Microfibrillated Cellulose proven to create value in full scale papermaking

Microfibrillated Cellulose proven to create value in full scale papermaking

Per Svending1, Edenil Santos da Costa2

1 Imerys Minerals AB. Sweden
2 Imerys do Brasil, Brazil

ABSTRACT

Imerys recently announced the commercial break-through in processing of pulp to microfibrillated cellulose (MFC) for use in paper industry applications. Imerys’ MFC offers paper makers the opportunity to become more cost competitive or to develop new differentiated products. Application experience from full scale papermaking is presented with emphasis on how cost savings can be achieved when replacing market pulp with filler and MFC. Further there are examples of how MFC can help the paper maker improve quality of paper as well as paper coatings.

Keywords: MFC, microfibrillated cellulose, filler, opacity, porosity, coating

History and current state of the art of “conventional” MFC.

  • Conventional MFCFirst made in the 80’s
    • Very high energy demand (25-30 MWh/ton)
    • Using expensive and sophisticated grinding equipment
    • Expensive and very high capex/capacity ratio
  • Known to be ideal as a strength aid in paper.
  • Conventional state of the art MFC
    • Pulp pre-treatment to soften up the fibers
    • Significantly reduced energy demand
    • Still using expensive and sophisticated grinding equipment resulting in high capex/capacity ratio
    • Low solids product in gel form, often with high surface charge
    • Scale limitations preventing large volume applications

In practice “conventional” MFC is still restricted to high value applications.

FiberLean MFC is made from co-grinding pulp with filler

FiberLean MFC

Full scale trial experience with FiberLean

Full scale trial experience with FiberLean

  • 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.

FiberLean MFC base concept:

Facilitating increased filler content in papers.

Relative USD pulp price trend from April 2013

Relative USD pulp price trend

  • The gap between long and short fiber is back to what it was

Adding price trend in EUR paints another picture

Adding price trend in EUR

  • In EUR terms the price of pulp is now 15-20% higher!

Simplistic value calculation model for filler increase with MFC

Simplistic value calculation model

Numerics of value calculation model for filler increase with MFC

Numerics of value calculation model

  • In order to start creating value the price of MFC conversion needs to be below 2 500 $/dry metric ton.
  • Obviously it needs to be well below this to make filler increase worthwhile for the paper maker.

Tensile strength is improved by MFC addition

Tensile strength is improved by MFC addition

Tensile Energy Absorption increases more than tensile, i.e. stretch is improved.

Tensile Energy Absorption increases

Tear strength improves too, a result of better fiber network bonding.

Tear strength improves

Opacity improves with higher filler loading, but also from MFC

Opacity improves with higher filler loading

The impact of MFC on porosity is quite profound

Impact of MFC on porosity

FiberLean® performance summary

Base paper Reference FiberLean Comments
Ash 16% 29% +13% filler
Gurley porosity 26 58 Much tighter sheet
Scott Bond 550 605 +10%
IGT 490 490 =
Final paper Reference FiberLean Comments
Bulk 0,76 0,75 1% bulk loss
Stiffness 218 194 -11% stiffness
Gloss 70 70 =
Scott Bond 604 634 +5%
IGT 164 165 =
Calendering pressure* 200 170 With 20 parts less kaolin in the coating colour.

* Also going from 9 nips to 6 nips.

MFC has a strong positive impact on initial wet web strength

MFC has a strong positive impact on initial wet web strength

MFC is a good fit for increased filler loading

Impact on: Increased filler Increased filler with MFC Comments:
Cost savings: +++ + Cost of MFC…
Opacity: ++ +++ Even higher with MFC
Brightness: ++ +
Smoothness: + ++ Better with MFC
Drainage: ++ + MFC holds back some of the benefit
Strengths: +/- Wet-strength – runnability, dry strength – quality
Porosity: +++ Much lower porosity with MFC
Bulk: MFC doesn’t help. Needs paper making trade off’s

Key differerentiators compared to chemistry based concepts

Impact on: Increased filler Increased filler with MFC Comments:
Cost savings: +++ + Cost of MFC…
Opacity: ++ +++ Even higher with MFC
Brightness: ++ +
Smoothness: + ++ Better with MFC
Drainage: ++ + MFC holds back some of the benefit
Strengths: +/- Wet-strength – runnability, dry strength – quality
Porosity: +++ Much lower porosity with MFC
Bulk: MFC doesn’t help. Needs paper making trade off’s

FiberLean MFC coating improvements:

Improved coating performance through better base paper hold-out.

Opportunities from porosity reduction in base paper

  • Reduced coat weight
  • Improved gloss and smoothness
  • Reduced calendering to win bulk (to compensate for filler increase)
  • Use of cheaper coating pigments
  • Reduced binder demand
  • Better coater runnability

Less coating needed to get good coverage

Less coating needed to get good coverage

FiberLean MFC for product development:

Improved paper quality through use of MFC.

Adding MFC to a 250 CSF base at constant filler content (20%) to improve paper properties

Tensile Energy
Absorption
Tear Index Scott Bond Bendtsen Porosity Opacity
J/kg mN m2/g J/m2 ml/min %
Reference 792 5,7 209 258 87,8
1% MFC 924 5,7 288 180 88,2
2% MFC 859 5,8 291 114 88,3
4% MFC 1224 6,5 377 104 88,8

Adding MFC to a 550 CSF base at constant filler content (20%) to improve paper properties

Tensile Index Tensile Energy
Absorption
Tear Index Scott Bond Bendtsen Porosity Opacity
N m/g J/kg mN m2/g J/m2 ml/min %
Reference 14,8 200 4,1 40 2500 89,0
3% MFC 22,0 500 5,3 70 1300 89,5

Conclusions:

  • Use of MFC for P&W paper cost reduction or quality improvement is now established in the market.
  • Cost of MFC conversion needs to be (well) under € 2 500 per dry ton.
  • This is possible using an on-site MFC process with economy of scale.
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