Wednesday, 14 July 2010 10:56

What is the Difference between Cellulose and Cellulose? Viscose Fibre Solutions from Kelheim Fibres Featured

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Kelheim Fibres is already the sole manufacturer of short cut viscose fibres for paper applications in Europe – and improving the properties of speciality papers is now the target of the range of new fibres which Kelheim presented at this year’s Zellcheming meeting in Wiesbaden.

Offering tailor-made solutions for the specific needs of different paper applications, Kelheim has secured a position as an established supplier to the paper industry. Although existing paper types can be improved and modified by the use of short cut viscose fibres, the R&D team in Kelheim is developing new fibres with even more functionalities which are specially designed to meet the needs of the paper industry.

Kelheim produces around 75.000 tonnes of fully biodegradable viscose fibres for a wide range of end uses every year, all made of 100% environmentally friendly wood pulp, but the fibres remain a high-tech product with a consistent level of quality 365 days a year. Furthermore the composition of the fibre is exactly the same as the composition of wood pulp as traditionally used in paper making - nature's most abundant polymer, cellulose.

By the modification of specific parameters in the fibre making process, three properties of the individual fibres can be designed to meet the demands of the fibres' end use: cross section, the dimensions of the fibre, as well as its functionality.

Kelheim currently offers five different fibre cross sections (round, flat/crenulated, flat/smooth, y-shaped, and hollow) which each deliver specific benefits in a range of end uses. The fibre dimensions can be exactly designed to suit the further processing of the fibre and deliver the paper properties required. Kelheim offers fibre linear densities from 0,5-28 dtex (g/10.000m) and fibre lengths for wet processes from 3 to 12mm.

Finally, by the addition of coating, anionic or cationic modification of the fibres or by the inclusion of additives in the fibre matrix, Kelheim’s experts are able to create fibres with additional functionality.

Using this tool box, Kelheim has successfully created four new fibres particularly suited for the use in the manufacture of speciality papers:

-        The structure of the viscose fibre Verdi has been modified to deliver a higher intrinsic absorbency level. Linked to this are a gel effect on the fibre surface, self-extinguishing properties and an excellent dispersability in water.

-        The viscose fibre Bramante is characterised by its segmented hollow structure which delivers significantly increased absorbency in comparison to a standard viscose fibre.

-        The viscose fibre Dante proves that combining properties can deliver more than the sum of two parts. A combination of Verdi and Bramante fibre, Dante’s liquid absorption capacity is four times that of a standard viscose fibre. The gel effect, high dispersability and self-extinguishing properties are all inherent in the fibre.

-        The special structure of the Bellini fibre with its extremely flat cross section and its very smooth surface profile delivers a fibre with a very high self-bonding capacity – a fibre ideally suited for paper and wet laid applications. As a result of the high self-bonding capacity of these fibres Kelheim’s R&D has successfully produced a paper made from 100% viscose fibres – which has previously not been possible with standard viscose fibres.

Using its own in-house technical centre for paper development, Kelheim Fibres has been able to intensively test all of these products during their development. The results of this work and of a study conducted in close cooperation with the Institute for Paper, Pulp and Fibre Technology (part of the Graz University of Technology) were presented to the public at this year’s ZELLCHEMING General Meeting for the first time.

The work carried out has shown that speciality papers can benefit in a number of ways from the incorporation of these new fibres.

By the choice of the appropriate viscose fibre cross section the density of the paper can be precisely controlled: the density of the paper sheet decreases in proportion to the surface area of the fibre added.

In the same way, viscose fibres are used to improve and control the porosity of a paper – a crucial point for example in the production of tea bag or cigarette papers – or to modify the double fold properties of a sheet, an important factor for currency papers.

Even small quantities of viscose fibres can enhance the tear resistance of speciality papers: by the incorporation of 10% viscose fibres, the tear resistance of the paper can be increased on average by 40%! At the same time viscose fibres can improve the tear strength of the paper. In this manner an improvement in tear strength with a simultaneous increase of tear resistance is possible – which cannot be achieved by simply increasing the level of refining.

As well as this, papers incorporating viscose fibres generally exhibit better dewatering properties and, depending on the additive incorporated in the fibre, improved retention properties.

Furthermore, modified viscose fibres can add specific functionality to a paper.

Examples of Kelheim's products with added functionality are the fibres Poseidon and DeepDye. Poseidon is a viscose fibre with inherent ion exchange properties. In contrast to loose ion exchange granulates, it is possible to incorporate Poseidon fibres in papers or nonwoven fabrics and design filtration cartridges of any shape. Poseidon can be used for water softening, for example in tea bags or coffee pads or for the filtration of heavy metals for recycling purposes. Poseidon can remove destructive acids from all kinds of liquids and it can be used to generate an antimicrobial effect in a product by charging the fibres with metal ions such as silver or copper.

Deep-Dye is a chemically modified viscose speciality fibre with a dye absorption capacity up to 40 times higher than that of standard viscose products. Originally developed to optimise the dyeing process of textiles made out of viscose and PET, a wider range of possible applications has since been discovered - the fibre can be used in all areas which require fast and effective dye absorption, for example in filtration cartridges for the decolouration of the waste water.

With this wide range of products Kelheim Fibres is an ideal partner for the paper industry. The already impressive list of fibres developed and optimised for the paper industry is completed by the ability to create individual, tailor-made solutions for the different needs of the various paper manufacturers.

Kelheim Fibres GmbH is one of the world’s leading producers of viscose speciality fibres, combining more than 70 year’s of expert knowledge, the technical know-how of their staff and expertise in the practical application of cellulose chemistry.

Kelheim Fibres continuously uses its capability to innovate and develop new products coupled with the flexibility of its production plant to focus on the manufacture of viscose fibres for highly demanding end uses and niche markets. While the company remains the most important supplier for the world's tampon industry, the focus of its product portfolio shifts more and more in the direction of new speciality fibres.

Matthew North
Commercial Director
Kelheim Fibres GmbH
Tel: +49 (0)9441 99-368
Email: matthew.north@kelheim-fibres.com

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