SCIENTIFIC AND TECHNOLOGICAL FEATURES OF SYNTHESIS OF NEW ESTER PLASTICIZERS BASED ON RENEWABLE RAW MATERIALS

Abstract

Methods for the synthesis of ester non-toxic biodegradable plasticizers (hazard class 4) using renewable raw materials have been developed: glycerine-containing waste generated in the production of biofuels; citric acid 244, by microbial synthesis from molasses sugar production waste; polyatomic alcohol (neopoliol) – trimethylolpropane – a product of oxosynthesis obtained on the basis of natural gas. The target products are esters with a molecular weight range of 250-600, with low saturated vapor pressure, good thermal stability and polymer compatibility, and chemical inertia. The results of complex researches of processes of esterification of carboxylic acids with hydroxyl compounds in industrial homogeneous catalysts of different acidity (sulfuric acid, p-toluensulfonate, phosphoric acid) allowed determining the main approaches to the selection of raw materials chemical composition. This took into account the availability and toxicological characteristics and evaluation of the technological characteristics of esterification process to increase the conversion of raw materials and achieve a high selectivity for the target product. It is shown that to overcome the thermodynamic limitation in all processes, it is necessary to use a 6-7-fold molar excess of the second reagent: acid or alcohol. A solvent (benzene, toluene) is added to the initial mixture, which maintains a constant temperature and removes the reaction water in the form of an azeotrope. To isolate the target products from the reaction mass, it is proposed to use a film evaporator operating under vacuum (p=5-10 mm Hg, t=105-120 ℃). Samples of tributyrin glycerin, triamyl citrate and triethanoate purity ≥ 98% were obtained. The main physical-chemical properties were determined. A comparison with known industrial analogues was carried out. Evaluation of key quality indicators confirms the possibility of their use as plasticizers in the formulation of PVC pastes.