Product classification
HS code for Polymeric 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 polymeric MDI under HS 3909.31
Polymeric MDI, or poly(methylene phenyl isocyanate), is classified under HS code 3909.31. This classification is governed by the General Rules of Interpretation (GRI) 1 and 6, which prioritize the terms of the headings and subheadings. Heading 3909 covers amino-resins, phenolic resins, and polyurethanes in primary forms. Subheading 3909.31 specifically identifies poly(methylene phenyl isocyanate), often referred to as crude MDI or PMDI. Unlike pure 4,4'-MDI, which is a chemically defined compound classified in Chapter 29, polymeric MDI is a mixture of isomers and higher-order oligomers. According to Chapter 39 Note 3, the term "primary forms" applies to liquids and pastes, including dispersions and solutions, as well as blocks of irregular shape, lumps, powders, granules, flakes, and similar bulk forms. Polymeric MDI is a critical raw material in the production of rigid polyurethane foams and is classified here because it is a polymer in a primary form that has not yet been processed into a finished article. The classification is further supported by the Explanatory Notes to the Harmonized System, which clarify that mixtures of isocyanates with a specific degree of polymerization belong in Chapter 39.
- Covers
- Crude MDI (Methylene diphenyl diisocyanate)
- Polymeric MDI (PMDI)
- Poly(methylene phenyl isocyanate) in liquid form
- Isocyanate mixtures with higher functionality
- Also under 3909.31
- BASF Lupranate MDI
- Covestro Desmodur MDI
- Dow PAPI MDI
- Wanhua Wannate MDI
Codes often confused with 3909.31
Common mistake. Polymeric MDI is frequently confused with pure MDI (4,4'-methylene diphenyl diisocyanate), which is classified under HS code 2929.10. The distinction lies in the chemical definition; pure MDI is a single, chemically defined organic compound, whereas polymeric MDI is a mixture of isomers and oligomers. Additionally, it may be confused with other amino-resins under 3909.39 if the specific poly(methylene phenyl isocyanate) structure is not identified.
Top exporters and importers of HS 390931 (the code used for polymeric MDI), 2025
In 2025, the largest exporter of HS 390931 (the code used for polymeric 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 polymeric 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 polymeric MDI
Brazil classifies polymeric 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 polymeric MDI
What is the HS code for Polymeric MDI?
The HS code for Polymeric 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 Polymeric MDI is 3909.31, which specifically covers poly(methylene phenyl isocyanate) in primary forms.
How do I classify Polymeric MDI for customs?
Polymeric 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.
What is the difference between HS 2929.10 and 3909.31?
HS 2929.10 is for chemically defined isocyanates like pure MDI, while 3909.31 is for polymeric versions which are mixtures of molecules with varying chain lengths.
Which countries are the top exporters of polymeric MDI (HS 390931)?
In 2025, the top exporters of HS 390931 (the code used for polymeric 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 polymeric MDI (HS 390931)?
In 2025, the top importers of HS 390931 (the code used for polymeric 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 Polymeric MDI the same in all countries?
The base HS code 390931 for Polymeric 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 polymeric MDI in Brazil?
In Brazil, polymeric MDI (HS 390931) is classified under NCM 3909.31.00.