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Fibers & Textiles

Fibers & Textiles Coloured PLA fibres The manufacture and dyeing of staple fibers made from PLA An article in bioplastics MAGAZINE (06/13) described in detail the behaviour of IRT (infrared transparent) biodegradable plastic mulch films. To summarize briefly the results: When exposed to strong sunlight or radiation, dark and black plastics heat up as a function of the radiation intensity. This effect is caused by the carbon black on the surface which absorbs radiation above 750 nm (nanometer). It also absorbs the UV (200-400 nm) and the visible radiation (VIS) in the range of 400-750 nm. The term Cool Black describes the effect that dark/black surfaces do not heat up but rather feel cooler to the touch due to reduced heat absorption. To reduce heat absorption there are three methods that differ based on the underlying principles of physics: a) Reflection This involves using fillers to reflect radiation. These may include titanium oxide (to whiten), zinc sulfide, talc, chalk, barium sulfate, etc. Aluminum and silver (as a coating) may also be used. This method is most popular due to the lower material costs and technical feasibility. b) Interference This involves using mica-based materials. Mica (often referred to as glimmer) is a sheet silicate and consists of four separate layers or sheets. Incoming radiation is refracted and dispersed as it enters every individual layer or sheet. This results in reduced heat absorption and lower temperatures. c) Thermal transmission IRT (infrared transparent) colouring refers to pigment mixtures which prevent or inhibit the complete absorption of energy (light) from the UV and the visible (VIS) range while at the same time allowing the energy from the near infrared (NIR) range to pass through to the greatest extent possible. The material does not absorb the heat but only allows it to pass through. Polymer Granart PET PA PP POY rund 48 f POY rund 80 f FDY rund 48 f FDY rund 80 f CF/BCF rund 48 f CF/BCF rund 80 CF/BCF trilobal 48 f CF/BCF trilobal 80 f CF/BCF trilobal 46 f CF/BCF rund 48 f CF/BCF rund 80 CF/BCF trilobal 48 f CF/BCF trilobal 80 f CF/BCF trilobal 46 f single fibre yarn count 6-15 dpf 6-15 dpf 3-07 dpf 3-07 dpf 14-25 dpf 14-25 dpf 14-25 dpf 14-25 dpf 14-25 dpf 9-15 dpf 9-15 dpf 9-15 dpf 9-15 dpf 9-15 dpf Fig. 3: Spinning machine Busschaert Eng. Spin Boy I (top) and corresponding technical titer parameters. (Source: Grafe) total yarn count 290-720 dtex 480-1200 dtex 140-340 dtex 240-560 dtex 670-1200 dtex 1120-2000 dtex 670-1200 dtex 1120-2000 dtex 900-1600 dtex 430-720 dtex 720-1200 dtex 430-720 dtex 720-1200 dtex 580-960 dtex Both effects (transmission and reflection) result in lower temperatures for dark / black coloured surfaces. In both cases, the UV and VIS range should block all radiation (light, heat). Both organic and inorganic pigments may be used, however carbon black is no longer allowed. The formulations for transmission differ than those for reflection. Which mixture is chosen also depends on the carrier polymer, e.g. amorphous, crystalline or semi-crystalline. The application of these effects on PLA-based staple fibers is an ongoing subject of internal tests. The following section describes the technical equipment for the production of staple fibers in the lab. This equipment was used for tests on the spin and colouring behaviours of PLA materials and on the application of IRT formulations on PA6 at first. The spinning results depend on the chemical, rheological and physical parameters of the PLA used. Due to technical reasons (adjustment of parameters) the facility was always 16 bioplastics MAGAZINE [05/14] Vol. 9

IMAGINE – If there was an easy way to identify your polymer. started up with PE. The following types were used: Natureworks PLA Biopolymer 2051D, PLA Ingeo 3052 and PLA Revode 190. The same yarn type was used for all variations: BDF/CF, titer: 1300 dtex/ 16 dpf, with plates for 2 x 40 holes without texturing. The pull-off speed of the winder was 1000 meter/min. The temperature program varied between 160 (Zone 1) and 200°C (Zone 5). With the Ingeo material, the spinning process went very well, even with the use of spinning oil. The wind-up process onto the coil went smoothly. The Revode material flowed well from the nozzle. It could be sucked up and wound around the godets very well. However, as soon as spinning oil was used, problems developed with the winding. If spinning oil was not used, the individual filaments would separate on the godets. In general, the stretching was too low and not ideal. It was not possible to draw the yarn on to the coil. The Natureworks 3251D material was used as the masterbatch carrier for colouring the PLA yarns. The colours yellow and brown were tested. The following observations were made: Without spinning oil, the take-up on the godet was very good but the multifilaments still stuck a bit. The yarn bobbins had a lot of lint and were more difficult to wind and unwind. Unfortunately, the spinning oil was necessary in order to prevent static charges and is therefore recommended. The task was to develop a spinnable formulation for the production of IRT (infrared-transparent) staple fibers. From the 3 synthetic polymers for staple fibers (PP, PA and PET), PA6 was chosen as the reference polymer. The titer settings were 1067 dtex / 13 dpf. Further tests will use the basic formulation, but with PLA as the carrier material. Socks and knitted stockings were knit from the yarn rolls providing a thermal simulation test. PA6.6 socks, coloured with carbon black, were used for comparison. We made it possible. The new DSC 214 Polyma. More than a DSC. Your Solution. The socks were then radiated for approximately 5 minutes with 4 x 1000-watt infrared lamps. The surface temperature of the socks was measured following radiation. The results are shown in the figure below. Granulate Extruder Spinning pump Spinnerets Filter Find out more: Cooling duct Stretching Texturing Winder Fig. 1: Melt-spinning set-up (Source: Grafe) NETZSCH-Gerätebau GmbH Wittelsbacherstraße 42 95100 Selb Germany Tel.: +49 9287 881-0 Fax: +49 9287 881 505 bioplastics MAGAZINE [05/14] Vol. 9 17

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