoxy resins, 77 499-501 health, safety, and environmental factors related to, 77 501-503 interaction with other flame retardants, 77 486... 

Since hdpe is a linear hydrocarbon polymer and, like linear alkanes, sputters when ignited, it burns readily unless admixed with alumina trihydrate (ATH) or other flame retardants. It has a solubility parameter of 7.9 H and low water absorption (0.01%). 

Melamine polyphosphate Melapur 200 Ciba (Switzerland) PA66/glass fibers, epoxies, synergistic blends with other flame retardants... 

Markezich, R.L. and Aschbacker, D.G., Chlorinated flame-retardant in combination with other flame retardants, ACS Symp. Ser., 599, 65-75, 1995. 

Recently, some reports have explored the potential of synergistic effect between silica and other flame retardants.53-55 For example, silica showed synergistic effect with alumina in polypropylene (PP)/ammonium polyphosphate (APP)—pentaerythritol (PER) intumescent-based system. The data indicate that the HRR values improved by incorporating silica into the intumescent-based formulation and the improvement was much more pronounced by combining both silica and alumina in the formulation. 

Other flame-retardants selected as priority chemicals for the EU Risk Assessment process included tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), tris(2-chloroethyl) phosphate (TCEP), tris (2-chloropropyl) phosphate (TCPP), tris(2-chloro-l-(chloromethyl)ethyl) phosphate (TDCP), and 2,2-bis(chloromethyl) trimethylene bis (bis(2-chloroethyl)phosphate) (V6). The flame-retardant synergist, antimony trioxide (Sb ), was also identified as a priority substance. Table 22.1 contains information on the EU Risk Assessments on the nine flame-retardants and one synergist. 

The Directive of the European Parliament and of the Council 2002/95/EC on the Restriction of the Use of certain Hazardous Substances in Electrical and Electronic Equipment (RoHS) was put into effect on July 1, 2006.75 76 It states that Member States shall ensure that new electrical and electronic equipment (EEE) put on the market shall not contain more than 0.1% of Pb, Hg, Cd, Cr(VI), poly-brominated biphenyls (PBBs), PBDEs, or 0.01% Cr(VI). All other flame-retardants are compliant with the provisions of the RoHS Directive and can be used in EEE. 

There is now discussion as to whether more substances, including other flame-retardants, should be added to the RoHS Directive. The history of the RoHS Directive and potential additions raises some very real concerns over the fundamental relationship between results of risk assessments under regulation 793/93, REACH registrations and evaluations, and the RoHS Directive. Consistency is needed between the REACH Regulation and the other EU directives. REACH evaluations will determine whether restrictions are necessary in all applications including electronic applications, and where authorization for use is necessary. 

CPSC staff performed a preliminary assessment of the potential health risks associated with the use of selected FR chemicals in upholstered furniture foam. FR-treated foam samples that could be used to meet the draft standard and were available to the CPSC staff for testing included melamine tris(l,3-dichloro-2-propyl)phosphate (TDCP) a mixture containing triphenyl phosphate (TPP), phenol isopropylated phosphate (PIP), and octyl tetrabromobenzoate (OTB). Other flame-retardants that could be used in foam have been discussed by the U.S. EPA Design for the Environment Program. Based on limited exposure or toxicity data, the following preliminary conclusions were published in 2006 ... 

VECAP has seen significant successes and was subsequently implemented in five other European Member States, North America, Japan, and other parts of Asia. It has expanded to reduce release potential of other flame-retardants to the environment, including phosphorus flame-retardants. This program is not only a flame-retardant program it is a model program for all polymer additives. Companies participating in VECAP follow a cycle of continuous improvement. This starts with a commitment to the Code of Good Practice and verification of the actual... 

Qiu, X., Marvin, C. H., Hites, R. A. (2007) Dechlorane plus and other flame retardants in a sediment core from Lake Ontario. Environ. Sci. TechnoL, 41 6014-6019. 

