EuroWire May 2018

Technical Article

Use of Sepiolite Masterbatches for Enhanced Fire Performance in Cable Compounds By Eric Xirinachs, Delta Tecnic

Abstract Delta Tecnic Masterbatch with Adins Clay additives based on Sepiolite has been developed for use in compound formulations, in combination with classic flame-retardant (FR) fillers to improve its fire safety properties and optimise the cost of the final FR compounds. Adins Clay, from Tolsa, is a new family of halogen-free Sepiolite powder additives that work in synergy with most flame-retardant systems, strongly boosting char formation and improving its properties during combustion, thus protecting the polymer from further fire propagation.

Fire resistance performance requirements that until now have been barely met by commercial fire-retardant systems can now be fulfilled using Delta Tecnic Masterbatch with Adins Clay additives.

is dispersed by defibrillation and can be modified with different kinds of agents like quaternary ammonium salts but also silanes and others, allowing a higher thermal stability and easier dispersion (see Figure 2 ). Dispersion of Sepiolite Getting a good dispersion into the matrix polymer is a key factor to obtain good flame-retardant properties. Sepiolite is a needle-like silicate additive, which is essentially constituted by an open bundle of fibres. Prior to forming a Masterbatch, this bundle is divided via mechanical stress into single crystal units, and those individual particles are then surrounded by polymeric bases, thus preventing those particles from reforming agglomerates (see Figure 3 ). Once the particles are divided and surrounded by the polymer, the Masterbatch is formed. This Masterbatch is designed to facilitate efficient processing. Delta Tecnic has achieved excellent dispersion of Sepiolite in the polymeric base, be it EVA or PVC, at 40 per cent and 30 per cent of additive content, respectively. ▲ ▲ Figure 3 : Dispersion of Sepiolite in Delta Tecnic Masterbatch

Sepiolite additive versus traditional lamellar clays

As a consequence of its structure, Sepiolite is very different from other synergists based on lamellar clays (see Figure 1 ). Thanks to its needle-like structure and its chemical surface, Adins Clay Sepiolite

▼ ▼ Figure 1 + Figure 1B : Traditional lamellar clays

▼ ▼ Figure 2 + Figure 2B : Sepiolite'sneedle-likestructure

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May 2018