Melamine Ethoxylates as Novel Formaldehyde Free Replacements of Resin Re-Tanning Agents

Abstract

Melamine urea formaldehyde condensates or resin re-tanning agents are commonly used in the leather industry. They give rise
to homogeneous filling, are easily and widely applicable, but generally contribute to free formaldehyde, measurable in emission
or extraction methods. Many projects to resolve this issue have been carried out. The weakness of the resin re-tanning is the reversibility of the bond formation between formaldehyde and two amino groups. The formaldehyde forms a methylene group after condensation with two amino groups and releases water. This methylene group can be hydrolyzed under acidic conditions to release formaldehyde again, reversing the synthesis.

Melamine ethoxylates were found to be a formaldehyde free, stable, and easily applicable alternative. Besides the fact that they are made without formaldehyde, it proved to be possible to incorporate renewable components into their synthesis, giving rise to an even more sustainable product. Another sustainable aspect of this chemistry is the delivery of the potential product as a concentrated liquid versus most resin re-tanning agents being placed into the market as spray dried powders, consuming significant amounts of energy in the process.

Melamine ethoxylates show advantages in application on leather in comparison with classical resin re-tanning agents. An insight
into the scope of application will be given, showing that melamine ethoxylates can be considered a formaldehyde free replacement for resin re-tanning agents