Glycoluril-Formaldehyde (GF) Resins

Properties and Applications

Glycoluril-formaldehyde resin (GF), also called tetramethylolglycoluril (TMGU), is a crosslinkable aminoplast produced by the reaction of glycoluril and formaldehyde.¹ TMGU is often reacted with alcohols to form tetraalkoxymethyl glycoluril resins. The alkoxymethyl functional groups readily react with resins containing hydroxyl, amide or carboxyl functional groups yielding three-dimensional thermoset polymer networks. The average functionality of GF resins is somewhat lower than that of melamine resins because there are only four alkoxymethyl functional groups per glycouril molecule whereas each MF triazine ring has six. Thus functional polymers cured with GF resins have a lower crosslink density than polymers cured with (etherified) melamine-formaldehyde (MF) and therefore improved film flexibility and toughness. They also have better adhesion to metallic substrates, release less formaldehyde on curing, and are typically UV resistant and thus can be used in exterior applications.

Highly alkylated glycoluril resins are compatible with a large number of resins including many acrylics, alkyds, polyesters and epoxies whereas unalkylated GF resins are water soluble.² Reactive polymers crosslinked with these resins have typically higher chemical resistance and better adhesion properties than polymers cured with MF resins. On the downside, they are much more expensive than MF resins and are somewhat less reactive, and thus have to be cured at higher temperatures and/or require strong acid catalysts to achieve high crosslink densities.

Alkylated glycoluril-formaldehyde resins are employed to crosslink industrial thermosetting resins, including alkyds, epoxies, and polyester-polyols. Important applications include flexible and chemical-resistant primers and coil of metal decoration enamels. However, their higher cost greatly limits their applications.

Manufacturers & Distributors

¹Glycoluril itself is synthesized by the addition of two moles of urea with one mole of glyoxal.
²Allnex Amino Crosslinker Product Guide - Cymel and Setamine Resins (2017)