Regeneration of Solvents for Washout Photopolymer Printing Plates as a Solution to Environmental Problem

Abstract

Much attention from the point of view of environmental protection is paid to the process of manufacturing photopolymer flexographic printing plates, where the waste is saturated with washout photopolymer components solutions that pose a potential hazard to the environment and require the introduction of additional measures for disposal or regeneration. Washout solutions are mixtures of organic solvents with washout photopolymer composition, which can be regenerated for reuse. Distillation was performed in a glass reactor on an oil bath with electric heating. The vapors were condensed in a direct-flow water-cooled reflux condenser. The quality of the regenerated mixed solvents was controlled by the refractive index. The refractive index was determined on a refractometer RL-2.

The following temperature regime of regeneration of the spent washout solution was established: the beginning of distillation (at 760 mm Hg) — 130°°C, distillation of the main fractions — 135…170°°C. After regeneration, 90…95°% of the distillation and up to 10°% of the photopolymer composition residue were obtained after distillation by the composition of solvents according to the values of the refractive index, for which a linear correlation was established.

The studies have shown the possibility of regeneration of the solution for washout the relief image of photopolymer printing plates by distillation. In this case, preference should be given to a mixture of solvent-isopentanol in proportions of 10:2 or 10:3, as such proportions allow to intensify the distillation process. The experimental results indicate the possibility of adjusting the composition of the solution after distillation according to the refractive index values, according to the obtained linear correlation.