CNC PYROBAN SF is a liquid material that is readily soluble in water at all concentrations and is stable indefinitely. It is very compatible with other flame retardants, ammonium sulfa-mate, etc., when combinations are desired. CNC PYROBAN SF is not hygroscopic. 

C min., is unique. CHLOREZ 760 is finding wide application in olefins, styrenes, adhesives, wire and cable and many other flame retardant areas. 

Fully effective without other flame retardants. 

Reactive polyols which contain halogen groups, phosphorus, or both, are offered by a number of suppliers for flame-netardant urethane-foam applications. These materials can be used alone, or with other flame retardants as synergists. Although reactive flame retardants may appear to be more costly initially, in the long run they may be found to be less expensive than the additive types (31). 

In the case of flame retardant silicone elastomer, many ingredients such as silica, platinum, and other flame retardant agents are incorporated into the base siloxane polymer. But there is no need to use the halogenated flame retardant agent, for example, bromine or chlorine compounds. This difference is an advantage of silicones compared with other synthetic polymers in terms of health and safety. 

Polybrominated biphenyls (PBBs) are inert, stable chemicals used primarily as additive flame retardants to suppress or delay combustion. In their use as flame retardants, PBBs were added to polymer materials, but were not chemically incorporated into the polymer matrix and therefore could migrate out of the polymer matrix with time. Hexabromobiphenyl was used as a Are retardant mainly in thermoplastics in electronic equipment housings. Smaller amounts were used as a Are retardant in coating and lacquers, and in polyurethane foam for auto upholstery. After the voluntary ban of hexabromobiphenyl in the late 1970s, polybrominated diphenyl ethers (PBDEs) and other flame retardants were used as replacements. 

The primary use of TBBPA is as a flame retardant in epoxy resin circuit boards and in electronic enclosures made of polycarbonate-acrylonitrile-butadiene-styrene (PC-ABS). Other applications of TBBPA include its use as a flame retardant for plastics, paper, and textiles as a plasticizer in adhesives and coatings and as a chemical intermediate for the synthesis of other flame retardants (e.g., TBBPA allyl ether). It is also been applied to carpeting and office furniture as a flame retardant. 

The next major class of flame retardant additives that are nonhalogenated is the phosphorus-based flame retardants, but even these materials have some regulatory environmental concerns.Other nonhalogenated flame retardants that are not phosphorus-based exist, including mineral fillers (i.e., Al(OH)3, Mg(OH)2), expandable graphite, mela-mine, and polymer nanocomposites combined with other flame retardants.Each of these materials has its own advantages and disadvantages, and effectiveness in one polymer system often does not translate into another system. 

In fire retardant applications, a combination of zinc borate with ammonium polyphosphate gives V-0 rating. The use of zinc borate permits a reduction in the amount of ammonium polyphosphate. Red phosphorus alone or in combination with ammonium polyphosphate or melamine phosphate also produced a V-0 rating. The heat release rate can be effectively improved by small additions (1-2 wt%) of silicone powder in combination with other flame retarding additives or at higher concentration (15 wt%) when used by itself. 

Flame retardant polyurethanes are mostly manufactured with compounds of phosphorus, such as ammonium phosphate or polyphosphate. Aluminum hydroxide alone or in combination with melamine is an alternate approach. In intumescent applications, graphite is frequently used. Calcium carbonate is useful as a flame retarding additive, in combination with other flame retarding materials, because of its large endothennic peak found in DTA curves. ... 

Starting in the 40 s. Dr. Toy and his co-workers at Victor Chemical Works began to develop flame-proof p lymers and later flame retardants for fibers like cotton and cellulose, based on cptionally partly brominated diallyl pho honates. (Figure 12) (20). A well known compound from this series, introduced as "Ihoresins", is diallyl cyanoethylphosphonate (21). Other flame retardants for rayon have been similarly established. 

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