Q&A: Getting The Lead Out Environmental concerns have forced compound vendors to reformulate PVC jacketing to exclude lead. What exactly does this mean for future wire & cable insulation?


By Len Vermillion, Managing Editor
PD&D, October 2004

These days, lead can be a heavy burden. Not only because of its weight, but also because of its dangers. Ever since the establishment of California's Safe Drinking Water and Toxic Enforcement Act, better known as Proposition 65, lead content has been regulated for everything from water to window blinds. Wire and cable polyvinylchloride (PVC) insulation and jacket materials are no exception.

Wire and cable insulation produced by compound vendors have traditionally included lead in their formulations because of it stabilizes and enhances certain performance characteristics. Current industry trends and environmental concerns, however, have led to the next generation of jacketing — lead-free.

Companies, such as Lapp USA, have committed significant resources to develop product reformulations in an effort to meet lead-free requirements. These manufacturers must address certain product safety performance characteristics such as high flammability resistance, electrical performance characteristics, and low smoke emission, so that regulatory agency requirements are satisfied.

While the majority of wire and cable insulation compound manufacturers have had great success in the development of these lead free types of formulations, there is another factor to consider on the road to full acceptance that has yet to be mentioned.

John Gavilanes, Director of Engineering at Lapp USA, believes that eventually, lead will be removed from the equation and replaced with a number of materials designed to give PVC jacketing the same performance characteristics. In the meantime, the elimination of lead in insulating wire and cable compounds will continues to receive a great deal of attention and substantial commitment from compound manufacturers. To find out why lead poses such a problem and how the absence of lead may affect PVC jacketing for better or worse, Product Design and Development asked Gavilanes to clear up a few questions.

Q: Are lead and other heavy metal compounds actually encapsulated in the PVC Compound?

A: Yes, lead and other heavy metals present in PVC are considered encapsulated in the compound.

Q: Will heavy metals leach out after processing?

A: Heavy metals can leach out after the processing of PVC under certain conditions. Lead will leach out of most PVC compounds when tested under USEPA TCLP protocol. As individual metals have their own characteristics and yield different results when tested to the same variables, a generalized statement cannot be given. As an example depending upon the pH range of the test fluid, each heavy metal will react differently as solubility and leach out will be affected. Another factor that must be considered would be the amount of time of exposed to the leaching fluid.

Q: Will the compounds contain other heavy metals?

A: Perhaps, it would really depend upon how one defines "heavy metals" and the compound formulation. Generally speaking when a compound is offered as lead-free, it will also be cadmium-free as the use of cadmium ingredients in compounds were eliminated some years back. This is a difficult question to answer with any degree of certainty, unless a specific list of "heavy metals" was provided. The term "heavy metals" is defined differently among the various countries. This would be a much easier question to answer if the Periodic Table of Elements were globally recognized and accepted.

Q: Are other heavy metals present in the compound? If so, why are they added?

A: Other heavy metals are present if they are intentionally added during the compounding process. For example, antimony is intentionally added as a flame retardant in many compounds. Some governing bodies define antimony as a heavy metal.

Q: Will there be any processing issues with lead/heavy metal-free compounds?

A: Non-lead compounds are formulated to process as closely as possible to the original product with lead. Concerning manufacturing equipment there is no considerable processing differences in the majority of instances. The one major difference in certain instances will be that once a non-lead material starts to adhere and break down in the equipment the degradation process happens at a quicker rate. There will be less time between the initial indications of char or burning and the need to shut down for clean out.

Q: Is there any physical or cosmetic changes with lead-free compounds?

A: There are no changes in physical and cosmetic appearance. Properties such as gloss level and hardness will also remain unchanged. There may be a tendency to shift on tight color tolerances, but this should only rarely happen.

Q: Are there any electrical performance issues with lead-free compounds?

A: There are still some issues with wet long-term insulation resistance with lead-free compounds. Jacket compounds can be made where the electrical properties are the same as the leaded versions. However, if there are critical electrical properties that are required they must be specified. If these critical properties are not specified then standard-grade non-lead stabilizers will used. These would be the first materials of choice and which may yield lesser electrical performance such as lower resistance, higher dielectric constant, and higher dissipation factors.