FIBIC EffNet programme report

Ohjelmatunnukset

Efficient Networking
Towards Novel Products and Processes
Programme Report 2010–2013

13
Ohjelmatunnukset

Efficient Networking
Towards Novel Products and Processes
Programme Report 2010–2013

Content

Foreword .........................................................................................................................................................5
High consistency forming of microfibrillated composite webs ................................................. 14
Foam Forming ............................................................................................................................................30
Fiber-based products for new applications ....................................................................................48
Microcelluloses and their characteristics .........................................................................................66
Resource-efficient papermaking concepts .....................................................................................90
Management of web uniformity based on imaging measurements .................................... 108
Expanded operating window for printing process enabling efficient use of
newly engineered fiber-web substrate ........................................................................................... 130
Optimizing structures and operation of entire production systems .................................... 146

Copyright Finnish Bioeconomy Cluster FIBIC 2013. All rights reserved.
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ISBN 978-952-67969-0-1 (paperback)
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FOREWORD

The Finnish forest industry is undergoing radical changes. The decline of the graphic
paper sector means urgent efficiency improvements in existing products and processes are needed together with the establishment of a new earnings base from novel
products and processes. In 2008 these needs initiated the Forestcluster research programme Intelligent and Resource Efficient Production Technologies (EffTech), of which
the three-year research programme Efficient Networking towards Novel Products and
Processes (EffNet) was a direct extension.
The high business volumes of the forest industry’s existing products presents a big
challenge for any new product to reach similar volumes. Transformation of the industry
will, for this reason alone, take time. All possible means to improve the competitiveness
of current production must therefore be taken in the meantime, as it is this competitiveness that will enable the risky, but necessary, renewal of the industry.
The overall goal of EffNet was to improve the competitiveness of the whole forest
cluster by developing radically new energy- and resource-efficient production technologies and by finding means to reduce capital intensiveness. The focus was twofold:
firstly to develop new energy- and resource-efficient web production technologies and,
secondly, to re-engineer the product concept of fibre-based products with nanocellulose. The target was to develop and demonstrate new types of products manufactured
from wood-based fibre material and to expand the current product portfolio offered by
forest cluster companies.
New technologies always carry risk. Cooperating across the whole value chain in a common programme towards a common goal, however, gives us the combined force needed
to create and evaluate new ideas and to bear the development and implementation risks.
EffNet has created bright opportunities to improve raw material efficiency and develop
new products. Our goal now is to carry these forward as successful innovations.

Jyrki Huovila
Metso Paper
Chairperson of Programme Management Group

5

NEW SOLUTIONS
AND
ADDED VALUE
FROM THE EFFNET PROGRAMME

Raw material, energy and water efficiency are

and use of new raw materials and novel fibre-

increasingly dominant drivers of forest indus-

based product concepts were created. Several

try investment. Incremental changes and lin-

technologies demonstrated at laboratory and

ear extrapolation of current practices will no

pilot scale show remarkable techno-economi-

longer guarantee a healthy and robust indus-

cal potential.

try. Future paper machine concepts will far outperform current technologies in resource and
capital efficiency. The most competitive prod-

Raino Kauppinen, Stora Enso:

ucts of today must be used to bridge the gap to

“The high applicability of the results reflects

the renewed forest industry of tomorrow.

the quality of the research and a clear

The EffNet programme addressed these

understanding of real-life challenges.”

challenges by exploring novel applications for
new materials, particularly nanocellulose. The
aim was to improve resource efficiency and
create a wider product space also within existing product categories.

Sharper competitiveness through foam
forming
The technology with the highest value crea-

New ideas, successful product concepts

tion potential was foam forming. The method
was shown to significantly reduce capital inten-

The EffNet programme targeted research ar-

siveness and resource consumption and thus

eas of key strategic importance to the paper

improve the competitiveness and sustainabil-

industry, the renewal of which requires high-

ity of current paper and board products. The

risk research towards achieving radical devel-

technology also paves the way for forest in-

opment steps. EffNet succeeded in delivering

dustry renewal by enabling raw materials to be

this calibre of research.

combined in revolutionary new ways, creating

In the EffNet research programme new
knowledge, practicable ideas for new products

6

unique opportunities for companies to enter
new value chains.

The development of foam forming in EffNet
has opened up a totally new research track for

Novel tools to improve production
efficiency

the development of novel products. This important achievement may not have been possible

Image-based measuring systems were devel-

without the combined force of a sizeable con-

oped to improve the process efficiency of both

sortium and public support. Foam forming pre-

existing and potential production systems,

sents exciting opportunities for the use of ex-

such as foam forming. The image-based quali-

isting raw materials and current production

ty monitoring technologies enable process op-

infrastructures, but also offers fertile ground for

timization and lead to direct improvements in

new, competitive applications beyond conven-

production efficiency. A developed new image

tional paper and board. Foam forming brings

analysis method for tissue paper provides fast

a fundamental change to the way fibre webs

and accurate information for optimizing crep-

can be formed and enables milestone improve-

ing in tissue production. The new method en-

ments in raw material efficiency. The technology

ables evaluation of the effect of chemicals in

opens up new product property windows and is

the creping process, thus leading to radical

set to make significant inroads in board making.

process efficiency improvements. Fast imaging technologies can improve competitiveness
in both current and future paper processes.

Knowledge and cost optimization
In today’s cost-pressure environment, the
need for new solutions is acute. In EffNet, the

Marjatta Piironen, Kemira:

biggest

“Innovative image-based technologies were

innovations in papermaking have

been achieved with high-filler concepts. Re-

developed in the EffNet programme. Without

search into microfibrillated cellulose filler ag-

EffNet this would have been very difficult or

gregates and starch-based biominerals also

even impossible.”

showed high potential for achieving good paper properties and cost savings. The development of binding fillers and novel utilization of
cellulose fibrils opens opportunities to develop
new paper grades and bring cost benefits.

Big potential from microfibrillated
celluloses

Printability research achieved important
new findings, expanding current knowledge

New technologies and utilization of microfibril-

and supporting the further development of

lated cellulose (MFC) in paper and board man-

printing papers. The printing efficiency results

ufacturing will impact the paper chemicals

have proven useful and practical. The partici-

industry in the future. The new knowledge cre-

pating companies have been able to utilize the

ated by EffNet will help companies design their

results in their existing business, for example

future chemical portfolios. MFC has consider-

by providing new pillars of customer support.

able application potential through combining

From the viewpoint of printing companies, one

various materials and techniques. One prom-

of the most promising results came from the

ising future application for MFC is in the fast-

development and test runs of a novel printing

growing industry of super-absorbent polymers.

paper. The test runs demonstrated good runnability of the new paper and the concept provides a firm basis for future development.

7

Power through networking

Creating value and new business

Close collaboration between companies and

The EffNet programme has contributed to new

EffNet researchers created new opportunities,

value and business creation in key areas of the

broader insight and networks for the future.

forest sector. These valuable results must now

According to the participants, networking has

be carried forward with further testing and eval-

been valuable and productive both within and

uation, for example at the pilot scale. Sever-

outside the research consortium. Close and

al participating companies have already based

open cooperation between key players and

their future business and development projects

experts generated a broad pool of expertise

on the research areas of the EffNet programme

and was considered an essential aspect of the

and will implement these projects in collabora-

programme.

tion with one or more EffNet partners.

The networks established in product safety

The results and technology concepts devel-

and characterization of nanocellulose were a

oped in the EffNet programme provide a sol-

valuable addition to the programme, and com-

id basis for further development towards new

pany seminars were also highly appreciated.

industrial solutions, generating value and new

Participants also gained insights into interna-

business opportunities for the forest industry.

tional research in several leading areas, such
as process design, image-based measurement,
nanocellulose applications and foam chemistry. The networking opportunities and contacts
built during the programme will be of significant
value in future development projects. Knowledge of the competence areas of researchers
in different universities and institutes will also
greatly facilitate future cooperation.

Jyrki Huovila, Metso:
“ Networking means having more power to
create new ideas and evaluate them throughout
the value chain, and to share the risks of new
technologies.”

8

The EffNet programme has had two impor-

Human technology, one of the strategic re-

tant strengths: effective networking between

search areas of the University of Jyväskylä,

partner companies, research institutes and

plays a central role in the interactive method-

academia in Finland, and a sufficiently long

ology for multi-objective optimization devel-

funding period. These have enabled serious

oped by the university’s industrial optimiza-

research efforts to generate radical solutions

tion research group. The research conducted

to improve the competitiveness of Finnish for-

in EffNet supports this major research area.

est industry companies.

The industrial optimization research group

The role of VTT Technical Research Centre of

participated in the Effnet programme in devel-

Finland in the EffNet programme has been cen-

oping and applying theory and methods and

tral and in line with VTT's objectives of creat-

software development for decision support.

ing high-level scientific and techno-economic
knowledge and know-how and generating technology and innovations for industry and society.

Kaisa Miettinen,
University of Jyväskylä, Department of
Mathematical Information Technology:

Erkki Hellén, VTT:

“The programme provided interesting and

“Without the five-year funding period, the next-

novel research problems and gave valuable

generation resource-efficient technology with

experience in dealing with the challenges of

the highest potential, foam forming, would have

complex real-world problems.”

not been developed to the level it is at now.”

The EffNet programme has demonstrated how
The research strategy of the Measurement In-

companies can collaboratively use Finnish

formation Group at Tampere University of Tech-

world-class research environments in effec-

nology is to develop generic design and oper-

tive and iterative ways to develop new prod-

ational methods for dynamic systems whose

ucts, leading to fruitful and continuous dia-

behaviour includes stochastic aspects. There

logue between researchers and industry. The

has been a strong synergy between programme

programme has activated international collab-

objectives and research objectives: the prob-

oration, built new contacts, educated young

lems specified by the programme have provided

researchers, created novel information and

practical test benches for generic research.

generated strategic opportunities for future
research and solutions development.

Risto Ritala, Tampere University of Technology:
“The combined scientific and application oriented research has provided us good opportunities for
publishing results and advancing the doctoral studies of our researchers.”

