Conventional textiles often contain residues of formaldehyde and are also unpleasant on the skin. For fire-fighters and other emergency personnel, however, clothing is the most important barrier to a potentially ‘hostile’ environment”. Corresponding wearing comfort plus a protective effect is therefore imperative and thus any new development highly desirable. The Swiss Materials Testing and Research Institute Empa has developed a chemical process that transforms conventional cotton textiles into a flame-retardant fabric that retains its skin-friendly properties.
Cotton is characterised by its ability to absorb large amounts of water and ensure a favourable microclimate on the skin. Not losing these properties and still being highly fire-resistant is the focus of development by the Swiss. They have succeeded in having these quasi-additional properties built directly into the cotton fibre through chemical modifications. Wash-resistant, flame-retardant cotton is produced in the industry by treating the fabric with flame retardants that chemically bond with the cellulose in the cotton. To date, this has been done using mostly formaldehyde-based chemicals, which are long-lasting but have other disadvantages. The OH groups of the cellulose are chemically blocked, which considerably reduces the cotton textile ‘s ability to absorb water and makes the textiles feel uncomfortable to wear.
Chemical Network in the Cotton Textiles
The novel phosphorus chemistry developed by Empa can also be used to develop other materials, such as hydrogels. These can be triggered in such a way that they deliver targeted doses of medication to a wound and also release dyes that alert medical professionals to problems. The developers use these properties of the process to form their own network inside the cotton. The resulting phosphine oxide network is also hydrophilic and therefore absorbs additional moisture. The flame-retardant finish does not contain formaldehyde, which could endanger textile workers in particular during production. And the process offers another advantage: the phosphine oxide networks do not wash out either – after 50 washes, 95 % of the flame retardant network is still present in the fabric.