SITCSection 5
U.S. imports of unsaturated polyesters, primary forms (n.e.s.) (SITC 57434) totaled $15.5M in April 2026, traded with 31 countries.
Importers of Unsaturated Polyesters, Primary Forms (N.E.S.) paid $766K in duties in April 2026 — an effective duty rate of 13% on $5.7M in dutiable value, based on actual customs collections rather than the published tariff schedule. Unsaturated Polyesters, Primary Forms (N.E.S.) imports of $15.5M in April 2026 ran 28% above the year-to-date monthly average of $12.1M.
Last updated: April 2026 dataUnsaturated polyesters in primary forms — those not elsewhere specified — are reactive thermosetting resins that cure when combined with a monomer such as styrene, making them foundational materials for fiberglass-reinforced composites, marine hulls, automotive body panels, and construction laminates. The 'N.E.S.' designation means this code captures residual unsaturated polyester types not broken out under more specific headings such as alkyd resins or PET. Trade professionals should note that the reactive nature of these resins may trigger hazardous materials shipping regulations (IMDG/IATA) depending on inhibitor levels and peroxide content in the formulation. Proper safety data sheets and inhibitor certification are standard documentation requirements.
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Because unsaturated polyester resins are often classified as flammable liquids or reactive materials under international transport regulations, importers typically need a current Safety Data Sheet (SDS), proper UN hazmat classification, and inhibitor concentration certification. Ocean shipments must comply with IMDG Code requirements, and air freight may be restricted depending on formulation.
The 'not elsewhere specified' qualifier means this code is a residual catch-all for unsaturated polyesters that do not meet the specific definitions of alkyds or other named polyester subheadings. Importers should first confirm the resin does not qualify under a more specific heading before defaulting to this code, as misclassification can affect duty liability and trade remedy exposure.
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| Country | Imports | Exports | Balance |
|---|---|---|---|
| CANADA | $7.5M | $13.0M | +$5.5M |
| MEXICO | $2.2M | $10.0M | +$7.8M |
| KOREA, SOUTH | $1.7M | $9K | -$1.7M |
| TURKEY | $1.3M | $6K | -$1.3M |
| SAUDI ARABIA | -- | $809K | +$809K |
Monthly import values over time