9

introduction

1. Background
The National Research Strategy of the Finnish

The focus of the EffNet programme is on de-

forest-based sector was published in 2006.

veloping radically new energy- and resource-

To help implement the strategy, the public-

efficient web production technologies and

private partnership Forestcluster Ltd was es-

designing

tablished in 2007 with the main goal of taking

concepts and novel, innovative products.

nanocellulose-based

production

forward the research priorities outlined in the

The overall goal of the EffNet programme

strategy. Today, the Finnish Bioeconomy Clus-

was to develop sustainable solutions to en-

ter (FIBIC) has activities in three strategic fo-

sure the leading position of the Finnish for-

cus areas: Intelligent, Resource-Efficient Pro-

est cluster in the large-scale production of fi-

duction Technologies, Future Biorefinery and

bre-based printed and packaging products.

Sustainable Bioenergy Solutions.

The three-year research programme had total

Research programmes are the core of FIBIC’s

budget of 15 million euros. The Finnish Funding

operations. Their aim is to foster collaboration

Agency for Technology and Innovation (Tekes)

between end-users, companies and research-

provided 60% of the financing, with the re-

ers in creating opportunities for research and

mainder sourced from the participating com-

new business through open innovation and new

panies and research institutes.

ways of networking, and to speed the transition
from research results to commercial products.
Intelligent and Resource Efficient Produc-

2. Programme portfolio and goals

tion Technologies (EffTech) was the first research programme launched by Forestcluster

The Efficient Networking Towards Novel Prod-

in 2008. In the second phase (2010-2013), the

ucts and Processes (EffNet) programme aimed

EffTech programme was divided into two in-

to enhance the competitiveness of the whole

terlinked programmes in order to sharpen the

forest cluster by developing radically new en-

research focus and to diversify the number

ergy- and resource-efficient production tech-

of research participants. The three-year re-

nologies and by finding ways to reduce the

search programmes, Value Through Intensive

capital-intensiveness of the cluster. The pro-

and Efficient Fibre Supply (EffFibre) and Effi-

gramme portfolio for the three years included

cient Networking Towards Novel Products and

ten work packages (see Figure 1).

Processes (EffNet) together cover the whole

demonstrating new products and technolo-

EffFibre programme focuses on improving the

gies based on the utilization of microfibrillat-

availability and supply of high-quality raw ma-

ed cellulose (MFC). The main emphasis was on

terial from Finnish forests and developing new

next-generation

production technologies for chemical pulping.

10

One half of the programme was targeted at

value chain from forest to printing press. The

technologies to expand paper and board prop-

resource-efficient

forming

erties and to allow the development of new fi-

solutions, most notably the printing process.

bre-based products outside traditional value

Concept generation by the participating com-

chains. The research focused on the two high-

panies orchestrated the detailed research or-

est potential technologies: foam forming and

ganized into studies on unit processes, quality

ultra-high consistency forming. In addition,

control and management, image-based meas-

the processability of microfibrillated cellulos-

urements, and the printing process.

es, development of binding fillers for paper
applications, and demonstration of new, value-added products were addressed. Special
attention was given to the sustainability and

3. Management of the
programme

product safety of microfibrillated cellulose.
The second half of the EffNet programme

The EffNet programme was administered by

developed production system concepts for

a Management Group (MG) comprising repre-

the existing printed products and packaging

sentatives from industry and academia. The

markets. The concepts seek efficiency excel-

execution of was headed by Programme Man-

lence in total cost of ownership and sustain-

ager together with Industrial and Scientific Co-

ability performance, such as water and carbon

ordinators. The daily management tasks were

footprint. Three core concepts were identified

performed in each Work Package (WP) under

and analysed: novel fines-coated printing pa-

the leadership of the WP manager.

per, high filler content SC paper based on a

The main tasks of the Management Group

bindable filler concept, and reduced material

have been to supervise the progress of the

consumption in folding boxboard production

programme with respect to the objectives of

based on a foam-formed middle ply. The re-

the national forest cluster research strategy

search went beyond the boundaries of current

and the EffNet programme plan, and to assess

business models by analysing opportunities

the scientific progress and techno-economic

for optimal efficiency throughout the whole

feasibility of the results. In 2011, the MG’s main

supply chain, including intensive analysis of

tasks included mid-term evaluation of the pro-

the processes involved in producing customer

gramme, organization of the discussions with

Efficient Networking towards
Novel Products and Processes

High
consistency
forming

Foam
forming

Fibre-based
products for
new
applications

Microcelluloses
and their
charasteristics

New processes and product
based on nanocellulose

Production
system
concepts
management

Resourceefficient
papermaking

Verification of concepts

Image based
measurements

Printing

Optimizing
structures and
operation
of entire
production
systems

Efficient mill concepts
with new unit processes

Figure 1. EffNet programme portfolio.

11

the shareholder companies of Forestcluster Ltd in order to harmonize the EffNet pro-

4. Participants and international
cooperation

gramme with the companies’ research strategies and to define the most important focus

The EffNet research programme brought to-

areas for the second period of the program.

gether the leading forest cluster companies

MG had the following members:

and research organisations related to papermaking technology, material science, modelling

• Jyrki Huovila, Metso Paper, Chairman

and simulation and machine vision research in

• Erkki Hellen, VTT, Scientific Coordinator

Finland. Eight companies and eight Finnish uni-

• Mika Hyrylä, UPM-Kymmene

versities and research institutes participated in

• Raino Kauppinen, Stora Enso

the programme. In addition, research was also

• Markku Leskelä, FIBIC

subcontracted from external partners.

(Lars Gädda until April 2012)
• Marjatta Piironen, Kemira

Industrial partners:

• Ari Pelkiö, Andritz
• Erkki Peltonen, Myllykoski

• Andritz

• Risto Ritala, Tampere University of

• Kemira

Tehnology, Scientific Coordinator

• Metso

• Hannu Saarnilehto, Sanoma News

• Metsä Board

• Pauliina Tukiainen, VTT,

• Myllykoski

Programme Manager

• Sanoma News

• Lauri Verkasalo, Metsä Board

• Stora Enso

(Ari Kiviranta until September 2011)

• UPM

• Seppo Virtanen, UPM,
Industrial Coordinator

Research organizations:

• Mikko Ylhäisi, Tekes
• Aalto University
Dissemination of EffNet programme resultsis

• Lappeenranta University of Technology

achieved with a number of different tools, the

• Tampere University of Technology

most important being the FIBIC research por-

• University of Eastern Finland

tal, accessible to EffNet programme partici-

• University of Helsinki

pants, and the FIBIC Ltd website (http://fibic.fi/

• University of Jyväskylä

programmes/effnet). Detailed project reports

• University of Oulu

and publications are available via the FIBIC por-

• VTT Technical Research Centre of Finland

tal. Programme seminars have also been held
annually, bringing together experts from ac-

International cooperation was built into the EffNet

ademic and industrial fields and providing a

programme and plays an important role in the de-

comprehensive overview of the programme’s

velopment of novel resource-efficient production

research activities and results.

technologies. Research organizations were encouraged to pursue international collaboration
for this purpose with the aim of strengthening
the position of Finnish research groups in international communities and opening up new
cooperation opportunities. The programme
participated in cooperation with six countries:

12

Canada, Germany, Ireland, Sweden, the UK
and the USA. Close links with the international scientific community are maintained, particularly in the areas of foam forming, multiparameter optimization, image analysis and
nanocellulose research. The cooperation initiated during EffTech was continued and broadened in EffNet.
Programme participants have been active
in presenting the programme results at international conferences and researchers have
arranged international workshops and conferences, such as the 21st International Conference of Multiple Criteria Decision Making,
at which EffNet research groups held a special
session on multi-objective process design for
systems with multi-objective operation. The
session generated valuable input from numerous international methodology experts. EffNet
participants have also been active participants
in international workshops aimed at promoting
the standardization of nanocellulose safety and
characterization test methods.
The EffNet programme was designed to minimize research overlap with related projects and
to maximize synergy between other research
activities. Many of the programme’s researchers were also involved in other related projects,
which ensured active information exchange
and rapid application of results. EffNet research
groups participated, for example, in the European Community's 7th Framework Programme
projects and several COST actions.
The EffNet programme’s core research also
supports several industry-driven projects aimed
at developing industrial applications. While many
of these projects are confidential, active participation of industrial partners within the programme has ensured active information flow, in
turn speeding the development process.

13

High consistency forming
of

microfibrillated
composite webs

c o n ta c t p e r s o n
Thad Maloney, thaddeus.maloney@aalto.fi

pa r t n e r s
Aalto University
Metso Paper
Metsä Board

14

Abstract
The purpose of this project was to develop a high consistency forming process
suitable for microfibrillated cellulose (MFC) composite webs and to outline a paradigm for manufacturing such webs. A MFC composite furnish was evaluated,
and a modular high consistency headbox and suitable approach flow system were
constructed. It was found that 8-10% solids was a suitable forming consistency.
Webs as low as 150 g/m2 were formed. It was also found that under certain conditions the web could be vacuum dewatered to as high as 33% solids with retention
close to 100%. Lab pressing studies showed a solids content of around 45% to be
achievable with a single shoe press. Excellent physical properties were attained,
including good formation, smoothness and light scattering. The results show it
should be possible to manufacture composites of this nature in large scale, both
the furnish cost and the investment costs look very attractive, and desirable product properties can be achieved.
This project demonstrates the manufacture MFC composite papers to be both
rational and feasible. The excellent intrinsic properties of MFC composite webs
means that it should be possible to find many viable new products in this category. The manufacturing solution is very different, and in many ways superior, to
traditional papermaking. There is ample value creation potential across the raw
material supplier–machinery manufacturer–producer–converter value chain.

