Fiber production: highest purity – best quality

The demand for eco-friendly and economically sound production lines for synthetic fiber manufacture is increasing worldwide. The extrusion system MRS fulfills both of those demands.

In addition to virgin material, Gneuss fiber manufacturing systems also process non-pre-dried PET post-consumer bottle flakes or production waste with a wide range of viscosities to produce high-quality fiber. Staple fiber such as hollow fiber and bi-component fiber can be produced, whereby in the latter case it is possible to produce different viscosities from one input material by applying different vacuums to two extruders. Further areas of application for the MRS extruder include the processing of bottle flake or production waste to carpet fiber (BCF) and the production of nonwovens, also as bicomponents. The use of 100% bottle flake can significantly reduce material input costs. These plastic recycling lines can be combined with all common fiber downstream equipment.

Advantages of Gneuss technologies in fiber manufacturing

OMNI plastic recycling systems offer many advantages when processing different reclaim materials and producing fibers:

  • Trouble-free and uniform polymer discharge: no fluctuations and variations
  • Consistent system availability
  • High IV stability even when processing materials with varying residual moisture levels
  • Different melt viscosities possible even when using the same input materials (viscosity can be set)
  • Controlled and constant viscosity
  • High melt purity even when using up to 100% reclaim
  • Ultra-fine filtration 12 – 40 µm
  • Significant energy savings

Innovative fiber production – recycling concepts for the direct spinning process

In the direct spinning process for fiber production, the PET melt is produced online by a chemical reaction in several steps before spinning. The last reaction step usually takes place in a large ring disk reactor, where the viscosity of the melt is increased from around 0.3 dl/g to 0.64 dl/g by removing glycol. Production waste (fibers with and without spinning oils) is usually sold or disposed of.

With the Gneuss recycling concepts for fiber manufacturing, this waste can be reused directly without affecting the quality of the end product. The previously shredded and agglomerated waste is melted in the MRS extruder and cleaned of volatile components such as adhering water or bound water as well as spinning oils and other spinning auxiliaries. In addition, the desired viscosity is preset in the MRS extruder. The efficient surface renewal rate in the degassing area of the MRS extruder is ideally suited for this purpose. The low-maintenance water ring pump vacuum condenses these impurities and concentrates them in the process water, which is atmospherically filtered.

After the melt has been cleaned of volatile components and the viscosity has been preset, solid components such as glass, wood, paper or ceramics are also removed using an RSFgenius or SFXmagnus rotary melt filter.

The melt viscosity is measured in real time and controlled directly using the online viscometer VIS. Depending on the selected recycling process, the viscosity of the melt is either reduced in a further step by adding glycol or in a further step specifically increased in the JUMP IV boost system.

Subsequently, the polymer melt is merged with the main, virgin polymer melt flow either upstream or downstream of the finisher.

Advantages of direct waste recycling with Gneuss recycling concepts

  • Direct processing of waste to fiber without loss of quality in the end product
  • High energy efficiency by saving an additional melting process
  • Precise viscosity adjustment to a single point
  • Simple, direct addition of TiO2 possible
  • Few, automated control interventions in the manufacturing process

Material introduction upstream of the finisher

Downstream of the MRS extrusion process, ethylene glycol is introduced into the melt flow and mixed with it. In this way, differing viscosities in the input material can be equalized. The glycolyzed melt is then filtered in the Rotary Melt Filtration System RSFgenius. Thanks to the low viscosity, fine filtration with a relatively small filtration system is possible. The purified polymer flows then through the Online Viscometer, which controls the quantity of ethylene glycol which is injected into the melt and in this way maintains a constant viscosity. With the help of a booster pump, the polymer is fed into the main polymer flow upstream of the finisher. With a static mixer, the reprocessed, glycolyzed material is mixed with the main material flow and the blend of recycled and virgin material passes into the finisher where the polycondensation takes place under vacuum and the PET melt passes on to the spinning beam from there.


Material introduction downstream of the finisher

After extrusion and filtration, the purified polymer melt is fed via a booster pump directly into the polymer melt pipe downstream of the finisher. The recycled content is mixed with the virgin polymer melt. The viscosity is set by means of the Online Viscometer and the process control system and matches that of the main polymer flow.

Gneuss recycling technology as a solution for fiber production

Gneuss systems for fiber production enable the processing of virgin material as well as non-pre-dried PET post-consumer bottle flake or production waste into high-quality fiber. Thanks to innovative recycling concepts, production waste can be reused directly without compromising the quality of the end product. The waste is melted in the MRS extruder, cleaned and preset to the desired viscosity. Ultra-fine filtration using a rotary melt filter then removes solid contamination. The melt viscosity is measured in real time and controlled directly using the online viscometer. The direct utilization of waste with Gneuss recycling concepts offers numerous advantages, including high energy efficiency and precise viscosity adjustment. The purified melt can be fed either before or after the finisher, with optimum melt purity being achieved in both cases.



Serving the growth market for staple fibers ecologically
Kunststoffe international 9/2012
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