Estudio para la reutilización de disolventes procedentes de la industria de la impresión flexográfica

Abstract

Production of flexible packaging has grown considerably during the last decade. This process usually employs the so called flexographic printing technique. It can use either water-based or solvent-based inks. In the flexible plastic packaging facility considered in this study, this type of printing is carried out with solvent-based inks. One characteristic of this process is the need to clean the printing machine circuit between different tasks in order to avoid ink contamination. This practice presents two serious drawbacks: a) the collected dirty solvent has to be sent to a hazardous waste manager and b) new solvent has to be introduced in the process involving additional expenses in raw materials. The aim of this project is to propose an industrial novel process for individually recovering the solvents used in the flexographic printing process to facilitate their reuse. For this purpose, specific objectives such as the study of the technological alternatives for the different stages and sizing of the main equipment are carried out. The main products to be recovered are n-butanol, ethanol and ethyl acetate. After preliminary filtration and sedimentation to remove most of the solids, n-butanol can be separated in a distillation column. Ethanol and ethyl acetate separation is not trivial because there is an azeotrope. Therefore, several technologies such as membrane separation, ionic liquid extraction or ultrasonically assisted distillation are considered. Finally, a technical solution is proposed and a preliminary economic evaluation of the selected strategy is compared to the present costs of solvent renewal and waste management. The main conclusion is that a new process that will contribute to reduce waste management as well as solvent reuse in a flexible packaging plant has been preliminary described. The need of further studies to fully define the viability of this process in the conventional process currently performed is also specify.