Keywords:
microfibrillated cellulose composites, high consistency forming, MFC dewatering

15

1. Background

must be removed, improve energy efficiency,
and simplify the manufacturing process. The

This project has its roots in the “Reengineer-

starting point of our investigation into the po-

ing Paper” philosophy. Simply put, this says

tential forming technology was a process pre-

that by rethinking the architecture of paper on

viously developed for traditional furnishes

a fundamental level we can design a new gen-

called ultra-high consistency forming (UHC), in

eration of paper products. More specifically,

which applied shear is used to deflocculate the

we are interested in the use of microfibrillat-

suspension before forming the web. The form-

ed cellulose, not as a functional additive, but

ing strategy investigated here has its origin in

as a major structural component in paper. The

the earlier UHC work of Professor Gullichsen

vast majority of current paper and board prod-

and co-workers. The possibility to use the UHC

ucts are essentially produced from mixtures

technology for a traditional furnish was also

of various pigments and pulp fibres. The func-

investigated.

tional performance of paper is largely limited
by the relatively large size of fibres. Moreover,
the product and property space of the fibre/

2. Objectives

pigment furnish approach has been largely exploited and existing products are mature. By

The objective was to develop a semi-pilot scale

including microfibrillated cellulose as a major

high consistency forming technology suitable

structural component in paper, the structure is

for forming MFC composite webs and establish

fundamentally altered and the potential prop-

a paradigm for manufacturing such webs. This

erty space is greatly expanded.

involved the following specific goals: 1) Construct a modular high consistency headbox and

By the time this project started it was already

approach flow system for the Aalto pilot ma-

clear that various MFC/pigment/fibre compos-

chine, 2) Develop the forming technology for

ites could achieve interesting properties. How-

MFC/pigment/fibre webs, 3) Outline a means

ever, it was not clear whether large-scale man-

for large-scale manufacturing, i.e., determine

ufacture of the composites would be possible.

the forming solids content and develop a water
removal strategy after forming, and 4) Test the

In order for MFC composites to become an

UHC concept on a folding box board (FBB) fur-

industrial reality, several problems must be

nish to identify any structural or potential pro-

solved. 1. The MFC must be manufactured in a

cess advantages to this forming method.

robust process with a rational cost structure;
2. Suitable forming technology must be found;
3. An energy efficient process must be devel-

3. Research approach

oped to dewater the web. This project did not
deal with point (1), but focused instead on the

1. Laboratory rheometer and former con-

forming technology. Sufficient evidence was

struction and tests. A lab device was built

gathered to show that dewatering was possi-

which allowed a suspension to be fluidized and

ble, and to outline a water removal strategy.

a web formed from the fluidized furnish. Several different slice arrangements for the lab

For composite webs containing a large amount

and energy values could be collected from the

therefore important to form at high consisten-

rheometer. This gave valuable information for

cy in order to reduce the amount of water that

16

former were constructed and tested. Torque

of MFC, dewatering is a potential problem. It is

the construction of the headbox. The objec-

tives of this study were to determine the upper

and increase bulk. Two MFC composite trials

solids content at which webs could be formed,

were carried out at the end of the project. A

identify possible speed limitations, quantify

bent blade bevelling system was added to the

web characteristics, and investigate 3-phase

headbox for the last trial.

systems to determine whether dispersed air
could help web forming.

The combination of lab and pilot studies was
used to determine whether the manufacture

2. Design and construction of the headbox. A

of pigment/MFC/fibre composites was rational

modular UHC headbox was designed and built.

and feasible and, if so, how it could be done.

The headbox has segments that can be taken off, modified and reattached. Two slice arrangements were constructed, and a third was

4. Results

later added.

4.1 Defining the property space
3. Design and construction of the approach
flow. An approach flow was added that al-

In traditional papers, the main structural com-

lowed handling of the high consistency fur-

ponents are fibres, with length dimensions of

nish, introduction of gas or other chemicals

1-5 mm and pigments usually in the range of

and in-line high shear mixing.

1-3 µm. The forming concept, dewatering strategy and unit operation design are all based on

4. Lab studies on composite sheet structure.

this broad raw material concept. In this pro-

The property spaces for combinations of pig-

ject, we introduce the use of microfibrillated

ment/MFC/fibre blends were examined. Need-

cellulose as a major structural component. In

ed sheet preparation methods were devel-

doing so, we are fundamentally changing the

oped. From this work a 70/20/10 mixture was

furnish characteristics, the product proper-

defined as the test furnish for process devel-

ties and the needed manufacturing concept.

opment.

A key problem faced is the fact that the range
of furnish mixtures is almost infinite, leading

5. Lab studies on the dewatering/rheology

to very different rheological and dewatering

of MFC composite furnish was carried out

characteristics and thus different forming and

using an immobilization cell rheometer. The

manufacturing strategies. In order to narrow

idea was to better understand factors govern-

the 3-component furnish to a more workable

ing the rheology at high consistencies and de-

concept, a laboratory study on various pig-

termine how MFC swelling and other factors

ment/MFC/fibre mixtures was carried out. For

control dewatering. Lab pressing studies were

this work the usual laboratory sheet forming

done with a press simulator.

method was modified by: increasing the forming solids, using a very fine wire, adding over-

6. Pilot studies with the UHC former. The first

pressure to the sheet mould, and using a press

pilot studies were done with traditional fibre

drying method to prevent sheet shrinkage.

furnishes – bleached hardwood (BHW) and
BHW/BSW blends. Here we learned to use

The raw materials used were scalenohedral

the equipment and ironed out many practi-

PCC with 2.4 µm average particle size, VTT

cal problems. 3-phase systems were also in-

coarse MFC, bleached birch Kraft, lightly re-

vestigated in which 10% dispersed air was

fined. The experimental design is shown in

used to reduce viscosity, improve formation

Figure 1. A sample of the results for certain

17

strength properties is shown in Figure 2. The

It should be noted that in this study we are tak-

important conclusions from this study are:

ing a snapshot of only one particular solution.
There are a huge range of pigments, fibrillated

• There are non-obvious synergistic effects

celluloses and fibres that can be brought to-

of the components, such as maximum

gether to meet various end-use requirements.

stiffness at 20/60/20 pigment/MFC/fibre.

We would also like to emphasize that the role

• There are synergistic optical effects

and requirements of each of the main compo-

between the MFC and pigment.

nents can be very different to classical paper-

Scalenohedral precipitated calcium

making systems. In this project, the idea was

carbonate (SPCC) prevents the MFC from

to find a furnish concept that would allow web

collapsing in consolidation, thus leading to

formation and dewatering and lead to a prod-

high light scattering for certain mixtures.

uct with desirable intrinsic properties. This

• MFC contributes to bonding, light scattering

puts certain restrictions on the needed com-

and surface smoothness; pigment to light

ponents and the workable mixtures. For ex-

scatter and surface properties; fibre mostly

ample, a high degree of pigment structure is

to tear strength.

desired to give bulk and to maintain poros-

• The combination of high pigment/modest

ity throughout water removal (a requirement

MFC quantity/low fibre was of specific

for efficient dewatering, pressing and drying).

interest to our study. This combination

Thus, highly structured PCC was chosen. Even

delivers excellent optics, high smoothness,

with suitable components, not all mixtures will

reasonable tensile and tear strength and

be workable. For example, in cases where the

very good bulk/smoothness. We therefore

fibre content becomes too high the formation

specified a composite mixture of 70/20/10

may deteriorate, and if the MFC content is too

SPCC/MFC/fibre. The furnish cost structure

high, water removal can be a limiting factor.

is also attractive due to the high amount
of pigment. In later work, the BHW was

4.2 Headbox design

changed to a previously dried, unrefined
bleached softwood Kraft to further improve

Our initial hypothesis was that when high

tear strength and dewatering properties.

amounts MFC are used, dewatering limitations

Figure 1. The experimental design used to define the property space of pigment/MFC/fibre composites.

18

were likely to be the most serious obstacle to

certain simplifications to the headbox design

developing an industrially feasible process.

and made the headbox modular in nature. The

This implies that the forming process should

headbox design is shown in Figure 3.

be carried out at high consistency. The higher
the consistency at which we could form, the

The basic idea in UHC forming with classical

less water that needed to be removed in sub-

furnishes is to deflocculate the pulp suspen-

sequent operations.

sion with a spinning rotor. If enough energy is applied, the viscosity of the suspension

As a starting point, we focused on the earlier

approaches that of water and the fibre flocs

work of Gullichsen et al., who developed ultra-

completely break up. This, in principle, pro-

high consistency forming (UHC). This concept

vides a route for forming webs at high consist-

has its roots in the development of medium

ency with good formation. The difficulty is that

consistency pulp technology, which is based

it is rather challenging to form a coherent web

on the deflocculation of a fibre suspension by

with an even velocity profile from a highly tur-

the application of sufficient shear. In several

bulent suspension. Thus, the design and relat-

projects, UHC headboxes were constructed

ed flow phenomena around the slice are cru-

and tested with traditional furnishes of up to

cial considerations.

10% solids content. The technology met with
some degree of success. Based on this earlier

Two different slice arrangements were con-

work a UHC headbox was designed which was

structed for evaluation (Figure 4). The “wedge”

suitable for the Aalto pilot machine. We made

arrangement was conceived by Gullichsen et al.

Figure 2. Results for strength properties from the experimental design.

19

In this arrangement, the distance from the fluid-

a coherent free jet which would then impinge on

ized suspension to the slice is very short, which

the forming wire. The distance from the turbu-

has a potential benefit in minimizing the refloc-

lent zone to the slice exit should be sufficient to

culation time. With the wedge assembly, the web

attenuate disturbances and create the required

is formed in the gap between the bottom of the

pressure drop to ensure an even flow profile. The

headbox and the moving wire. The shear from

design was based on the best results of lab tri-

the wire can potentially rearrange the fibres and

als where, somewhat surprisingly, a converging

improve formation. The wedge space also effec-

slice gave the best free jet formation for both fi-

tively attenuates disturbances arising from the

bre and MFC composite furnishes.

turbulent mixing conditions inside the headbox.
The rotor in the headbox is capable of a maxThe second slice geometry constructed was a

imum speed of 4500 rpm and is driven by a

converging geometry with an adjustable slice

22 kW motor. The pattern on the rotor is 3mm

opening. The idea in this arrangement is to form

high diamonds.

