Applications of FiberLean microfibrillated cellulose in and out of the paper industry

Biopolymerkolloquium, Potsdam, 24th January 2019

Jonathan Phipps

FiberLean microfibrillated cellulose – what is it?

• Simple wet media grinding process reduces cellulose paper pulp fibres to microfibrils
• Product has fibrils and fibre fragments over a wide range of length scales
• Fibres are mixed with micron-sized mineral particles to aid separation of fibrils

FiberLean microfibrillated cellulose – microstructure and properties

	Finest microfibrils form networks around mineral particles Very high surface area available for bonding and interaction Entangled fibrils can generate high viscosity in suspension Drying from water draws fibrils together to form strong bonds Dried and bonded fibrils are resistant to wetting and dispersion

FiberLean production for paper applications

• Satellite plant located at paper mill (3 operational)
• Pulp received, processed and delivered at low solids (<4% cellulose in water)
• Product fed direct to papermaking process (no dewatering or drying required)

Rheological properties of FiberLean Microfibrillated Cellulose

	Entangled fibril networks High low-shear viscosity at low solid concentration (<2%) High yield stress Very shear-thinning – approaches water viscosity at > 104 s-1 Can be sprayed or jetted at high speed

FiberLean in Papermaking

Papermachine Schematic

Paper structure, fillers and microfibrillated cellulose

Optimisation of filler content

Property Changes with microfibrillated cellulose and filler increase

Paperboard grades

Corrugated board

“White top”

Folding boxboard

• Packaging grades are multilayer structures because they need to be resistant to bending
• Filler is used only in the surface layers for optical and printing properties
• Layers are formed individually and pressed together when wet – web is only placed in tension afterwards

Paperboard stiffness

• Bending a sheet of material causes stretching of the outer surface and compression of the inner surface
• At small deformations, resistance to stretching and compression must be equal

• Resistance to bending – bending stiffness – is therefore directly related to the elastic modulus of the material
• Modulus (E) = Force / (x-section area x strain)
• For paper, x-section area depends on pressing and calendering, so instead we define tensile stiffness index (TSI): –
  TSI = Force/ (width x gsm x strain)
• TSI is not very sensitive to pressing or calendering

For a single layer, Bending stiffness = (E x thickness3 ) /12

= (TSI x gsm x thickness2) /12

Stiffness is very sensitive to thickness

FiberLean mfc in paperboard outer layer

• Addition of mfc allows filler increase and weight reduction without loss of tensile stiffness

FiberLean microfibrillated cellulose in boxboard – full scale example

Improved brightness, constant stiffness, lower cost

Coating FiberLean Microfibrillated Cellulose at the ‘wet end’

Alternative method for making white top paperboard

Coating FiberLean Microfibrillated Cellulose at the ‘wet end’

Coating onto wet, rough base at 500 m/min	High quality print on low speed coated base
Coating from 500 m/min trial

Using FiberLean Microfibrillated Cellulose as a precoat for barrier coatings

• Food packaging needs water and/or oxygen vapour barrier
• Aim to replace laminated polyethylene layers with water-based latex barrier coatings
• Recyclable, repulpable, reduction in plastic content
• Current paperboard products are too rough to allow defect-free coatings
• Microfibrillated cellulose applied by wet end technique provides enhanced smooth surface

Porosity and Barrier properties

Using Microfibrillated Cellulose as a thickener in decorative paint

HEC (hydroxyethyl cellulose)

FiberLean MFC

Dry film properties with Microfibrillated Cellulose – illustrative example

Spinning fibres from suspensions of FiberLean Microfibrillated Cellulose

• Fibre Spinning by hand from syringe with hypodermic needle

• Narrow needles and low solids make stronger fibres – fibril alignment