A METHOD OF DYEING A SUBSTRATE COMPRISING ELASTOMERIC FIBRE AND NON-ELASTOMERIC FIBRE, AND A DYED SUBTRATE COMPRISING THESE FIBRES

The present invention relates to a method of dyeing a substrate comprising (i) elastomeric fibre containing at least 30 wt. % of a first polymer having a glass transition temperature T of less than 60° C. and (ii) non-elastomeric companion fibre containing more than 50 wt. % of a second polymer, said second polymer being polymer having no glass transition temperature or polymer Shaving a glass transition temperature T2 that is at least 20° C. higher than T1, said method comprising: a) contacting the substrate with a dyeing medium to produce a pre-dyed substrate comprising 10 dyed elastomeric fibre and dyed companion fibre; b) contacting the pre-dyed substrate with an extraction medium at a temperature Te and a pressure Pe, to produce a high fastness dyed substrate, said extraction medium comprising at least 50 wt. % of supercritical or liquefied carbon dioxide; wherein Te exceeds Tg1,extraction and wherein Te is less than Tg2,extraction in case the companion 1 fibre contains more than 50 wt. % of polymers having a glass transition temperature T2; Tg1,extraction representing the glass transition temperature of the first polymer in carbon dioxide at pressure Pe; and Tg2, extraction representing the glass transition temperature of the second polymer in carbon dioxide at pressure Pe. 20 The present method enables the production of dyed substrates containing elastomeric fibre as well as non-elastomeric companion fibre that exhibit extremely high colour fastness because the dye is almost exclusively contained in the companion fibres. The present invention also provides a dyed substrate that can be obtained by the 2 aforementioned dyeing method.