• Prakash, Baranivignesh
• Pääkkönen, Elina
• Kiiskinen, Harri
• Siilasto, Roope

Abstract

Resource-efficientprocessingisoneofthepathwaystomanufacturingsustainablefoam-formed products. Replacingthecurrentfoaming methodswithHigh-ConsistencyFoam(HCF)canreduce resourceconsumptionintermsof water, andequipmentfootprint. Therefore,wecarriedoutpilot-scale HCF trials to address requirements on the process equipment and parameters to generate low-densityporousstructures.ThepilotscaleHCFunitcomprisedof unitoperationsinthefollowing order: (a) 200 L mixing tankwith pitched blade turbines, (b) centrifugal pump with an air-removal system, (c) Headbox with 5 mm and 8 mm rectangular openings and (d) pilot machine with 300 mmand 700 mmweb, impingementand through-airdriers.A mixture of softwood(SW)and hardwood(HW),from 8% to 14%consistencies,were used. 4 to 6 g/L of non-ionic Simulsol 10 was used as a surfactant.Wefoundthat a dualimpellersystem cangeneratehomogeneousHCFwith14%consistency(50%SW+50%HW)resultingin the lowestwetfoamdensityof160g/L. Besides,higher mixing power wasrequiredfor pure SW foam compared toHW foam. The headbox with an 8 mmopening and640mmwidthworkedbetter,whereasthe 5mmopeningencountered frequent blockageprobably due to the too-low flow rates. A minimum flow rate of 0.2 L/sec was required to avoid backpressureand to distribute the foam inside the headbox evenly. Highly porous low-densitysamplesin the density of 20-80 kg/m3were examined using x-ray tomography to detect the structures’flowchannels/weakpoints. HWwaseasierto foamwithoutflocks,butthestructurewasbrittle whereas themixture of HW andSW enhanced the structure. In summary, an improved understanding ofthe operating parameters of different unit operations (mixer, pump, head box,and pilot machine) to form low-density webs with HCF was achieved.

Topics

• porous
• density
• tomography
• size-exclusion chromatography
• surfactant