3909.10.00.00 - Urea resins; thiourea resins

This HTS classification covers urea resins and thiourea resins when presented in their primary forms. These are synthetic thermosetting resins produced through the polymerization of urea or thiourea with aldehydes, such as formaldehyde. Urea resins are widely used as adhesives in particleboard and plywood, as well as in laminates, coatings, and molding compounds due to their good hardness, scratch resistance, and clarity. Thiourea resins, while less common, share similar properties and applications.

It is important to distinguish this category from its sibling entries. Specifically, 3909.20.00.00 pertains to melamine resins, which are also amino-resins but derived from melamine. Similarly, 3909.40.00.00 covers phenolic resins, a distinct class of thermosetting polymers. The polyurethane category, 3909.50, represents a completely different type of polymer chemistry. Therefore, classification under 3909.10 hinges on the specific base materials and the resulting chemical structure of the resin.

As this is a leaf node within the HTS structure, there are no further subdivisions under 3909.10.00.00. Classification at this level is definitive and relies on confirming the presence of urea or thiourea as the primary constituent in the resin. Exporters and importers should ensure that the product's chemical composition aligns with the definition of urea or thiourea resins to avoid misclassification.