Figure 3. The high consistency headbox. The headbox is modular and can be taken apart and refitted.

Figure 4. The two slice arrangements. Right: A converging geometry with controllable slice profile; Left:
The “wedge” concept.

20

4.3 Approach flow and wet end

tion only and pressing and drying of samples
would be done in lab devices. The UHC experi-

The approach flow that was designed and

ments with BHW furnish also utilized the press

built is shown in Figure 5. A 1-cubic metre,

and dryer section of the pilot paper machine.

well-mixed delivery tank is used as both the

It was originally planned that the forming ex-

make-down and machine chest. A number

periments would be done at low speed, 5-10

of pumps were tested. The most suitable for

m/min. It was our initial hypothesis that the

our system was a flexible impeller pump with

forming dynamics would be fairly decoupled

variable speed control. This system can han-

from the machine speed, since the turbulence

dle fibre furnishes in the range 1-5% and MFC

is generated by external means. However, this

composite furnishes up to 10% solids. A high

turned out not to be correct – the forming me-

shear mixer was installed before the headbox.

chanics were strongly coupled to speed and

Prior to the mixer, gas or chemical additives

generally improved as the speed increased.

could be added. A recirculation line after the

The operating speed was thus often 30-40 m/

mixer could be used for basis weight control or

min. A method for capturing samples off the

for mixing the furnish before the trials. Three-

wire at this higher speed was developed.

phase forming experiments can be done by
adding air and a suitable surfactant and then

4.4 Lab-scale forming studies

forming microbubbles either in the high shear
mixer or directly in the headbox.

The above concept presented a number of design challenges. Various mechanical designs

The headbox contact and position relative to

needed to be tested with different furnishes,

the wire can be adjusted. Furthermore, the

each with different rheological characteris-

vacuum box positions can be adjusted to allow

tics. This required focusing in from a range of

forming either directly on the vacuum zone, or

furnish characteristics and possible headbox

prior to vacuum. Since the main experimental

design solutions to a more narrowed forming

work will be done at elevated consistencies, no

and furnish concept. To facilitate the design of

provision for capturing or recirculating white

the pilot headbox and investigate web forming

water was made. It was planned that MFC

mechanics for a range of furnishes, a small-

composite trials would utilize the former sec-

scale lab former was constructed.
The principle of the former was that several li-

Figure 5. Approach flow for the UHC former.

21

tres of stock could be fluidized in a chamber.

number of different furnishes (Figure 7). The

The torque, rotor speed and temperature were

experiments with BHW explored whether small

recorded. The suspension could then be ex-

amounts of dispersed air could be used to im-

truded through a slice (different slice geom-

prove the flow and web forming characteristics.

etries were constructed) forming a free jet.

The MFC composite furnish experiments con-

The condition of the free jet could be exam-

centrated on finding the upper solids content

ined with a high speed camera. A system for

at which jet forming was still achievable. At this

evaluating the quality of the free jet was put

stage we were certain that dewatering the fur-

in place. With this set-up it was possible to ex-

nish would be extremely difficult, so emphasis

amine what types of furnishes, conditions and

was placed on maximizing the solids content.

slice geometries would lead to the best qual-

The main findings from the experiments are:

ity jets (Figure 6). The limitations of the device
were that it did not allow web capture, the web

• From the BHC furnishes coherent jets

speed could not be controlled, and the flow

could be achieved at 6% and lower solids.

duration was short, so that steady-state con-

The presence of 10% dispersed air (0.02%

ditions were not really achieved.

sodium dodecyl sulphate SDS dispersant)
improved jet formation.

The lab rheometer/former was used to test a

• The jet speed was 200-300 m/min,

Figure 6. Schematic and actual lab rheometer/forming device. The various possible slice openings are
shown on the right (slice opening 2mm). On average, the “modified long narrowing lip” gave the best
web forming characteristics.

Figure 7. Examples of free jets formed under high shear conditions from the lab rheometer. On the left is
a poor jet formed from a BHW suspension at 6% solids with one of the less successful slice geometries.
On the right is an excellent coherent jet of MFC composite furnish at 9.3% solids.

22

indicating that sufficient machine speed is

ological properties and dewatering can be

needed to form good webs. Pilot trials later

gathered. In these studies, a couple of differ-

confirmed this.

ent MFC grades were used, with either high or

• The application of high sheer generally
improved jet formation.
• The jet quality of the 70/20/10 MFC

low swelling. The influence of the fibre fraction
was studied, as was the solids content. A sample of the results is shown in Figure 8.

composite furnishes was excellent.
• The highest solids content at which web

The main findings from these experiments are

forming was possible for MFC composite

summarized below (note that further descrip-

furnish was 15% in the case of PCC as a

tion of this work and related publication can be

filler and 18% in the case of dispersed filler-

found in the Processability and preservability

grade ground calcium carbonate (GCC).

of microcelluloses section of this report).

Because the GCC had poorer dewatering
properties than PCC, the pilot trials were
conducted with 2.4 µm SPCC.
• While these experiments show that

• The furnish behaves as a gel and is highly
shear thinning.
• The gel rheology is governed by its water

maximum forming solids could be as high

binding, which in turn is controlled by the

as 15-18%, practical pumping difficulties

swelling of the MFC. Thus, although MFC

limited the pilot trials to around 10% solids

is only 20% of the furnish, it governs the

in the case of MFC composite furnishes.

rheological characteristics.
• MFC swelling also strongly influences

4.5 Lab rheology/dewatering studies
Common experience is that the addition of just
a few per cent of MFC to a handsheet or pilot
paper machine can often have a severe negative impact on all stages of water removal.
In deploying 20% MFC, we therefore expected water removal to be highly problematic.
Indeed, handsheets formed for the 70/20/10
furnish required overpressure and several
minutes to drain the water. However, forming
and removing water from a high consistency
furnish is very different to a handsheet and the
furnish is so completely different to traditional
fibre stock that poor water removal could not
be assumed. Practical experience proved this
to be the case.
The first clues that the 70/20/10 furnish could
be dewatered came from studies performed
with a Physica MRC-300 rheometer. This instrument allows simultaneous application of
shear and vacuum dewatering, so that information about the relationship between rhe-

Figure 8. Immobilization cell dewatering experiment with different composite furnishes. Lower gap position corresponds to easier dewatering. The upper curves use a highly swollen grade
of MFC (24 ml water/g solids swelling), the lower
curves a less swollen grade, VTT course MFC (9
ml/g swelling), used in machine trials. The closed
simples show the effect of 10% fibre in the furnish,
which increases dewatering for the furnish with
VTT course MFC.

23

dewatering of the furnish. The VTT coarse

tion, the PCC does not bind any water. The net

MFC with a network swelling of 9 ml/g

bound water in the web is less than traditional

(measured in a modified WRV test) had

paper, even when considering that MFC has a

much better dewatering characteristics

higher bound water content than Kraft fibres.

than a fine oxidized MFC with a swelling

Although our wet pressing research is still in

power of 24 ml/g.

its early stages, it is worth commenting that

• The application of shear helps dewatering

the pressing characteristics of the composite

• The presence of pulp fibres appears to have

web material are very different to traditional

a small positive influence on dewatering by

paper. The composite web is compressible to

helping to open flow channels.

the point where the filler network does not allow further compression and does not re-ex-

Further studies were begun at the end of the

pand. In ordinary paper, the web is highly com-

project to examine the press dewatering of

pressible, but expands and draws water back

the composite furnish. These studies are being

into the structure in the nip-rewetting phase.

carried out with a MTS press simulator which

It is clear from both the vacuum and press

can simulate fairly realistic pressing condi-

dewatering experiments that water remov-

tions. The results are shown in Figure 9. The

al from this kind of furnish can be surprisingly

results show that for this furnish at 100 g/m2

easy if the furnish characteristics and appro-

and 20% initial solids content, 45% solids con-

priate water removal strategy are understood.

tent can be achieved with a single shoe press.

Clearly, this is an area for further research.

Thus, if the web can either be formed at about
20% solids or at lower solids and vacuum de-

4.6 FBB trials

watered to 20% solids then pressing is completely feasible. Although we have not yet be-

The aim of this part of the project was to test

gun the drying experiments at the time of this

the UHC forming method with a fibre fur-

report, it is unlikely that the drying will be a

nish to determine whether suitable formation

problem. If the web permeability is sufficient

could be achieved and bulk could be improved.

to allow water transport in wet pressing, then

About 10 trials were run with a BHW or BHW/

it will allow steam transport in drying. In addi-

BSW furnish. Overall, the technology proved

Figure 9.
Moisture ratio after
pressing for a 100 g/m2
70/20/10 MFC composite
web with 20% initial
solids content. The MFC
used was MF-Daicel.

24

challenging with fibre furnishes. However, the

• Based on these trials it was decided that
the headbox needed to be rebuilt with a

following findings were also made:

free jet geometry and that the furnish flow
• Several trials were conducted with the

and flocculation characteristics should be

wedge arrangement shown in Figure 4. In

improved. This was achieved by dispersing

these trials, it was found that a web could

10% gas into the furnish stabilized with

be formed in the solids range 1-5%, but the
formation of the web was not acceptable.

0.01% SDS dispersant.
• The use of the free jet improved the

Figure 10 shows that when the headbox is

forming, but low machine speed was still

lifted from the wire and the rotor is on, the

a problem. When 10% air was dispersed

condition of the jet is chaotic. The wedge

in the headbox with the high shear mixer,

attenuates pulsation, but formation is

the formation and bulk improved markedly

limited if the velocity flow through the slice

and were at a good level for this machine

is not even. In these trials the application of

type (Table 1). In our opinion, the 3-phase

shear helped the forming somewhat.

forming solution has potential and further

• The low speed of our pilot machine gave a

improvements can be made by adjusting

somewhat misleading picture, especially at

the headbox turbulence conditions and

higher solids contents. Forming conditions

attenuating flow disturbances.

clearly improved as the machine speed
increased.

Figure 10. Left: Jet condition with the headbox lifted from the wire; Right: The web formed with the headbox against the wire.

