Vat Dyes for Fiber Blends

Polyester fibers are dyed to a considerable extent by selected low-molecular vat dyes with satisfactory fastness properties. They can be applied on CEL±PES fiber blends by the Thermosol process. Vat dyes are used for PA±CEL blends when the highest possible wetfastness is required . The coloring strength on the PA component depends on the type of PA fiber and on dyeing conditions (the depth of shade on PA 6 is deeper than on PA 66). The lightfastness of some vat dyes can be lower on PA than on cellulose fibers. The advantage of using vat dyes is that in a single bath with selected products, dyeings of the same shade are obtained on both components. For instance, C.I. Vat Orange 26 [12237-49-9], C.I. Vat Blue 4, 69800 [81-77-6], C.I. Vat Blue 14, 69810 [1324-27-2], C.I. Vat Brown 55, 70905 [4465-47-8], C.I. Vat Blue 9,
C.I. Vat Blue 25, 70500 [6247-39-8] are widely applicable (in the exhaust and pad steam  process).  The  dye  yield  on  the  PA  component  increases  with  increasing temperature. With a dyeing time of 60 min, the most favorable temperature for the dyes mentioned above is 80±90 DC. The additives to the dyebath and the dyeing processes are the same as those used for dyeing cellulose fibers alone