Flame retardants zinc compounds

If the tmns isomer of maleic acid, fumaric acid, is used instead, the resultant product has been characterized most often as tetrabasic, but sometimes as polybasic, lead fumarate. It is probably a mixture of C2H2[C(0H)(0—Pb—OH)2]2 and C2H2[C(0—Pb—0H)2]4, although intermediate products are possible. As with tetrabasic lead sulfate, this stabilizer is off-white or cream-colored and is UV light-sensitive, again yielding black colloidal PbO. Its major use is in low-smoke flame-retardant PVC compounds, where the long failure time provided helps to compensate for instability caused by other additives, particularly zinc compounds and brominated... 

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

Antimony trioxide (SbaOj). It is produced from stibnite (antimony sulphide). Some typical properties are density 5.2-5.67 g/cm- pH of water suspension 2-6.5 particle size 0.2-3 p,m specific surface area 2-13 m-/g. Antimony trioxide has been the oxide universally employed as flame retardant, but recently antimony pentoxide (SbaOs) has also been used. Antimony oxides require the presence of a halogen compound to exert their fire-retardant effect. The flame-retarding action is produced in the vapour phase above the burning surface. The halogen and the antimony oxide in a vapour phase (above 315 C) react to form halides and oxyhalides which act as extinguishing moieties. Combination with zinc borate, zinc stannate and ammonium octamolybdate enhances the flame-retarding properties of antimony trioxide. 

Zinc oxide occurs in nature as mineral zincite. It is the most important zinc compound and has numerous industrial applications. Zinc oxide is the pigment in white paints. It is used to make enamels, white printing inks, white glue, opaque glasses, rubber products and floor tiles. It is used in cosmetics, soaps, pharmaceuticals, dental cements, storage batteries, electrical equipment, and piezoelectric devices. Other applications are as a flame retardant, as a UV absorber in plastics, and a reagent in analytical chemistry. A major application of zinc oxide is in the preparation of most zinc salts. In medicine, the compound is used as an antiseptic, an astringent and a topical protectant. 

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. 

Shen, K.K. 1988. Zinc borate as a flame retardant in halogen-free wire and cable systems. Plastics Compounding, Edgell Communication, Cleveland, OH, November/December. 

Flexible PVC (Table 15.6) is made by polymerizing at 40-55°C and then compounding with 20-80 PHR (parts per hundred of resin) of dioctyl phthalate and/or other monomeric liquid plasticizers (e.g., dioctyl adipate for low-temperature flexibility, oligomeric polyesters for permanence, organic phosphates for flame-retardance), plus a synergistic stabilizer system usually composed of barium or calcium soap, zinc soap, epoxidized fatty ester, and organic phosphite. 

Still, some harmful compounds can appear in waste plastics, e.g. additives containing antimony, cadmium, lead, zinc, or hexavalent chromium, and plasticizers. Brominated flame retardants spreading into the environment is another reason for concern and a rational argument for dealing with WEEE and ASR-plastics [37]. 

Use Manufacture of carbon tetrachloride, trichloroethylene, chlorinated hydrocarbons, polychloro-prene (neoprene), polyvinyl chloride, hydrogen chloride, ethylene dichloride, hypochlorous acid, metallic chlorides, chloracetic acid, chlorobenzene, chlorinated lime water purification, shrinkproofing wool, flame-retardant compounds, special batteries (with lithium or zinc) processing of meat, fish, vegetables, and fruit. For information, refer to the Chlorine Institute, 2001 L St., NW, Suite 506, Washington DC 20036. 

Certain tin compounds, particularly zinc hydroxystannate (ZHS) and zinc stannate (ZS), are effective flame retardants in a wide range of polymeric substrates and offer technical advantages over many competitive additives ... 

Special considerations presence of zinc, copper, iron and nickel compounds accelerated dehydrochlorination combination of basic magnesium carbonate and aluminum hydroxide is used as flame retardant and smoke supressant chlorinated polyethylene adsorbs on the surface of titanium dioxide forming a layer 1-20 nm thick depending on the aciii/base interaction parameter of titanium dioxide ... 

