Flame Retardant Treatments

Phosphoric Acid-Based Systems for Cellulosics. Semidurable flame-retardant treatments for cotton (qv) or wood (qv) can be attained by phosphorylation of cellulose, preferably in the presence of a nitrogenous compound. Commercial leach-resistant flame-retardant treatments for wood have been developed based on a reaction product of phosphoric acid with urea—formaldehyde and dicyandiamide resins (59,60). 

Flame-Retardant Treatments For Wool. Although wool is regarded as a naturally flame-resistant fiber, for certain appHcations, such as use in aircraft, it is necessary to meet more stringent requirements. The Zirpro process, developed for this purpose (122,123), is based on the exhaustion of negatively charged zirconium and titanium complexes on wool fiber under acidic conditions. Specific agents used for this purpose are potassium hexafluoro zirconate [16923-95-8] [16923-95-8] K ZrF, and potassium hexafluoro titanate [16919-27-0], K TiF. Various modifications of this process have been... 

Flame Retardant Treatments for Timber, Wood Information 2/3, Sheet 3, Timber Research and Development Association (1988)... 

Toxicological investigations of tetrakishydroxymethylphosphonium salts [(HOCH2)4P+ X X = Cl, THPC X = (S04)0,5, THPS] and their derivatives, used for the flame-retardant treatment of cotton, have been carried out (cf. Table 9). It was concluded that the salts and their urea condensation products are harmful to animals on oral or dermal application. Moreover, at sublethal doses, the salts gave no evidence of carcinogenesis in rodents when applied by the dermal or gavage routes. The polymers produced from them did not exhibit any adverse reactions194. 

Tetrakishydroxymethylphosphonium salts (THPC, THPS, etc.) are of major importance as raw material monomers in the flame-retardant treatment of cotton (industrial protective clothing, furnishing fabrics, etc.). Proban chemicals are produced from THPC or THPS with urea194. These compounds have been often patented as additives of natural and artificial fibres210,211, coatings 212,213 and in fire-proofing solution for wood214. 

Flame relardanls are used in smolder-resistant upholstery fabric, combination flame retardant-durable press performance, flame-retardant treatments for wool, thermoplastic fibers (Tris. decabromodiphenyl oxide-polyacrylate finishes. Antihlu/e 19. nylon finishes), polyester-cotton fiber blends (THPOH-ummonju-Tris finish, decabromodiphenyl oxide-polyacrylate finish. THPC-amide-polytv illy I bromide) finish, THPOH-NHi and Fyrol 76. LRC-UX) finish, phusphonium salt-urea precondcn-satej. cotton-wool blends, and core-yam fabric,... 

The implications of using inorganic salt flame-retardant treatments with timber." BRE Information IS 13/74. 

Kandola, B., Horrocks, A. R., Price, D., and Coleman, G., Flame retardant treatment of cellulose and their influence on the mechanism of cellulose pyrolysis, Revs. Macromol. Chem. Phys., 1996, C36, 721-794. 

LeVan, S.L. and Tran, H.C. 1990. The role of boron in flame retardant treatment. First International Conference on Wood Protection with Dijfusable Preservatives Proceedings, vol. 47355, November 28-30, Nashville, TN, Forest Product Research Society, Madison, WI, pp. 39-41. 

Another flame-retardant treatment for wool based on exhanstion of an anionic species is the use of tetrabromophthalic anhydride, TBPA (Fig. 8.16), which hydrolyses to the carboxylic form during application. Use of TBPA at 10 % on weight of fabric under acid conditions provides effective flame retardancy that is dnrable to dry cleaning and mild laundering conditions (cold water washing at nentral pH). But TBPA is suspected to generate polybrominated dioxins under burning conditions. 

Polyester fabrics when burned exhibit a melt-drip behaviour. Since the fabric melts away from the flame, some polyester fabric constructions can actually pass vertical flame tests without any flame-retardant treatment. The waiving of melt-drip specifications for children s sleepwear has allowed untreated polyester garments to be sold into that market. 

Uses Durable flame retardant treatment for cellulosics. For use by PROBAN licensees only. 

