Wednesday, April 16, 2008

Stability of Melamine Formaldehyde Resin

Aqueous solution of melamine resin adhesive are much less stable than those of urea resins; they are therefore normally spray-dried soon after manufacture producing a powder glue with a storage life of least a year. The user re-dissolves the powder in water to give solution that remain stable for a few days depending on temperature and resin concentration. Instability result in the solution becoming cloudy and later semi-solid. In its early stages this state can be reversed by heating the resin to 40o to 50oC provided no hardener has been added.

Partial etherification of low molecular weight resins with one of the lower alcohols, in particular methanol, improves stability in the liquid state. These resin, which can be produced with infinite solubility in water, are valuable in textile applications but have not found much use as adhesives. A method of related to melamine and also reacts with formaldehyde as well as methanol formaldehyde resins is inferior to melamine resins it may be expected that a co-condensate would have downgraded properties according to the ratio of dicyamide to melamine.

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