TECHNOLOGY FOR OBTAINING SUPERCONCENTRATES (MASTERBATCH) BASED ON ALCOHOLYSIS PRODUCTS OF SECONDARY POLYETHYLENE TEREPHTHALATE

Abstract

Regularities of alcoholysis of secondary polyethylene terephthalate (RPET) by diethylene glycol (DEG) have been studied. It is shown that with an increase in the amount of diethylene glycol taken for alcoholysis from 0.1 mol to 0.4 mol per 1 mol of the elementary unit of HPET, a decrease in molecular weight from 1480 to 707 and the associated melting point from 215 to 145 °C are observed, and also intrinsic viscosity from 0.075 to 0.05 dl/g. The physicochemical properties of the products of alcoholysis of SPET (PAPET) have been determined. It has been revealed that PAPET is slightly colored and this is an undesirable factor affecting the individuality of the color of masterbatches based on them. Washing out with PAPET leads to some increase in the molecular weight values and related other indicators of the final oligomers. The structure of PAPET has been studied by infrared spectroscopy and differential scanning calorimetry. It has been revealed that PAPET synthesized at a molar ratio of SPET : DEG of 1:0.4, in which the dropping point according to Ubellode is 155 °C, is most suitable for obtaining superconcentrates. On the basis of PAPET obtained under these conditions, formulations of black and white masterbatches for polyethylene terephthalate fibers have been developed. To ensure uniform dispersion of white (TiO2) and black (K-354 carbon black) pigments, polyethylene wax was added to the superconcentrates. Masterbatches have been obtained by dry method in a twin screw compounder equipped with a double strand head and a granulator. The technological properties of the developed black and white superconcentrates have been determined, which turned out to be very close to those of the superconcentrates used in production. Conducted production tests of these masterbatches have showed that they are not inferior in terms of performance to similar industrial masterbatches used for dyeing threads.