Preparation of a near-infrared radiation-sensitive coating comprising acrylate-functional poly(acrylonitrile–styrene) latex particles

A reactive quaternary ammonium salt containing double bonds, N -(2-(acryloyloxy)ethyl)- N -allyl- N , N -dimethyl-ammonium bromide (AEADAB), was synthesized by the reaction of 2-(dimethylamino)ethyl acrylate with allyl bromide. Acrylate-functional poly(acrylonitrile–styrene) (PAS) latex particles were prepared by a two-step method. First, the mini-emulsion polymerization of styrene and acrylonitrile in the presence of a reactive emulsifier (SE-10N) was employed to prepare the PAS particles. The PAS latex was then precipitated via ion-exchange reaction with AEADAB aqueous solution to obtain the AEADAB-modified acrylate-functional PAS latex particles. The PAS latex was also treated with tetrabutylammonium bromide (TBAB) aqueous solution to prepare the TBAB-modified latex particles. The modified latex particles could be re-dispersed in some organic solvents such as 2-butanone, acetone, 1,4-dioxane and tetrahydrofuran to form stable non-aqueous dispersions. In addition, a water-dispersible multi-acrylate polymer (M-PMVMA) was prepared by the reaction of poly(methylvinylether-alt-maleicanhydride (PMVMA) with methoxypolyethylene glycol and 2-hydroxyethyl acrylate. Coating solutions were prepared with the polymer particles, M-PMVMA, iodonium bis(4-methylphenyl)hexafluorophosphate, and a near-infrared (NIR) absorbing agent (IR830). The NIR radiation-sensitive coating was prepared by applying the coating solution onto the aluminum lithographic substrate. An infrared laser exposure and processing of the exposed coating formed a visible image on the substrate. The image quality and image adhesion to the substrate was investigated. Results showed that the NIR radiation-sensitive coating worked by heat-induced coalescence of the polymer particles and free radical crosslinking polymerization occurred during the exposure step. The coating derived from AEADAB-modified acrylate-functional PAS latex particles provided a better image quality compared with that derived from TBAB-modified PAS latex particles.