Process for preparing liquid compositions of etherified melamine formaldehyde resins

A process for preparing a liquid composition of an etherified melamine formaldehyde resin, the process comprising:

• i. reacting melamine, formaldehyde and a primary C1-C6-alkanol at least temporarily under acidic conditions in the presence of an excess of the primary C1-C6-alkanol, which means that a molar amount of the primary C1-C6-alkanol employed in i. exceeds a molar amount of formaldehyde employed in i., to obtain a mixture of the etherified melamine formaldehyde resin, water, unreacted formaldehyde and unreacted primary C1-C6-alkanol;
• ii. distilling off at least 50% of the unreacted primary C1-C6-alkanol, unreacted formaldehyde and water comprised in the reaction mixture obtained in i., to obtain a concentrated composition of the etherified melamine formaldehyde resin;
• iii. diluting the concentrated composition of the etherified melamine formaldehyde resin by addition of at least one solvent;
• the at least one solvent being selected from the group consisting of water, a primary C1-C6-alkanol, a solvent B, and mixtures thereof, where the solvent B is selected from the group consisting of a C1-C2-alkoxy-C2-C4-alkanol, a secondary C3-C6-alkanol, a tertiary C4-C6-alkanol, an aliphatic monoketone having 3 to 8 carbon atoms, a cyclic monoketone having 5 to 8 carbon atoms, a C1-C6-alkyl ester of a C1-C4-alkanoic acid, a C1-C2-alkoxy-C2-C4-alkyl ester of a C1-C4-alkanoic acid and an aromatic hydrocarbon;
• wherein in iii. both of the following measures a) and b) are taken, where measure a) is performed first and then measure b) is taken:
• a) adding water or a mixture of water and at least one organic solvent, which is selected from the group consisting of water-miscible organic solvents B as defined herein and the primary C1-C6-alkanol and mixtures thereof, to the concentrated composition of the etherified melamine formaldehyde resin obtained in ii. and removing at least a major portion of the added water by evaporation under reduced pressure;
• b) subsequently adding at least one solvent thereby diluting the concentrated composition of the etherified melamine formaldehyde resin in iii., where the at least one solvent comprises at least 50% by weight, based on a total weight of solvent used, of at least one organic solvent B.