9902.11.67 - Ion-exchange resin comprised of a copolymer of methacrylic acid cross-linked with divinylbenzene, in the hydrogen ionic form (CAS No. 50602-21-6) (provided for in subheading 3914.00.60)

This HTS category, 9902.11.67, specifically covers a specialized ion-exchange resin. The material is defined by its composition: a copolymer of methacrylic acid that has been cross-linked with divinylbenzene. Crucially, it is presented in its hydrogen ionic form, identified by CAS Number 50602-21-6. This particular resin is designated for temporary or special classification purposes, as indicated by its placement within Chapter 99, and is further referenced as being provided for in subheading 3914.00.60, suggesting its underlying material classification within the broader plastics and articles thereof.

Distinguishing this entry from its sibling categories is paramount. While sibling categories at the root level, such as those pertaining to live animals (Chapters 01), represent broad product groups, 9902.11.67 is an extremely specific, technologically advanced material. Its classification within Chapter 99 signifies it is not a standard, general merchandise item but rather subject to specific trade provisions or temporary restrictions. Unlike broader classifications of polymers, this entry targets a particular functional resin with a precise chemical structure and ionic form.

As this is a leaf node within the HTS, there are no further subcategories branching from 9902.11.67. The classification is specific enough that no further subdivision is necessary within this temporary provision. Therefore, the focus remains on correctly identifying and documenting the precise characteristics of this ion-exchange resin to ensure accurate customs declaration and compliance under the special provisions of Chapter 99.