Patent ID: 6828465
Filing Date: 2004-12-07
Classification: C07C

Abstract:
A process for preparing crystals of an adduct of a bisphenol and a phenol comprising:(a) preparing a solution containing bisphenol and phenol; and (b) crystallizing continuously said adduct of bisphenol and phenol in one or more crystallization devices which comprise a crystallization tank, a circulating pump and a cooler; wherein,the residence time of the liquid being crystallized in the crystallization tank is 2 to 12 hours; crystallization is performed in 1 to 5 stages, each of said stages containing the one or more crystallization devices; the temperature in the crystallization tank in the last crystallization stage is 40 to 70Â° C.; the concentration of bisphenol in the inflow to the first crystallization stage is 15 to 40 wt. %; in the outflow from the last crystallization stage the concentration of bisphenol in dissolved form in the mother liquor is 10 to 20 wt. % and the proportion of crystallized solids in crystals of the adduct of a bisphenol and a phenol is 20 to 30 wt. %; a suspension of crystals of said adduct of bisphenol and phenol is circulated through each crystallization tank at a specific pump energy of at most 150 Watts/m3, and said suspension of crystals of said adduct of bisphenol and phenol is circulated through said cooler having a top and a bottom at a speed of 1 m/s to 5 m/s from said top of said cooler to said bottom of said cooler.