Chapter 39 covers plastics and articles thereof, including polymers in primary forms, synthetic resins, plastic semi-finished products and articles. This chapter is classified by polymer type and processing stage. Primary forms include liquid, paste, block, powder, granule, etc. Unsaturated polyester, as a thermosetting resin, is an important category of this chapter and is widely used in fiberglass reinforced plastics, coatings, adhesives and other fields. Heading 3907 covers polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters. Among them, polyesters include unsaturated polyesters, saturated polyesters, etc. This heading is subdivided by chemical structure. Unsaturated polyester, because it contains carbon-carbon double bonds, can be further cross-linked and cured, which distinguishes it from saturated polyester. The first 2 digits 39: indicates Chapter 39, plastics and articles thereof. Digits 3-4, 07: indicates heading 3907, specifically polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters. Digits 5-6, 91: indicates subheading 390791, namely unsaturated polyester, specifically unsaturated polyester in primary forms, including liquid or paste resins, granules, powders, etc. This subheading is not further subdivided, but care should be taken to distinguish it from saturated polyester (390799). This product is unsaturated polyester, belongs to the polyester category, and is in primary form, which conforms to the description of heading 3907. Unsaturated polyester, because it contains unsaturated double bonds, can undergo cross-linking reactions, which distinguishes it from saturated polyester (390799) and alkyd resins (390750). At the same time, if it is waste and scrap or articles, it should be classified under other chapters, so it is classified under 390791.
Chapter
Chapter 39 covers plastics and articles thereof, including polymers in primary forms, synthetic resins, plastic semi-finished products and articles. This chapter is classified by polymer type and processing stage. Primary forms include liquid, paste, block, powder, granule, etc. Unsaturated polyester, as a thermosetting resin, is an important category of this chapter and is widely used in fiberglass reinforced plastics, coatings, adhesives and other fields.
Heading
Heading 3907 covers polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters. Among them, polyesters include unsaturated polyesters, saturated polyesters, etc. This heading is subdivided by chemical structure. Unsaturated polyester, because it contains carbon-carbon double bonds, can be further cross-linked and cured, which distinguishes it from saturated polyester.
Digit Breakdown
The first 2 digits 39: indicates Chapter 39, plastics and articles thereof. Digits 3-4, 07: indicates heading 3907, specifically polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters. Digits 5-6, 91: indicates subheading 390791, namely unsaturated polyester, specifically unsaturated polyester in primary forms, including liquid or paste resins, granules, powders, etc. This subheading is not further subdivided, but care should be taken to distinguish it from saturated polyester (390799).
Classification Basis
This product is unsaturated polyester, belongs to the polyester category, and is in primary form, which conforms to the description of heading 3907. Unsaturated polyester, because it contains unsaturated double bonds, can undergo cross-linking reactions, which distinguishes it from saturated polyester (390799) and alkyd resins (390750). At the same time, if it is waste and scrap or articles, it should be classified under other chapters, so it is classified under 390791.
📝 Declaration Elements
Product name: Fill in the product name, which should specifically be unsaturated polyester resin, and may include the brand or model. Appearance: Describe the appearance in primary form, such as liquid, paste, granules, powder, etc. Composition and content: Indicate the content of unsaturated polyester and whether solvents, fillers, etc. are contained. Types of monomer units: Indicate the main monomers, such as maleic anhydride, propylene glycol, etc. Whether modified: State whether it has undergone chemical modification, such as epoxy modification, acrylic modification, etc. Use: Fill in the main use, such as fiberglass reinforced plastics, coatings, adhesives, etc. Brand: Fill in the brand or manufacturer name. Model: Fill in the model or specification. Product name: Unsaturated polyester resin; Appearance: light yellow viscous liquid; Composition and content: unsaturated polyester 85%, styrene 15%; Monomer units: maleic anhydride, propylene glycol; Whether modified: unmodified; Use: used to manufacture fiberglass reinforced plastic products; Brand: XX; Model: UP-123. Confusing unsaturated polyester with saturated polyester, resulting in incorrect classification under 390799. Failure to indicate whether solvent is contained; if solvent is contained, classification may be affected. Mistakenly classifying unsaturated polyester articles (such as fiberglass reinforced plastics) under 390791, when they should actually be classified under other headings of Chapter 39 or Chapter 70, etc.