Some of the inorganic compounds, snch as antimony trioxide (Sb203), or boron-based componnds, snch as zinc borate, fnnction as synergists rather than directly as flame retardants bnt enhance the effectiveness of the latter. Antimony trioxide is used mainly with halogenated flame retardants. 

Aluminum trihydrate, magnesium hydroxide, calcium and zinc molybdates, antimony pentoxide, and zinc borate are examples of inorganic compounds used as flame retardants in the manufacture of household furniture, upholstery, wall coverings, draperies, and carpets (National Research Council (NRC), 2000). Antimony trioxide is sometimes used in combination... 

There have been substantial efforts to improve the flame resistance of nylons. Various halogen compounds (synergized by zinc oxide or zinc borate) and phosphorus compounds have been used (see the section on Flame Retardation in Chapter 1). They are, however, dark in color. 

When a PA is to be used in applications requiring self-extinguishing characteristics and flame retardant properties, it is necessary to resort to the addition of a flame retardant. Flame retardant formulations, known in the field of poly(ester)s, can be widely adapted to PAs. Brominated poly(styr-ene) in combination with an antimony compound, such as sodium antimon-ate, can be used." The performance is improved when a minor amount of calcium oxide is added. The thermal stability of these compositions is much better in comparison to formulations with magnesium oxide or zinc oxide. 

Tributyl (tetradecyl) phosphonium chloride Tri (P,P -dichloroisopropyl) phosphate Trimethyl phosphate Triphenylphosphine oxide Tris-dibromopropylisocyanurate 4-Vinylcyclohexene Zeolite Zinc oxide Zirconium potassium hexafluoride flame retardant compounds Chlorine... 

There are several fillers and inoiganic/organic additives used in flame retarded materials and these include antimony oxide, aluminum trihydrate, zinc borate, ammonium octamolybdate, and zinc stannate. The details related to the composition required and performance characteristics of inorganic additives can be found in specialized monograph. Some of these compounds are discussed below in relation to their effects on enhancement of performance of phosphate plasticizers. 

Molybdenum compounds are effective in PVC, especially when coupled with zinc compounds. In addition, these compositions are flame-retardant. For example, 1.5 phr. of Sb20s and 1.5 phr. of Kemgard 911 in plasticized PVC raised the oxygen index from 28 to 33.5 % while the mass of solid particles filtered from the combustion products in an Arapahoe smoke chamber (cf. Fig. 4.1 in Section 4.1.1.1) lessened by 32.6 per cent. 4 phr. of the same additives in rigid PVC enhanced the oxygen index from 41 to 58 % and reduced smoke production by 48 per cent. ... 

Representatives of various industries [17] have examined some smoke depressants and flame retardant resins introduced by various US Companies in relation to US legislation. These include smoke suppressed polyvinylchloride (PVC) (BE Goodrich) and polyurethane (PU) foams (Mobay Chemical), and smoke suppressant additives from Climax Molybdenum, and Sherwin-Williams (molybdenum compounds), Solem Industries, and Alcoa Chemicals (aluminium trihydrates, for polypropylene (PP) and PVC), Dover Chemical Corp., (aromatic bromine compound for PP), and US Borax (zinc borate). 

In PVC partial replacement of antimony oxide not only provides synergy for flame retardancy, but also improves smoke reduction, which can be enhanced by addition of ATH. Just as important, due to antimony oxides costing more, partial replacement by zinc borate can result in considerable savings on cost, usually between 30 and 60%. Total replacement of antimony oxide in the presence of a halogen containing system is possible. In polyamide, Firebrake ZB plus a compound like OxyChem s Dechlorane Plus maintains a V-0 rating in the UL94 tests. 

Molybdenum and zine eontaining compounds have been used as flame and smoke suppressants for a variety of polymers. These metal containing species normally act to assist the build-up of char on the pol mier surface. This ehar is presumed to be the main method of flame retardancy. Halogenated systems form a large proportion of the market for molybdenum and zinc compounds. 

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