PROCEDIMIENTO PARA LA PREPARACION DE LIGANTES CATODICAMENTE DEPOSITABLES AUTO-RETICULANTES PARA EL ESMALTADO DE INMERSION ELECTRICO EN BASE DE CONDENSADOS DE ALQUILFENOL-FORMALDEHIDO

摘要

Cathodically depositable self-crosslinking binders for electrodeposition based on alkylphenol-formaldehyde condensates wherein an alkylphenol-formaldehyde condensate having a molecular weight of at least 500 and a hydroxyl value of between 100 and 700 mg KOH/g, modified through self-condensation or etherification of the phenolic hydroxy groups, obtained through a reaction catalyzed with a base (component A), is reacted simultaneously or separately with (B) amines which carry a tertiary amino group and at least one hydroxy group or primary or secondary amino group (component B) and (C) aromatic or aliphatic or cycloaliphatic polyisocyanates (component C), the weight ratio of components being chosen in order that for each mole of component (B) 2 to 4 NCO-equivalents of component (C) are present and that the resultant isocyanate-group-free reaction product has an amine value of between 40 and 120 mg KOH/g is described. The binders are internally platicized to provide increased flexibility of coatings prepared from the binders which are essentially chip resistant.