- ▸ Hardener/crosslinker for weatherable two-component (2K) polyurethane coatings
- ▸ Crosslinks hydroxyl acrylic and polyester resins into high-gloss, abrasion-resistant films
- ▸ Automotive-refinish, transportation and industrial-maintenance topcoats
- ▸ High-durability wood and protective coatings requiring UV stability
A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.
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HDI biuret is a light-stable aliphatic polyisocyanate crosslinker — the biuret of hexamethylene diisocyanate (HDI), the standard hardener for durable, non-yellowing two-component polyurethane coatings. Identity: CAS 28182-81-2.
What it is
HDI biuret (CAS 28182-81-2, an HDI homopolymer) is a liquid polyisocyanate made by linking HDI into a biuret structure with low residual free monomer. It is one of the two workhorse aliphatic crosslinkers for 2K PU.
How it works
Its isocyanate (NCO) groups react with the hydroxyl groups of a polyol resin to crosslink into a tough polyurethane film; being aliphatic, it is light-stable and non-yellowing, giving excellent gloss and weathering. The biuret structure offers good hardness and chemical resistance.
Applications
HDI biuret is used as the hardener in two-component automotive, industrial and protective polyurethane coatings, paired with a hydroxyl polyol. Compare the lower-viscosity HDI isocyanurate trimer and HDI allophanate.
Forms, grades and handling
HDI biuret is supplied as a clear liquid (often in solvent) in drums and bulk; specify NCO content and viscosity. Properties are typical reference values; the Certificate of Analysis (CoA) for the lot you buy governs. Isocyanates are moisture-sensitive and require respiratory/skin precautions; handle per the current Safety Data Sheet (SDS). Each lot ships with CoA, TDS and SDS.
Bulk supply and RFQ
RawSource sources HDI Biuret Polyisocyanate direct from producers in bulk, with CoA, TDS and SDS per lot. Tell us your binder system, cure schedule and the performance you need, and we will quote the right grade. See the polyurethane catalysts guide for the catalysts that drive these reactions.
Typical Properties
Typical reference values, not a specification; the Certificate of Analysis (CoA) for the lot governs.
| Property | Typical Value |
|---|---|
| Chemical / class | Aliphatic polyisocyanate (HDI biuret) |
| Function | Light-stable PU crosslinker |
| CAS Number | 28182-81-2 |
| Handling | Refer to the current SDS |
Regulatory & registration requirements
- TSCA (US):
- REACH (EU): Not determined from public registry
- EC number: 500-060-2
TSCA Inventory flag XU: a substance exempt from reporting under the Chemical Data Reporting Rule (40 CFR 711) (EPA flag legend).
Source: EPA TSCA Inventory (July 2025 release) · ECHA CHEM — retrieved 2026-07-12
Frequently Asked Questions
What is HDI biuret used for?
HDI biuret (CAS 28182-81-2) is a light-stable aliphatic polyisocyanate crosslinker for durable, non-yellowing two-component polyurethane coatings (automotive, industrial, protective), reacting with a hydroxyl polyol.
What is the difference between HDI biuret and HDI trimer?
Both are light-stable HDI-based crosslinkers; the biuret tends to give good hardness and chemical resistance, while the isocyanurate trimer offers higher thermal/UV durability and often lower viscosity. Choice depends on the coating requirements.
How is bulk HDI biuret supplied and quoted?
RawSource supplies HDI biuret in bulk with CoA, TDS and SDS per lot. Pricing is quote-based on grade and volume; submit an RFQ with your binder system and cure schedule.
What is the REACH and TSCA regulatory status of HDI Biuret Polyisocyanate?
HDI Biuret Polyisocyanate (CAS 28182-81-2) is listed as Active on the U.S. EPA TSCA Inventory; its REACH registration status is not determined from the public ECHA registry.