Preparation and characterisation of inks for let printing onto textile materials

Abstract

The feasibility of using thermal drop-on-demand ink jet printing to print pigmented ink systems onto textile materials was investigated. Preliminary studies showed that a novel binder system, Synthappret BAP (traditionally used as a shrink resist treatment for wool), could be successfully incorporated within a screen ink formulation for printing onto cotton fabric. Such a printing ink produced a high quality print which offered the required fastness properties of a textile print whilst maintaining a soft fabric handle. The cross-linking mechanism/properties of the Synthappret BAP were fully characterised. It was found that Synthappret BAP underwent rapid self cross-linking at elevated temperatures. There was no significant evidence of the cross-linking of the Synthappret BAP and the textile fibres. However, the Synthappret BAP was capable of (a) diffusing into the fibre matrix and (b) entrapping the pigment particles, thus, successfully fixing the pigment to the substrate. Such fixation resulted in a high degree of washfastness and rubfastness. Following the initial success of applying Synthappret BAP as a binder for textile printing, various ink jet printing inks suitable for textile printing were developed. Such inks were tested for physical characteristics required of a typical ink jet printing ink and successfully printed using a desktop ink jet printer. Successful printing of an array of textile materials was achieved. Based on initial trials of such inks further investigation was carried out in order to improve/ensure the following criteria were met: . Suitability for a one pack printing process. . Excellent stability of inks including pH and freeze- thaw stability of pigmented inks thus giving indications on possible shelf life. . Excellent printability on cotton and polyester. . Excellent washfastness on cotton and polyester. . Excellent fabric handle after printing. . Acceptable rubfastness and lightfastness of printed cotton and polyester