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Issue 05/2015

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Fibers & Textiles

Fibers & Textiles Efficiency boost in PLA fibre recycling Figure 1: The newly developed Counter Current core technology of the INTAREMA ® generation offers major benefits for temperaturesensitive plastics such as PLA Figure 2: With Counter Current technology capacity remains at a constantly high level over a much broader temperature range Throughput With Counter Current technology Without Counter Current technology Temperature inside Preconditioning Unit PATENTED Thanks to the new INTAREMA ® plant generation launched by EREMA (Ansfelden, Austria) in 2013, bioplastics can now be recycled far more efficiently than before. The processing benefits with fibres are particularly notable. These are due above all to the innovative technologies of the preconditioning unit and the new Counter Current core technology. Fibres offer a large surface area for dirt and moisture to adhere to – PLA fibres in particular are hygroscopic and extremely sensitive to moisture. In order to protect PLA from hydrolytic degradation in the course of mechanical recycling, moisture has to be removed early on – ideally prior to extrusion. This takes place in the preconditioning unit of the new Intarema systems where the material is cut, homogenised, degassed, heated, dried and additionally compacted. Due to the low specific weight the compacting is particularly important so the extruder can subsequently be fed continuously. Dr. Gerold Breuer, Erema Head of Marketing & Business Development explains: The multifunctional treatment in our recycling system is so effective that the cut and dried PLA fibres can be melted, filtered and then pelletised in the extruder with minimal shear stress. We know from rheological measurements of recycled materials that the valuable polymer structure is retained and there is no viscosity degradation. The newly developed Counter Current core technology of the Intarema generation offers benefits for temperature-sensitive plastics such as PLA. Counter Current shows its strengths in the border area between the preconditioning unit and tangentially connected extruder. Inside the preconditioning unit the rotation of the rotor disc which is equipped with tools forms a rotating spout so that the material is circulating the whole time (fig. 1). In the Counter Current system this material spout – unlike the previous technical standard – moves against the direction of the extruder. As a result, the relative speed of the material in the intake zone, i. e. when passing from the preconditioning unit to the extruder, increases to such an extent that the extruder screw acts in the same way as a cutting edge which now cuts the plastic. The result of this inverse tangential configuration: the extruder handles more material in a shorter time. Thanks to this improved material intake, capacity is not only increased, it also stays at a constantly high level (fig. 2) over a much broader temperature range. The operation range for optimum system capacity has thus been extended considerably. In addition to this there is also greater flexibility in the selection of the optimum operation point. This is of particular advantage when processing very (temperature-) sensitive materials and especially very light materials with low energy content such as PLA fibres or thin packaging films. 12 bioplastics MAGAZINE [05/15] Vol. 10

Fibers & Textiles QMilk fibres close to market launch QMILK fibre is a 100 % natural and renewable textile fibre made of nonmarketable milk and produced using an eco-friendly process. The textile fibre is multifunctional, antibacterial, compostable and flame retardant. Qmilk fibre has a natural, silk-like quality and very good color absorbency. Founded in 2011, Qmilch GmbH (Hanover, Germany) now boasts 20 employees who work in a two-shift system; the company operates a production line with an annual capacity of 1,000 tonnes. Now getting ready to enter the market with the first fibres the initial focus will be in the technical sector, followed by the clothing and home textile industry. As Qmilk fibres are made from casein, they are characterized by their protein composition. Casein is similar to sheep wool in its structure. However, unlike in wool keratin, there are no sulfate bridges. Just like wool, Qmilk fibres have a better thermal insulation capacity than cellulose fibres. “It is quite important to have knowledge of the general chemical properties and possibilities for implementation to understand the mode of reaction and behavior of Qmilk fibres,” says Anke Domaske, founder and CEO of Qmilch. Casein is a globular protein and consists — in addition to aminodicarboxylic acids — of diaminocarboxylic acids and cystine. Hence casein exhibits (in analogy to keratin) amphoteric properties and can bind acids and bases to form salts. Even if Qmilk fibres are made from regenerated proteins, they are not regenerated protein fibres, simply because the proteins were not present in the form of fibres and can therefore not be regenerated from fibres. In fact, the proteins are formed into fibres only after they have been dissolved, in the course of which their initial morphology is destroyed. Qmilk is not a thermoplastic, but belongs structurally to the thermosets. This means no fixed melting point of the material can be detected. Therefore, it shows a high fire protection classification (B1-B2, DIN 4102-1 and DIN 75200) and is not electrostatic. The molecular weights are found in a range from several thousand to several million units. No spin finishing needs to be applied during manufacturing. In comparison to cellulose fibres, Qmilk fibres are highly alkali sensitive, yet with a greater acid resistance. The fibre can therefore be readily stained with wool dyes in the acidic range. Qmilk fibres are easily dyeable in the spinning process, as well as yarn and piece dyed. The fibres can be used in textile fibre blends, as well as in 100 % Qmilk textiles. The colour crystals of the milk protein casein provide exceptional colour brilliance. Spun-dyed processes in particular offer high colour strengths, because the pigment is incorporated directly into the polymer matrix. Qmilk uses a side stream of the food industry. About 2 million tonnes of milk are annually discarded in Germany alone (worldwide about 100 million tonnes) because they do not meet the legal requirements as a food. The CO 2 emitted during the production of this non-food milk is bound, as the milk is further processed into a high quality raw material. The feedstock is abundant: now that the European milk quota legislation (1984 until March 2015) has been abolished, the production of milk – including all unavoidable byproducts or waste streams – continues to rise. Qmilk can be produced from contaminated milk products, process water in the dairy industry or expired milk. MT Fibres exiting the dies Staple fibres The fibres are getting texturised bioplastics MAGAZINE [05/15] Vol. 10 13

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