Test point

SDS
(% stock)

Added Air
(%)

Deflocculation

Bulk
(cm3/g)

Formation
(g/m2)

1

0

0

before HB

1,99

35

2

0

0

In HB

1,96

48

3

0

10

before HB

1,92

37

4

0

10

In HB

1,94

43

5

0,01

10

before HB

2,15

20

Table 1. Sheet bulk and formation for 3-phase forming at 1.8% solids content with free jet arrangement.
Samples were pressed and dried on machine.

25

4.7 MFC composite trials

als require about 0.5 m3 of material, so a considerable quantity of MFC is needed. Note that

The aim of this project was to demonstrate the

we have made some modifications that allow

feasibility of producing MFC composite webs in

trials to be made with about 200 litres of stock.

a reel-to-reel operation. The lab work, equip-

Sample capture is a further challenge.

ment construction and the fibre furnish trials
were conducted in preparation for the com-

Three trials were conducted, as summarized

posite forming trials. The industrial realization

below:

of MFC composite products requires broader
research beyond the lab scale. Furthermore,

Trial 1: The furnish was 70/20/10 PCC/VTT

pilot-scale experiments are needed to identify

course MFC/BSW unrefined. Machine speed

the fundamental issues for in-depth research.

5-10 m/min. Grammage was about 500 g/m2.

Our first MFC trials validate this point.

Free jet arrangement. Solids 7-8%.

The MFC trials entailed numerous practical

• A web could be formed that was not

challenges, especially as the target was a highconsistency process. The MFC is produced locally at about 3% solids content, the PCC from
a decanter is at 30-35% solids, and ordinary

visually very even. Low speed was also a
limiting factor here.
• Samples were collected by applying blotting
paper to the web to remove samples

chemical pulp is available at 4%, unless thick

(Figure 11). This proved cumbersome.

stock is used. This limits the solids of the furnish

• Retention was close to 100% and some

to 9-10%, unless the MFC solids content can be
raised. Furthermore, the components must be

dewatering was achieved on the vacuum
section with couch solids at 10.5%.

brought together and thoroughly mixed. Mixing

• When the sample was pressed-dried, bulk

is of paramount concern when using any nano-

was 1.30 cm3/g and smoothness 3.5 PPS.

material, especially MFC-type products. The tri-

Formation was also good, showing that the

Figure 11. Taking samples in the first MFC composite trial.

26

gelatinous characteristic of the web means

• The web is still quite plastic even after wet

that the structure can be greatly altered

pressing. Final surface smoothness will

after forming the web, contrary to a normal

likely be controlled by the drying section

papermaking furnish. Fibres in the gel,

conditions.

when well dispersed, do not reflocculate
like a normal papermaking suspension.

Trial 3. The purpose of this trial was to reduce
the Grammage further to the 100-200 g/m2

Trial 2: The purpose of this trial was to push

range, to test the bent blade concept, and to

the solids content to 10%. At this point we

examine wire section dewatering. The furnish

were still convinced that a high forming solids

was the same as in Trial 2, but the solids con-

content was needed due to dewatering limita-

tent was lowered to 7%.

tions. The furnish composition was the same,

• A bent blade with adjustable contact angle

except that Daicel MFC was used. 400 g/m2
grammage. Conclusions:

and blade flexibility was added to the
headbox, as shown in Figure 13.
• The first suction box was moved under the

• At 10% solids, trial conditions were
considerably more difficult, e.g. pumping,
flow through headbox.
• Recirculating 1 hour through the high
shear mixer proved a good way to mix
components.
• A methodology for capturing samples was
developed (see Figure 12).
• Bevelling experiments indicted that
both the grammage and profile could
be controlled and any formation issues
corrected by appropriate use of a bent
blade system after web formation.
• The role of both the wire and felt were
of apparent importance. It seems that
different forming fabrics than are normally
used for traditional furnishes will be

blade.
• The slice opening was reduced to achieve
a target grammage of 200 g/m2. The
grammage in the trial ranged from 150 g/m2
to 250 g/m2.
• The lateral spread of the furnish was
remarkable at high blade pressure: a 15 cm
wide web of 300 g/m2 spread to 30 cm and
150 g/m2.
• Couch solids content varied in the trial
considerably from 12% to as high as 33%.
Ash retention also varied from 92-100%.
• The basic forming concept is moving in a
promising direction, though considerable
development is still needed to test and
adjust various aspects.
• Based on observations during the trial, we

required. This aspect should be included in

do not believe there are any restrictions on

continuation projects.

producing low-grammage webs.

Figure 12. Left: The sampling method of placing wire on wire. Right: Bent blade experiments demonstrate the plasticity of the furnish and that extreme lateral movement of the furnish is possible.

27

A major aim of this project was to outline a para-

tained through the consolidation process, other-

digm for manufacturing MFC composites of the

wise efficient water removal will not be possible.

type investigated here. Shortly stated, the forming consistency should be 8-10% solids content.
The forming should include high shear mixing
either before or in the headbox, as component

5. Exploitation plan and impact
of results

mixing and the shear thinning behaviour of the
suspension are essential. A bevelling blade or

Nanocellulose is one of the most promising devel-

other means can be used to adjust the profile

opments in the forest cluster in recent years. The

and grammage. The web can be vacuum dewa-

development of industrial processes to produce

tered to a suitable solids content for press entry.

high-volume composites or next-generation pa-

Pressing can be done with existing press technol-

per and board products from fibrillated cellulos-

ogy, though attention must be paid to the press

es represents one of the most important manu-

fabric. The web can be smoothed prior to drying

facturing challenges of our time. This project did

to achieve good surface properties. Since web

not, and could not, develop such a manufacturing

shrinkage and planar deviation are an issue, re-

process. This requires a project of much greater

straint during drying via Condabelt technology or

scope. However, we did obtain strong evidence

some other approach is warranted. The furnish

that it is very possible to manufacture MFC com-

must be designed such that porosity is main-

posite webs on a large scale and that it is rational

Figure 13.
Bent blade used to
bevel the furnish after
forming.

Figure 14. The bentblade UHC former in use.
Under some conditions
the web had a high
solids content, was
surprising strong and
could be peeled off the
table. The web had the
feel of a fabric. The trials
gave many surprising
and fascinating insights
into the nature of the
new composite.

28

and feasible to do so – both from the product and

Dimic-Misic, K., Puisto, A., Gane, P., Niemin-

process point of view. While further research is

en, K., Alava, M., Paltakari. J. and Maloney, T.

required, we obtained considerable evidence that

The role of MFC/NFC swelling in the rheologi-

we are on the right track and gained useful expe-

cal behavior and dewatering of high consist-

rience in dealing with MFC furnishes and forming

ency furnishes, Submitted to Chemical Engi-

on a somewhat larger scale.

neering Journal, 2013.

The successful development of MFC compos-

Rantanen, J., Lahtinen, P. and Maloney, T.

ite manufacturing technology should not be

(2013): Property Space for Fibre, Microfibrillar

viewed as an instrument to improve cost struc-

Cellulose and Precipitated CaCO3 Composite

ture, but rather as a gateway to an entirely new

Sheets, Int. Paperworld IPW,(5).

industry. The bulk of the results have not been
widely published yet. Despite this, several inter-


national companies are interested in exploiting

(2012): Property space for fibre, microfibril-

the results and continuing development work in

lar cellulose and precipitated CaCO3 Compos-

this area. Discussions are underway.

ite sheets, Zellcheming annual conference and
expo, June 26.-28. 2012, Wiesbaden.

6. Networking

(2012): Strength property space for fibre, mi-

The project was carried out in cooperation with

crofibrillar cellulose and precipitated CaCO3

Aalto University and Finnish forest cluster com-

Composite sheets, PaPSaT annual seminar

panies. The pilot former was built at the Depart-

2012, October 2.-3. 2012, Espoo, 48-52.

ment of Forest Products Technology, Aalto University. The project was headed by Thad Maloney

Rantanen, J. and Maloney, T. (2011): Novel

at the Department of Forest Products Technol-

manufacturing method for nanocellulose con-

ogy. Professor Kuosmanen at the Mechanical

taining web based products, PaPSaT annual

Engineering department lead the former con-

seminar 2011, August 22.-24. 2011, Lappeen-

struction. Professor Mika Alava at the Phys-

ranta, 42-49.

ics Department lead the furnish rheology work.
Each of the above is located at Aalto University.

Rantanen, J. and Maloney, T. (2011): Ultra high
consistency forming research using novel raw

7. Publications and reports

materials, COST Training school - New technologies for treatments in the end-of-use of
packaging materials, September 12.-15. 2011,

Dimic-Misic, K., Puisto, A., Paltakari, J., Alava,

Zagreb, 107-116.

M., Maloney, T. The influence of shear on the
dewatering of high consistency nanofibrillated
cellulose furnishes, Cellulose, 8/6/2013.
Dimic-Misic, K., Sanavane, Y., Paltakari. J.,
and Maloney, T. Small scale rheological observation of high consistency nanofibrillar material based furnishes. Journal of Applied Engineering Science, ISSN, 1451-4117, 2013

29

Foam
Forming
Petri Jetsu, petri.jetsu@vtt.fi

pa r t n e r s
VTT
Metso Paper
Metsä Board
Stora Enso
UPM-Kymmene

30

Abstract

Foam forming shows high resource efficiency potential and great promise as
a next-generation technology in the manufacture of fibre products. It enables
production of lightweight structures (high bulk) from various raw materials,
gives excellent formation independent of fibre length and shows excellent
dewatering properties for furnishes containing MFC. All of these offer ways
for forest industry companies to improve their competiveness, reduce capital
costs, significantly save resources, and promote sustainability. A semi-pilot
foam forming environment, built at the Technical Research Centre of Finland
(VTT), enables the production of structures with grammages from 15 to 150g/
m2 and forming at speeds up to 300m/min with consistencies as high as 4-5%.
The results indicate that in the case of folding box board, foam technology
together with advanced raw materials (here MFC as the strengthener) could
reduce manufacturing costs by 25% and carbon and water footprints by 45%
and 38%, respectively. The estimated reduction in total cost of ownership is
about 35%. Currently, the technology is being scaled up to pilot scale in another project to ease the adoption of the technology by industry. The potential
is huge, but several technological issues, such as an optimal foaming aid
concept, automation and control systems, and suitable processes to achieve
excellent printing surfaces while maximizing bulk, have to be tackled before
foam technology can be transferred to production scale.

