Study On Carrier Dyeing Of Meta-Aromatic Polyamide Fibers

Meta-aromatic polyamide fibers,such as Nomex^?(Dupont) and Conex^?(Teijin),are highly resistant to heat decomposition,and have inherent flame resistance,which are frequently used in protective clothing for working clothes of firemen or oil field workers.However,these fibers are highly crystalline and have a high glass trasitional temperature,which make meta-aromatic polyamide fibers difficult to dye.Carrier dyeing at'high temperature is by far the most practical method for dyeing meta-aromatic polyamide fibers.Among different kinds of carrieres,acetophenone is recognized as the one of the most economic choice, which would result in deep color.However,acetophenone,processing strong aromatic odor,would causes problems in workshop during production and for the end-use of clothes.It is thereby unacceptable and needed to be replaced by the more suitable one.The present paper studied the carrier dyeing of Nomex^?ⅢA with basic dyestuff,and the purpose of research is as below:(1) to find out the more suitable carrier for dyeing,which shuld have all the properties such as notoxicity,non-odor,economic,etc.(2) to reveal how the inorganic electrolyte affect the dyeing.(3) to explore the machanism of dyeing, namely the adsorption and diffusion of dyes in fibers.As the result of the work,three carrieres,named NCHP,PE,DMP, showed prospective results.Considering the high cost of NCHP and low effectiveness of PE and DMP to get deep color,the combination of these carriers are tried,which are named CD-1 for the combination of NCHP and PE,and CD-2 for the combination of DMP and PE.The former is suitable for dyeing middle/deep color and the later is suitable for dyeing light/middle color.Five inorganic electrolyte are used to study the effect of electrolyte on dyeing,and we find that it's the anion that promote the dyeing.At last,the machanism of dyeing has been studied,and the results of the research are listed blow:(1) The adsorption of cationic dyes on aromatic polyamide blongs to Freundlich type.The dyes are attracted to fibers by hydrogen bonding and van der Waals forces.(2) The carrier makes the glass trasitional temperature(T_g) and the dyeing-transitional Temperature(T_d) of the fiber decreased,thus the accelerration of the diffusion of dyes is resulted.(3) during dyeing without carrier,an increase in dyeing temperature causes an decrease in the affinity of dyes,and such system is exothermic.Contrarily, during the dyeing with carrier,an increase in dyeing temperature causes an increase in the affinity of dyes,and such system is endothermic.