Are you considering to switch from brominated flame retardants (with antimony trioxide) to halogen-free? Consider Exolit™ OP.

• Electrical connectors, circuit breakers, and housing components made from engineering plastics must meet UL 94 V-0 flame retardancy in most applications while maintaining dimensional stability and mechanical strength. Brominated systems with ATO have been widely used in these applications but face increasing scrutiny from OEMs because of environmental requirements and supply chain exposure to ATO volatility. 
• Exolit™ OP in polyamide connector applications: Exolit™ OP 1400 is a non-halogenated flame retardant for reinforced PA6, PA66, and high-temperature polyamides. It achieves UL 94 V-0 while maintaining the mechanical properties of the glass-fiber-reinforced matrix. It is used in switches, plugs, and structural housing components in industrial and consumer electrical installations.

• E-mobility applications, including high-voltage connectors, charging systems, and battery housing, place demanding requirements on flame retardant materials. Systems operating at 800 V and above require both superior electrical insulation and long-term stability under thermal and moisture stress.
• Exolit™ OP 1266 (TP) for high-voltage connectors: Exolit™ OP 1266 (TP) provides a stable comparative tracking index (CTI) of 600 V even after extended storage periods in PBT systems. It achieves UL 94 V-0 at a sample thickness of 0.4 mm at dosing levels of 15–20%. This combination of thin-wall V-0 performance and stable CTI makes it suitable for high-voltage connector applications in 800 V+ e-mobility platforms.
• Exolit™ OP 1242 (TP) addresses hydrolysis in e-mobility: Exolit™ OP 1242 (TP) is formulated for PBT applications where hydrolysis resistance is critical – relevant for components exposed to humidity, condensation, or cleaning fluids in under-hood or charging system environments. It maintains flame retardant performance and mechanical properties under hydrolytic stress conditions.
• Exolit™ OP 1400: Exolit™ OP 1400 is the preferred flame retardant for reinforced polyamides due to its excellent thermal and hydrolytic stability.

• Consumer electronics and household appliances require flame retardant materials that maintain appearance, dimensional stability, and electrical insulation under repeated thermal cycling. OEM sustainability requirements and ecodesign regulations increasingly specify halogen-free materials for these product categories.
• The phosphinate chemistry in Exolit™ OP is compatible with thin-wall injection molding in PA and PBT. UL 94 V-0 is achievable at low wall thickness, supporting component miniaturization in smartphones, laptops, and small appliances. The non-hygroscopic nature of DEPAL contributes to dimensional stability in humid environments.
• Newly developed Exolit™ OP grades address the glow wire requirements for reinforced polyamides in unattended household appliances (glow wire flammability index GWFI and glow wire ignition temperature GWIT)
• Does Exolit™ OP affect the color or surface quality of molded parts? Exolit™ OP does not adversely affect the color development of PA or PBT compounds. The halogen-free chemistry can be combined with typical UV and light stabilizers, supporting consistent color quality in visible consumer-facing components.

• Rail and aviation applications require materials that meet rigorous fire, smoke, and toxicity (FST) standards. Engineering plastics used in seating components, cable management systems, and interior panels must comply with sector-specific fire regulations while being processable at scale.
• What fire safety standards does Exolit™ OP support in transport applications? Exolit™ OP-based compounds have been validated in PA and PBT systems for transport applications requiring low smoke emission and reduced toxicity during combustion. The ENFIRO project (Life Cycle Assessment of Environment-Compatible Flame Retardants, Prototypical case study) confirmed that phosphinate-based systems produce less smoke and fewer undesirable combustion products compared to brominated alternatives – relevant for enclosed transport environments where evacuation safety is a design criterion..
• How does the environmental profile of Exolit™ OP support transport OEM requirements? Exolit™ OP grades hold GreenScreen Assessment (benchmark 3 for DEPAL) and TCO certification (TCO Certified Accepted Substance List), and have been evaluated under the US EPA Design for Environment program (Design for the Environment Alternatives Assessments). These third-party assessments support OEM and Tier 1 documentation requirements for substances of concern and environmental compliance. In 2025, Clariant self-classified DEPAL as very persistent and very mobile (vPvM) in Europe, according to the Classification & Labelling Regulation. However, this classification is still subject to final experimental tests based on a request from ECHA (European Chemicals Agency).

