Melamine Resins

Highly methylated melamine resins are a part of commercial hexamethoxymethylmelamine (HMMM). They primarily vary in terms of alkylation degrees and monomer contents. All are effective cross-linking agents for hydroxyl, carboxyl, and amide functional polymers. The practical equivalent weight for most of these resins is between 130-180. Their advantages include low VOCs, high film flexibility and durability (especially when used with flexible structured resins), excellent formulation stability (particularly in aqueous systems formulated at pH 8-9), good scratch resistance, and good

inter-coat adhesion. As typical with melamine resins, they are colorless with minimal color development, possess excellent outdoor durability, and demonstrate good heat resistance. Resins in this series, due to their high alkylation degrees, require a strong acid catalyst for acceptable curing response when baked at 125-150°C. Typically, 0.2-0.4% p toluenesulfonic acid based on total binder solids is recommended. The optimum concentration of acid catalyst depends on the basicity of other
components in the formulation and should be determined experimentally. Using a blocking amine for the acid catalyst and adding alcohol for stabilization in the formulation can enhance formulation
stability.