Aromatic phosphates

Commercially available flame retardants include chlorine- and bromine-containing compounds, phosphate esters, and chloroalkyl phosphates. Recent entry into the market place is a blend of an aromatic bromine compound and a phosphate ester (DE-60F Special) for use in flexible polyurethane foam (8). This paper describes the use of a brominated aromatic phosphate ester, where the bromine and phosphorus are in the same molecule, in high temperature thermoplastic applications. 

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). 

Figure 4. Flame Retarding Polycarbonate/PET Polyester Alloy 1. brominated polycarbonate oligomer 2. brominated polystyrene 3. brominated aromatic phosphate ester...

The most common chain extenders are the dianhydrides (also known as tetracar-boxylic dianhydrides). The most common of these is pyromellitic dianhydride (PMDA). The latter can be used in synergistic combinations with hindered phenolic aromatic phosphates such as IRGANOX 1425 manufactured by Ciba Geigy [6-8], The hindered phenolic aromatic phosphate is used at levels of 0.1-2.5 wt%. The hindered phenolic aromatic phosphate is an advantageous co-synergist since it... 

Amino and functional aromatic phosphates, phosphonates, and phosphine oxides have also been used as reactive components to impart flame retardancy to cured epoxy resins. Phosphine oxides are particularly hydrolytically stable and several studies have been reported, for example, of the curing of epoxy resins with bis(aminophenyl) alkyl and aryl phosphine oxides65-67 (Structure 5.19). The relative performances of epoxies cured with aromatic diamine hardeners containing phosphine oxide, phosphinate, phosphonate, or phosphate units have recently been assessed.68 Aromatic phosphine oxides have been functionalized also with maleimide and hydroxyl groups for use as epoxy resin hardeners.69,70... 

Quantitative risk assessments have been performed on a variety of flame-retardants used both in upholstered furniture fabric and foam. The National Research Council performed a quantitative risk assessment on 16 chemicals (or chemical classes) identified by the U.S. Consumer Product Safety Commission (CPSC). The results were published in 2000.88 The 16 flame-retardants included in this NRC study were HBCD, deca-BDE, alumina trihydrate, magnesium hydroxide, zinc borate, calcium and zinc molybdates, antimony trioxide, antimony pentoxide and sodium antimonate, ammonium polyphosphates, phosphonic acid, (3- [hydroxymethyl]amino -3-oxopropyl)-dimethylester, organic phosphonates, tris (monochloropropyl) phosphate, tris (l,3-dichloropropyl-2) phosphate, aromatic phosphate plasticisers, tetrakis (hydroxymethyl) hydronium salts, and chlorinated paraffins. The conclusions of the assessment was that the following flame-retardants can be used on residential furniture with minimal risk, even under worst-case assumptions ... 

Polystyrene and PPO are miscible polymers, and HIPS is typically used in these blends for greater toughness. HIPS-PPO blends can be flame retarded with brominated flame retardants, but perhaps of more interest are blends flame retarded with aromatic phosphates. Phosphates are thought to act through promotion of charring of PPO, but may also have some vapor-phase activity. Typical levels of PPO used to achieve a UL 94 V-0 rating are 30-50% these blends also contain 10-20% of an aromatic phosphate [28]. 

Polycarbonate and ABS are not miscible, but blends are compatible and have excellent toughness. PC-ABS blends are also flame retarded with aromatic phosphates. These blends are typically very high in polycarbonate (70-80%) and also contain at least 10% of an organic phosphate. PC-ABS blends are preferred for unpainted applications because of their excellent UV stability. 

Further studies on the photoisomerization of ci5-cyclohexene and cycloocta-1,3-diene have been reported. Again the work has focused on enantiodiffer-entiation. In this case a series of optically active chiral sensitisers (3) have been used under conditions where solvent and temperature have been varied. Some of the o-disubstituted and tetra substituted amide sensitisers afford mixtures with enantioisomeric excesses of 14%. The influence of pressure and temperature on the asymmetric photochemistry of cyclooctene has been reported. A variety of chiral sensitisers were used. Some of these are shown in (4). Other work has shown that aromatic phosphates, phosphinates and phosphines (e.g. 5-8) can also sensitise the isomerism of cyclooctene. Moderate stationary-state ratios were obtained. 

Both acid and alkaline phosphatases have been used to cleave aliphatic and aromatic phosphate monoesters. Table 13-6 shows typical examples ordered according to the substrate class. This table includes an example where the enzymatic reaction was run with a sensitive substrate (entry 1), and examples where regio- or a stereoselectivity was required (entries 2 and 5, respectively). 

An aromatic phosphate, phenyl ester of phosphoric acid... 

