39079100
PLASTICS AND ARTICLES THEREOF›Polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters, in primary forms
Other polyesters - Unsaturated
Product characteristics and classification
CN code 390791 covers other unsaturated polyesters in primary forms. Unsaturated polyester resins (UP, UPR) are prepolymers containing unsaturated bonds (usually from maleic anhydride or fumaric acid) that can be cross-linked using styrene or other reactive monomers. Uncured UP resins are liquids or pastes that, upon addition of initiator (peroxide) and accelerator, cure into a cross-linked polymer with excellent mechanical properties. UP resins are the primary matrices for glass fibre reinforced composites (GRP/FRP) used in construction, automotive, boats, tanks and industrial installations. Products come as liquid resins, most commonly in styrene solution.
Regulatory requirements and safety
Importing unsaturated polyester resins into the EU is subject to REACH. Styrene contained in UP resins is a REACH-registered substance with CLP classification as potentially damaging to hearing organs. Residual maleic anhydride is an irritant. UP resins in styrene solution require SDS addressing styrene hazards including inhalation exposure. The VOC Directive limits styrene emissions during lamination. UP resins for food contact (e.g. drinking water tanks) must comply with relevant national and EU water and food contact material regulations. Transport of UP resins in styrene solution is subject to ADR Class 3.
Trade and customs procedures
When importing UP resins under CN code 390791, customs documentation should include a specification with resin type (orthophthalic, isophthalic, vinyl ester), styrene content, viscosity, reactivity and commercial form. Duty rates should be verified in the TARIC system. Major UP resin producers include Polynt-Reichhold, Scott Bader, AOC Aliancys, BASF and Chinese manufacturers. The UP resin market exceeds 10 million tonnes annually. Transport is in drums or IBC containers as ADR Class 3 dangerous goods.
Properties of Other unsaturated polyesters and trade applications
Other unsaturated polyesters classified under CN code 3907 91 are polymers in primary forms (granules, powder, liquid, block) imported as feedstock for plastics processing. Import requires REACH registration, Safety Data Sheets and technical specifications including molecular weight, density and melt flow index (MFI). Products intended for food contact must comply with Regulation (EU) 10/2011 and be listed on the positive monomer list.
Frequently asked questions
What is the difference between UP resins and alkyd resins?
UP resins (unsaturated polyesters, code 390791) are cross-linked with reactive monomers (styrene) into hard composites. Alkyd resins (code 390750) are oil-modified polyesters that air-dry as paint binders. Both are polyesters but differ in curing mechanism, composition and application.
Are vinyl ester resins classified under code 390791?
Vinyl ester resins are epoxy-modified polyesters with unsaturated chain ends. Classification of vinyl ester resins may depend on their exact chemical structure - they are most commonly classified under code 390791 as unsaturated polyesters. Consultation with the customs authority is recommended in case of doubt.
What hazards does styrene in UP resins pose?
Styrene in UP resins is a volatile, flammable substance that may cause damage to hearing organs through prolonged exposure. Adequate ventilation and personal protective equipment are required during UP resin lamination. The resin importer should provide SDS with styrene hazard information.
What technical specifications are needed for import of CN 3907 91?
Import of CN 3907 91 requires specifications: molecular weight, density, MFI, comonomer composition. SDS and REACH registration above 1 tonne/year are mandatory. For food-contact applications, compliance with Regulation (EU) 10/2011 is required.
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