Waste to Fibre

Waste to Fibre

For the direct spinning process, Gneuss offers recycling concepts where production waste is melted, purified from volatile contaminants such as spin finish oils and preparation oils, and fed direct into the spinning process.

In the direct spinning process, PET is polymerised in several steps before being fed directly to the spinning beam. The final reaction stage typically takes place in a ring disc reactor or finisher, where the viscosity is lifted from approximately 0,3 dl/g to 0,64 dl/g by the extraction of ethylene glycol. The waste created in the production process (fibre waste, coated with spin finish oils) is typically disposed off or sold off at a low price.
With the Gneuss recycling concepts, this waste can be directly reprocessed, without detrimentally affecting the quality of the end product. The size-reduced and agglomerated waste is melted in the MRS extruder where it is devolatilised – volatile contaminants such as absorbed or surface water, spin finish oils or other processing oils are extracted. Further, the required viscosity is adjusted in the MRS extruder. The intensive surface area exchange rate in the MRS extruder makes it especially suitable for this application.
The low-maintenance water ring vacuum system condenses the volatile contaminants and concentrates them in the process water, which is filtered atmospherically. Once the volatile contaminants have been removed and the viscosity is adjusted, solid contaminants such as glass, wood, paper and ceramics are filtered out with the Gneuss Rotary Filtration System RSFgenius or SFXmagnus.
With the Online Viscometer VIS, the melt viscosity is measured in real time and directly adjusted. Depending on the recycling process, the viscosity is specifically reduced by means of ethylene glycol injection or in a further step specifically increased in the IV boost system JUMP.
Subsequently, the polymer melt is merged with the main, virgin polymer melt flow either upstream or downstream of the finisher.

Application examples:

Material introduction upstream of the finisher

Material introduction downstream of the finisher

Advantages of direct recycling with the Gneuss recycling concepts

  • Direct processing of waste to fibre without loss of quality
  • Highly energy efficient – no need for an additional melting process
  • Exact viscosity adjustment to a set point
  • Simple, direct introduction of TiO2 possible
  • Few (and automated) control interventions in the main process