Product classification
HS code for Butyl rubber: 4002.31
Rubber, synthetic, isobutene-isoprene (butyl) rubber (IIR), in primary forms or in plates, sheets or strip.
Classification of butyl rubber under HS 4002.31
Butyl rubber, scientifically designated as isobutene-isoprene rubber (IIR), is a synthetic elastomer renowned for its unique properties. Its classification under HS code 4002.31 is highly specific and accurate, as this subheading explicitly identifies "isobutene-isoprene (butyl) rubber (IIR)" within the broader category of "Synthetic rubber and factice derived from oils, in primary forms or in plates, sheets or strip" (4002). This precise description directly corresponds to the chemical composition and common industrial nomenclature of butyl rubber, which is a copolymer of isobutylene with a small percentage of isoprene. The code encompasses the material in its initial, unprocessed forms, such as bales, crumbs, or sheets, prior to its conversion into finished articles. Its classification within Chapter 40, which covers rubber and articles thereof, is based on its polymeric nature and its role as a raw material in the rubber industry.
- Covers
- Isobutene-isoprene rubber (IIR)
- Halogenated butyl rubber (e.g., chlorobutyl rubber, bromobutyl rubber), provided they are in primary forms or plates, sheets, or strip.
- Butyl rubber crumbs
- Butyl rubber bales
- Also under 4002.31
- ExxonMobil Butyl
- Lanxess Butyl
- Arlanxeo Butyl
- Bicycle inner tubes
- Pharmaceutical vial stoppers
Codes often confused with 4002.31
Common mistake. Misclassification of butyl rubber can occur if its specific chemical structure is not carefully considered. HS 4002.19, which covers "Other styrene-butadiene rubber (SBR) (other than latex)", is a common point of confusion, as both are synthetic rubbers. However, SBR is derived from styrene and butadiene monomers, fundamentally different from the isobutene-isoprene monomers of butyl rubber. Similarly, HS 4002.20 for "Butadiene rubber (BR)" is distinct, as BR is a homopolymer of butadiene. The explicit mention of "isobutene-isoprene (butyl) rubber (IIR)" in 4002.31 is crucial for accurate differentiation. Furthermore, if butyl rubber has been compounded with fillers or other additives but not yet vulcanized, it might be mistakenly classified under HS 4005, "Compounded rubber, unvulcanised, in primary forms or in plates, sheets or strip". However, 4002.31 is reserved for the pure synthetic rubber in its primary forms, before significant compounding.
Top exporters and importers of HS 400231 (the code used for butyl rubber), 2025
In 2025, the largest exporter of HS 400231 (the code used for butyl rubber) in UN Comtrade data was Russia, with about 30% of world exports; the largest importer in UN Comtrade data was China, with 40% 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 400231, not only butyl rubber.
Top exporters 2025 · share of world exports
- 1 Russia* ~$203M 30% of world exports · partner records ↗
- 2 Saudi Arabia $128M 19% of world exports
- 3 China $80M 12% of world exports
World total: $669M Reported figures on UN Comtrade ↗
Top importers 2025 · share of world imports
- 1 China $249M 40% of world imports
- 2 Thailand $53M 8.5% of world imports
- 3 India $34M 5.5% of world imports
World total: $624M 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 marked * did not, so their figures add up what other countries recorded trading with them, and their exports are valued at buyers' CIF prices. 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 butyl rubber
Brazil classifies butyl rubber under NCM 4002.31.00: HS 4002.31 with 00 added.
Source: Siscomex NCM table, updated Oct 2026. The Portuguese text on each NCM page is the official one.
Questions about butyl rubber
What is the HS code for Butyl rubber?
The HS code for Butyl rubber is 400231 (Rubber; synthetic, isobutene-isoprene (butyl) rubber (IIR), in primary forms or in plates, sheets or strip). The HS code for Butyl rubber is 4002.31.
How do I classify Butyl rubber for customs?
Butyl rubber is classified under HS code 400231 — Rubber; synthetic, isobutene-isoprene (butyl) rubber (IIR), in primary forms or in plates, sheets or strip. This is a 6-digit subheading level code.
What are the key properties of Butyl rubber?
Butyl rubber is known for its excellent impermeability to gases, good resistance to heat, ozone, and chemicals, and high damping properties, making it suitable for inner tubes, seals, and pharmaceutical stoppers.
Which countries are the top exporters of butyl rubber (HS 400231)?
In 2025, the top exporters of HS 400231 (the code used for butyl rubber) in UN Comtrade data were Russia (about $203M, 30% of world exports), Saudi Arabia ($128M) and China ($80M). World exports came to about $669M, 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 butyl rubber (HS 400231)?
In 2025, the top importers of HS 400231 (the code used for butyl rubber) in UN Comtrade data were China ($249M, 40% of world imports), Thailand ($53M) and India ($34M). World imports came to about $624M, 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 Butyl rubber the same in all countries?
The base HS code 400231 for Butyl 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 butyl rubber in Brazil?
In Brazil, butyl rubber (HS 400231) is classified under NCM 4002.31.00.