A Review of Recent Progress in Phosphorus-based Flame Retardants

Abstract

Recent patent and technical works indicate a growing interest in halogen-free solutions with the predominance of the literature focusing on phosphorus-based flame retardants. Patents published on the flame retardancy of polycarbonate and its blends significantly exceed the number of patents on flame retardancy of any other polymer. Bridged aromatic diphenyl phosphates, especially resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate) have found broad application because of their good thermal stability, high efficiency, and low volatility. Another actively reported group of compounds are the metal salts of dialkylphosphonic acid as well as calcium hypophosphite, which have recently been found to be particularly effective in poly(butylene terephthalate) and polycarbonate. These products are synergistic with a number of phosphorus and nitrogen-containing compounds, such as melamine salts, which seem to be very efficient and commercially useful in nylons. Printed wiring boards comprise the largest market for flame-retardant polymeric materials. Recently, there has been a strong interest in halogen free solutions in East Asia and Europe. A recent halogen-free introduction is the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, which can be reacted into epoxies. Another reactive product with some processing and property advantages is poly(m-phenylene methylphosphonate). Because of the banning of pentabromodiphenyl ether in Europe and voluntary withdrawal of this product from the market in the US, the polyurethane (PU) industry is searching for a more environmentally acceptable low-scorch alternative. Both halogenated and halogen-free solutions are being considered but the PU industry seems to have a preference for the halogen-free products, generally containing phosphorus.

Effect of Meltable Triazine-DOPO Additive on Rheological, Mechanical, and Flammability Properties of PA6

“…Considering the small reduction of T 5 in the PA6/DTE-DOPO formulation as compared to neat PA6, it seems that the thermal decomposition process of this formulation may be initiated with the release of the FR additive. Additionally, an increased rate of the main degradation process, i.e., sharp curves in the DTG, indicates that the decomposition of the additive may catalyze the scission of the PA6 chains due to the acidic character of the DOPO derivatives [23]. The TGA data in nitrogen suggests that when DTE-DOPO additive was combined with PA6, it resulted in a slight increase in the char formation as compared to the PA6/Exolit OP 1230 formulation.…”

“…Phosphorus-based FRs are among the most efficient and versatile flame retardants, and most of them can act through a combination of vapor-(inhibition of active species in gas phase) and condensed-phase reactions (promotion of the polymer carbonization and char formation) [21,22]. A solution for obtaining sustainable, but also efficient FRs is provided by compounds containing phosphorus (P) and nitrogen (N) as possible synergists [23,24]. The most important nitrogen-containing flame retardants are melamine and its derivatives.…”

Performance of a Novel Sulfonate Flame Retardant Based on Adamantane for Polycarbonate

“…9,10 As a kind of flame retardant additive for PC, sulphonate flame retardant have significant ability to reduce the generation of smoke, heat and toxic carbon monoxide gas during PC combustion. 11,12 This has stimulated the interest in synthesis of new sulphonate flame retardants.…”

“…37, No. 4,2013 48 h, a white precipitate formed gradually and was filtered. Then the precipitate was neutralized by 2 mol/L NaOH and a pH=8 had been achieved.…”

“…2 And research has been diverted to the flame retardants free of bromine and chlorine together with environmental considerations, such as sulfur-, silicone-, or phosphorous-based flame retardants. [3][4][5][6][7][8] Among them sulfonate salts such as potassium perfluorobutane sulfonate, are found particularly effective in flame retardancy of PC even at very low loading. 9,10 As a kind of flame retardant additive for PC, sulphonate flame retardant have significant ability to reduce the generation of smoke, heat and toxic carbon monoxide gas during PC combustion.…”