Microfibrillated Cellulose – Mineral Composites for Paper and Paperboard Applications

TAPPI PaperCon 2015, Atlanta, Georgia
Authors: Per Svending & Dr. Jon Phipps
Presenter: Leslie McLain

A Unique Process for Microfibrillated Cellulose

• Processing of 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 pulp
• No pre-treatment of fiber required.
• The final product is a MFC/mineral composite.

An industrial scale, MFC process for on-site installation

Example of on-site installation with 3 000 dry ton per year capacity.

A Unique Method for Increasing Filler Content

• Composite of filler and MFC
  • Can be tailored to fit the application
    • Type of filler
    • Type of pulp
    • The level of MFC in the composite
• Optimized for strength in wet-end application
  • Fibrils are relatively coarse and low in charge
  • Provide good bridging of filler with the paper web
  • Minimum impact on wet-end chemistry
  • Allows significant increase in filler loading without detrimental side effects
• Low solids final product
  • Solids are typically around 5%
  • Ideally produced on-site using mill pulp as raw material

The Composite is made out of Filler and Fiber

Paper Surface with Applied Composite

Note the similarity between the original composite and the product as retained in the paper.

The association between the filler and the MFC remains through the paper making process.

Filler increase with GCC without strength additives

impact on paper properties when going from 20% to 30% filler

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

Impact of MFC on paper strength

It is possible to increase filler by 10% or more and maintain strength

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

Impact of MFC on optical properties

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

Impact of MFC on other properties

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

• 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.
• The porosity impact can be important for ink or coating hold-out.
• While initial drainage slows down there is a positive impact on couch and press solids.

PCC filler in 100% BHKP

Pilot machine trial data

PCC filler + MFC Composite in BHKP

Pilot machine trial data

PCC filler + MFC Composite in BHKP

Pilot machine trial data

Initial wet strength increases (TEA index)

Note:
From pilot trial
at Innventia.

Excellent paper machine runnability despite increased filler.

Commercial example to increase WF Base Paper Filler:
Tensile and Scott Bond Response

Topping up regular filler through increasing addition of composite containing 17% MFC and 83% GCC.

Runnability on paper machine maintained through increase in initial wet web strength.

Selecting correct filler loading – simplified example

Filler Loading and Basis Weight with MFC

Pilot paper machine data

Filler Loading and Basis Weight with MFC

Pilot paper machine data

Filler Loading and Basis Weight with MFC

Pilot paper machine data

Filler Loading and Basis Weight with MFC

Pilot paper machine data

Conclusions

• Converting a small part of the pulp to MFC opens up new opportunities.
• The traditional idea of replacing pulp with filler and MFC is exciting and can offer nice cost savings.
• The idea of using MFC to tailor a paper grade to meet required opacity and strength targets with minimum raw material use is even more exciting
• There could be major fiber savings.
  • The example given suggests:
    • 24% fiber savings from 2% MFC
    • 34% fiber savings from 4% MFC

Acknowledgments:

Per Svending
Jon Phipps
David Skuse
Tom Larson
Jung Lee
Chris Bonds
Danny Ingle
Par Andersson
John Husband
Adrian Hughes
Dawn Kent
Sapphire Wilson-Claridge