Glass Industry
Tin and its compounds find a number of applications in the glass industry. Whereas
a molten tin metal bath is used in the manufacture of high quality ‘float’ glass,
electrically conductive sintered tin(IV) oxide electrodes are widely used in the
production of lead crystal glass. Tin(II) oxide is a component of gold – tin and copper
– tin ruby glasses.
Tin(IV) oxide coatings have been applied on to glass substrates for many years.
Very thin films have been used extensively to strengthen and impart scratchresistance to returnable bottles and jars, and slightly thicker films have been
deposited to create an iridescent appearance on the glass surface for decorative
purposes.
However, much greater interest is now shown in thicker films (greater than 1 micron)
which, although still optically transparent, are electrically conductive (particularly
when doped with other elements such as fluorine, boron or antimony). As a
consequence, tin-based glass coatings find widespread and growing use in de-icing
windscreens for aircraft and cars, electroluminescent displays, electrical field
shielding, and especially low-emissivity windows (‘e-glass’ for energy saving
construction).
Although the tin coating itself is based on tin(IV) oxide, several tin chemicals have
found use as precursors for forming the tin oxide film – tin(IV) chloride, tin(II)
chloride, butyltin trichloride, methyltin trichloride and dimethyltin dichloride. The area
of glass now being treated is very large and the global market is thought to consume
4,000 – 5,000 tonnes per annum of tin, and growing rapidly because of the urgent
need for energy conservation.