Tin Fire Retardants
Tin Fire Retardants
Although a wide range of chemicals have found use as fire retardants over the years, many are facing increasing scrutiny either because of their inherent toxicity or their negative impacts in the environment. In view of a clear industrial demand for safer, more effective fire retardants, ITRI commenced its work on the development of novel tin-based additives during the mid-1980s.
This innovative research directly led to the commercial introduction of two specific tin-based fire retardants – zinc hydroxystannate (ZHS) and zinc stannate (ZS) – and evaluation trials at ITRI and elsewhere demonstrated their effectiveness both as flame retardants and smoke suppressants in a wide range of polymers.REFS
Primarily developed as non-toxic replacements for antimony trioxide (ATO), ZHS and ZS sales have grown slowly but steadily over the past 20 years or so. However, widespread usage has been hampered mainly because of their high cost compared with ATO.
Substitution of ATO by safer alternatives has become a priority issue for many end users because of its classification as a Category 3 carcinogen and a skin irritant, and the search for viable replacements has intensified recently because of the all-time high antimony price.
An earlier ITRI market survey indicated 2009 global usage of ZHS/ZS of around 750 tonnes, equivalent to ca. 325 tonnes of tin metal. For comparison, global ATO consumption is estimated at over 90,000 tonnes per annum and it is widely expected that alternative fire retardants, including ZHS/ZS, could replace at least 10 – 20% of this market in the next 3 – 5 years.
Aside from ATO replacement, similar or maybe even greater tonnage potential for ZHS/ZS exists in the halogen-free sector, where growth is clearly evident particularly in the European and Japanese electrical / electronic sector.
Leading manufacturers of ZHS/ZS are running at production capacity and are reported to be struggling to meet current demand. Consequently, the use of tin in fire retardant additives is expected to be one of the end applications most likely to grow in the immediate future.
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