ISO 1043-4:2021

Overview

ISO 1043-4:2021, "Plastics - Symbols and abbreviated terms - Part 4: Flame retardants," defines a uniform system of symbols and abbreviated terms to identify flame retardants incorporated into plastics. The second edition (2021) updates the code list and clarifies marking rules to improve material identification, traceability and communication across manufacturing, supply chain and recycling activities.

Key topics and requirements

• Scope: Provides standardized symbols for flame retardants added to plastics materials.
• Symbol format: Symbols use the abbreviated term FR (capital letters) immediately followed by a two‑digit code in parentheses, e.g. FR(23).
• Identification threshold: Only flame retardants present at a mass fraction greater than 1% must be identified.
• Code groups: Code numbers are grouped by chemical class, including:
  • Halogenated compounds (codes 10–29) - e.g., chlorinated, brominated systems, polybrominated diphenyl ethers, HBCD (hexabromocyclododecane)
  • Nitrogen compounds (code 30)
  • Organic phosphorus compounds (codes 40–42)
  • Inorganic phosphorus compounds (codes 50–55)
  • Metal oxides/hydroxides and salts (codes 60–66) - e.g., aluminium hydroxide, magnesium hydroxide, antimony(III) oxide
  • Boron and zinc compounds (codes 70–73)
  • Silicon compounds (codes 75–76), graphite (80) and unallocated ranges for future additions
• Updates: The 2021 edition adds new code numbers (for example 26, 27, 53–55) and incorporates earlier amendments.

Practical applications

• Material identification and marking: Use FR codes on product markings, labels and data sheets to indicate the type of flame retardant in the polymer.
• Regulatory compliance & reporting: Supports documentation required by chemical and product regulations, and simplifies hazard or content declarations.
• Design & formulation: Helps compounders and material scientists choose or document flame retardant types during polymer formulation.
• Recycling & end-of-life management: Facilitates sorting and treatment decisions by recyclers and waste managers aware of flame retardant chemistry.
• Procurement & supply chain: Enables purchasers and suppliers to communicate exact flame retardant classes concisely.

Who should use this standard

• Plastics engineers, compounders and formulation chemists
• Product designers and OEMs specifying materials
• Regulatory, compliance and quality teams
• Material suppliers, recyclers and testing laboratories
• Standards writers and specifiers

Related standards

• ISO 1043-1 (basic polymers)
• ISO 1043-2 (fillers and reinforcing materials)
• ISO 1043-3 (plasticizers)
• ISO 11469 (generic identification and marking of plastics products)

Keywords: ISO 1043-4:2021, flame retardants, plastics symbols, FR code, material marking, HBCD, antimony oxide, flame retardant codes, plastics identification.