POLYURETHANE-BASED PRECURSOR AND HOLOGRAPHIC POLYMER DISPERSED LIQUID CRYSTAL COMPOSITE FILM USING THE PRECURSOR

摘要

PURPOSE: A polyurethane-based precursor and a holographic polymer dispersed liquid crystal (HPDLC) composite film using the precursor are provided, to obtain a high efficiency and low operating voltage and contraction rate by controlling the phase separation and interaction with liquid crystal. CONSTITUTION: The polyurethane-based precursor is obtained by reacting a compound having 1-4 hydroxyl groups at the end, a compound having 2-4 isocyanate groups at the ends and a carbon-carbon double bond compound having an hydroxyl group at the end in the ratio of 1:2:2 by equivalence. The HPDLC composite film is obtained by mixing 100 parts by weight of a photoreactive mixture comprising the polyurethane-based precursor, a crosslinking agent selected from acrylate compounds having 2-5 vinyl groups and a reactive diluent selected from monovalent or divalent acrylate/non-acrylate compounds in the ratio of 1 : 0.5-5 : 0.1-2 by weight; and 0.1-5 parts by weight of a photoinitiator; and 20-75 parts by weight of nematic or ferroelectric liquid crystal.