Low addition of melamine salts for improved UF adhesives water resistance

Abstract

Melamine/acid salts such as melamine acetate, melamine formate and melamine oxalate, function both as efficient hidden hardeners of UF resins for plywood as well as upgrading the performance of simple UF resins for plywood through approximately 10% by mass melamine grafting to yield comparable strength durability of premanufactured MUF resins of 30%–40% melamine mass content, hence of resins of much higher mass content of melamine. The system works by simple addition of a melamine salt in the UF gluemix eliminating the need to premanufacture a MUF resin. The effectiveness of melamine grafting in the glue-mix and during hot pressing has been found to depend from the relative solubility of the melamine salt which depends from both the acid strength of the acid as well as the number of acid functions in the salt. The reasons why traditional, premanufactured MUF resins waste 2/3 or more of the melamine used in them, and why the system presented is so much more effective by not wasting melamine are presented and discussed.