Keywords:
Foam forming, folding box board, microfibrillated cellulose

31

1. Background

refining. Forming structures from a wide variety of raw materials ranging from nanomaterials

The foam forming research continues the work

to centimetre-long fibres and materials of lower

started within the Re-Engineering Paper (REP)

density than water make this an attractive tech-

project during the first two years of the Ef-

nology for new fibre-based products. For exam-

fTech programme. The REP project originally

ple, foam forming naturally provides excellent

aimed at developing resource-efficient means

formation even with long fibres as well as the

of paper production utilizing microcellulose

possibility to form high-bulk structures. It also

and at developing advanced multi-scale mod-

enables forming of multilayered structures with

els to support this aim. The main findings of

excellent layer purity even for lightweight prod-

REP related to foam forming were:

ucts. The technology is already used for nonwoven applications on an industrial scale.

• Foam forming has been identified as the
most potential resource-efficient and
sustainable technological alternative

2. Objectives

to produce microcellulose-containing
products. It enables efficient dewatering

Objectives of the study were to expand paper

and production of fibre-based products

and board properties with new resource-effi-

not achievable with current papermaking

cient furnish and technology concepts and to

technology.

offer ways to radically improve energy, water

• Lightweight packaging board is the product

and raw-material efficiency by utilizing foam

concept with highest potential in terms of

forming technology with microfibrillated cellu-

market size and growth and product value.

lose containing furnishes.

• Microcelluloses have been demonstrated
to give various novel product properties
(e.g. high stretch). These properties

3. Research approach

have been shown to depend strongly on
both microcellulose quality and process

The work is based on the competencies de-

conditions.

veloped in the EffTech programme. In the ReEngineering Paper (REP) project, two main

The main technical challenges in utilizing mi-

advantages of foam forming were identified:

crocelluloses in product manufacturing re-

1) Possibility to generate extremely uniform

lated to forming and dewatering. Since mi-

webs (very good formation) and 2) Potential

crocelluloses bind water efficiently, they are

to make bulky structures. In the REP project

not compatible with current paper machines,

some demo structures were generated, but

where high wire section drainage is important.

very little attention was put to control of pro-

Therefore, forming at high solids content is a

cess and product properties such as forma-

crucial step in solving the dewatering prob-

tion, orientation and strength.

lems inherent in nanomaterial applications.
In the EffNet programme, a semi-pilot scale
Foam forming is a potential technology for next-

gle and multi-layer features was constructed

forming of web structures at high consistency

at VTT’s KISU facility. Controllability of sheet

with closed water systems and offers high en-

structure, product properties and process lim-

ergy saving potential in pumping, drying and

32

foam forming research environment with sin-

generation paper and board making. It enables

its, such as jet-to-wire ratio, consistency and

vacuum levels, were studied in dynamic condi-

The following improvements were carried out

tions. Laboratory-scale experiments were also

during the first modernization of the single-

carried out. The main focus was utilization of

layer foam forming environment:

foam forming technology combined with microcellulose (MFC) containing furnishes in mul-

• New headbox

ti-layered board making. The target was to in-

• New headbox feeding pump

crease the bulk of the folding box board (FBB)

• Improved foam recovery capacity through

middle ply by 50-100%, which offers radical en-

additional exhaust pump

ergy, water and raw material savings and considerably reduces carbon and water footprints.

As the new headbox and forming section is a

Other studied cases were SC and fine paper.

closed unit, there is no free slice jet in the head-

Development work also included foam chem-

box area. The headbox was designed on the ba-

istry research together with the SP Technical

sis that the same headbox could also be used

Research Institute of Sweden. Research related

for forming multi-layered web structures. The

to manufacturing of MFCs was excluded, so all

new headbox feeding pump enables pumping

utilized MFC grades were developed elsewhere.

of foamed suspensions at high consistency levels (up to 5%). Start-up of the single-layered

The foam forming results were highly promis-

web forming environment took place in No-

ing. Significant potential was identified for raw

vember 2011. The single-layer foam forming en-

material and energy savings in the manufacture

vironment modernization was finalized in May

of folding box board. Changing from water-laid

2012 and provides the following features:

technology to foam forming reduces manufacturing costs and carbon footprint by 25% and

• Improved foam recovery capacity

45%, respectively. Investment costs are also

• Improved pumping capacity

reduced by 25% in greenfield installations. In

• Improved mixing conditions in the feeding

addition, foam forming broadens the range of
product properties and products, creating new
business opportunities for the forest industry.

pulper
• Improved approach system for foamed
furnish
• Measurements for process control

4. Results

A schematic picture of the single-layer foam
forming process is presented in Figure 1. The

4.1 Dynamic foam forming environment

main principle of the foam-laid forming process
consisted in the process foam being recirculat-

The objective was to construct a dynam-

ed within the flow loop and the raw materials

ic foam forming research environment to en-

being mixed with the process foam in a pulper.

able the forming of single and multi-layered

The quality of new and recovered process foam

web structures at speeds of up to 200 m/min

is controlled on-line by adjusting mixing condi-

to be studied. During the project a new foam

tions within the foam generator. Mixing condi-

forming research environment was designed

tions are then adjusted on the basis of these

and constructed around an existing semi-pi-

foam conductivity measurements. In single-

lot scale forming environment at VTT. Devel-

layer mode, both open and closed headbox-

opment work was divided into two phases: 1)

wire geometries are possible to run (Figure 2).

construction of single-layer facilities and 2)
construction of multi-layering facilities.

33

Figure 1. Schematic diagram of the single-layer foam forming process.

Figure 2. Left: Single-layer open headbox based forming unit; Right: Closed headbox based forming unit.

Figure 3. Schematic diagram of the multi-layer foam forming process.

34

The modernization of the multi-layer foam
forming environment was finalized in June
2013 and includes a manifold, a feeding chest
and a feeding pump for each layer. The layered
web structure is generated within the headbox. A schematic diagram of the multi-layer
foam forming process is presented in Figure 3.
Achievements of the developed dynamic
foam forming environment:

Single-layer structures in a continuous process
• Grammages up to 150 g/m2
• Headbox consistency up to 4-5%

Figure 4. Formation in foam forming is independent of fibre type and of superior quality to water
laying.

• Speed up to 300 m/min
• Open and closed headbox-wire geometry
Multilayer structures in batch mode
• Forming of two- and three-layer web
structures

formed samples typically starts to decrease
when the grammage decreases below a cer-

4.2 Enhanced product properties

tain value (typically 50 – 60 g/m2) as the flocks
start to dominate the lateral strength behav-

One of the inherent properties of foam-formed

iour. As foam prevents flocculation to a great

products is their excellent formation. Figure 4

extent, the tensile index remains constant

illustrates this for three types of fibres. Most

even at very low grammages. This can have an

notable is that with foam forming the forma-

important impact on low-grammage products.

tion is independent of fibre type. Especially,

The experiment was conducted with both dy-

the specific beta formation was enhanced by

namic foam and water formers.

69% when spruce chemithermomechanical
pulp (CTMP) was used. The experiments were

Sheets made in the laboratory (static forming)

done with a dynamic, single-layer former.

were compared with dynamic foam and waterformed samples and sample data from the Finn-

One consequence of the excellent formation

ish Pulp and Paper Research Institute (KCL) pilot

is enhanced strength at low grammage, as

paper machine. The data for the static and dy-

shown in Figure 5. The tensile index of water-

namic samples is shown in Table 1.

Table 1. The data for the static and dynamic foam and water formed samples.
Static (laboratory sheet mould)

Dynamic

Pulp: CTMP spruce
MFC: Daicel MFC
Grammages: water 230 g/m2; foam 75, 105 and 150 g/m2
Pressing: no pressing, 1 pin roll and 10 pin roll
Disintegration: hot and cold

Pulp: CTMP spruce
Grammage: 105 g/m2
Pressing: no pressing, 0.5, 1.5 and 3.5 bar
Disintegration: hot

35

When MFC is added to the foam-forming furnish we enter brand new territory in terms of
the bulk – Scott Bond relationship. We can make
lightweight structures that are strong enough
with high bulk. Such structures are unattainable with water forming because high bulk levels cannot be reached. Figure 7 further illustrates this by showing that with a 10% addition
of MFC, all of the critical strength properties of
Figure 5. At low grammages the tensile strength
of foam-formed sheets is clearly higher due to improved formation.

the 54% lighter laboratory-scale sheets are at
the same level as the water-laid reference.
As a consequence of the positive effect of MFC,
a test series using six different grades of MFCs

The most important outcome of our research

were run at the laboratory scale in order to de-

is shown in Figure 6: structures with the same

termine their effect on both z-directional and in-

strength can be produced with half the raw

plane strength properties. The pulps used in the

material. Without MFC a clear trend can be

study were pine kraft and spruce CTMP pulp and

seen. Scott Bond values decrease rapidly as

the amount of MFC added was 0% (a reference),

bulk increases from 2 cm3/g to 4 cm3/g. Howev-

5% and 15%. The sheets prepared were dried

er, if the bulk is greater than 4 cm3/g, increased

after forming without wet pressing. The results

bulk lowers the Scott Bond values only slowly.

from the test series are shown in Figure 8.

Very high bulk (> 6 cm3/g) can be achieved only
with foam forming. Thus, without any strength

According to the results, different MFC grades

additives, the only way to obtain a strong

seem to behave rather similarly in bulk vs.

enough structure (Scott Bond > 100 J/m2) is to

strength comparisons. However, in the case of

compress the structure sufficiently.

modified Scott Bond, the coarser and cheaper

Figure 6. Scott Bond values of CTMP sheets as a function of bulk. Board properties can be expanded
through a combination of foam forming (for high bulk) and strength additives. The green triangles are
typical values for CTMP sheets made on the KCL pilot paper machine. The blue squares and brown diamonds are values from static and dynamic water-formed and foam-formed studies, respectively. The
circles show the values of the foam-formed samples with different Daicel MFC contents.

