3905.91 - Copolymers:

This HTS category, 3905.91, encompasses "other" copolymers where the primary components are vinyl acetate or other vinyl esters. It specifically addresses vinyl polymers that do not fall under the more specific headings within Chapter 39, but are distinct from the "other" vinyl polymers mentioned in the parent category. The "other" designation here signifies that these copolymers are not exclusively vinyl acetate or other vinyl esters in their entirety, but rather contain them as significant, though not necessarily sole, polymeric constituents.

Distinguishing this category from its sibling, 3905.99, relies on the specific nature of the vinyl ester components and their proportions within the copolymer. While both fall under the broader "Other" subheading for vinyl polymers, 3905.91 focuses on those where vinyl acetate or other vinyl esters are the defining or major co-monomers. The scope of 3905.99 would typically be reserved for vinyl polymers where vinyl acetate or other vinyl esters are either absent or present in minor, non-defining quantities, or are based on different vinyl monomer groups entirely.

Within 3905.91, further classification is provided by subcategories based on the specific weight percentage of vinyl acetate derivatives. Subcategory 3905.91.10.00 is designated for copolymers containing 50 percent or more by weight of derivatives of vinyl acetate, indicating a strong reliance on this particular vinyl ester. The remaining copolymers, where vinyl acetate derivatives constitute less than 50 percent by weight or are absent but other vinyl esters are present, are classified under 3905.91.50.00.