'Zero-Halogen' Compounds Meet Tough IEC Smoke-Toxicity Standards Yet Eliminate Conventional Trade-Offs in Processing

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ATLANTA, GEORGIA, U.S.A., May 3, 1999: Two new series of completely halogen-free insulation and jacketing compounds enable manufacturers of copper and fiber optic cable for communications and data transmission to meet European requirements for minimal smoke toxicity without sacrificing productivity, it was announced today by Teknor Apex at Interwire. Tradenamed Fireguard LSZH (Low-Smoke/Zero-Halogen), the compounds have passed International Electrical Code (IEC) tests for communications and data cable, according to Donald G. Ouellette, Industry Manager.

Noting that last year Teknor Apex had introduced non-halogenated Fireguard compounds that passed IEC and Underwriters Laboratories (UL) flammability tests for riser cable, Ouellette said the new LSZH products were developed "primarily for companies that manufacture or distribute in Europe, where smoke-toxicity restrictions are the most stringent."

Fireguard LSZH compounds are already in commercial use in the U.S., said Ouellette, and have proved more processable than other non-halogenated materials. "In one data cable application, our new compound required only 75% of rated extruder motor horsepower at a line speed of 700 ft./min. (215 m/min.), as against 90% for a competing compound. And because the Fireguard product exhibited less die drool, it could be run at higher speeds."

The Fireguard LSZH 1000 Series consists of four grades, with Shore D hardness from 43 to 56 and limiting oxygen index (LOI) from 35 to 53%. The 2000 Series, based on a different polymer, includes five grades with hardness values from 38 to 53 and LOI from 35 to 52%. Prices in the U.S. range from $1.05 to $2.50/lb.

In IEC 332-3C tests, cables with jackets and buffers of Fireguard LSZH compound exhibited maximum char lengths of 78 cm (Fireguard LSZH Grades 1001 and 1004), 80 (Grade 2002), 87 (Grade 2003), and 89 (Grade 2006) in a procedure whose maximum limit is 250 cm. All grades were rated at under 6.0 pH in the IEC-754-2 test for acidity of gases. Two Fireguard LSZH compounds have also met UL 1666 riser-cable requirements for fiber optic applications.

"This advanced flame and smoke performance comes without sacrificing physical properties essential for reliable cable performance in installation and end-use," Ouellette said. In standard tests, tape samples extruded from Fireguard LSZH compounds exhibited tensile strength values from 1,120 to 2,070 psi (7.72 to 14.4 MPa) and elongation at break values from 120 to 540%. Brittle points were consistently below -20 °C, and one grade was rated at -46 °C.

Under development is a third Fireguard LSZH series formulated to meet UL 1666 requirements for riser cable, according to Ouellette.

The new zero-halogen compounds readily accept standard polyethylene- or EVA-based color concentrates, Ouellette said, even in the case of grades formulated for the highest oxygen indices. He noted that affiliate Teknor Color Company specializes in developing color concentrates for the wire and cable industry. "For customers that meet volume requirements, Teknor Color can also supply pre-colored Fireguard LSZH compounds."