New Flame-Retardant Materials Match Strength of Traditional PBT

EnvaliorBridging the long-term performance gap in flame-retardant plastics, a halogen-free polybutylene terephthalate (PBT) compound has been introduced, offering mechanical strength comparable to that of traditional halogenated alternatives.

Pocan BFN4135, a new material from Envalior, a global manufacturer of sustainable and high-performance engineering materials, is the first grade in its new product series. Until now, halogen-free flame-retardant PBT has lagged behind halogenated PBT in terms of strength and elongation at break, limiting its use in demanding applications. Envalior states that this gap has now been narrowed, opening the door to applications including connectors, connector housings, and bobbins.

Lucas Lichius, Global Product Manager for PBT at Envalior, stated: “The key advantage of our PFOS-free material innovation lies in its state-of-the-art flame-retardant packaging, which complies with the latest and upcoming sustainability, health, and workplace safety requirements.” “As a result, processors can avoid the risk of unexpected portfolio changes driven by regulatory developments, benefiting from greater planning certainty and long-term investment security.”

Designed for direct replacement

Pocan BFN4135 is designed to provide a robust combination of tensile modulus, tensile strength, Charpy impact strength, elongation at break, and shrinkage behavior. Measured according to ISO 527-1/-2 standards, its elongation at break reaches 2.4%, which helps reduce the risk of stress cracking in finished parts.

Crucially, this material is designed to replace traditional halogenated flame-retardant PBT grades—including those with 30% glass fiber—in processors’ applications without requiring significant changes to injection molding parameters. Because its shrinkage behavior is nearly identical to that of existing compounds, manufacturers can continue using their current tooling, thereby reducing conversion costs and minimizing transition time.

Fire safety compliance with electrical performance

This compound combines robust fire resistance with high electrical safety. In tests equivalent to the Underwriters Laboratories UL 94 flammability standard, it achieved the top V-0 rating at a wall thickness of just 0.75 mm, allowing designers to create thinner components without compromising safety.

In accordance with IEC 60112, the material has a Comparative Tracking Index (CTI A) of 450, which is significantly higher than comparable halogenated grades. Variants under development are expected to achieve the maximum CTI A value of 600. These high ratings make this material series particularly suitable for high-voltage DC applications, including fast-charging infrastructure and AI data centers.

Reduce waste, reduce maintenance

Processing performance is another key selling point. In hot runner injection molding systems, the compound exhibits minimal viscosity fluctuations, supporting stable manufacturing conditions. This stability translates into lower scrap rates, reduced tool maintenance, and fewer production interruptions—enabling processors to lower operating costs and boost productivity.

Envalior spent several years developing halogen-free flame-retardant PBT grades with enhanced mechanical properties. The company recently launched two related materials, Pocan BFN4221Z and Pocan BFN4231Z, designed for insert molding and overmolding applications involving metal components exposed to rapid temperature fluctuations. These compounds exhibit high elongation at break and strong thermal resistance, reducing the risk of stress cracking caused by thermal shock.

Increased regulatory and economic pressures

In recent years, the demand for halogen-free flame-retardant PBT has surged. A major driving factor is the long-term price increase of raw materials used in halogenated flame retardant systems, such as antimony trioxide and bromine. Although the rate of price increases has slowed, volatility remains high, prompting many processors to seek more stable alternatives.

Meanwhile, as global regulatory pressures intensify, halogenated flame retardants are facing increasing scrutiny in terms of workplace safety, sustainability, recyclability, and environmental impact. These combined market and regulatory forces are the key drivers behind Envalior’s development of this new generation of materials.

More information about Envalior’s material portfolio is available through the company’s MaterialAdvisor, a suite of digital tools and services that help customers find, select, and evaluate materials for their applications.

Envalior is a global leader in sustainable and high-performance engineering materials, with annual sales of approximately €3 billion. Its product portfolio includes PA6, PA66, PBT, PA46, PPS, TPC (TPE-E), PET, PA4T, PA410, and thermoplastic composites. The company operates 18 production sites and 12 R&D centers worldwide, employing more than 4,000 people across markets such as mobility, electronics and electrical, consumer goods, and industrial products. Envalior was established in 2023 through the merger of Lanxess Performance Materials and DSM Engineering Materials.