Improved fibre product properties using foam-based forming process You can use cover page with one or two photos or without photos Foams and Minimal Surfaces - 12 years on Tuomo Hjelt VTT Technical Research Centre of Finland

Foam forming principles Air content 66% Foam forming principles An aqueous foam an excellent suspending medium: Pseudoplastic nature allows for the dispersion of relative long fibers under high shear conditions Fibers are in effect ”frozen” in their dispersed state Excellent formation of fibers in web Small density

Foam forming process Fibers are mixed with the foam Fiber-foam is pumped to the head box From head box foam is spread to wire Foam is sucked away using underpressure Remaining fiber web is dried 3 4 2 1

Homogenous mass distribution Foam bubbles are attached to fiber surface Fibers covered with bubbles do not interact with each other flocculation of fibers is prevented

Reduced density Smaller hydrostatic pressure compared to water forming Foam bubbles acts as a ”ghost” particles increasing porosity

Enhanced water removal Foam formed structures contain more large pores Large pores are beneficial to water removal Strength additives do not prevent water removal water formed foam formed

Improved retention of polymers and small particles There is narrow channel between fiber wall and foam bubble Polymers and small particles are forced close to fiber surface Short range interactions are enough for interaction

Summary Foam forming a new interesting forming method for different kind of fibers Currently a lot of interest from industry Involves many interesting phenomena need for more research

TECHNOLOGY FOR BUSINESS Final slide is optional in VTT’s internal presentations