4002.39.00.00 - Other

This HTS category, 4002.39.00.00, encompasses "Other" synthetic rubber and factice derived from oils, specifically within the broader group of isobutene-isoprene (butyl) rubber (IIR) and halo-isobutene-isoprene rubber (CIIR or BIIR). It serves as a residual category for these types of synthetic rubbers that do not fall under the more specific classification. These materials are typically produced in primary forms such as bales, granules, or powders, or as plates, sheets, or strip.

The key distinction of this category lies in its exclusion of the precisely defined isobutene-isoprene (butyl) rubber (IIR) classified under 4002.31.00.00. While both categories deal with IIR and related halo-versions, 4002.39.00.00 is reserved for those instances that, for reasons of formulation, specific physical properties, or manufacturing process, do not precisely meet the criteria for the sibling classification. This can include mixtures of IIR with other synthetic polymers or specific processing aids that alter its characteristics from standard IIR.

As this is a leaf node in the HTS, there are no further subcategories. Therefore, the classification into 4002.39.00.00 is determined by a process of elimination, ensuring that the material is indeed an isobutene-isoprene (butyl) rubber or a halo-isobutene-isoprene rubber, but does not qualify for the more specific heading 4002.31.00.00. Classification relies on a thorough understanding of the specific composition and properties of the imported or exported rubber product, referencing technical data sheets and analytical reports where necessary.