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3M: Halogen-free Cable Insulation Reduces Risk

Each year, computer cable worth hundreds of millions of dollars is sold worldwide to link computers, monitors, printers and other electronic equipment. Halogen-based chemistries containing fluorine, chlorine and bromine are used in many types of insulating and fire retardant materials. In addition, halogenated chemicals often are added to other insulating materials to decrease flammability or add fire-retardant characteristics.

In instances where fire exceeds the capability of flame-retardant materials to perform, the halogenated materials will burn. When this happens, by products of combustion include acidic vapors such as  hydrofluoric acid, hydrochloric acid or hydrogen bromide. In case of fire involving large quantities of halogen-containing polymer materials, an acid-filled smoke could have a toxic effect on living things that have been exposed. Acid smoke also destroys metal within the burn zone, and the dark, thick nature of the smoke will potentially render sensitive equipment useless, impair the ability of individuals to escape a fire or prevent firefighters from performing their tasks.

While the presence of computer cable itself is not likely to create significant hazards in a fire, it is viewed by some as a potential contributor and non halogenated products would be preferred. Various proposals have been made in Europe to restrict halogen-containing electronic equipment.

A team within Interconnect Solutions Division was formed to develop a halogen-free insulation material that would perform as well as the materials currently in use. The team tried numerous formulations before finding a satisfactory balance of a new non halogenated compound and non halogenated base polymer. This formulation results in the proper balance of physical performance and flame retardancy. The insulation material and the flameretardant system used in 3M’s halogen-free cables contain no more halogens than would be found as an acknowledged trace contaminant or background level.

• 3M’s halogen-free cable insulation features lower toxicity, lower smoke generation and lower corrosivity than cables with halogen-containing insulation materials.
  
• The pH of smoke from halogen-free cable insulation is H6.0 which means it is less acidic and less corrosive than smoke generated from burning halogenated products.
  
• Halogen-free cable insulation meets UL horizontal flammability requirements, as well as IEC 332-1 and  332-2.

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