Flame retardant phosphate-based

Ammonium phosphates were first recommended for flame retarding theater curtains by Gay-Lussac in 1821. Mono- and diammonium phosphates, or mixtures of the two, are widely used to impart flame resistance to a wide variety of cellulosic materials such as paper, cotton, and wood.21 These salts have proven to be highly efficient at relatively low costs of application. They are also very effective in preventing afterglow. However, flame-retardant formulations based on these salts are generally nondurable, because they are water soluble and, therefore, are easily susceptible to leaching out from the material matrix. 

Many intumescent flame retardants are based on mixtures of polyols, amines such as melamine, and phosphates such as ammonium polyphosphate. These have not been much used in vinyl because of potentially degradative effects and because of equivalent protection being supplied by phosphate plasticizers. Ammonium polyphosphate (APP), used mostly as fertilizer, is available in polymer grades from Clariant under the trade name Exolit AP. Similarly, there seems to have been little use of red phosphoras, available as Exolit RP. Work in other areas suggests investigation of... 

With a recent push toward non-brominated flame retardants, phosphorus-based alternatives, such as phosphate esters, are used more frequently for various applications. Their use as plasticizers is also well known. However, their function as environmental stress crack agents of various thermoplastics is less well recognized. Two case studies, one - in which a triaryl phosphate was a component of the formulation, the other - in which it was migrating from an adjacent component illustrate some of the problems with their use. Fractographic analysis and various analytical techniques were used to determine a root cause of each of the two failures. 

The tetramethylol derivative of DABT, prepared by reaction of DABT with alkaline aqueous formaldehyde, polymerized readily on cotton. It imparted excellent flame retardancy, very durable to laundering with carbonate- or phosphate-based detergents as well as to hypochlorite bleach. This was accomphshed at low add-on without use of phosphoms compounds or antimony(III) oxide (75—77). 

THPC—Amide—PoIy(vinyI bromide) Finish. A flame retardant based on THPC—amide plus poly(vinyl bromide) [25951-54-6] (143) has been reported suitable for use on 35/65, and perhaps on 50/50, polyester—cotton blends. It is appUed by the pad-dry-cure process, with curing at 150°C for about 3 min. A typical formulation contains 20% THPC, 3% disodium hydrogen phosphate, 6% urea, 3% trimethylolglycouril [496-46-8] and 12% poly(vinyl bromide) soUds. Approximately 20% add-on is required to impart flame retardancy to a 168 g/m 35/65 polyester—cotton fabric. Treated fabrics passed the FF 3-71 test. However, as far as can be determined, poly(vinyl bromide) is no longer commercially available. 

An electric conductive rubber base containing carbon black is laminated with an electric conductive cover layer of phosphoric acid ester plasticizer and other ionic surfactants to prepare antistatic mats, where the covers have colors other than black. It is also reported that alkyl acid phosphates act as color stabilizer for rubber. Small amounts of phosphate esters are helpful in restoring reclaimed rubber to a workable viscosity [284,290]. Esters of phosphoric acid are used in the production of UV-stable and flame-retarded alkylbenzenesulfonate copolymer compositions containing aliphatic resins and showing a high-impact strength... 

An overview is provided of ongoing risk assessments on halogenated phosphate ester flame retardants in Europe. On the basis of the so-called second and fourth Priority lists on Existing Chemicals (Council Regulation No793/93) three chlorinated phosphate ester flame retardants are selected. The selection is based on their hazard profile, volume and use pattern. The three substances involved are TCPP, TDCP and TCEP (Antiblaze V6 from Albemarle is also involved but, due to confidentiality, is not discussed. An outline is provided from a European point of view on topics such as methodology of risk analyses, data-gaps and worst case approach, industry involvement, downstream participation and possible impact of final report on industry. 2 refs. 

