Commercial Manufacture and Application of Microfibrillated Cellulose in Paper and Paperboard

Per Svending, Imerys Mineral AB, Sweden
September 17th 2015

Specialty Papers Conference
Milwaukee WI, USA

Publicised images of “cellulose nanofibrils” show great diversity

FiberLean™ microfibrillated cellulose (MFC), a recent addition to the papermakers toolbox

Surface micrograph of finepaper containing FiberLean MFC and filler

The FiberLean™ MFC process

• Co-grinding pulp to MFC in the presence of minerals.
  • The mineral acts as a very fine grinding media
• Robust and reliable equipment of relevant industrial scale.
• On-site manufacturing, using a minor side stream of mill pulp.
• No pre-treatment of fiber required.
• The FiberLean product is a MFC/mineral composite.

Co-grinding pulp to MFC in the presence of mineral

• Relatively coarse fibrils.
• Fibril length is important for wet end addition
• A wide range of pulps can be used
• Also flexible with regard to the mineral
  • GCC
  • PCC
  • Kaolin
  • Talc
  • TiO₂

Commercial scale experience with FiberLean™ MFC

• Close to 50 full scale trials on 21 paper machines to date
  • In Europé, North America, South America and Asia.
• Trials ranging from a few hours to several days.
• Extensive experience across segments
  • 6 mills in UWF
  • 6 mills in speciality and mechanical paper
  • 8 mills in CWF
  • 2 mills in Packaging
• 3 commercial contracts for on-site MFC plants.

Impact of MFC on paper strength

Lab study
Mesmer recirculating hand sheets (12 sheets)
70% Eucalyptus, 30% NBSK, 550 CSF
Intracarb 60 filler

It is possible to increase filler by 10% or more and suffer no strength loss.

Impact of MFC on paper tensile

Lab study
Mesmer recirculating hand sheets (12 sheets)
70% Eucalyptus, 30% NBSK, 550 CSF
Intracarb 60 filler

Behaviour of MFC in the tensile stress-strain curve

Pilot study
80% Eucalyptus, 20% NBSK, 500 CSF
Intracarb 60 filler

Behaviour of MFC in the tensile stress-strain curve

Pilot study
80% Eucalyptus, 20% NBSK, 500 CSF
Intracarb 60 filler

Impact of MFC on paper tensile

Lab study
Mesmer recirculating hand sheets (12 sheets)
70% Eucalyptus, 30% NBSK, 550 CSF
Intracarb 60 filler

Impact of MFC on optical properties

Lab study
Mesmer recirculating hand sheets (12 sheets)
70% Eucalyptus, 30% NBSK, 550 CSF
Intracarb 60 filler

Impact of MFC on other properties

Lab study
Mesmer recirculating hand sheets (12 sheets)
70% Eucalyptus, 30% NBSK, 550 CSF
Intracarb 60 filler

• The porosity impact can be important for hold-out of ink or coating colour.
• Density can be regained by trading the positive impact on smoothness and bond strength with less intense calendering and/or use of coarser fiber, such as CTMP.
• While initial drainage slows down there is a positive impact on couch and press solids.

FiberLean™ performance summary

Full scale results from adding FiberLean to increase filler level in a woodfree paper

The strength of the paper is maintained at increasing levels of filler and MFC.

Beyond the primary target application of filler increase in P&W papers there are new product development opportunities to pursue

• Based on porosity reduction
  • Improved hold-out of coatings
• Based on strength and opacity
  • De-materialisation

Reduction in coat weight to reach a given gloss level

Adding FiberLean™ MFC to specialty paper at constant filler loading

all chemical pulp at 250 CSF and 20% filler

To facilitate applications like this FiberLean can be supplied at up to 50% MFC content with the balance being almost any type of mineral filler.

Selecting correct filler loading to reach a given opacity and strength at minimum basis weight

Selecting correct filler loading and sheet weight with FiberLean™

Pilot paper machine data

Selecting correct filler loading and sheet weight with FiberLean™

Pilot paper machine data

Selecting correct filler loading and sheet weight with FiberLean™

Pilot paper machine data

Selecting correct filler loading and sheet weight with FiberLean™

Pilot paper machine data

Summary and conclusions

• MFC is now available for commercial use in papermaking
• Filler increase in P&W paper is a key application
• Several product development projects for packaging and specialty papers are ongoing
• Using MFC and filler to tailor a paper grade to required opacity and strength targets with minimum material use offers one of the most exciting opportunities.

Acknowledgements

To my colleagues at Imerys FiberLean R&D in Par Moor Centre in the UK who have done most of the test work, and especially to Dr Jon Phipps, who designed and ran the constant opacity/strength experiments.