Formaldehyde → Melamine formaldehyde

Participants

Reaction Steps

The melamine resin (1) is disclosed in Japanese Patent Application Laid-open No. 73267/1994 (JP-A-6-73267) and can be produced by reacting about 0.8 to 10 moles (preferably 0.8 to 5 moles, more preferably 1 to 3 moles, and particularly 1 to 2 moles) of formaldehyde with each mole of melamine in aqueous solution or aqueous dispersion. Thus, for example, a mixture of melamine with an aqueous solution of formaldehyde is reacted at pH about 8 to 9 and a temperature of about 50 to 90° C. and as the solution develops turbidity with progress of condensation reaction, the condensation reaction is stopped by, for example, cooling at a suitable stage. This reaction mixture is dried by a spray-drying or other method to provide a particulate crude melamine-formaldehyde condensate. This particulate crude melamine-formaldehyde condensate is washed with warm water (about 50 to 70° C.) for a suitable time (e.g. 10 min. to 3 hrs., preferably about 30 min. to 1 hr.) and filtered. The residue is dissolved in dimethyl sulfoxide. This dimethyl sulfoxide solution is filtered to remove the insoluble matter and the filtrate is poured in a large excess of acetone. The precipitate is recovered by filtration and dried to provide a purified melamine-formaldehyde polycondensate as white powders.

Provenance & Evidence