Flame retardant terephthalate

In poly(ethylene terephthalate) (14—16) and poly(methyl methacrylate) (17—19), the mechanism of action of phosphoms flame retardants is at least partly attributable to a decrease in the amount of combustible volatiles and a corresponding increase in nonvolatile residue (char). In poly(methyl methacrylate), the phosphoms flame retardant appears to cause an initial cross-linking through anhydride linkages (19). 

Polyester Fibers Containing Phosphorus. Numerous patents describe poly(ethylene terephthalate) (PET) flame-retarded with phosphoms-containing diftmctional reactants. At least two of these appear to be commercial. 

This phosphinic anhydride [15171 -48-9] C H O P, is then reacted with glycol and other precursors of poly(ethylene terephthalate), to produce a flame-retardant polyester [82690-14-0] having phosphinate units of the stmcture —0P(0)(CH2)CH2CH2C00—. Trevira 271 is useflil for children s sleepwear, work clothing, and home flirnishings. A phosphoms content as low as 0.6% is reported to be sufficient for draperies and upholstery tests if melt-drip is not retarded by print pigments or the presence of nonthermoplastic fibers (28). 

Propylene oxide has found use in the preparation of polyether polyols from recycled poly(ethylene terephthalate) (264), haUde removal from amine salts via halohydrin formation (265), preparation of flame retardants (266), alkoxylation of amines (267,268), modification of catalysts (269), and preparation of cellulose ethers (270,271). 

Convincing evidence for phosphorus/bromine synergy has now been found in a 2/1 polycarbonate/polyethylene terephthalate blend. Phosphorus and bromine blends were studied as well as compounds which have both elements in the same compound. The relative flame retardant efficiencies of phosphorus and bromine are also reported. 

A 2/1 blend of polycarbonate and polyethylene terephthalate (PC/PET) was flame retarded with bromine, phosphorus, a blend of bromine and phosphorus, and compounds containing both phosphorus and bromine in the same molecule. All compositions contained 0.5 % Teflon 6C as a drip inhibitor and where specified 5 % of an impact modifier. 

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). 

Aromatic polyphosphonates have been found to be especially effective flame retardant additives for polyester compositions (j), 1, 8), especially for polyethylene terephthalate. 

PBDEs are used in different resins, polymers, and substrates at levels ranging from 5 to 30% by weight (EU 2001). Plastic materials that utilize PBDEs as flame retardants include ABS polyacrylonitrile (PAN) polyamide(PA) polybutylene terephthalate (PBT) polyethylene (PE) cross-linked polyethylene (XPE) polyethylene terephthalate (PET) polypropylene (PP) polystyrene (PS) high-impact polystyrene (HIPS) polyvinyl chloride (PVC) polyurethane (PUR) and unsaturated polyester (UPE). These polymers and examples of their final products are summarized inTable 5-2 (Hardy 2002 WHO 1994a). 

Condensation monomers having the benzimidazolin-2-one ring system have found utility as modifiers in polyester synthesis. In particular, halogenated diols (73) and dicarboxylic acids (74) may be incorporated (78MI11100) into polyethylene terephthalate) or poly(butyl-ene terephthalate) at fairly low levels to impart flame retardancy. This can be accomplished without adverse effects upon other polymer properties. 

POLYARYLATES. These are clear, amorphous thermoplastics that combine clarity, high heat deflection temperatures, high impact strength, good surface hardness, and good electrical properties with inherent ultraviolet stability and flame retardance. No additives or stabilizers are required to provide these properties. Polyarylates are aromatic polyesters that are manufactured from various ratios of iso- and terephthalic acids with bisphenol A.1 The resultant products are free-flowing pellets which can be processed by a variety of thermoplastic techniques in transparent and... 

Blends of iso- and terephthalates give amorphous, transparent resins, mosdy yellow in color. Heat-deflection temperatures are higher than those of 100% PC resins and depend on the iso- to terephthalate ratio. For example, a resin with a 1 1 ratio has a value of 160°C. These resins are flame retardant mechanical and electrical properties are similar to those of PC resins. The notched Izod impacts are lower at 150—300 J/m (4.7—5.6 fflbf/in.), even in thick sections. Long-term uv radiation stabilities are excellent, but yellowness increases during initial exposure owing to photo-Fries rearrangements (80), wherein 0-hydroxy-benzophenone units are produced along the polymer chains. 

The use of trimellitates is expected to regain ground lost due to TMA shortages in the late seventies. Polymeries will continue to be used in those areas where high solvent extraction resistance and migration are major concerns. Phosphates are expected to continue their growth in flame retardant applications. Also, new capacity for dioctyl terephthalate (DOTP) has been announced(25). 

