Unsaturated Polyester Resin for Fiberglass
A liquid unsaturated polyester resin in primary form used as a base for composite materials in boat hulls and automotive parts. It falls under HTS 3907.91.5000 as an unsaturated polyester, not specifically named elsewhere, meeting the subheading note for polymers where the monomer units predominate by weight. Supplied in drums for industrial compounding with fiberglass reinforcement.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If saturated polyester like PET
Saturated polyesters such as polyethylene terephthalate are classified under 3907.61, differing by saturation level despite both being polyesters.
If polymerized as finished epoxy resin
Epoxide resins in primary forms fall under 3907.30 initially, but if reprocessed into polymers, may shift to Chapter 39 other polymers.
If pre-mixed with fillers as polyester putty
Mixtures with pigments or fillers exceeding certain thresholds become glaziers' putty under 3214, not primary polymers.
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Import Tips & Compliance
• Verify monomer composition exceeds 95% for the predominant unit per subheading notes to avoid reclassification; provide supplier certificates of analysis for Customs; watch for solidification indicating non-primary form
Related Products under HTS 3907.91.50.00
Gelcoat Unsaturated Polyester Resin
Thixotropic unsaturated polyester resin formulated as gelcoat for surface finishes on fiberglass reinforced plastics in marine and RV applications. Classified in HTS 3907.91.5000 as 'other' unsaturated polyester in primary liquid form, per polymer classification rules based on predominant monomer content. Used prior to curing with MEKP hardener.
Casting Unsaturated Polyester Resin
Low-viscosity unsaturated polyester resin designed for casting cultured marble countertops and decorative solid surfaces. It qualifies under HTS 3907.91.5000 as other unsaturated polyester in primary forms, with predominant monomer units per subheading note (a). Typically cured with fillers like ATH for opacity.
Marine-Grade Unsaturated Polyester Resin
Iso-polyester resin variant with enhanced water resistance for boat building and underwater composites. Falls under HTS 3907.91.5000 as other unsaturated polyester in primary form, classified by predominant comonomer weight under Chapter 39 notes. Ortho or iso-phthalic based formulations.
Clear Polyester Casting Resin
Crystal-clear unsaturated polyester resin for embedding objects in paperweights and art sculptures. Classified HTS 3907.91.5000 for other unsaturated polyesters in primary forms, adhering to monomer predominance rules. Low odor, styrene-monomer diluted.
Spray-Up Unsaturated Polyester Resin
Medium-reactivity unsaturated polyester resin optimized for spray-up fabrication of large FRP parts like tubs and pools. HTS 3907.91.5000 covers this as other unsaturated polyester, primary form per weight-based polymer notes. Compatible with continuous roving.
Iso-NPG Unsaturated Polyester Resin
Neopentyl glycol (NPG) modified isophthalic unsaturated polyester resin for corrosion-resistant panels and tanks. Under HTS 3907.91.5000 as other unsaturated polyester in primary forms, with NPG units predominant but not chemically modified per notes. High HDT properties.