Pretreatment of silk fabric surface with with amino compounds for inkjet printing

This research studied the pretreatment of silk fabric with amino compounds for ink jet printing. The pretreatment is expected to increase smoothness of the fabric surface. The pretreating solutions were serine, glycine, aspartic acid, sericin, chitosan, and Sanfix 555. The non-treated and treated fabrics were printed with the in-house formulated, pigmented inks and later steamed to fix the ink on the fabric surface. The inks had a pH in the range of 8 – 9 and exhibited the Newtonian flow in which the viscosity remained constant at 2.5 mPa s. The surface tension of the inks was approximately 44 mN m⁻¹, and the average particle sizes were approximately 100 nm. Zeta-potential of the inks was in the range from (-42) to (-51) mV. The inks were stable for at least 10 months (for the magenta and black inks) and a year (for the cyan and yellow inks) confirmed by micrographs of SEM and TEM. The inks prepared were suited for printing with the piezo type ink jet printer. It was concluded that the pretreatments containing the amino compounds improved hydrophilicity of the silk fabric except chitosan. The color gamuts from the sericin, chitosan, and Sanfix 555 pretreatments were wider than those from the amino acid pretreatments. The chroma of the cyan color was the most improved. The fabric after the pretreatment with the sericin showed a significant improvement in the dry crock fastness while the wet crock fastness was improved by serine and glycine. The chitosan slightly improved both dry and wet crock fastness. Wash fastness of the printed fabrics was excellent. The stiffness of the silk fabrics obtained from the chitosan pretreatment was significantly higher than other pretreatments which were similar to the non-treated one. The coated chitosan compacted the fibers to a bundle of yarns and gave a wider inter-yarn space. Thus, the fabric treated with chitosan yielded a higher air permeability. The ink penetration in sericin and chitosan coated layers was shorter than those of amino acids, enhancing ink deposition on the fabric surface. Some mentioned amino compounds from the pretreatments could hold and fix additional inks on the fabric surfaces, resulting in a wider color gamut of the inks. Department Imaging and Printing Technology