Synthesis and characterization of poly[(methyl methacrylate)‐co‐(methacrylic acid)] for a UV‐sensitive aqueous base developable lithographic plate

Abstract

AbstractSyntheses of the copolymers of methyl methacrylate and methacrylic acid were carried out by free radical chain polymerization in the presence of benzoyl peroxide (BPO) as an initiator. The effects of the monomer ratio and polymerization time on the averaged molecular weights, polydispersity index, and glass transition temperature were investigated. FTIR and NMR were used for functional group characterization, GPC for average molecular weights and the distribution, elemental analysis for CHO content, and DSC for the glass transition temperature. The copolymers were mixed with tripropylene glycol diacrylate (TPGDA) and trimethylol propane ethoxylated triacrylate (TMPEOTA), 2‐hydroxy‐2‐methyl‐1‐phenyl‐propan‐1‐one (Darocur® 1173) and benzophenone (Darocur® BP) with anthraquinone for visibility of images. The photosensitive coating was spin‐coated onto the anodized aluminum plate on which a thin film was formed. The wet film was then coated with PVA solution as an oxygen barrier layer. The plate assembled with a control wedge and a black color separation film was exposed to UV radiation at different exposure times. The plate was developed in a dilute alkaline developer. The resulting plate was evaluated for its reproduction properties in terms of surface properties (hydrophilic/hydrophobicity) by contact angle measurement of image/nonimage areas, resolution by microline, tone reproduction, and adhesion tests. The article describes the results of the syntheses, characterizations, and uses of the copolymer as a binder of a negative, lithographic printing plate. The present lithographic printing plate is good for a medium viscosity printing ink to produce medium printing quality on uncoated paper. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1829–1837, 2002