HS code · 6-digit subheading

HS Code 4002.31 – Rubber; synthetic, isobutene-isoprene (butyl) rubber (IIR), in primary forms or in plates, sheets or strip

HS code 4002.31 is the 6-digit subheading for rubber, synthetic, isobutene-isoprene (butyl) rubber (IIR), in primary forms or in plates, sheets or strip. It is used for butyl rubber bales, IIR sheets, butyl rubber compounds, IIR pellets and butyl sealant base.

What HS 4002.31 covers

This HS code covers isobutene-isoprene (butyl) rubber (IIR) in primary forms, including bales, sheets, or strips. Butyl rubber is a specialized synthetic polymer highly valued for its exceptional impermeability to gases and excellent damping properties, making it crucial for applications requiring air retention or vibration isolation. It is primarily traded between a limited number of chemical producers and manufacturers of inner tubes, pharmaceutical stoppers, sealants, and protective linings. Its unique barrier properties ensure consistent demand in niche industrial and medical sectors. Key aspects of this trade include stringent quality requirements for medical applications and the specialized manufacturing processes involved in its production.

Covers
  • Butyl rubber bales
  • IIR sheets
  • Butyl rubber compounds
  • IIR pellets
  • Butyl sealant base
  • Butyl inner tube material
Examples
  • ExxonMobil Butyl
  • Lanxess Butyl
  • Arlanxeo Butyl
  • Bicycle inner tubes
  • Pharmaceutical vial stoppers

Codes often confused with 4002.31

Common mistake. Can be confused with halo-butyl rubber (400239) if the halogenation isn't specified, or other general synthetic rubbers (e.g., 400299) if its specific chemical structure isn't recognized.

4002.39Rubber; synthetic, halo-isobutene-isoprene rubber (CIIR or BIIR), in primary forms or in plates, sheets or strip4002.99Rubber; synthetic, n.e.c. in heading 4002, (other than latex), in primary forms or in plates, sheets or strip

Top exporters and importers of HS code 400231, 2025

In 2025, the largest exporter of HS code 400231 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.

Top exporters 2025 · share of world exports

  1. 1 Russia* ~$203M
  2. 2 Saudi Arabia $128M
  3. 3 China $80M

World total: $669M Reported figures on UN Comtrade ↗

Top importers 2025 · share of world imports

  1. 1 China $249M
  2. 2 Thailand $53M
  3. 3 India $34M

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 4002.31

Brazil does not split HS 4002.31: its NCM code is 4002.31.00.

  1. 4002.31.00 Isobutene-isoprene (butyl) rubber (IIR)Borracha de isobuteno-isopreno (butila) (IIR)

All Brazil NCM codes in heading 40.02 →

Source: Siscomex NCM table, updated Oct 2026. The Portuguese text is official; the English is our translation.

Questions about HS 4002.31

What is HS code 400231?

HS code 400231 is a 6-digit subheading in the Harmonized System that covers: Rubber; synthetic, isobutene-isoprene (butyl) rubber (IIR), in primary forms or in plates, sheets or strip. This HS code covers isobutene-isoprene (butyl) rubber (IIR) in primary forms, including bales, sheets, or strips. Butyl rubber is a specialized synthetic polymer highly valued for its exceptional impermeability to gases and excellent damping properties, making it crucial for applications requiring air retention or vibration isolation. It is primarily traded between a limited number of chemical producers and manufacturers of inner tubes, pharmaceutical stoppers, sealants, and protective linings. Its unique barrier properties ensure consistent demand in niche industrial and medical sectors. Key aspects of this trade include stringent quality requirements for medical applications and the specialized manufacturing processes involved in its production.

What products fall under HS code 400231?

Butyl rubber bales, IIR sheets, Butyl rubber compounds, IIR pellets, Butyl sealant base, Butyl inner tube material

What are common misclassifications for HS code 400231?

Can be confused with halo-butyl rubber (400239) if the halogenation isn't specified, or other general synthetic rubbers (e.g., 400299) if its specific chemical structure isn't recognized.

Which countries are the top exporters of goods under HS code 400231?

In 2025, the top exporters of HS code 400231 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 goods under HS code 400231?

In 2025, the top importers of HS code 400231 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.

How is HS code 400231 structured?

HS code 400231 is a 6-digit subheading under the Harmonized System. The first 2 digits (40) identify the chapter, digits 3-4 (02) identify the heading, and digits 5-6 (31) specify the subheading. This code is standardized globally by the World Customs Organization.

What is the Brazil NCM code for HS code 400231?

In Brazil, HS code 400231 is NCM 4002.31.00. The last two digits are 00 because Brazil does not split this HS code further.