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SITCSection 2
U.S. imports of butyl rubber (iir) and halobutyl rubber (ciir/biir) (SITC 23213) totaled $5.7M in April 2026, traded with 16 countries.
Importers of Butyl Rubber (IIR) and Halobutyl Rubber (CIIR/BIIR) paid $142K in duties in April 2026 — an effective duty rate of 9.3% on $1.5M in dutiable value, based on actual customs collections rather than the published tariff schedule. Butyl Rubber (IIR) and Halobutyl Rubber (CIIR/BIIR) imports of $5.7M in April 2026 ran 11% above the year-to-date monthly average of $5.1M.
Last updated: April 2026 dataButyl rubber (IIR) and its halogenated derivatives — chlorobutyl (CIIR) and bromobutyl (BIIR) — are defined by their exceptionally low gas permeability, which makes them the standard material for tire inner liners, pharmaceutical stoppers, and pressure-sensitive sealants. Halobutyl grades carry reactive halogen sites that enable co-vulcanization with general-purpose rubbers, a processing advantage that commands a price premium over standard IIR. The distinction between IIR and CIIR/BIIR is commercially significant and should be clearly stated on shipping documents, as the grades serve different compounding applications.
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Chlorobutyl (CIIR) and bromobutyl (BIIR) can be co-cured with diene rubbers like NR and SBR in the tire carcass, eliminating the need for a tie-gum layer. Standard IIR does not co-vulcanize readily with these polymers, making halobutyl grades the preferred choice for modern tubeless tire construction despite their higher cost.
The commercial invoice and certificate of analysis should clearly state whether the product is IIR, CIIR, or BIIR, along with the Mooney viscosity and halogen content where applicable. Customs examiners may request technical data sheets if the grade designation is ambiguous, particularly when the unit value differs significantly from typical IIR benchmarks.
Monthly import values over time
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