| 摘要 |
1536011 Producing UF resins directly from catalytically oxidized methanol P M PUIG 18 Feb 1976 [13 May 1975] 6356/76 Heading C3R [Also in Division C2] A process for the production of urea-formaldehyde adhesives or resins process comprises the stages of: (a) catalytically oxidizing methanol with air; (b) condensing the gases emanating from the catalytic oxidation of the methanol, whereby condensable products therein are condensed in the form of a solution; (c) separating the solution containing condensed products obtained in stage (b) from the uncondensed gases remaining after said condensation stage; (d) cooling the uncondensed gases from stage (c) and washing the cooled gas in a washing column with a solution comprising cold polymerized formaldehyde which takes up the methanol and formaldehyde present in the uncondensed gases; (e) distilling the solution obtained in stage (c) in order to recover separately methanol and a concentrated aqueous formaldehyde solution, the formaldehyde content of which is at least partially in polymerized form; (f) distilling the solution obtained in stage (d) in order to recover the methanol taken up into said solution and to isolate the formaldehyde in the form of an aqueous solution thereof containing polymerized formaldehyde; (g) passing a portion of the aqueous formaldehyde solution obtained in stage (f) to distillation stage (e) and recycling another portion of the aqueous formaldehyde solution obtained in stage (f) to step (d) as the cold polymerized washing solution therein; and (h) mixing the concentrated aqueous solution of formaldehyde obtained in stage (e) with urea under conditions of predetermined pH and temperature in order to obtain urea-formaldehyde adhesives or resins. Distillation stages (e) and (f) may be carried out in a single column. |