Chem. Descrip. Aromatic phosphate ester, sodium salt Uses Detergent, emulsifier, wetting agent tor heavy-duty, all-purpose, hard-surf., and metal cleaners emulsifier tor min. oil, crude oil, pesticides paraffin dispersant for oil treatment prolongs life of wax and resin floor finishes... 

Chem. Descrip. 85% DE-71 (pentabromodiphenyl oxide), 15% aromatic phosphate... 

Chem. Descrip. Aromatic phosphate ester of ethoxylated nonylphenol, free acid CAS 51811-79-1... 

Tensile yield strength decreases with an increase in the plasticizer concerrtratiorr At higher values of stress intensity, fatigue occrrrs by shear yielding and this is more likely to occur as a function of increased concerrtration of the plasticizer The creep resistance of PVC was increased by use of reactive plasticizer Flexural modtrlus of PC and PPE was increased by the increase in concentration of plasticizers such as aromatic phosphates and phthalates. ... 

Several recent patents concern thermoplastic polyesters for electrical goods. DuPont has disclosed a moulding composition for PBT, to which is added a reinforcement and a mixture of melamine pyrophosphate with an aromatic phosphate oligomer. The physical properties are reported to be good (EP 903370). 

Phthalates have a strong cost advantage over the competition, and alternatives are used only when phthalates are unsatisfactory. Other plasticisers include the citrates, trimellitates, adipates, sebacates, maleates, gjutarates, palmitates, oleates, stearates, laurates, benzoates, aromatic phosphates, the alkyl sulfonates of phenol, and derivatives of petroleum and of butene. There... 

The most widely used alternatives are ahphatic esters, together with aromatic phosphates, the trimellitates, citrates, the aliphatic polyesters and the epoxidised vegetable oils. 

A nucleating agent masterbatch for polyolefin resin has excellent in dispersibility in a polyolefin resin, improves transparency and mechanical strength and has excellent thermal resistance. It contains aromatic phosphate salt. Compound is used for production of parts for the consumer electrical appliances, such as refrigerators, washing machines and many other household products. ... 

Manufacture of liners for cabinet of a refrigerator requires addition of nucleating agent, which is P-nucleating agent. Aromatic phosphate salt is used in additive master-batch for home appliance production. ... 

Saba, C.S., Forstes-, N.H. ReactioDS of aromatic phosphate esters with metals and their oxides. Tribol. Lett. 12, 135-146 (2002). doi 10.1023/A 1014081523491... 

Aromatic phosphate polymers were foimd to have good transparency, hardness, and adhesion, but too brittle and hydrolytically imstable. 

Oligomeric aromatic phosphates have been patented and commercially used as flame-retardant additives mainly for impact-resistant polystyrene blends with polyphenylene oxide and polycarbonate blends with acrylonitrile-butadiene-styrene (ABS) copolymers (130,131). They have also been shown useful in thermoplastic polyesters (92). The principal commercial examples are based on phenol and resorcinol (Akzo-Nobel s Fyrolflex RDP) or phenol and bisphenol A (Akzo-Nobel s Fyrolflex BDP or Albemarle s Ncendx P-30). Although these have the diphosphate as their principal ingredient, they also contain higher oligomers. 

Yuan CY, Chen SY, Tsai CH, Chiu YS, Chen-yang YW. Thermally stable and flame-retardant aromatic phosphate and cyclotriphosphazene-containing pol5nirethanes synthesis and properties. Polym Adv Technol May 2005 16(5) 393-9. 

These aromatic phosphate esters in free acid form find application in nearly all fields that use surfactants. They are especially suited for use as emulsifiers for polymers, pesticides, cleaning fluids and other compounds. 

In general purpose applications competitively priced thermosets are used for the printed circuit board base material which is usually FR4 (Flame Retardant) . One of the main flame retardants used in America is to have tetrabromobisphenol-A reacted into the epoxy resin. Non-halogen systems include additives such as alumina trihydrate, alumina trihydrate/red phosphorus and aromatic phosphates. Flame retardant epoxy coatings are reported to use ammonium polyphosphate with char-forming additives. 

The increase in effectiveness of aromatic phosphates when combined with halogenated derivatives, as observed in [84, 85], could be caused by the conversion of triarylphosphate into acidic derivatives of Phosphorous phorus according to reactions similar to (B). This reaction prevents tb conversion of triarylphosphate in the gas phase, reinforces the effect of the phosphorus compound on the processes occurring in the condensed phase and at the same time, controls the supply of CgHsC 1 in the gaseous phase, which is the source of HCl in the flame. Monophosphoric acids formed during reactions (A) - (C) can be converted into polyphosphoric acids by the scheme given above,... 

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