9902.11.77 - Ion-exchange resin and chelating resin with an aminophosphoric functional group, polystyrene resin with aminophosphonic acid groups (CAS No. 125935-42-4) in spherical beads with a mean particle size between 0.30 and 1.20 mm (provided for in subheading 3914.00.60)

This classification pertains to specialized ion-exchange and chelating resins designed with specific functional groups and physical characteristics. Specifically, it covers polystyrene resins modified with aminophosphonic acid groups, identifiable by CAS No. 125935-42-4. These resins are presented in spherical bead form, with a precisely defined mean particle size ranging from 0.30 to 1.20 mm. The "provided for in subheading 3914.00.60" notation indicates that these goods are a specific subset of the broader category of ion-exchangers based on polymers, which are themselves classified under Chapter 39 of the HTS.

As this node represents a leaf node within the HTS database, there are no further subcategories to explore. Its distinctiveness lies in the precise chemical composition (aminophosphoric functional group), the polymer base (polystyrene), and the controlled physical form (spherical beads with a specific particle size range). This level of specificity differentiates it from broader classifications of resins or polymers that may not possess these exact attributes or are intended for different applications, ensuring accurate tariff application.