FIELD: chemistry.
SUBSTANCE: invention relates to increasing molecular weight during heat treatment of a polyester coupled with use of latent heat of granulation. According to the method, raw polyester material in the form of a melt is forced through an outlet opening, granulated in a stream of cooling water and, after passing through the cooling water section, separated from the stream of cooling water. The obtained granulate layer is subjected to heat drying and subsequent treatment by feeding a gas stream consisting of a gas or a mixture of gases into the granulate layer. In the next step, neither the used granulate, nor the fed gas, or the mixture of gases of the gas stream is heated using external energy. The gas stream passes in the opposite direction of the granulate in a conditioning apparatus and the average temperature of the granulate layer before the input of said step is set higher than 170°C.
EFFECT: higher efficiency of the method.
13 cl, 2 dwg, 3 tbl
