Pigment and Disperse dyestuffs for Inkjet Inks: Disperse dyes for polyester and nylon and pigments present a more difficult set of problems for ink makers. Both exist in water as dispersion of small particles.These inks must be prepared with high degree of expertise so that the particles will not settle or agglomorate (flocculate). The partcile msize must have an average of 0.5 micrometer and the particle size distribution must be very narrow with more than 99% of the particles smaller than 1 micrometer in order to avaoid clogging of the nozzle.
Since pigment printing accounts for over 50% of all conventional textile printing, it is an attractive target for inkjet develpers. Several of the major jet ink producers have recently launched new pigment systems. Although still prone to some problems of handle and rub fastness, they offer excellant wash and light fastness and have the great advantage of universal application to almost to all fibers and subsrates. The major outstanding problem with their use in the inkjet system is how best to formulate and apply the resins which are required to bond the pigment particles to the fabric surface. Several different approaches, from spraying resin through a separate jet head to screen printing binder over an inkjet printed color have been suggested. In the long run, improved resin binder technology to prevail, allowing trouble free formulation and printing from a single inkjet head for each color.
While reactive and acid dyes will always retain some place within the overall market, it seems increasingly likely that disperse and pigment links will represent the way forward for inkjet printing of textiles. Print head and machine design and materials handling arrangements will need to relect this trend. |
