EuroWire July 2024

Technology News

Resistance without sacrificing mechanical properties

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Delta Tecnic has developed a solution for HFFR outer sheaths

protection of the polymer used. The addition of carbon black plays a fundamental role in this aspect, but achieving the precise proportion can be a challenge. When a specific carbon black content is required, such as 2.5 per cent in a poly- mer filler, it is necessary to understand how to properly dose the masterbatch. If starting from a masterbatch containing 40 per cent carbon black, the dosage must be adjusted to 6.25 per cent to achieve the necessary concentration in the cable sheath. This precise dosage process is critical to ensuring the integrity of the material and its ability to effectively resist fire. The importance of cables in the fire safety of buildings is a factor that cannot be underestimated. These elements not only provide electrical connectivity, but also play a critical role in containing and preventing the spread of fire within a structure. In buildings with high public attendance, such as hospitals or shopping centres, regulations require compliance with strict requirements to ensure that cables do not contribute to the spread of fire. The CPR regulations at European level establish standards to evaluate the behaviour of plastics used in cables when exposed to fire. One of the key requirements is that the cables must not drip when burned, which implies the need to incorporate significant quantities of flame retardants in their composition. Delta Tecnic https://deltatecnic.com

The demand for materials with high fire resistance has led to the adoption of compounds such as HFFR (halogen-free flame-retardant), especially in cables intended for outdoor environments. Delta Tecnic has developed a safe solution for the manufacture of HFFR outer sheaths. Traditionally, carbon black has been added to plastic compounds for outdoor cable sheaths when using XLPE, TPU and PVC, to protect the sheath from UV light rays. However, in the case of sheaths with HFFR compounds, this solution has a disadvantage: the carbon black, while protecting the polymer, worsens the mechanical properties in this type of compound. This is due to the formulation – with high percentages of fireproof fillers – being at the very limit in terms of mechanical properties. Delta Tecnic has taken a different approach to overcome this obstacle: a masterbatch that incorporates a smaller amount of carbon black, accompanied by ultraviolet filter additives to protect the polymer against the damaging effects of the sun. This solution allows the cable to maintain performance outdoors while minimising the impact on its mechanical properties. The masterbatch is dosed at just two per cent. Manuel Miret, area manager and new product developer at Delta Tecnic, said, “We have been offering this innovation for more than five years, and the results speak for themselves: excellent acceptance and superior performance compared to standard solutions.” According to Delta Tecnic, in the manufacturing process of a cable jacket it is crucial to ensure adequate

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July 2024