Product name
Fill in the product name, which should specifically be unsaturated polyester resin, and may include the brand or model.
⚠️ Writing only "polyester resin" or "resin" without indicating unsaturated.
Appearance
Describe the appearance in primary form, such as liquid, paste, granules, powder, etc.
⚠️ Mistakenly writing it as "article" or "finished product".
Composition and content
Indicate the content of unsaturated polyester and whether solvents, fillers, etc. are contained.
⚠️ Failure to indicate the proportion of solvent or filler, resulting in incorrect classification.
Types of monomer units
Indicate the main monomers, such as maleic anhydride, propylene glycol, etc.
⚠️ Omitting monomer information, making it impossible to determine unsaturation.
Whether modified
State whether it has undergone chemical modification, such as epoxy modification, acrylic modification, etc.
⚠️ Failure to state modification, which may affect classification.
Use
Fill in the main use, such as fiberglass reinforced plastics, coatings, adhesives, etc.
⚠️ The description of use is too broad, such as "industrial use".
Brand
Fill in the brand or manufacturer name.
⚠️ Failure to fill in "none" when there is no brand.
Confusing unsaturated polyester with saturated polyester, resulting in incorrect classification under 390799.
Failure to indicate whether solvent is contained; if solvent is contained, classification may be affected.
Mistakenly classifying unsaturated polyester articles (such as fiberglass reinforced plastics) under 390791, when they should actually be classified under other headings of Chapter 39 or Chapter 70, etc.
🎯 Classification Logic
The core basis for classification is whether the product is unsaturated polyester in primary form. First confirm that it belongs to the plastics category of Chapter 39; secondly, heading 3907 covers polyesters, and subheading 390791 specifically refers to unsaturated polyester. Judgment should be made based on chemical composition, monomer units, degree of unsaturation, etc. If it is saturated polyester, it is classified under 390799; if it is alkyd resin, it is classified under 390750. 390799 Other polyesters: Saturated polyesters, such as PET, PBT, etc., do not contain unsaturated double bonds and cannot be cross-linked and cured. 390750 Alkyd resins: Alkyd resins are formed by polycondensation of polyols, polyacids and fatty acids. They belong to polyesters but are generally classified under 390750. 390690 Other acrylic polymers: Acrylic polymers, although they can be cross-linked, have a different chemical structure and are not polyesters. 390730 Epoxide resins: Epoxide resins contain epoxy groups and have a different curing mechanism, and are classified under 390730. 390791 Unsaturated polyester: This code; it must be ensured that it is in primary form and unsaturated. Is it in primary form? Does it contain unsaturated double bonds? Does it belong to the polyester category? Has it been modified? Does it contain solvents or fillers?
Basis
The core basis for classification is whether the product is unsaturated polyester in primary form. First confirm that it belongs to the plastics category of Chapter 39; secondly, heading 3907 covers polyesters, and subheading 390791 specifically refers to unsaturated polyester. Judgment should be made based on chemical composition, monomer units, degree of unsaturation, etc. If it is saturated polyester, it is classified under 390799; if it is alkyd resin, it is classified under 390750.
Confused Codes：
390799 - Other polyesters
Saturated polyesters, such as PET, PBT, etc., do not contain unsaturated double bonds and cannot be cross-linked and cured.
390750 - Alkyd resins
Alkyd resins are formed by polycondensation of polyols, polyacids and fatty acids. They belong to polyesters but are generally classified under 390750.
390690 - Other acrylic polymers
Acrylic polymers, although they can be cross-linked, have a different chemical structure and are not polyesters.
390730 - Epoxide resins
Epoxide resins contain epoxy groups and have a different curing mechanism, and are classified under 390730.
390791 - Unsaturated polyester
This code; it must be ensured that it is in primary form and unsaturated.
Self-Check：
✓ Is it in primary form?
✓ Does it contain unsaturated double bonds?
