The Dow Chemical Company

Feng-Chih Chang

Robert P Shirtum

David E Busby

Susan A Wernl

Michael L Heather

Glen R Ladewig

Robert L Hearn, Jr

Epoxy resins are prepared by dehydrohalogenating the reaction product of a polyhydric phenol with an excess of an epihalohydrin in the presence of a quaternary ammonium compound wherein prior to dehydrohalogenation, the excess epihalohydrin is removed and an organic solvent is added and at least a portion of the dehydrohalogenation is conducted in the presence of added quantities of a quaternary ammonium compound.

Process for the preparation of epoxy resins

Occluded organic solvent is removed from bisphenol crystals by placing in water maintained at a temperature sufficient to form a molten water-bisphenol phase, holding at that temperature for a time sufficient to transfer the organic solvent to the water phase, flash distilling the organic solvent, cooling molten water-bisphenol phase to produce crystallization and thereafter recovering the bisphenol.

Purification of bisphenols by removing residual solvent

A method of purifying bisphenols by (1) crystallizing the crude bis from a single liquid phase containing water, bis and an organic solvent, (2) stripping the remaining mother liquor (containing the impurities) of solvent and water, and (3) mixing it with phenol, (4) contacting the mixture of phenol and mother liquor with a cation exchange resin to convert the impurity to the desired product, (5) stripping the phenol and (6) recycling the remainder to the initial crystallizing step.

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Lake Jackson, TX, United States of America

Feng-Chih Chang