Study On The Special Carboxyl Dyes And Their Complex Dyeing Properties For Alginate Fiber

As a new type of green biomass synthetic fiber,alginate fiber is renewable,degradable and has excellent properties.However,it is subject to the problem of low dyeability,which seriously restricts it from becoming an promising textile fiber.Based on the structure and properties of alginate fibers,we propose that the carboxylic acid dyes shoud be suitable to the coloration of such fibers.The metal ions existed in alginate fiber can form covalent bonding with both carboxyl dyes and fiber,and thus,resulted in firmly adsorption and fixation of dyes on alginate fiber.In this paper,polycarboxylic acid?Polymaleic anhydride?type macromolecular dyes?PMA-D1,PMA-D2?and small molecular dyes D1?D10 which also contains carboxylic acid type were prepared to study their dyeing properties and mechanism on alginate fibers.Two dyes,PMA-D1 and PMA-D2,were prepared by grafting different chromophorets on PMA with polymaleic anhydride?PMA?as the backbone.The optimal dyeing process was determined by single factor method using a“two-bath and two step”dyeing process:Al³⁺content added was 15%,pretreatment p H was 6,pretreatment temperature 40?,pretreatment time 60 min,2%?o.w.f?,dyeing temperature 70?,dyeing time 60 min,bath ratio 1:30.The dyeing results suggest that these dyes can be fixed on alginate fiber by the formation of coordination bonding between carboxyl groups in dyes and metal ions fedded in fiber.Under the dyeing conditions,the dyeing adsorption of the two dyes reached more than 75%,the strength loss of dyed fiber was less than 7%.The morphology of the fiber surface was maintained well according to the test of SEM.To get azo-dyes containing carboxyl groups,p-nitroaniline,aniline,2,4-dinitroaniline,p-aminobenzenesulfonic acid were used to get diazo components,and the coupling components containing carboxyl groups were synthesized from aniline,chloroacetic acid,acrylic acid,etc.The anthraquinone dye D10 containing carboxylic groups was synthesized by substitution reaction of 2-amino-anthraquinone and ethyl bromoacetate.The structure of10 dyes was characterized by NMR and IR.The maximum absorption wavelength of ten dyes was determined by ultraviolet-visible absorption spectroscopy.The dyeing properties and mechanism of small molecular dyes D1?D10 which contains carboxylic acid type on alginate fibers were studied.Four dyes,D1,D2,D6 and D10 were selected to determine the optimal dyeing process:Al³⁺content was 2g/L,2%?o.w.f?,dyeing temperature 80?,dyeing time 70min,bath ratio 1:20.Under the dyeing conditions,the dyeing adsorption of D2,D6 reached more than 85%,the dyeing adsorption of D10 reached more than 60%.The results showed that the small molecular dyes which contains carboxylic acid type can form covalent bonding with fiber.Due to the higher solubility,compared to PMA-D1 and PMA-D2,the small molecular dyes permeated into the fiber easier.The dyeing properties of small molecular dyes were also improved.The strength loss of dyed fiber was less than 5%.The morphology of the fiber surface was maintained well according to the test of SEM.The dyeing behaviour and results of these two types of dyes containing carboxyl groups showed that these dyes can give excellent dyeing performance and fastness properties,thus have a good application prospect in the future.