HECOL270 Lecture 16: HECOL 270 lecture 16
30 Sep 2016
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Colourants - dyes and pigments ! dyes: ! organic compounds that are:! Insoluble in water or in solvents ! Or adhered to fabric surface by mixing with a bonding agent, glue it on to fabric surface! Bonding agent (resin) must be properly cured ! Pigment colouration may rub off fabric surface ! Yarn tension control during the package winding process and consistency of the package (cid:133) (cid:133) (cid:132) (cid:3) (cid:3) (cid:3) (cid:3) (cid:3) density are key variables that must be accurately controlled for high quality dyed yarns! (cid:3) (cid:3) (cid:3) 2 bath method - rst bath with dye for rst bre. second bath with dye for second bre ! Cotton needs a vat or reactive dye and dye applied from a water solution ! So3h (sulphonic acid) examples of auxochrome reactive groups:! 1)! large and commercially signi cant group of water soluble dyes! direct dyes are attracted to the -oh groups of cellulosic.
