High solids product from MFC/ mineral composite materials allow attenuated performance of functional minerals and cellulose microfibrils in a wide range of industrial applications
May 14 2018
David Skuse and Sean Ireland
FiberLean Technologies Limited
Introduction
- Microfibrillated Cellulose (MFC) known for many years
- Utility for increased bonding in fibre-based structures, viscosification, re-inforcement
- MFC use has been limited by high process energy requirement and equipment complexity
- We have developed a cost effective grinding-based method for the production of mineral/ MFC composites from minerals and cellulose pulp
- Cellulose fibres are co-processed with mineral particles. The mineral particles act as micro-grinding media, thus, reducing the energy requirement
- The process can be accomplished using robust, industrially proven grinding equipment
- Commercialised as FiberLean® MFC
- We have been able to produce mineral/ MFC composites with a wide range of pulps and minerals
- FDA FCN for food contact paperboard
- 8000 dry metric tonnes pa of fibril capacity (40 000 dry metric tonnes of mineral/ MFC composite) installed and operational across three continents. Further capacity under construction
- Processing and handling of mineral/ MFC composites are dominated by the high viscosity of MFC arising from presence of high surface area hydrophillic fibrils. Typical fibre solids is ~2%
Photograph (a) and micrograph (b) of mineral/ MFC composite showing the high viscosity and fibrillar structure
Typically, use of mineral/ MFC composites in a web-based system and with a concomitant filler increase is associated with:
Excellent performance stability- Increased initial wet web strength
- Minimal impact on wet end chemistry
- Overall positive impact on drainage
- Improved dry mechanical properties
- Improved opacity
- A much tighter sheet (reduced porosity)
- Improved coating hold out
- Improved smoothness
- Maintaining bulk when fibre is replaced by higher specific gravity filler is a challenge but can be managed
Performance observations: Wood free paper filler top-up
Product characterisation and test methods
- Product characterisation is straightforward; solids; percent of solids that is fibre, viscosity and in-house tensile test
In-house tensile test and handsheet data show good correlation for a range of mineral/ MFC composites samples prepared with varying processing conditions.
Running full-scale trials with low solids products
- Running full-scale trials with MFC difficult due to low solids, viscous product
- Our solution was to build a production plant producing a dewatered crumble product
- Approximately 80 full-scale paper machine trials to date
 Mineral MFC composite filter cake product form |
 Mineral/ MFC composite production plant in the UK, 2000 dry metric tonnes pa of fibril capacity. Operational since Q4 2013 |
Product form
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Product form
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Product form
Filter cake (~10-15% MFC fibre solids)- Buckets, barrels, big bags
Filter cake
Bag weight ~ 1000 kg (~2200 lb) = 150 kg (~330 lb) dry MFC
Largest shipments to date
292 bags = ~44 tonnes (~48 short tons) of dry MFC
Regulatory clearance
- Cleared through Environment Canada, Health Canada, US EPA and US FDA (FCN 1582, for 5 wt.% fibrils in packaging board)
- BfR application filed for consideration under recommendations XXXVI, XXXVI/1, XXXVI/2, and XXXVI/3
Mineral/ MFC composites with a range of fibers
(BSK -Bleached Softwood Kraft, UBSK – UnBleached Softwood Kraft, Euca- Eucalyptus, TMP – Thermo-Mechanical Pulp, DIP – DeInked Pulp. Control – admix of BSK1 and mineral), 80:20 60%<2um GCC: fibre
It is possible to prepare effective mineral/ MFC composites from a wide range of fibers
Mineral/ MFC composites with a range of minerals
It is possible to prepare effective mineral/ MFC composites from a wide range of minerals
Scanning electron micrographs of mineral/ MFC composites samples
prepared with a range of different minerals (80:20, mineral/ NBSK, mineral/
MFC composite)
Mineral/ MFC composites evolving performance
- There have been improvements in product tensile and viscosity performance since the initial launch in 2014. With more to come
Tensile and viscosity performance of a series of laboratory and pilot scale prototype mineral/ MFC composite products (80:20, mineral/ MFC composite)
Mineral/ MFC composite performance comparable to other MFCs
Mineral/ MFC merchant plant concepts
Mineral/ MFC merchant plant concepts
- A high solids MFC product form is highly desirable since it allows merchant sales
- It is easy to dry MFC but the challenge is effective redispersion in water at customer location
- Mineral/ MFC composites can be dried to high solids and then redispersed in water with low energy input and the original properties restored
Mineral/ MFC merchant plant concepts: High solids product forms
High solids mineral/ MFC composite product form ((50:50, 60%<2um GCC/ NBSK mineral/ MFC composite, 51% solids))
High solids Mineral/ MFC Composites: product stability
Mineral/ MFC composites display peformance stability for > 150 days when stored in intermediate bulk containers under ambient conditions
Applications
Conclusions
- Mineral/ MFC composites are produced using a cost-effective, robust process and have proven full-scale availability
- Mineral/ MFC composites can be produced using a wide range of minerals and pulps
- The tensile and viscosity behaviours of mineral/ MFC composites have improved since the intial product launch in 2014
- Mineral/ MFC composites give at least equivalent behaviour to other MFCs in paper and board applications
- High solids mineral/ MFC composite product forms can be fully re-dispersed to their original properties and allow the operation of merchant plants
- We believe that mineral/ MFC composites are an important additive for a wide range of applications
- These mineral/ MFC composite materials have been commercialised as FiberLean® MFC