Improving mechanical properties and chemical resistance of ink-jet printer color filter by using diblock polymeric dispersants

The diblock copolymers of polystyrene and poly(tert-butyl acrylate) (PSt-b-PtBA) with various molecular weights and hydrophobic/hydrophilic (styrene/acrylic acid) chain length were prepared by atom transfer radical polymerization (ATRP). Selective hydrolysis of the diblock copolymers (PSt-b-PtBA) resulted in amphiphilic block copolymers of polystyrene and poly(acrylic acid) (PSt-b-PAA). The amphiphilic block copolymers of PSt-b-PAA with average molecular weight (M-n) < 7500 were proved to be critical in dispersing the pigments of UV curable ink jet inks for manufacturing the color filter. Incorporating DB2 diblock copolymer dispersants with styrene/acrylic acid ratio at 1.5 allowed more UV curable compositions in the red and blue inks without deteriorating pigment dispersing stability and jetting properties of the ink-jet inks. The ink drops can be precisely ejected into the tiny color area. Better properties of the cured red stripe such as nanoindentation hardness and chemical resistance were found. The competing absorption of UV light by the blue pigment hindered the through cure of monomers near the interface between glass substrate and the blue stripe. This leads to lower hardness and poor chemical resistance of the UV cured blue stripe. (c) 2005 Wiley Periodicals, Inc.