Antimony Oxide Flame Retardant Additives

The German Federal Institute for Materials Research Testing has concluded that antimony oxide in plasticised PVC may be replaced to a certain degree by zinc sulfide. They studied 5% total loadings of the additives either alone or in mixtures. Synergism was observed for the mixtures. ZnS alone appeared to have no effect, yet a 50/50 mixture gave an equivalent flame retardancy as antimony oxide alone. 

Molybdenum Oxide. Molybdenum compounds incorporated into flexible PVC not only increase flame resistance, but also decrease smoke evolution. In Table 10 the effect of molybdenum oxide on the oxygen index of a flexible PVC containing 50 parts of a plasticizer is compared with antimony oxide. Antimony oxide is the superior synergist for flame retardancy but has Httle or no effect on smoke evolution. However, combinations of molybdenum oxide and antimony oxide may be used to reduce the total inorganic flame-retardant additive package, and obtain improved flame resistance and reduced smoke. 

In polymers such as polystyrene that do not readily undergo charring, phosphoms-based flame retardants tend to be less effective, and such polymers are often flame retarded by antimony—halogen combinations (see Styrene). However, even in such noncharring polymers, phosphoms additives exhibit some activity that suggests at least one other mode of action. Phosphoms compounds may produce a barrier layer of polyphosphoric acid on the burning polymer (4,5). Phosphoms-based flame retardants are more effective in styrenic polymers blended with a char-forming polymer such as polyphenylene oxide or polycarbonate. 

Semimetal that occurs as a tin-type, brittle form and as a yellow, unstable, nonmetallic form. Its main use is in alloys to harden other metals. Without the addition of antimony, lead would have remained the "softy" of the Periodic Table. But with antimony, lead ruled the print world and later found use in the production of rechargeable batteries. It can be found in older ceramic glazing (yellow orange). Everyday encounters antimony sulfide in match heads and red rubber, antimony oxide is used as a flame retardant. Pure antimony is starting to become of interest in the electronics sector. 

The antimony oxide/organohalogen synergism in flame retardant additives has been the subject of considerable research and discussion over the past twenty-five years (1-17). In addition to antimony oxide, a variety of bismuth compounds and molybdenum oxide have been the subject of similar studies (18-20). Despite this intensive investigation, relatively little has been conclusively established about the solid state chemical mechanisms of the metal component volatilization, except in those cases where the organohalogen component is capable of undergoing extensive intramolecular dehydrohalogenation. 

The flame retardant performance of various flame retardant additives in a commercial polycarbonate/ABS alloy were compared. No antimony oxide was required. The data shows brominated phosphate to be a highly efficient flame retardant in this alloy (Table XI). An alloy composition containing 14% brominated phosphate and no antimony oxide gives a V-0 rating (Table XII). The melt index of this alloy containing 12% brominated polystyrene was 7.6 g/10 min. (at 250°C) the equivalent resin containing brominated phosphate had a melt index of 13.3 g/10 min. 

The SSP behavior of co-polyesters with rigid or voluminous comonomers, such as the flame retardant additive 9,10-dihydro[2,3-di-9-oxa-(2-hydroxyethoxy)-carbonylpropyl]-10-phosphaphenanthrene-10-oxide, or the ionic compound, sodium 5-sulfoisophthalate, is inhibited. This also occurs in the melt phase and cannot be improved by the use of catalysts [56], The results of studies examining the influence of employed catalysts with respect to stability and quality of the polymer suggest the use of antimony catalysts. The thermal or thermo-oxidative stability is, however, reduced by the interaction of the catalyst with the carboxylic groups of the polymer [57],... 

NYACOL PRODUCTS INC. Colloidal Antimony Oxide Flame Retardant Additives(Continued) ... 

Antimony oxide by itself is essentially useless as a fire-retardant additive. However, in combination with other materials, it is by far the most widely used antimony-containing flame retardant additive. It is generally used with bromine- or chlorine-containing compounds (32). 

Thermoguard . [Atochem/Plastics Additives] Antimony oxide or braminated compds. flame retardants. 

Examination of flame-retarding additives was done by Heeren et al. using a direct temperature controlled pyrolysis external ion source and a 7 T FTICR. Samples were taken from common household appliances such as TV set housings, computer casings, and others and were pulverized to powder form. Direct heating of the filament probe with dried sample produced spectra with two distinct regions, corresponding to evaporation of nonbonded additives and pyrolysis of the polymer matrix. The xmknown polymer blends were foxmd to contain brominated biphenyls, brominated diphenyl ethers, tetrabromoBisphenol-A and its butylated isomers, polystyrene, and antimony oxides. 

Of all the polyolefins, LDPE is the most difficult to make flame-retarded. Deca-bromodiphenyl oxide is a suitable additive when combined with antimony trioxide but the immense migration of the agent to the surface may greatly deteriorate the appearance of the product. The flammability rating V-2 according to UL 94 (cf. Section 3.1.5.2) is attained with 9 per cent of Saytex BT 93 and 3 per cent of antimony trioxide while a formulation with 52 per cent of LDPE, 12 per cent of Saytex BT 93, 6 per cent of antimony trioxide, and 30 per cent of talc is rated V-0. ... 

Reducing the flammability of polymers is an important issue. Different types of fillers are used to improve the polymer properties. Flame retardant additives include phosphorous-based compounds, nitrogen-containing, chlorinated and brominated compounds, antimony oxide, metal hydroxides, etc. [16-18]. The difiiculty of reducing the polymer flammability is connected with finding effective fillers. 

At or above 70% chlorine content, the materials are solids with softening temperatures from 103 to 160°C. These are useful as flame-retardant additives particularly for polyoleflns, rubber, paints and adhesives. A typical formula for meeting UL 94 V-0 with polyethylene uses 20-24% chloroparaffin and 8-10% antimony oxide (27). Above the 13-carbon chain length, the toxicological characteristics of the long-chain chloroparaffins [63449-39-8] is very favorable. 

The predominant metal oxide flame retardant is antimony trioxide, SbjOj, which finds substantial usage in PVC (see Figure 1), in other halo-polymers, and (in conjunction with halogenated additives) in other systems. It is effective at low loadings, which means that its use can... 

Cblorina.ted Pa.ra.ffins, The term chlotinated paraffins covers a variety of compositions. The prime variables are molecular weight of the starting paraffin and the chlorine content of the final product. Typical products contain from 12—24 carbons and from 40—70 wt % chlorine. Liquid chlotinated paraffins are used as plasticizers (qv) and flame retardants ia paint (qv) and PVC formulations. The soHd materials are used as additive flame retardants ia a variety of thermoplastics. In this use, they are combiaed with antimony oxide which acts as a synergist. Thermal stabilizers, such as those used ia PVC (see vinyl polymers), must be used to overcome the inherent thermal iastabiUty. 

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