The red allotropic form of phosphorus is relatively nontoxic and, unlike white phosphorus, is not spontaneously flammable. Red phosphorus is, however, easily ignited. It is a polymeric form of phosphorus, thermally stable up to ca. 450°C. In its finally divided form, it has proved to be a powerful flame-retardant additive.18 Elemental red phosphorus is a highly efficient flame retardant, especially for oxygen-containing polymers such as polycarbonates and polyethylene terephthalate). Red phosphorus is particularly useful in glass-filled polyamide 6,6, where high processing temperature (about 280°C) excludes the use of most phosphorus compounds.19 In addition, coated red phosphorus is used to flame retard nylon electrical parts, mainly in Europe and Asia.20... 

Poly(butylene terephthalate) (PBT) and poly(ethylene-2, 6-naphthenate) (PEN) can be reactively flame retarded with the same types of reagent35 as are used for PET, for example, Structure 5.10. 

Day, M., Suprunchuk, T., and Wiles, D. M., Combustion and pyrolysis of poly(ethylene terephthalate) II. Study of the gas-phase inhibition reactions of flame retardant systems, J. Appl. Polym. Sci., 1981, 26, 3085-3098. 

Wang, D.Y., Ge, X.G., Wang, Y.Z., Wang, C., Qu, M.H., and Zhou, Q. 2006. A novel phosphorus-containing poly(ethylene terephthalate) nanocomposite with both flame retardancy and anti-dripping effects. Macromol. Mater. Eng. 291 638-645. 

Gao, F., Tong, L., and Fang, Z. 2006. Effect of a novel phosphorous-nitrogen containing intumescent flame retardant on the fire retardancy and the thermal behaviour of poly(butylene terephthalate). Polym. Deg. Stab. 91 1295-1299. 

Braun, U. and Schartel, B. 2008. Flame retardancy mechanisms of aluminium phosphinate in combination with melamine cyanurate in glass-fibre-reinforced poly (1,4-butylene terephthalate). Macromol. Mater. Eng. 293 206-217. 

Whereas UL 94 delivers only a classification based on a pass-and-fail system, LOI can be used to rank and compare the flammability behavior of different materials. In Figure 15.2 the increasing LOI values are presented for different polymers as an example POM = poly(oxymethylene), PEO = poly(ethyl oxide), PMMA = poly(methyl methacrylate), PE = polyethylene), PP, ABS, PS, PET = polyethylene terephthalate), PVA = poly(vinyl alcohol), PBT, PA = poly(amide), PC, PPO = poly(phenylene oxide), PSU, PEEK = poly(ether ether ketone), PAEK = poly(aryl ether ketone), PES, PBI = poly(benzimidazole), PEI = poly(ether imide), PVC = poly(vinyl chloride), PBO = poly(aryl ether benzoxazole), PTFE. The higher the LOI, the better is the intrinsic flame retardancy. Apart from rigid PVC, nearly all commodity and technical polymers are flammable. Only a few high-performance polymers are self-extinguishing. Table 15.1 shows an example of how the LOI is used in the development of flame-retarded materials. The flame retardant red phosphorus (Pred) increases... 

Braun U, Bahr H, Sturm H, Schartel B. Flame retardancy mechanisms of metal phosphinates and metal phosphinates in combination with melamine cyanurate in glass-fiber reinforced poly(l,4-butylene terephthalate) The influence of metal cation. Polym. Adv. Technol. 2008 19 680-692. 

M. Day and D. M. Wiles, Influence of temperatnre and environment on the thermal decomposition of polyethylene terephthalate fibres, with and withont the flame retardant tri(2,3)-dibromopropyl phosphate., J. Anal Appl J rolysis, 7, 65-82, (1984). 

T. Bhaskar, J. Kaneko, A. Muto, Y. Sakata, E. Jakab, T. Matsui, and M. A. Uddin, Effect of poly(ethylene terephthalate) on the pyrolysis of brominated flame retardant containing high impact polystyrene and catalytic debromination of the liquid products, J. Anal. Appl. Pyro., 71, 765-777 (2004). 

Aromatic polyesters formed from 4,4 -isopropylidenebis(2,6-dibromophenol), from various analogous bisphenols differing in the character of the bridge [94] or from 2,2 -bis[3,5-dibromo-4-(2-hydroxyethoxy)phenyl]propane and terephthalic or isophthalic acids possess [194] good thermal resistance and flame retardance. 

Polyphosphates derived from 4,4 -dihydric phenols or 4,4 -isopropylidenebis-phenol, bis(2,6-dibromophenol) and having an active moiety like 154 impart flame retardant properties [ W]. Thermostable polyesters were prepared by addition of bis(2-hydroxyethyl)phosphate prior to the final step of the polycondensation of ethylene glycol with dimethyl terephthalate [205]. Zinc salt of polydithiophosphate obtained by reaction of phosphorus pentasulfide with 4-substituted anisole was tested as AO in lubricating oils and greases. 

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