Why Flame Retardancy Matters in PP and PET Fibers
Flame retardancy in fibers is essential for reducing ignition risk, limiting flame spread, lowering heat release, minimizing smoke development and dripping, and helping manufacturers comply with regional and application-specific fire standards.
- Automotive
- Construction and insulation materials
- Upholstery and mattresses
- Carpets and curtains
- Public transportation interiors
Standards for Evaluating Fire Performance
When evaluating the fire performance of polypropylene (PP) and polyester (PET) yarns, a combination of internationally recognized standards is used to ensure both material safety and end-use compliance.
From LOI (ISO 4589) for intrinsic flammability screening, to UL94 for dripping and self-extinguishing behavior, and application-driven standards such as FMVSS 302 (automotive), EN 13501-1 (construction & flooring), and NFPA 701 (interior textiles), each test provides critical insight into actual fire performance.
Key considerations include:
PP yarns: focus on flame spread and dripping behavior
PET yarns: improved baseline resistance, but still require FR enhancement for compliance
Ultimately, the end use defines the applicable standard. Reliable flame retardant performance is not defined by a single test — it is the result of optimized formulation and targeted compliance with the right standards.
At Global Colors, we tailor masterbatch solutions to meet demanding fire safety requirements, helping customers achieve performance, safety, and regulatory confidence.
Following extensive research and trials, Global Colors has commercially launched FR masterbatches that offer solutions to some of the most common challenges in the plastics industry.
Flame Retardants for Polypropylene Yarns
ROMBEST® FR PP 351 is a product containing halogen-based active ingredients with synergists, offering high flame retardant efficiency at low dosage. It is designed for PP extrusion in non-woven applications for automotive, upholstery, and mattresses.
Tests revealed good melting properties, the ability to maintain the mechanical properties of the material, high heat resistance (up to 280°C), self-extinguishing behavior, low smoke, and no dripping during the trials.
When used at a 3% let-down ratio into a PP-homo matrix, it passes:
- B2 classification of DIN4102
- V2 classification of UL94
ROMBEST® FR PP 331 is a halogen-based product designed for PP extrusion and injection applications without affecting the transparency of the final article. It is suitable for non-woven applications for automotive, upholstery, and mattresses.
When used at a 3% let-down ratio into a PP-homo matrix, it passes:
- B2 classification of DIN4102
- V2 classification of UL94
When used at a 2% let-down ratio, it offers excellent performance in terms of burning time and longer residual length, without dripping and without smoke during the tests, making it a cost-effective option versus FR PP 351.
ROMBEST® FR PP 3040HF is a halogen-free solution based on a combination of active ingredients with synergistic effect, designed for demanding technical textiles and nonwovens. It can also be used in injection molding and PP film extrusion.
Tests demonstrated its ability to maintain the mechanical stability of yarns and showed high heat resistance (up to 270°C) without burning drips during FR trials.
Performance data includes:
- At an addition of 7.5% – 15.0%, it passes the GWIT at 775°C/1 and 2-nd and GWFI at 960°C/1 and 850°C/2, without significant impact on the mechanical PP-R
- At an addition of 6.8% – 9.8% in 100 g/m² PP non-woven, it passes BS5852-Part 1:1979, schedule 4 part 2 (cigarette test)
- At an addition of 13.5% – 16.5% in 100 g/m² PP non-woven, it passes BS5852-Part 1:1979, schedule 3 part 3 (match test)
Flame Retardants for Polyester Yarns
ROMBEST® FR PET 9141 is a halogen-free flame retardant masterbatch for PET fibers, including fabrics for upholstery and curtains, monofilaments, synthetic hairs, and carpets. It is characterized by perfect dispersion, complete melting, and minimal impact on mechanical properties.
Key performance data:
- Recommended addition rate: 9.5% – 12.5% LDR into the PET resin
- At an addition of 7.5%, it ensures 6000 ppm Phosphorous into the end article
- At an addition of 12.5%, the Limited Oxygen Index (LOI) value reaches min 30%
Furthermore, it imparts higher melt strength to r-PET with low IV and improves the spinning process of r-PET contaminated with polyethylene or polypropylene.
Flame retardants for PP and PET fibers are essential for meeting modern fire safety requirements across a wide range of applications. Advances in halogen-free and synergistic FR systems allow manufacturers to better balance fire protection, processing efficiency, and sustainability.
As regulations evolve and demand for safer materials continues to grow, the development of efficient and compliant flame retardant solutions for PP and PET yarns will remain a key focus for both the plastics and textile industries.
The Global Colors R&D department can offer tailor-made solutions that address the unique specifications of every customer’s production.
Looking for the right flame retardant solution for your yarn or fiber application?
Contact our team to discover how our FR additives can elevate your products and support your production goals.