It is generally understood that a suitably flame retarded fabric should retain this property under conditions of wear, wash and weather. Furthermore, the flame retardant component should not effectively alter the fabric characteristics including hand, drape, adsorbency, strength and durability. In addition, this component should not adversely modify other chemicals designed to impart color, size, mildew resistance, water repellency and the like. Finally, the incorporation of a flame retardent treatment in the processing cycle of the fabric should not burden the user with excessive cost. 

Yet another problem which may confront the engineer is the presence of very hot particles. Whether from combustion, drying, or other process, these particles have been known to be carried with the gas stream into the filtration compartment, where they present a serious risk of fire. (In certain conditions even ostensibly nonflammable polyaramid fibres have been found to ignite.) Consequently, if adequate particle screening is not provided, the fabric may require a special flame retardant treatment. 

These factors usually mean that the majority of acceptable flame retardant treatments involve one of the following chemical processes ... 

Headliners are particularly complex textile-based composites because not only do they incorporate acoustic insulative materials but they also incorporate components such as internal mirrors, interior lighting, and associated wiring - a particular fire hazard. A typical structure described by Fung and Hardcastle shows that up to seven or more component layers may be present in a modem headliner, as outlined in Table 11.11 such a structure is truly a technical textile. The whole composite must be thermoformable with individual layers bound together using adhesive films or powders. Careful selection of each component is essential if it is to pass FMVSS 302 without the need for additional flame retardant treatment. 

The same with flame-retardant treatment on the inner surface 75 0.55... 

Kozlowski R, Wesolek D, Wladyka-Przybylak M, Duquesne S, Vannier A, Bourbigot S and Delobel R (2007), Intumescent flame-retardant treatments for flexible barriers. Materials Science, 97(1), pp. 39-61. 

Dermeik E, Braun R, Lemmer KH and Lung M (2006), WO 2006/102962, Process for the flame-retardant treatment of fiber materials. 

It is probably evident from the above introductory discussion, and important to realise, that the whole issue of heat and fire protection with respect to textiles is a complex area involving knowledge of elements of fire science, flame retardant treatments, development of heat and fire resistant fibres and derived textile structures and the inter-relationships between regulations, applications and markets. The bibliography lists a number of prime sources of information in these areas, and for an overview of textiles for fire and heat protection the reader should refer in particular to a recent article by this author. In this chapter, the focus will be only on high performance textiles in which fire and heat protection are essential requirements. 

Modem fire protection techniques have developed through multidiscipline activities in science and engineering and involve careful selection of materials, end-use product design and manufacture, and fire performance and risk assessment. Reducing the flammability of materials is still an essential primary fire safety consideration. PP is an inherently flammable material and therefore flame retardant treatment of the polymer is an essential consideration in relation to fire safety. For material scientists, however, it is also very important to be aware of developments in fire safety science and engineering including the transition from prescriptive to functional regulation of fire safety in many coimtries. 

Ramie reinforced PLA biocomposite with flame retardancy by using APP on preserving the environmental fiiendly character of biocomposites has been studied. Here, natural fibers can be used as char formers in association with APP to increase the char yield of biocomposites. The flame retardancy of biocomposites is obtained by three means (Fig. 4.36). PLA is blended with APP, then the resulting flame-retarded PLA is combined with ramie fibers (ramie fibers with flame retardant treatment by APP is compoimded with PLA) PLA and ramie both of which have been flame-retarded by APP are blended together. 

Bostic et al. (113) reported on a series of PCT fabrics treated with selected phosphorus- and halogen-containing flame retardants which were studied by static oxygen bomb calorimetry. The amount of heat evolved when these fabrics were burned in the open atmosphere was determined indirectly using calculations based on Hess law of summation. The heat evolution, when corrected for contributions due to burning of the flame retardant, appeared to correlate with the efficiency of the flame retardant treatment and was interpretable in terms of mechanisms of flame retardant action. 

The flammability properties described earher show the potential in specific segments of the apparel market. PLA fabrics with no flame retardant treatments have passed the US tests 16 CFR1610, and have also achieved the standards specific for children s sleepwear, 16 CFR 1615 and 16 CFR 1616. 

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