✓ Does it belong to the polyester category?
✓ Has it been modified?
✓ Does it contain solvents or fillers?
❓ FAQ
How can unsaturated polyester and saturated polyester be distinguished? The degree of unsaturation can be determined by testing the iodine value or bromine value, and technical data can also be checked to see whether unsaturated monomers such as maleic anhydride are contained. Saturated polyesters such as PET and PBT do not contain unsaturated double bonds. How should unsaturated polyester resin containing styrene solvent be declared? When declaring, the styrene content must be indicated. If styrene is used as a solvent and the content is relatively high, classification may be affected. It is usually still classified under 390791, but the composition must be declared truthfully. Under which code should unsaturated polyester fiberglass reinforced plastic articles be classified? Fiberglass reinforced plastic articles are plastic articles and should be classified under other headings of Chapter 39 according to their specific shape and use, such as 3921 or 3926, rather than 390791. Are modified unsaturated polyesters still classified under 390791? If after modification they still retain the basic characteristics of unsaturated polyester, they are usually classified under 390791. If after modification they become other polymers, such as epoxy-modified, they may be classified under other headings. How should unsaturated polyester powder be classified? Primary forms include powder, so unsaturated polyester powder is still classified under 390791. How can the import tariff rate for 390791 be checked? It can be checked through the website of the General Administration of Customs or the China Council for the Promotion of International Trade. Tariff rates change, so the latest tariff schedule shall prevail. How should composition and content be filled in when declaring? The content of unsaturated polyester should be filled in, as well as the content of solvents, fillers, additives, etc., such as unsaturated polyester 85%, styrene 15%. How should unsaturated polyester and alkyd resin be distinguished? Alkyd resins are formed by polycondensation of polyols, polyacids and fatty acids, and are usually classified under 390750; unsaturated polyesters do not contain fatty acids and contain unsaturated double bonds, and are classified under 390791.
Q: How can unsaturated polyester and saturated polyester be distinguished?
A: The degree of unsaturation can be determined by testing the iodine value or bromine value, and technical data can also be checked to see whether unsaturated monomers such as maleic anhydride are contained. Saturated polyesters such as PET and PBT do not contain unsaturated double bonds.
Q: How should unsaturated polyester resin containing styrene solvent be declared?
A: When declaring, the styrene content must be indicated. If styrene is used as a solvent and the content is relatively high, classification may be affected. It is usually still classified under 390791, but the composition must be declared truthfully.
Q: Under which code should unsaturated polyester fiberglass reinforced plastic articles be classified?
A: Fiberglass reinforced plastic articles are plastic articles and should be classified under other headings of Chapter 39 according to their specific shape and use, such as 3921 or 3926, rather than 390791.
Q: Are modified unsaturated polyesters still classified under 390791?
A: If after modification they still retain the basic characteristics of unsaturated polyester, they are usually classified under 390791. If after modification they become other polymers, such as epoxy-modified, they may be classified under other headings.
Q: How should unsaturated polyester powder be classified?
A: Primary forms include powder, so unsaturated polyester powder is still classified under 390791.
Q: How can the import tariff rate for 390791 be checked?
A: It can be checked through the website of the General Administration of Customs or the China Council for the Promotion of International Trade. Tariff rates change, so the latest tariff schedule shall prevail.
Q: How should composition and content be filled in when declaring?
A: The content of unsaturated polyester should be filled in, as well as the content of solvents, fillers, additives, etc., such as unsaturated polyester 85%, styrene 15%.
Q: How should unsaturated polyester and alkyd resin be distinguished?
A: Alkyd resins are formed by polycondensation of polyols, polyacids and fatty acids, and are usually classified under 390750; unsaturated polyesters do not contain fatty acids and contain unsaturated double bonds, and are classified under 390791.
⚠️ Disclaimer: HS code classification, declaration elements, tariff rates and regulatory conditions on this page are for reference only and do not constitute legal advice on customs classification. Tariff rates and regulations are subject to change; the latest announcements from the General Administration of Customs and on-site determinations shall prevail. Please consult professional customs brokers or customs authorities before import/export.