| 摘要 |
1,054,379. Purifying epoxy resins. INVENTA A.G. FUR FORSCHUNG UND PATENTVERWERTUNG. Nov. 12, 1963 [Nov. 13, 1962], No. 44649/63. Heading C3B. A process for purifying crude, hardenable epoxy resin mixtures prepared by reacting polyphenols with epihalohydrins in the presence of of alkali hydroxide comprises heating the crude mixture to above 100‹ C., expanding the mixture by way of a pressure holding valve into the head of a gravity film evaporator heated to 120-300‹ C., whereafter the crude mixture flows downwardly on the evaporator surface, separating the partly purified resin, dissolving this resin in an organic solvent and filtering the insoluble salt from the solution, heating the solution of resin to a temperature above the boiling point of the solvent, expanding the solution by way of a pressure holding valve into the head of the gravity film evaporator which is heated to 20-200‹ C. above the boiling point of the solvent, whereafter the solution flows downwardly on the evaporator surface, and drawing pure resin off at the sump of the evaporator while withdrawing the solvent from the evaporator and condensing it. |
