Saturday 27 December 2014

Viscose for Flushable Nonwovens

Sebastian Basel, the Speciality Papers Business Manager of Kelheim Fibres GmbH (Germany) provided an update on their continuing developments with short-cut viscose fibres for wet-laid nonwovens.  He noted the need for more convenience and felt this could be provided by having a single wet-wipe substrate which could be used for baby, toddler, cleaning and moisturising wipes, all of which could be disposed of into the sewerage system.

Unfortunately the flushing of non-flushable wipes has caused problems in sewage systems around the world and the requirements of these waste systems has to be respected by adherence to the lastest, 3rd edition of the INDA/EDANA Flushability Guidlines. Products which fail any one of the sequence of 7 tests for flushability and biodegradability must now be labelled as Non-Flushable.

Wet-wipes have to do the seemingly impossible, i.e. be strong in use and weak in the toilets and sewers while maintaining attractive softness, purity, absorbency and bulk.  The key to success is maintaining adequate strength in the controlled wetness of the wipe pack while achieving rapid dispersion in an excess of turbulent water in the toilet.  Mr Basel argued that wipes made from short fibres dispersed in water had a better chance of meeting these requirements than wipes made of longer fibres using carding.  Hydroentanglement bonding of these wet-laid short fibres enabled production of strong products with just the right amount of “hydro-disentanglement” potential required in flushing. Furthermore certain cross-sectional shapes achievable with the viscose process improve strength in use while simultaneously improving the dispersibility in the sewage system.  Finally, only substrates with a majority of biodegradable fibres such as viscose would meet the guidelines.

In summary, hydroentangled wet-laid nonwovens made with Kelheim’s flat-section Viloft viscose fibre provided the best bet for meeting the current flushability requirements.

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