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Cyclized Rubber (Alkylated Chlorosulfonated Rubber) from Japan

Cyclized rubber is produced by treating natural rubber with sulfuric acid or other agents to create cyclic structures, yielding a harder derivative used in paints and varnishes. It appears in primary flake or powder form. Falls under HTS 3913.90.1000 as a chemical derivative of natural rubber not elsewhere specified.

Duty Rate — Japan → United States

12.5%

Rate breakdown

9903.05.4912.5%Section 301 (forced labor) — Japan (col1 rate < 12.5 percent): MFN < 12.5% → total duty capped at 12.5%

Import Tips

Submit chemical structure analysis proving cyclization of natural rubber polyisoprene to confirm 3913 classification

Label clearly as 'primary form' to distinguish from finished articles in Chapter 40 or 39 headings

Watch for misclassification as reclaimed rubber (4003) if processing involves devulcanization