EFFECT OF DYE STRUCTURE ON AFFINITY FOR FIBERS 



121 



AFFINITY OF DIRECT DYES FOR CELLULOSE 



DYE AF(KEAL) 



NH2 SOsNa 



NaOaS^ NH2 CHaO^ 

 Na03(S 



3:^..N^>0 



HO yy "^ 



>_N*^'^"W^S03Na 



-6.7 



caHso^Q- 



S03Na 



OC2H5 



— 4.6 



S03Na 



SO3N0 



-9.2 



Fig. 7 



The best direct dyes contain a number of electron donor or acceptor groups 

 capable of hydrogen bond formation with the many hydroxyl groups present 

 in cellulose. Affinity is greatly promoted by the presence of at least two groups 

 selected from those listed in Fig. 12. There is some evidence that favorable 

 spacing of such groups will lead to exceptionally great affinity as in the case 



LINEARITY AND AFFINITY 



<>" 



N0O3S 



^ 



HO 



H-0 



GREATER AFFINITY 



^/t" ,1 . > - '^i\ «r» \ 



'LJi:^ * 





a^ 



Na03S 

 Na03S 



HO 



LESS AFFINITY 



Fig. 8 



