Product classification
HS code for Crude MDI: 3909.31
Amino-resins, n.e.c. in heading no. 3909, in primary forms, poly(methylene phenyl isocyanate) (Crude MDI, polymeric MDI).
Classification of crude MDI under HS 3909.31
Crude MDI, technically known as poly(methylene phenyl isocyanate) or polymeric MDI, is classified under HS code 3909.31. This classification is situated within Chapter 39 of the Harmonized System, which covers plastics and articles thereof. Heading 3909 specifically addresses amino-resins, phenolic resins, and polyurethanes in primary forms. Crude MDI is a complex mixture containing 4,4'-diphenylmethane diisocyanate along with its isomers and higher molecular weight oligomers. Unlike pure MDI, which is a chemically defined compound with a specific molecular structure, crude MDI is considered a polymer in primary form due to its variable composition and polymerization. The classification under 3909.31 is precise because the subheading explicitly names poly(methylene phenyl isocyanate). This follows the legal notes of Chapter 39, which define "primary forms" as liquids, pastes, blocks, lumps, or similar bulk forms. Because crude MDI is typically traded as a dark, viscous liquid mixture used primarily in the production of rigid polyurethane foams for insulation and construction, it meets the criteria for primary forms. It is distinguished from the pure isocyanates of Chapter 29 (specifically 2929.10) because it is a mixture of polymers and not a single, isolated organic compound. The presence of multiple isocyanate groups and the polymeric nature of the substance are the deciding factors that move it from the chemical chapter (29) to the plastics chapter (39).
- Covers
- Polymeric MDI (PMDI)
- Crude diphenylmethane diisocyanate
- Poly(methylene phenyl isocyanate) in liquid form
- Technical grade MDI mixtures
- Also under 3909.31
- BASF Lupranate MDI
- Covestro Desmodur MDI
- Dow PAPI MDI
- Wanhua Wannate MDI
Codes often confused with 3909.31
Common mistake. Crude MDI is often misclassified under HS code 2929.10, which is reserved for pure, chemically defined isocyanates like pure MDI or TDI. Another common error is using 3824.99 for chemical mixtures, but since crude MDI is a polymer in primary form, Chapter 39 takes precedence according to the General Interpretative Rules.
Top exporters and importers of HS 390931 (the code used for crude MDI), 2025
In 2025, the largest exporter of HS 390931 (the code used for crude MDI) in UN Comtrade data was China, with 17% of world exports; the largest importer in UN Comtrade data was China, with 8.1% 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 390931, not only crude MDI.
Top exporters 2025 · share of world exports
- 1 China $1.3B 17% of world exports
- 2 Germany $1.2B 15% of world exports
- 3 Belgium $1.1B 13% of world exports
World total: $8.0B Reported figures on UN Comtrade ↗
Top importers 2025 · share of world imports
- 1 China $628M 8.1% of world imports
- 2 Türkiye $518M 6.7% of world imports
- 3 India $431M 5.6% of world imports
World total: $7.8B 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 crude MDI
Brazil classifies crude MDI under NCM 3909.31.00: HS 3909.31 with 00 added.
Source: Siscomex NCM table, updated Oct 2026. The Portuguese text on each NCM page is the official one.
Questions about crude MDI
What is the HS code for Crude MDI?
The HS code for Crude MDI is 390931 (Amino-resins; n.e.c. in heading no. 3909, in primary forms, poly(methylene phenyl isocyanate) (Crude MDI, polymeric MDI)). The HS code for crude MDI (polymeric MDI) is 3909.31.
How do I classify Crude MDI for customs?
Crude MDI is classified under HS code 390931 — Amino-resins; n.e.c. in heading no. 3909, in primary forms, poly(methylene phenyl isocyanate) (Crude MDI, polymeric MDI). This is a 6-digit subheading level code.
Why is crude MDI not in Chapter 29?
Chapter 29 is for separate chemically defined organic compounds. Crude MDI is a mixture of polymers and oligomers, which qualifies it as a plastic in primary form under Chapter 39.
Which countries are the top exporters of crude MDI (HS 390931)?
In 2025, the top exporters of HS 390931 (the code used for crude MDI) in UN Comtrade data were China ($1.3B, 17% of world exports), Germany ($1.2B) and Belgium ($1.1B). World exports came to about $8.0B, 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 crude MDI (HS 390931)?
In 2025, the top importers of HS 390931 (the code used for crude MDI) in UN Comtrade data were China ($628M, 8.1% of world imports), Türkiye ($518M) and India ($431M). World imports came to about $7.8B, 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 Crude MDI the same in all countries?
The base HS code 390931 for Crude MDI 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 crude MDI in Brazil?
In Brazil, crude MDI (HS 390931) is classified under NCM 3909.31.00.