Preparation of an In Situ Crosslinked Polymer Coating and a Double-Layered Thermal CTP Plate

The research relates to a method for preparing an in-situ crosslinked polymer coating. It has excellent solubility in aqueous alkaline solution, but didnt dissolve in general organic solvents and water. The crosslinked polymer coating was made through the reaction of a copolymer derived from diacetone acrylamide (DAAM) and ethacryloyloxyethyl-carbazochrome-p-toluenesulfonamide (MCTS) with a crosslinking agent, isonicotinyl hydrazide. The two components were dissolved in 3-methoxypropanol to prepare the coating solution, which was then coated to a grained and anodized aluminum substrate and dried at 120 °C for 5 min to obtain the crosslinked coating. There exists intermolecular hydrogen bond between the pyridine ring of isonicotinyl hydrazide and the sulfonamide group of the MCTS unit of the copolymer. The reaction between the hydrazide group and the carbonyl group during the drying process generated the hydrazone bond, resulting in the crosslinked polymer coating. The intermolecular hydrogen bond and the covalent bond render the coating insoluble in most organic solvents. However, the hydrogen bond was readily broken down when the coating was exposed to aqueous alkaline solution due to the ionization of the sulfonamide group, causing rapid dissolution of the coating. The coating was also used as the under-layer for the preparation of a double-layed CTP plate. The performance of the double-layed CTP plate was preliminarily studied.