Exolit™ OP is based on DEPAL – aluminum diethylphosphinate – the pure form of which is sold as Exolit™ OP 1230. All Exolit™ OP grades for polyamides are built on this phosphinate chemistry. DEPAL works through a dual mechanism. In the gas phase, volatile diethylphosphinic acid interrupts the chemical reactions in the flame zone. In the condensed phase, an aluminium phosphate residue forms a protective char layer on the polymer surface, acting as a barrier against heat and oxygen. This combined action achieves UL 94 V-0 flame retardancy in reinforced polyamide and polyester systems. Unlike brominated flame retardants, this mechanism does not require antimony trioxide as a synergist and does not rely on fluorinated polymers such as PTFE as anti-drip agents.

Exolit™ OP is a halogen-free flame retardant range used in engineering plastics including PA6, PA66, high-temperature PA, PBT, and PET as well as in some elastomers like TPU and TPEE (based on polyurethane or polyester). It is used in electrical connectors, circuit breakers, consumer electronics housing, household appliances, e-mobility components, and transport applications requiring UL 94 V-0 flame retardancy and some cable insulations.

DEPAL (aluminum diethylphosphinate) is the core active substance in all Exolit™ OP grades for polyamides. It is a phosphinate salt that works through a combined gas-phase and condensed-phase flame retardant mechanism. Clariant invented and commercialized DEPAL in 2004 and holds patents covering the substance, its formulations, and its application in engineering thermoplastics.

Exolit™ OP achieves equivalent UL 94 V-0 performance without bromine, chlorine, or antimony trioxide. It does not require PTFE as a co-additive. Compared to brominated/ATO systems, Exolit™ OP-based compounds have lower density, produce less smoke during combustion, and retain flame retardant performance through mechanical recycling cycles. The EU ENFIRO project (Life Cycle Assessment of Environment-Compatible Flame Retardants, Prototypical case study) confirmed that halogen-free phosphinate systems offer similar fire performance while producing less smoke and fewer undesirable combustion products.

Manufacturers are switching away from brominated flame-retardant systems for two main reasons. The first is supply chain risk. Approximately 75–80% of global antimony trioxide production is concentrated in China. Export controls on antimony, introduced citing national security concerns, combined with environmental restrictions in key production regions, have contributed to price volatility and availability uncertainty in recent years. Manufacturers relying on ATO as a flame-retardant synergist have faced production planning challenges as a result. The second is the push for halogen-free materials. Demand for halogen-free solutions in electrical, electronic, and automotive applications is growing, driven by sustainability commitments, environmental certifications, and material specifications from OEMs. Exolit™ OP addresses both factors with a commercially proven chemistry that has been in use since 2004 and validated by independent research.

Yes. Exolit™ OP retains its flame-retardant properties after multiple mechanical recycling cycles. This is confirmed through testing and is increasingly relevant for electronics and automotive applications where recycled content requirements are growing.

Two grades are specifically developed for PBT in e-mobility: Exolit™ OP 1242 (TP) for hydrolysis-resistant applications, and Exolit™ OP 1266 (TP) for high-voltage applications requiring a stable CTI of 600 V. Both achieve UL 94 V-0 at 0.4 mm wall thickness at 15–20% dosing levels. Exolit™ OP 1260 combines flame retardancy with good mechanical properties.

Exolit™ OP is produced at two manufacturing sites. The Knapsack facility in Germany is a world-scale plant that has supplied Exolit™ OP since its commercial introduction in 2004. The Daya Bay facility in Huizhou, Guangdong Province, China, represents Clariant's CHF 100 million investment in halogen-free flame-retardant capacity. Its two production lines support growing demand in Asia and globally, particularly in e-mobility and E&E applications. Local technical expertise at Daya Bay supports customers in the Asia Pacific region with application development and qualification support.