Preparation and Characterization of Novel Preimidized Semi-alicyclic Polyimide Alignment Layers with Low Curing Temperature and High Voltage Holding Ratio for TFT-LCDs.

Novel preimidized semi-alicyclic polyimide (PI) alignment layers with low curing temperature and high voltage holding ratio (VHR) have been successfully developed in order to meet the demands for liquid crystal (LC) alignment used in thin film transistor driven liquid crystal display devices (TFT-LCDs). For this purpose, a series of PI resins were first prepared from an alicyclic dianhydride, 3,4-dicarboxy-1,2,3,4,5,6,7,8-decahydro-1-naphthalenesuccinic dianhydride or hydrogenated tetralin dianhydride (HTDA) and various aromatic diamines by a twostep chemical imidization procedure. The derived PI resins showed good solubility in N-methyl-2-pyrrolidone (NMP) and other polar aprotic solvents. The PI varnishes were made from the PI resins, NMP solvent and butyl cellulose (BC) leveling agent with a solid content of 6.0 wt%. PI alignment layers cast from the preimidized PI varnishes showed good LC alignment ability and good optoelectronic features with the pretilt angles in the range of 2.542.92° and voltage holding ratios (VHR) higher than 98% at room temperature. [ABSTRACT FROM AUTHOR]