The early patent disclosures have claimed the application of a wide spectrum of gas-evolving ingredients and phosphorus-based organic molecules as flame retarding additives in the electrolytes. Pyrocarbonates and phosphate esters were typical examples of such compounds. The former have a strong tendency to release CO2, which hopefully could serve as both flame suppressant and SEI formation additive, while the latter represent the major candidates that have been well-known to the polymer material and fireproofing industries.The electrochemical properties of these flame retardants in lithium ion environments were not described in these disclosures, but a close correlation was established between the low flammability and low reactivity toward metallic lithium electrodes for some of these compounds. Further research published later confirmed that any reduction of flammability almost always leads to an improvement in thermal stability on a graphitic anode or metal oxide cathode. 

While all these phosphate-based cosolvents were shown to be rather stable on various cathode materials, Xu et al. concentrated the evaluation effort on the reduction behavior of these flame retardants at the surface of graphitic anode materials. Figure 76 shows the results obtained with electrolytes containing high concentrations of TMP, TEP, and HMPN. 

Benzoylresorcinol based phosphate esters are obtained by reacting a benzoylresorcinol compound with a chlorophosphate, e.g., benzoylresorcinol with diphenyl chlorophosphate or phosphorus oxychloride. These esters can function both as flame retardants and UV stabilizers for PC/ABS and a series of other polymers (78). 

R.B. Durairaj and G.A. Jesionowski, Benzoylresorcinol-based phosphate ester compounds as flame retardants, US Patent 7 439 289, assigned to Indspec Chemical Corporation (Pittsburgh, PA), October 21, 2008. 

A series of compounded flame retardants, based on finally divided insoluble ammonium phosphate together with char-forming nitrogenous resins, has been developed for thermoplastics.23 These compounds are particularly useful as intumescent flame-retardant additives for polyolefins, ethylene-vinyl acetate, and urethane elastomers. The char-forming resin can be, for example, an ethyle-neurea-formaldehyde condensation polymer, a hydroxyethyl isocyanurate, or a piperazine-triazine resin. Commercial leach-resistant flame-retardant treatments for wood have also been developed based on a reaction product of phosphoric acid with urea-formaldehyde and dicyandiamide resins. 

Mixed esters, such as isopropylphenyl diphenyl phosphate and tcrt-butylphenyl diphenyl phosphate, are also widely used as both plasticizers/flame retardants for engineering thermoplastics and hydraulic fluids.11 These esters generally show slightly less flame-retardant efficacy, when compared to triaryl counterparts however, they have the added advantage of lower smoke production when burned. Some novel oligomeric phosphate flame retardants (based on tetraphenyl resorcinol diphosphate) are also employed to flame retard polyphenylene oxide blends, thermoplastic polyesters, polyamides, vinyls, and polycarbonates. 

A predominantly vapor-phase mechanism of flame retardation has been proposed for flame retardants based on triphenylphosphine oxide and triphenyl phosphate has been proposed (Scheme 5.1). 

Boron compounds such as borax and boric acid are well-known fire retardants in cellulosic products and coatings.12 However, the use of boron compounds such as zinc borate, ammonium pent-aborate (APB), melamine borate, boric oxide, boron phosphate, and other metal borates in polymers has become prominent only since early 1980s.3 6 This chapter will review the chemical and physical properties, the end-use applications, as well as the mode of actions of major boron compounds as fire retardants in different applications. Since boron-based flame retardants are extensively used and quoted in literature, only those formulations of commercial importance and representative literature examples will be discussed and/or cited in this chapter. 

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 ... 

At Bolton, we also have attempted to introduce volatile and possible vapor phase-active, phosphorus-based FR components in back-coating formulations.60 62 The selected FRs included tributyl phosphate (TBP), a monomeric cyclic phosphate Antiblaze CU (Rhodia Specialties) and the oligomeric phosphate-phosphonate Fyrol 51 (Akzo). When combined with an intumescent char-forming pentaerythritol (PER) derivative (NH1197, Chemtura) and applied as a back-coating on to cotton and polypropylene substrates, significant improvements in overall flame retardancy were observed. 

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