Sodium antimonate

Table 2. Properties of Antimony Pentoxide and Sodium Antimonate...

Sodium Antimonate. Sodium antimonate [15593-75-6] Na SbO, another antimony synergist of commercial importance, has an antimony content of 61—63 wt % and a bulk density of 39.4—46.4 kg/m. Properties are given in Table 2. It is made by oxidizing antimony trioxide using sodium nitrate and caustic. It is a white powder and has a pH of around 9—11 when dissolved in water. 

Sodium antimonate contains less antimony than either antimony trioxide or pentoxide and is thus less effective. However, its unique pH and low refractive index makes the antimonate the most desirable synergist for polymers that hydrolyze when processed with acidic additives or in polymers for which deep color tones are specified. Sodium antimonate costs approximately 3.30—4.40/kg and can be obtained from either Elf Atochem NA under the Thermoguard name or from Anzon Inc. as a Timinox product. 

The niter and fresh caustic soda, required to maintain the fluidity of the salt bath in the reactor chamber, are added gradually. When the color of the saturated salts turns from a dark gray to white, the impurity metals are at their highest state of oxidation, and the lead content of the spent salts is very low. In a modification, the arsenic and tin are selectively removed as sodium arsenate and sodium stannate, followed by the removal of antimony as sodium antimonate. 

Wet Process. The sodium arsenate and stannate slag are treated by a leach and precipitation process to produce calcium arsenate, calcium stannate, and a sodium hydroxide solution for recycle. The sodium antimonate filtercake containing selenium, tellurium, and indium is treated in a special metals refinery to recover indium and tellurium. 

By-Product and Secondary Antimony. Antimony is often found associated with lead ores. The smelting and refining of these ores yield antimony-hearing flue, baghouse, and CottreH dusts, drosses, and slags. These materials may be treated to recover elemental antimony or antimonial lead from which antimony oxide or sodium antimonate may be produced. 

Antimony Compounds. The greatest use of antimony compounds is in flame retardants (qv) for plastics, paints, textiles, and mbber. Antimony compounds used in flame retardants are antimony pentoxide, sodium antimonate [15593-75-6] Na[Sb(OH) ], and, most importantly, antimony trioxide. These compounds, when used alone, are poor flame retardants however, when combined with halogen compounds, they produce mixtures that are effective. 

Antimony trioxide and sodium antimonate are added to specialty glasses as decolorizing and fining agents, and are used as opacifiers in porcelain enamels. Antimony oxides are used as white pigments in paints, whereas antimony trisulfide and pentasulfide yield black, vermilHon, yeUow, and orange... 

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). 

Table VII shows that sodium antimonate is antagonistic with the phosphorus/bromine compound in 30% glass filled PET polyester resin.

Antimony oxide flame retardants act as depolymerization agents for PET. Instead, sodium antimonate is the synergist of choice. 

Generally, flame retardants for engineering PET compositions are based on bromine-containing compounds (such as brominated polycarbonate, decabro-modiphenyl oxide, brominated acrylic, brominated polystyrene, etc.). Such compounds are available commercially (such as from the Ethyl Chemical Corporation, Great Lakes Chemical Corporation, Dead Sea Bromine Company, etc.) In addition, the flame-retardant package generally contains a synergist, typically sodium antimonate. PET may also be flame-retarded with diarylphosphonate, melamine cyanurate or red phosphorus. 

The two main brominated flame retardants used commercially in PET are PyroChek 68PB (see Figure 14.18) and Saytex HP-7010 (Albemarle). Both of these flame retardants are based on brominated polystyrene. While there are similarities between these flame retardants, they are not equivalents. There are quality and performance differences between these two products as they use different raw materials (i.e. polystyrenes) and the process for bromination is different. Saytex HP-7010 has better thermal stability and colour control than does PyroCheck 68 PB. However, if higher flow characteristics are a necessary property of the FR-PET, then Pyrocheck 68 PB would be the product of choice. Sodium antimonate is the appropriate synergist in PET since it is more stable at the higher processing temperatures required of PET and does not cause depolymerization of this polyesters. 

Sodium antimonate Thermoguard FR sodium antimonate OxyChem... 

PET requires special flame-retardant chemistry since the antimony oxide synergist that is normally used in combination with brominated flame retardants causes de-esterification of the PET chain and concomitant molecular weight loss. In place of antimony oxide, PET requires a sodium antimonate synergist. Another problem with antimony trioxide is that it decreases the thermal stability of the brominated flame retardant which then produces hydrobromic acid which degrades the PET. 

Mercuric chloride Unknown s Sodium antimonate Unknown s... 

The sparingly soluble sodium antimonate is filtered out of the solution. The yellow-orange antimony pentasulfide precipitates out on treatment with hydrochloric acid. 

Antimony pentasulfide reacts with caustic soda forming soluble sodium thioantimonate, Na3SbS4. It is sparingly soluble in sodium antimonate, NaSbOs. It forms a yellow solution with ammonia, and leaves a residue of antimony trisulfide, Sb2S3 and sulfur. 

Sodium antimonate and thioantimonate are formed when a mixture of antimony trisulfide and sulfur are added to an excess boiling aqueous caustic soda solution ... 

Stable hydrosols may be obtained similarly by reduction of arsenious oxide, dissolved in aqueous sodium hydroxide containing some other protective colloid such as gelatin or egg-albumin, by means of alkaline pyrogallol.6 Salts of metallic acids, such as sodium antimonate or calcium plumbate,-with or without the addition of protalbic acid, may also be employed as protective colloids.1... 

This anhydrous zinc borate is recommended for use in engineering plastics processed at temperatures higher than 300°C which is the upper limit of Firebrake ZB processing temperature. It is reported to be an effective smoke suppressant in chlorofluoropolymers for plenum cable applications.66 Recently it was claimed that this anhydrous zinc borate can replace antimony oxide (or sodium antimonate) completely in high temperature polyamide applications. Like its hydrated analog, this anhydrous zinc borate can also improve CTI, thermal stability, and the color stability of polyamide containing halogen sources.67 68... 

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 ... 

Sodium antimonate.—This substance is precipitated by the interaction of potassium antimonate and a concentrated solution of a sodium salt, its formation affording a means of testing for sodium. The white, amorphous salt may be regarded as the hydrated meta-antimonate, NaSb03,3 H20, or, since one molecule of water is expelled above 200° C., it may be considered a pyroantimonate, Na2H2Sb207,6H20.12 Its heat of formation from the elements is 346 4 Cal.13... 

All salts of sodium, potassium, and ammonium are soluble except NaSb(OH),. (sodium antimonate), KoPtCl (potassium hexachloro-platinate), (NH4).,PtCl,p K3Co(NO.,),i (potassium cobaltinitrite), and (NH4),Co(N02),. ... 

The oxides and acids of antimony resemble those of arsenic, except that antimony in antimonic acid has coordination number 6, the formula of antimonic acid being HSb(OH)3. A solution of potassium antimonate, K+[Sb(OH)g], finds use as a test reagent for sodium ion sodium antimonate, NaSb(OH)3, one of the very few sodium salts with slight solubility in water (about 0.03 g per 100 g), is precipitated. The. antimonate ion condenses to larger complexes when heated this condensation may ultimately lead to macromolecular structures, such as... 

Ryton R-10 7006A 25212-74-2 Sodium Antimonate 11112-10-0 Sodium Palmitate 408-35-5... 

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