Mesta jute fiber has been modified with sodium sulfite in presence of MEA (monoethanolamine) and bleached with hydrogen peroxide. Bleached modified jute has been dyed with Reactive Red HE3B, Reactive Blue R, Direct Green BL and Direct Red 6BL. The light and wash fastness, multifabric staining, and breaking strength of dyed bleached modified mesta jute has been studied and compared with that of dyed bleached raw mesta jute. Modification significantly improves whiteness index, light and wash fastness, less staining. On exposure to UV light loss in breaking strength of dyed modified bleached mesta jute with Reactive Red 120 is minimum in comparison with other dyes.
Key Words: Modification, mesta jute, bleaching, color fastness, breaking strength
Reactive and direct dyes are available synthetic dyes amongst the commercial dye range. They are still the brightest and the most brilliant in hue of the synthetic dyes and widely used for the dyeing of cotton, jute, kenaf, flax. Dyes of this type are anionic in character and in general owe their water solubility to the presence of sulfonate groups (HSO3). However, since jute itself adopts an anionic surface charge in water, these dyes have low intrinsic affinity for the fiber. The repulsive charge between dye and jute fiber can be overcome by adding an electrolyte such as sodium chloride or sodium sulfate, which has the effect of screening the surface charge on the fiber . Jute fiber possesses good affinity than cotton with direct dyes due to the presence of lignin. But from the practice, it has been observed that they possess very poor color fastness on jute. A number of attempts have been made to modify the jute fiber using different type of metal salt, vinyl monomers to improve of the color fastness properties [2-7]. A few efforts were made to improve the light fastness which is the major problem for jute when it is exposed to sun light . But no researcher tried to delignify jute fiber and sulfonation of lignin in jute fiber for the improvement of the color fastness properties.
In the present investigation an effort was made to improve bleaching and color fastness properties of reactive and direct dyes applying on bleached modified mesta jute fiber. An assessment of whiteness index, light and wash fastness, and breaking strength of dyed bleached modified mesta jute has been done. The results have been compared with that of bleached raw mesta jute fiber.
Bleached raw and modified mesta jute fibers were used as material for the investigation. Direct Red 6BL (C.I. 35780), Direct Green BL (C.I. 34045), Reactive Red HE3B (C.I. 25810) and Reactive Blue R (C.I. 61200) were obtained from commercial sources and were used as received. All other chemicals used were of C.P. grade and were used as such without further purification.
Mesta jute fiber was modified with 15% (owf) of sodium sulfite in presence of 0.5 %( owf) MEA (monoethanolamine) as a delignifying agent at 150C for 3.0 hrs .
Scouring and bleaching
In order to remove the wax, oil, resin and coloring matter from the fiber, first, all fibers were scoured by standard method with a solution of 4 % sodium carbonate, 1% sodium hydroxide and 0.5 % wetting agent at 75 C for 0.5 hour . It was then bleached by standard method in laundering ometer with 2.1 % hydrogen peroxide together with 6 % sodium silicate and 0.5% sodium carbonate to maintain pH 11 initially. Percentage was based on the weight of the material, in the liquor ratio of 15:1. Bleaching was continued for 1.5 hour at 95C. It was then washed and dried .