MFC as coating binder

PTS Coating Symposium

05-06 September 2017, Munich

Per Svending, FiberLean Technologies Ltd
Johannes Kritzinger, FiberLean Technologies Ltd

Contents

• What is FiberLean^® MFC and FiberLean Technologies Ltd?
• A novel concept for coating with MFC as sole binder.
• Printing results on paper produced with MFC-mineral composite coating.
• Thoughts on market fit for this concept.

FiberLean^® Technologies Ltd is focused on MFC

• A “Technology Joint Venture” between Imerys and Omya
  • Imerys and Omya both offer unique networks and know-how to facilitate commercialization of FiberLean products
  • 60 employees in the JV
• Industrial process
  • Co-grinding pulp and mineral
  • Robust, reliable and scalable
• Multiple customer implementations
  • Satellite plants for paper and packaging customers
  • Installed capacity 40k tons of FiberLean^® MFC
• Growing portfolio of Applications and Intellectual Property

On-site plants are relatively significant in size

Example of a FiberLean on-site plant

Minimizing cost through use of available raw-materials (pulp, filler, energy) and infrastructure.

Avoiding transport of low solids MFC-mineral composite slurry.

Technical presence to improve tailoring of process and product to meet customer objectives.

A conceptual view of the filler increase concept

• MFC and filler replacing pulp
• Maintained PM efficiency
• Maintained quality
• Cost reduction!

MFC-mineral composite is not suitable for conventional coating

High viscosity despite low solids

• MFC with good binding power is high in viscosity.
• This solids content (7,5%) is still well below what is feasible for conventional coating.

Wet-in-wet coating on top of the wire section

• FiberLean^® MFC applied as a low solids slurry on top of the still consolidating base layer.
• The composite of MFC and mineral has the ability to stay on the surface without penetrating into the base.
• The top layer can be drained using existing foils and vacuum boxes.
• Pressing and drying works as normal but with press solids increased.
• The top layer is strong and has good adhesion while offering excellent coverage, low porosity and good smoothness.

Generic mass balance, including water, on the wire

The composite structure prevents penetration into the base and makes wet-end coating possible

SEM pictures of a composite with 20% MFC from NBSK and 80% GCC at different magnifications.

Increased press solids with the composite on top

Similar couch solids

+3% press solids

Assuming that the base linerboard had constant web press solids of 44% then the top layer reached a solids level of about 69% !

MFC-mineral composite coating at the wet-end

Pilot paper machine samples of FiberLean on Top on Kraftliner.
The different bases used in three trials visible on the right edge.

The coating has interesting properties

• High opacity for good optical coverage.
• Good adhesion and Z-directional strength.
• Excellent surface smoothness.
• Very low permeability.
• High stretch to avoid cracking at fold.
• Microporous structure suitable for printing.
• Ideal for making white boxes.

Properties as a function of coat weight

Pilot scale trial results.
Base substrate: 86 g/m² unbleached kraft linerboard.

White Top Linerboards

Compromise between strong base and printable surface

Adding a soft nip for smooth and matte finish

Single nip soft calendering at 7,3% moisture

With light calendering it is possible to make a premium smoothness, matte surface and still be within the normal WTL brightness range.

Print evaluation of pilot machine produced paper

Printing trials, summer 2017

• Roll-to-roll printing trials
  • Aqueous Inkjet, Screen GP IJC (Cambridge) in the range of 50 – 150 m/min
  • Wet-in-wet Flexo, Omya (Oftringen) at 100 m/min
• Commercial reference papers
  • White Top Kraftliner (WTKL)
  • White Top Testliner (WTTL)
  • Double coated high gloss White Top Testliner (CWTTL)
• MFC-mineral composite ”FiberLean on Top” WTL, uncalendered
  • Mineral 1-4
• Pore structure analysis of papers and individual layers

Flexo smearing from non-dried ink

Smearing overview

• Sized MFC-mineral composite coatings compared to quality White Top Liner brands.
• Smearing from 2×100% C+M wet-on-wet with printed web going through double rollers 0,3 seconds after print.
  •  CWTTL 39%
  • WTTL 4%
  • WTKL 4%
  • M1 6%
  • M2 5%
  • M3 3%
  • M4 1%

Roll to roll aquous Inkjet printing results

Bleeding overview

• Sized MFC-mineral composite coatings compared to quality White Top Liner brands.
• 33% extra drying had to be applied to CWTTL to avoid sticking.

Roll to roll aqueous Inkjet printing results

Ink density inbetween coated and uncoated

Print properties as a function of pore structure

Coated WTTL and MFC-mineral composite coated WTL

The corrugated box market is being transformed

• The primary function of corrugated boxes is to protect goods during transport.
• The market is huge with some 160 Mton per year of linerboard and medium made worldwide.
• Growth is broadly in line with GDP.
• Demand for PRINTED boxes is growing significantly faster and will drive a transformation of the industry.

Growing demand for printed corrugated board

Most high quality white boxes of today do not use White Top Liner as the print surface

• Post-Print, printing post-corrugation, is restricted to low/no impact print methods, i.e. Flexo and Inkjet, in order not to crush the medium.
• Pre-Print offers higher quality but is more costly.
  • Label – A pre-printed paper or board is glued on top of the corrugated board.
  • Lamination – A pre-printed board or WTL is used as the top layer in the corrugated board.

Current approaches to white corrugated boxes

Good quality print surface is achieved at significant extra cost

Digital printing destined to take over packaging

• Falling average print job volume.
• Cost of digital print dropping with lower cost ink and growth in size and speed of printing presses.
• The break-even point in cost is moving rapidly.

Inkjet printing for packaging is evolving rapidly

The water challenge in printing

Excellent print definition in aqueous Inkjet

Pictures scanned off inkjet printed samples from pilot scale FiberLean on Top, wet-end coating.

MFC-mineral composite WTL can be tailored to suitable printing properties by varying the mineral. High quality printing combined with high absorption and rapid drying is possible.