GB1153697A - Recovery of Aromatic Formaldehyde Resins by Steam Sparging and Vacuum Distillation - Google Patents

Abstract

1,153,697. Aromatic formaldehyde resins, purification. ESSO RESEARCH & ENG. CO. 12 Feb., 1968, No. 6808/68. Heading B1B. A resin, produced by reacting formaldehyde (or a polymer thereof) with one or more aromatic hydrocarbons in the presence of an acid catalyst, is separated from the crude reaction product by introducing it through line 14 into zone 11 where it is treated with steam, supplied through sparging device 13, so that an aqueous phase and an oil phase are formed; after allowing the two phases to separate, the oil phase is transferred through lines 20 and 22 into distillation column 23 which is maintained under subatmospheric pressure whereby water and formaldehyde, aromatic hydrocarbons, and low molecular weight polymers are removed as overhead and sidestream fractions, and the purified resin is withdrawn as bottoms fraction through line 28. A solution of sodium carbonate may be introduced through line 16 into the crude resin in zone 11 before the steam-sparging operation. Alternatively, water and aromatic hydrocarbons may be introduced through lines 29, 31. The separated oil phase is passed into a second sparging zone 35 and, after steam-treatment and separation, the second oil phase is transferred to the distillation column 23, which is also supplied with sodium carbonate solution. Instead of using column 23, the unreacted formaldehyde and aromatic hydrocarbons, as well as the low molecular weight polymers, may be removed from the oil phase by submitted it, in the form of a film, to vacuum flashing.