The Felting Shrinkage of Knitted Wool Fabrics: The Mixing of Undertreated Fibres with Shrinkproofed Wool

An investigation is reported in which the natural flame-resistance of wool is improved by treatment with various mono-organotin salts. Treatments based on mono-organochloro- and bromostannates confer an adequate flame-resistance at tin levels of less than 1%. The active species present in the wool is likely to be a halogen-containing mono-organotin oligomer. On washing, hydrolysis of the tin-halogen bonds occurs, the treatment being rendered ineffective in all cases. Two of the compounds investigated showed negligible water-repellent properties on a wool gaberdine fabric.

For the fluorostannates, which did not give satisfactory flame-resistance on wool, the tin appears to be taken up onto the fabric as an anion of the type [RSnF_n(OH)_5-n]^2-. This closely resembles the mode of action of commercial inorganic fluorostannate formulations.

A sample of wool that had been treated with a mothproofing formulation based on triphenyltin chloride was shown by ^119mSn Mössbauer spectroscopy to contain triphenyltin hydroxide, Ph₃SnOH, as the active species.