Cymel 105 Modified methylated melamine resin Cytec Crosslinking / Coupling / Curing Agents >> Amine >> Melamine-formaldehyde Coatings >> Waterborne Ethanol Insoluble in water Soluble in xylene HIGH SOLIDS METHYLATED MELAMINE RESINS HIGHLY METHYLATED MELAMINE RESINS Highly methylated melamine resins consist of com-mercial versions of hexamethoxymethylmelamine (HMMM). They differ primarily in their degree of alkylation and monomer content. All are efficient crosslinking agents for hydroxyl, carboxyl and amide functional polymers. The practical equivalent weight for most of the resins is 130-180. Advantages are low VOCs; high film flexibility and toughness when used with inherently flexible backbone resins; excellent formulation stability, especially in waterborne sys-tems formulated at a pH of 8-9; good mar resistance; and good intercoat adhesion properties. As typical with melamine resins, all are low in color and color development, have excellent exterior durability and good heat resistance. Because of their high extent of alkylation, the resins in this series require the addi-tion of a strong acid catalyst for acceptable cure response when baked at 125-150°C. Typically, 0.2- 0.4% p-toluene sulfonic acid based on total binder solids is recommended. The optimum concentration of acid catalyst depends on the basicity of the other components in the formulation and should be deter-mined experimentally. Using a blocking amine for the acid catalyst and adding a stabilizing alcohol to the formulation can enhance formulation stability. The last two resins in the series, CYMEL 104 and CYMEL 105 resins, are blends of CYMEL 303 resin and Reactol * 180 polyol. The presence of the polyol increases the cure response, film hardness and cor-rosion resistance of the coating. CYMEL 105 CYMEL 303 resin modified with 40% polyol . Very fast cure response. High solids, highly methylated melamine resins modified with polyol. Used as an effective crosslinking agent for hydroxyl, carboxyl and amide functional polymers. Offers low VOC, high film flexibility and toughness, formulation stability, good mar resistance and good intercoat adhesion properties. Gives low color and color development, very good exterior durability and good heat resistance. Requires addition of a strong acid catalyst. Provides very fast cure response. Increases film hardness and corrosion resistance of coating.