- ▸ Hardener for high-solids, low-VOC two-component (2K) polyurethane coatings
- ▸ Crosslinks hydroxyl acrylic and polyester resins into weatherable, light-stable films with reduced solvent demand
- ▸ High-solids automotive refinish and OEM coatings
- ▸ Low-VOC industrial-maintenance and protective coatings
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.
Request SDS →
Low-viscosity HDI trimer is a high-solids, light-stable PU crosslinker — an HDI isocyanurate grade engineered for low viscosity, enabling high-solids and lower-VOC two-component polyurethane coatings. Identity: CAS 28182-81-2.
What it is
Low-viscosity HDI trimer (CAS 28182-81-2) is an aliphatic HDI isocyanurate polyisocyanate optimized for reduced viscosity, so it needs less solvent to reach application viscosity.
How it works
Like other HDI trimers its NCO groups crosslink with polyol hydroxyls to a durable, non-yellowing film; the low viscosity supports high-solids, low-VOC formulations without sacrificing weathering performance.
Applications
It is used in high-solids and low-VOC two-component polyurethane coatings (automotive, industrial), with a hydroxyl polyol. Compare standard HDI trimer and HDI allophanate.
Forms, grades and handling
Supplied as a clear liquid 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 Low-Viscosity HDI Trimer 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 (low-viscosity HDI trimer) |
| Function | Light-stable PU crosslinker (high-solids) |
| 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 low-viscosity HDI trimer used for?
Low-viscosity HDI trimer (CAS 28182-81-2) is a high-solids, light-stable aliphatic polyisocyanate crosslinker for low-VOC two-component polyurethane coatings, giving durable non-yellowing films with less solvent.
How is bulk low-viscosity HDI trimer supplied and quoted?
RawSource supplies low-viscosity HDI trimer 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 Low-Viscosity HDI Trimer Polyisocyanate?
Low-Viscosity HDI Trimer 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.