36

Figure 7. With a combination of foam forming and MFC it is possible to make sheets at the laboratory
scale that are 54% lighter but have the same strength values as water-formed, heavier sheets. Water-formed sheets of grammage 230g/m2 (red squares), foam-formed sheets of grammage 105g/m2
with MFC (purple circles) and without MFC (blue diamonds). The green triangles indicate the estimated
strength values achievable with wet pressing for foam-formed sheets.

Figure 8. Effects of addition of six different MFC grades to pine and spruce CTMP pulps. Above: Modified
Scott Bond as a function of bulk. Below: Tensile index as a function of bulk. The right end points of the
lines equate to 5% addition and the left end points to 15% addition.

37

VTT MFC gave slightly higher values compared

ter laboratory wet pressing (3.5 bar, 5+2 min).

to the more refined and expensive VTT MFC.

The shrinkage potential study was based on

On the other hand, the more refined VTT MFC

a free shrinkage drying method allowing in-

gave a higher tensile index value. This exam-

plane shrinkage, but partly constraining curl-

ple illustrates that the choice of MFC should

ing (drying between wires). The results of the

depend on the required paper properties.

shrinkage potential measurements are shown
in Figure 9 (Left). According to the results,

In order to study the dimensional stability

the shrinkage potential of foam-laid papers is

of water-laid and foam-laid papers and sol-

smaller compared to water-laid papers. Foam-

ids content, the next test series were run us-

laid papers are also not as sensitive to MFC

ing pre-refined pine kraft pulp and VTT coarse

content as water-laid papers. The dryness lev-

MFC. The characteristics were measured af-

el of foam-laid papers is also higher after wet

Figure 9. Left: Foam-formed samples shrink less in free drying than water-formed samples at MFC contents of 0, 2.5, 5, 10, 15 and 20% and wet pressing conditions 0, 1.5 or 3.5 bar. Right: The solid content of
foam-formed sheets is higher after wet pressing (3.5 bar 3+2 min) than that of water-formed sheets at
MFC contents of 0%, 2.5%, 5% and 10%. The MFC used in the test series was VTT coarse MFC.

Figure 10. Left: In-plane strength properties of foam and water-laid samples (geometric average of tensile index values of foam samples) as a function of bulk (variables: MFC content and wet pressing pressure). Right: Z-directional strength of unpressed foam and water-laid samples as a function of bulk (variable: VTT coarse MFC content).

38

pressing (Figure 9, right). The MFC amounts

namic water-laid and foam-laid forming meth-

used can be reasonably high due to the open

ods are presented in Figure 11. Water is removed

structure of the foam-formed samples. This is

more easily than viscous foam, leading to lower

not an option in water forming, because the

vacuums in water-laid forming. Corresponding-

water drainage properties would be deterio-

ly, vacuums were higher in the removal phase

rated excessively. In our foam forming stud-

of process foam. After the removal phase, vac-

ies the solids content after wet pressing varied

uums were approximately at the same level in

from 45 to 55% also at high levels of MFC ad-

both forming methods. In the closed headbox

dition (10%, 15% and 20%).

based forming process vacuum levels were still
higher. This was mainly because most of the

In summary, foam-laid technology enables the

process foam was dewatered under the deck of

production of high-bulk structures. When this

the closed headbox and the quality of the paper

is combined with its good water drainage prop-

web was better with the closed headbox, thus

erties, allowing the addition of high levels of

leading to higher vacuum levels.

strengthening agents such as MFC, products
with both very high bulk and adequate strength

The tensile strength ratio and specific beta-

can be made. Figure 10 shows the possibili-

formation behaviour in the case of the closed

ties for strength compensation in foam-formed

headbox former is presented in Figure 12. The

samples for different wet pressing levels.

results show that a wide tensile strength ratio
can be achieved. The minimum tensile strength

4.3 Process research

ratio was around 3 and, correspondingly, the
maximum tensile strength was around 8. The

In the process research, refined chemical pine

achieved maximum tensile strength ratio was

pulp was used as the fibre raw material and the

exceptionally high compared to normal wet-

average grammage of the samples was 80 g/m2.

forming values. The specific-beta formation
values were also at a very good level, varying

The vacuums in the forming section for dy-

between 0.35 √g/m – 0.60 √g/m.

Figure 11. Vacuums in the forming section.

39

Figure 12. Tensile strength ratio can be controlled extensively in foam forming by altering the jet-to-wire
ratio without affecting the excellent formation.

Figure 13. Geometric tensile index and specific beta-formation as a function of forming consistency.

Figure 14. Geometric tensile index and specific beta-formation as a function of density of the process foam.

40

The geometric mean of tensile index and spe-

ing agents and papermaking raw materials in

cific beta-formation as a function of forming

aqueous foam-fibre systems was of great inter-

consistency is shown in Figure 13. As can be

est. The research was carried out in close coop-

seen, paper quality deteriorates with higher

eration between SP (Technical Research Insti-

consistency. The maximum forming consist-

tute of Sweden, formerly YKI) and VTT.

ency achieved was ~ 4.5%. The limited mixing
capacity in the foam chest (foam pulper) and

Foaming aid screening and foaming tests

the limited dewatering capacity in the form-

The foaming behaviour of pulp formulations, in

ing section prevented the attainment of higher

the presence of three ionic and four non-ion-

forming consistencies.

ic foaming aids, was tested with a tailor-made
foaming testing device and procedure devel-

The geometric mean of tensile index and specif-

oped by VTT. Foaming aids for testing were

ic beta-formation as a function of density of the

chosen based on their reported good foam-

process foam is shown in Figure 14. Paper qual-

ing properties, availability as bulk chemicals,

ity was weakened significantly when the aver-

as well as insensitivity to changes in tempera-

age density of the process foam was increased.

ture and pH within limits relevant to the foamforming process. The results from foaming

4.4 Foam chemistry

tests indicated that, of the foaming aids tested, three enabled relatively rapid generation

Much is known about the properties of pure

of the required foam-fibre volume. The list and

aqueous foams. However, extremely little is

molecular structure of the most rapidly foam-

known about the chemical interactions be-

ing chemicals are shown in Table 2.

tween foaming agents and papermaking raw
materials in aqueous foam-fibre systems. The

Foam-formed handsheets with different fur-

objective of the study was to increase under-

nish recipes (44 different recipes) were made

standing of the basic mechanisms related to

and tested to evaluate the effect of the select-

fibre-foam chemistry, foamability and foam

ed foaming agents on the formation and re-

stability. In particular, gaining an understand-

tention processes, the technical properties of

ing of the chemical interactions between foam-

the handsheets and the performance of other

Table 2. The most rapidly foaming chemicals and their molecular structures.

41

chemicals used in paper/board manufacturing

(see Figure 15, left). Furthermore, at AKD

in the presence of the foaming aids. The results

dosages ≥ 3 kg/t, the water absorbency of

obtained from the handsheet tests showed

water-formed handsheets was higher than

that the type of foaming aids used has signifi-

that of foam sheets made using the non-

cant effects on the mechanical properties and
quality of paper. The main findings of the handsheet tests can be summarized as follows:

ionic surfactant.
5. Foam-formed sheets gave higher dryness
after forming and wet pressing than waterformed sheets. Foaming type and dosage

1. Foam-formed handsheets are bulkier than

had a significant impact on dewatering (see

water-formed handsheets after constant

Figure 15, right). Foaming aid dosage had no

wet pressing conditions. The type of

effect on the mechanical properties of the

foaming aid has a significant effect on bulk.
2. The formation of foam-formed sheets was
better than that of water-formed sheets. In
the presence of ionic polymers, the charge
of the used foaming aid has a significant
effect on formation.
3. The in-plane mechanical properties (tensile
strength) of foam-formed samples were

samples.
6. Filler retention was significantly higher with
foam-formed sheets utilizing a non-ionic
foaming aid than an anionic foaming aid.
7. The effect of cationic strength additives on the
strength increase of foam-formed handsheets
was lower in the presence of anionic foaming
aids than with non-ionic foaming aids.

somewhat similar to water-formed sheets at
a given bulk level. However, the out-of plane

The potential of utilizing the selected foaming

properties (Scott Bond delamination energy

aids in the practical foam forming of paper was

and Z-directional strength) of foam-formed

verified in a semi-pilot trial based on a fine pa-

samples, which are crucial for the functionality

per recipe. The results obtained during the tri-

of board, were clearly lower than for water-

als indicated that the findings made in the lab-

formed sheets at a given bulk level.

oratory tests were also valid in more dynamic

4. Sizing with alkyl ketene dimer (AKD) was

surroundings. It was also noticed that the se-

greatly dependent on the type of foaming

lection of utilized foaming aids must be done

aid used. Ionic sodium lauryl ether sulfate

together with the selection of the utilized re-

(SLES) and SDS required significantly higher

tention system. In conclusion, understanding

AKD dosage to achieve similar Mini-Cobb30

and control of fibre-foam chemistry is a key for

values to non-ionic alkyl polyglucoside

successful tailoring of final product properties.

Figure 15. Left: The effects of AKD dosage on Mini-Cobb30 value of foam- and water-formed handsheets. Right: The effects of foaming aid type and dosage on dryness after wet pressing for foam (and
water) formed handsheets.

