Special Properties of HMMM.
There is one member of the melamine-formaldehyde coating resin family that deserves special consideration.    This is hexamethoxymethylmelamine(HMMM). This is a methylated rather than a butylated or isobutylated product.     HMMM, as opposed to melamine-formaldehyde resins of the usual type, does not self-condense to any great degree.   The reaction is primarily with the sites on the backbone of the principal film former, the alkyd resin.
This means that embrittlement with aging, such as imparted when the conventional melamine resin self-condenses, is not present.     It means also that the distribution of molecular structure is more linear,  imparting better flexibility.
If one-half the amount of a butylated melamine-formaldehyde resin is replaced by HMMM in a given formulation, and the difference made up with alkyd resin, the formulation will have equal hardness, better gloss, better chemical resistance, and better stability.
Because of the inherent stability of the HMMM molecule, acid catalyst are necessary to initiate a reaction with the hydroxyl groups on the alkyd resin; however, such catalyzed mixtures are package stable, contrary to experience with other melamine ?formaldehyde coating types.
HMMM will react with thermosettable acrylic polymers, either through hydroxyl or carboxyl groups, with the same improvement in properties as described for alkyd types.
HMMM is compatible with epoxy resins and may be used in the same manner as urea-formaldehyde resins are used to cross-link these polymers.       Less is required, and improvements in initial color, gloss, and chemical resistance may be expected.