PROCESS FOR PREPARING THERMOSETTING UREA FORMALDEHYDE RESINS AND THEIR USE FOR IMPREGNATING AND/OR COATING SUPPORTING WEBS OF WOOD-BASED BOARDS

A method for preparing thermosettable urea-formaldehyde resins having a urea to formaldehyde molar ratio of 1:1 to 1:1.5 wherein urea and formaldehyde are first reacted in an aqueous solution at a molar ratio of 1:1.5 to 1:4 in the pH range between 7.5 to 10, and then condensing the reactants in a p...

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Bibliographische Detailangaben
Hauptverfasser:	HOLTSCHMIDT, ULRICH, HELLWIG, DIETER, SCHAMBERG, ECKEHARD
Format:	Patent
Sprache:	eng ; ger
Schlagworte:	ADHESIVES CHEMICAL PAINT OR INK REMOVERS CHEMISTRY COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS COMPOSITIONS BASED THEREON COMPOSITIONS OF MACROMOLECULAR COMPOUNDS CORRECTING FLUIDS DYES FILLING PASTES IMPREGNATING OR COATING OF PAPER INKS LAYERED PRODUCTS LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS METALLURGY MISCELLANEOUS APPLICATIONS OF MATERIALS MISCELLANEOUS COMPOSITIONS NATURAL RESINS ORGANIC MACROMOLECULAR COMPOUNDS PAINTS PAPER NOT OTHERWISE PROVIDED FOR PAPER-MAKING PASTES OR SOLIDS FOR COLOURING OR PRINTING PERFORMING OPERATIONS POLISHES PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D PRODUCTION OF CELLULOSE PULP COMPOSITIONS TEXTILES THEIR PREPARATION OR CHEMICAL WORKING-UP TRANSPORTING TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G USE OF MATERIALS THEREFOR WOODSTAINS
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Beschreibung
Zusammenfassung:	A method for preparing thermosettable urea-formaldehyde resins having a urea to formaldehyde molar ratio of 1:1 to 1:1.5 wherein urea and formaldehyde are first reacted in an aqueous solution at a molar ratio of 1:1.5 to 1:4 in the pH range between 7.5 to 10, and then condensing the reactants in a pH range from 4 to 6 to a precipitation number of 1:1.5 to 1:10, thereafter adjusting the pH to 7 to 10 and adding the remaining urea to obtain a molar ratio of 1:1 to 1:1.5 and continuing the reaction until a precipitation number of 1:0.5 to 1:3 is obtained. The products obtained have a uniform molecular weight and good penetration properties when used to impregnate supporting webs for coating wood-based panels.