Product classification
HS code for CIIR rubber: 4002.39
Rubber, synthetic, halo-isobutene-isoprene rubber (CIIR or BIIR), in primary forms or in plates, sheets or strip.
Classification of CIIR rubber under HS 4002.39
CIIR rubber, or Chlorinated Isobutene-Isoprene Rubber (commonly known as Chlorobutyl), is classified under HS code 4002.39. This classification is found in Chapter 40, which covers rubber and articles thereof. Within the 4002 heading for synthetic rubber, sub-heading 4002.31 covers regular isobutene-isoprene (butyl) rubber (IIR), while 4002.39 is the "other" category that specifically captures the halo-isobutene-isoprene derivatives, including both CIIR and BIIR (Bromobutyl). The classification is determined by the chemical modification of the base polymer; the addition of chlorine atoms to the butyl rubber backbone provides the material with unique properties such as faster cure rates and better adhesion to other rubbers. To be classified here, the material must be in primary forms like bales, blocks, or sheets, and must not yet be vulcanized or compounded with fillers.
- Covers
- Chlorobutyl rubber in primary forms
- CIIR synthetic rubber bales
- Unvulcanized chlorinated isobutene-isoprene sheets
- Halo-isobutene-isoprene rubber (CIIR)
- Chlorinated butyl rubber crumbs
- Also under 4002.39
- Arlanxeo Chlorobutyl
- ExxonMobil Bromobutyl
- Lanxess Bromobutyl
- Tubeless tire inner liners
- Pharmaceutical bottle stoppers
Codes often confused with 4002.39
Common mistake. The most frequent misclassification is using 4002.31, which is reserved for standard, non-halogenated butyl rubber (IIR). Another error involves 4002.99 for "other" synthetic rubbers, but since CIIR is a specific halo-derivative of IIR, 4002.39 is the legally correct specific sub-heading. If the rubber is already mixed with carbon black or silica, it must be moved to 4005 (compounded rubber).
Top exporters and importers of HS 400239 (the code used for CIIR rubber), 2025
In 2025, the largest exporter of HS 400239 (the code used for CIIR rubber) in UN Comtrade data was the United States, with 23% of world exports; the largest importer in UN Comtrade data was China, with 18% of world imports. Countries that did not report 2025 data are estimated from partner records, which can understate them.
Figures cover everything classified under HS 400239, not only CIIR rubber.
Top exporters 2025 · share of world exports
- 1 United States $336M 23% of world exports
- 2 Singapore $300M 20% of world exports
- 3 Belgium $236M 16% of world exports
World total: $1.5B Reported figures on UN Comtrade ↗
Top importers 2025 · share of world imports
- 1 China $310M 18% of world imports
- 2 Belgium $224M 13% of world imports
- 3 India $116M 6.8% of world imports
World total: $1.7B Reported figures on UN Comtrade ↗
How these figures are built
109 countries reported 2025 trade to UN Comtrade in HS 2022, and their own totals are used. Countries that did not report are estimated from what other countries recorded trading with them. Those estimates miss trade with other non-reporting countries, so they can be low, and a non-reporting country can rank higher than shown or be missing from the list. World totals add both and leave out trade between two non-reporting countries. Figures are in current US dollars; reported imports are mostly valued CIF and exports FOB, and exports include re-exports. The UN Comtrade links show the underlying records; they can also list a few reporters left out here (regional groups and older HS editions).
Source: UN Comtrade (United Nations Statistics Division), 2025 annual data.
Brazil NCM code for CIIR rubber
Brazil classifies CIIR rubber under NCM 4002.39.00: HS 4002.39 with 00 added.
Source: Siscomex NCM table, updated Oct 2026. The Portuguese text on each NCM page is the official one.
Questions about CIIR rubber
What is the HS code for CIIR rubber?
The HS code for CIIR rubber is 400239 (Rubber; synthetic, halo-isobutene-isoprene rubber (CIIR or BIIR), in primary forms or in plates, sheets or strip). The HS code for CIIR (Chlorobutyl) rubber is 4002.39.
How do I classify CIIR rubber for customs?
CIIR rubber is classified under HS code 400239 — Rubber; synthetic, halo-isobutene-isoprene rubber (CIIR or BIIR), in primary forms or in plates, sheets or strip. This is a 6-digit subheading level code.
Is Bromobutyl rubber (BIIR) classified under the same code?
Yes, both Chlorobutyl (CIIR) and Bromobutyl (BIIR) fall under the halo-isobutene-isoprene rubber category of 4002.39.
Which countries are the top exporters of CIIR rubber (HS 400239)?
In 2025, the top exporters of HS 400239 (the code used for CIIR rubber) in UN Comtrade data were the United States ($336M, 23% of world exports), Singapore ($300M) and Belgium ($236M). World exports came to about $1.5B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Which countries are the top importers of CIIR rubber (HS 400239)?
In 2025, the top importers of HS 400239 (the code used for CIIR rubber) in UN Comtrade data were China ($310M, 18% of world imports), Belgium ($224M) and India ($116M). World imports came to about $1.7B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Is the HS code for CIIR rubber the same in all countries?
The base HS code 400239 for CIIR rubber is internationally standardized for the first 6 digits across 200+ countries. Individual countries may add additional digits for national tariff lines and specific classifications.
What is the NCM code for CIIR rubber in Brazil?
In Brazil, CIIR rubber (HS 400239) is classified under NCM 4002.39.00.