Method of dyeing a substrate comprising elastomeric fibre and non-elastomeric fibre, and a dyed subtrate comprising these fibres

A method of dyeing a substrate comprising:

• (i) elastomeric fibre comprising at least 30 wt. % of a first polymer having a glass transition temperature T1 of less than 60° C., and
• (ii) non-elastomeric companion fibre containing more than 50 wt. % of a second polymer, the second polymer being polymer having no glass transition temperature or polymer having a glass transition temperature T2 that is at least 20° C. higher than T1, the method comprising:
• (a) contacting the substrate with a dyeing medium to produce a pre-dyed substrate comprising dyed elastomeric fibre and dyed companion fibre;
• and
• (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, the extraction medium comprising at least 50 wt. % of supercritical or liquefied carbon dioxide;
• wherein Te exceeds Tg1,extraction wherein Te is less than Tg2,extraction in case the traction and traction companion 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.