TECHNOLOGY FOR REMOVING FREE FORMALDEHYDE FROM UREA-FORMALDEHYDE RESINS

The relevance of the study is caused by high danger of technogenic emission of formaldehyde into the environment. The main anthropogenic source of formaldehyde is the production of particle board, which uses urea-formaldehyde resins. The paper proposes a technology for removing free formaldehyde from urea-formaldehyde resins, which will increase the safety and environmental friendliness of products based on them. The results of the work will make it possible to safely utilize and make the most optimal use of the available georesources, thereby solving one of the main tasks of geoecology. The aim of this work is to develop a method for reducing the toxicity of urea-formaldehyde resins by removing free formaldehyde. Objects: urea-formaldehyde resins characterized by the possibility of formaldehyde emission. Methods: modeling of the optimal process parameters; laboratory methods for formaldehyde removal; laboratory methods for studying the physical and mechanical properties of the modified urea-formaldehyde resin; modeling the required equipment and technological scheme. Results. The authors have developed the laboratory installation to remove formaldehyde from urea-formaldehyde resins and selected the optimal conditions for the process: the recommended pH range is 3,5...4,0, the temperature is recommended to be maintained in the range of 20-40 degrees C, the amount of sodium hydrosulfite should be 1,5...1,75 of the stoichiometric ratio, the process is recommended to be carried out at atmospheric pressure. On the basis of a laboratory setup, a technological scheme for production of environmentally friendly urea-formaldehyde resins, consisting of two stages: the preparation of the sodium hydrosulfite reagent and its interaction with ureaformaldehyde resin, was developed. The necessary main and auxiliary equipment was selected for the technological scheme. The process requires two jacketed reactors with a stirrer, three dosing pumps and a hydrochloric acid storage tank. Within the framework of this study, the investigation of the physical and mechanical properties of the modified urea-formaldehyde resin was carried out. The results obtained deviate somewhat from the results of the study of the original urea-formaldehyde resin, but are within the permissible limits.