42

4.5 Foam forming concept and
evaluations

sumptions underneath of figure 17, a 25% reduction in production costs can be expected
(Figure 17). The calculations are based on the

The financial impacts and costs of adaption of

laboratory and semi-pilot scale results. Pro-

the foam technology are discussed in this sec-

duction in square metres is assumed to be the

tion. Folding box board (FBB) is used as a ref-

same, i.e., the volume of the reference water

erence case. The main changes required to re-

forming machine is 400,000 t/a and the foam

build a FBB machine are illustrated in Figure

forming machine 245,000 t/a (same speed,

16. A foam forming rebuild costs in the region

width and efficiency).

of EUR 10 million. The main changes to the
system are the conversion to a closed head-

Assumptions to achieve these results are:

box (which might, in some cases, not even be

Fibre: Reduction of basis weight from 270 g/

necessary) and installation of a foam genera-

m2 to 166 g/m2. Basis weight of the middle lay-

tor for mixing and dispersing, vacuum pumps

er is reduced from 192 g/m2 to 88 g/m2. MFC is

and a vacuum line for foam removal. In addi-

considered as fibre, a dosage of 20% is used

tion, minor automation updates are expected.

in calculations. It is also assumed that MFC re-

The consistency is assumed to increase from

places chemical pulp. This results in a total fi-

1% to 2.5%, so existing tank volumes are suf-

bre cost of 496 €/t.

ficient. Fresh water intake and outgoing water quality are assumed to remain unchanged.

Energy: Total energy consumption reduction
is estimated to be 20% (per tonne). This arises

There were two main outcomes of the FFB

from higher consistency (2.5%) as lower mass

case. Firstly, significant resource savings were

flows are needed but also due to lower basis

expected for both new forming technologies,

weight needed for the final product. Use of the

especially if microcellulose was used to in-

same energy levels in forming results in higher

crease the strength properties. Secondly, the

solids content before pressing. For example, for

savings potential is realized only if the value is

the reference case an increase from 19% to 24%

calculated per unit area (€/km2). Using the as-

is obtained using the same pulp mix (Birch/pine/

Figure 16. Foam rebuild
FBB concept with changes
highlighted.

43

CTMP). The same energy used in pressing re-

38%. Reductions are realized mainly through re-

sults in higher solids content after pressing. This

duced basis weight. For water footprint, the wa-

results in a total energy cost of 31 €/t.

ter scarcity is different in different regions of
the world; in Finland, where water resources are

Water: 13 m3/t water needed for production

readily available, the water scarcity footprint is

(4€/t). This is based on forming at higher con-

low in both cases (reference and foam FBB).

sistency (2.5%) and improved retention.
During the estimated 20-year lifetime of a maChemicals: Chemical cost per tonne for the

chine line, with 9% interest, the reduction in

reference are assumed to be 86 €/t. For foam-

total cost of ownership (TCO) can be about

ing chemicals the cost is assumed to be 8€/t

35%. This estimation arises from savings in

(SDS: 0.31% dosage, 2700€/t)

operating, investment, interest (shorter payback of machine when operating cost savings

For carbon footprint, the reduction is 45%, as

are assumed to be used to reduce loans fast-

shown in Figure 18. Water footprint reduction is

er), logistics and insurance costs.

Figure 17. Estimated savings potential for foam-formed folding box board.

Figure 18. Carbon (left) and water footprints (right).

44

5. Exploitation plan and impact
of results

jects. Based on the results, we strongly believe
that foam forming will lead to a new manufacturing platform for fibre-based products as it 1)

Foam forming technology can significantly im-

requires significantly less raw materials, water

prove competitiveness, reduce capital intensive-

and energy than conventional manufacturing,

ness, reduce consumption of resources and im-

2) remarkably improves many product proper-

prove the sustainability of current products. At

ties, 3) enables exploitation of new raw mate-

the same time, it paves the way for the renew-

rial combinations, 4) offers a sustainable solu-

al of the forest industry by enabling raw materi-

tion for manufacturing a wide range of products,

als to be combined in new ways, thus opening

such as paper, board, tissue, hygiene products,

up opportunities for companies to create novel

insulation materials, filters and other added val-

value chains. This will create new business op-

ue products from bio-based, long fibres and 5)

portunities for large companies as well as small

offers possibilities for both large companies and

and medium sized enterprises (SMEs). Within

SMEs to create novel value chains.

this programme the concept was demonstrated
at the laboratory and semi-pilot scale. The next
step – validating the achievements at the pilot

6. Networking

scale – has already started in one project, SMEs
are seeking value-added applications in another

The research was carried out jointly by VTT

project, and several companies are also taking

and Finnish forest cluster companies. Table 3

active steps in this area through their own pro-

presents the research partners and their roles.

Table 3. Partner organisations and their research roles.

Partner

Role

VTT Technical Research centre of Finland,
Fibre Process Knowledge Centre

Foam forming research, demo products manufacturing, fibre network modelling and concept
evaluation

Metso Paper

Process knowhow, demo products specifications, commercialization perspective

Metsä Board

Demo products specifications, concept evaluation, commercialization perspective

Stora Enso


UPM-Kymmene


SP Technical Research Institute of Sweden
(former YKI)

Foam chemistry research, understanding of
basic mechanisms related to fibre-foam chemistry, foamability and stability

45

7. Publications and reports
Publications:

Hellén, E., “Lightweight fibre materials through

Al-Qararah, A. M., Hjelt, T., Kinnunen, K., Be-

dustrial Applications –seminar, Espoo, 2013.

foam technology”, Biomaterials - Towards Inletski, N., Ketoja, J. A., Exceptional pore size
distribution in foam-formed fibre networks.

Hellén, E., “Renewal by combining novel form-

Nordic Pulp Paper Res. J. 27, 226-230 (2012).

ing technologies with advanced raw materials”, EffFibre&EffNet Workshop, 2012.

Al-Qararah, A. M., Hjelt, T., Koponen, A., Harlin, A., Ketoja, J. A., “Bubble size and air content

Hellén, E., “Beyond paper and board - Leap

of wet fibre foams in axial mixing with macro-

in resource-efficiency with nanocellulose and

instabilities, Colloids and Surfaces A: Physic-

new forming techniques”, Forestcluster Annu-

ochemical and Engineering Aspects, Volume

al seminar, 2011.

436, 5 September 2013, Pages 1130-1139.
Hjelt, T., Kinnunen, K., Lehmonen, J., Beletski,
Lappalainen, T. and Lehmonen, J., “ Determi-

N., Hellén, E., Liljeström, V., Serimaa, R., Miet-

nations of bubble size distribution of foam-fi-

tinen, A., and Kataja, M., ”Intriguing structur-

bre mixture using circular Hough transform”,

al and strength behaviour in foam forming”,

Nordic Pulp and Paper Research Journal, 2012,

PPPS 2011, Graz.

Vol 27, no. 5, 930-939.
Lehmonen, J., Jetsu, P., Kinnunen, K. and
Lehmonen, J., Jetsu, P., Kinnunen, K. and

Hjelt, T., ”Potential of microfibrillar cellulose in

Hjelt, T., “Potential of foam-laid forming tech-

water-laid and foam-laid papers” 2013 Tappi

nology in paper applications”, approved to

International Conference on Nanotechnology

Nordic Pulp and Paper Research Journal.

for Renewable Materials.

Kinnunen, K., Lehmonen, J., Beletski, N., Jet-

Mira, I., Andersson, M., Boge, L., Blute, I.,

su, P. and Hjelt, T., “Benefits of foam technol-

Salminen, K., Lappalainen, T., Kinnunen, K.,

ogy and its applicability in high MFC addition

“Foaming behaviour of cellulose pulp fibre-

structures”, approved to FRC.

surfactant systems used for novel production
of fibre-based materials”, Formula VII, 1 July 13
- 4 July 2013, Université de Haute Alsace, Mul-

Presentations:

house, France.

Al-Qararah, A. M., Hjelt, T., Kinnunen, K., Belet-

Poranen, J., Kiiskinen, H., Salmela, J., Asi-

ski, N., Ketoja, J. A., “Exceptional pore size distri-

kainen, J.,Keränen, J., Pääkkönen, E., “Break-

bution in foam-formed fibre networks”, Int. Pa-

through in papermaking resource efficiency

per Physics Conf. 2012, Stockholm, Sweden.

with foam forming”, PaperCon, Atlanta, 2013.

Hellén, E., ”Resource efficiency with foam

46

Poranen, J., “Resource efficiency with foam

forming”, Tissue World, Barcelona, 2013.

forming”, EffFibre & EffNet Seminar, 2012.

Posters:
Lappalainen, T., Salminen, K., Kinnunen, K.,
Järvinen, M., Mira, I., Boge, L., Andersson, L.,
M. and Carlsson, G. ”Laboratory scale investigation of foam forming”, EffFibre & EffNet
Seminar, 20.11.2012.
Lehmonen, J., Kinnunen, K., Hjelt, T., “Significant process improvements using foam forming”, Forestcluster Annual seminar, 2011.
Kinnunen, K., Lehmonen, J., Hjelt, T., Jetsu, P.,
“Foam forming facilities and demonstrations”,
EffFibre & EFFNet Seminar, 2012.
Kinnunen, K., Hjelt, T., Lehmonen, J., Jetsu,
P., Hellén, E., Kiiskinen, H., Poranen, J., ”Foam
forming - renewal of fibre products”, SHOK
Summit, 2012.
Salminen, K., Lappalainen, T., Kinnunen, K.,
Andersson, M., Isabell, M., ”Foam chemistry”,
EffFibre & EFFNet Seminar, 2012.

47

Fibre-based

products
for new applications

Erkki Hellén, erkki.hellen@vtt.fi

pa r t n e r s
VTT
Aalto University
Helsinki University
Kemira
Stora Enso
Tampere University of Technology
UPM

48

effnet Programme report

Abstract
Demonstrations of new fibre-based products focussed on utilizing microfibrillated or microcrystalline celluloses in various applications and determining the
potential of foam forming technology to manufacture value-added products.
Filler-MFC composites were shown to offer a cost-effective substrate for printed
electronics applications with a superior temperature tolerance that only special
plastics can compete with. The performance of four different demonstrators
printed on the composite were comparable to those printed on plastic reference
substrates: conductors by inkjet, a LC resonator by screen printing, a near field
communication RFID tag by screen printing, and transistors by flexo printing.
Lightweight structures (densities 8-26 kg/m3; bulk 38-120 cm3/g) having thermal
conductivities comparable to commercial mineral and stone wool insulation materials were made from basic papermaking raw materials using foam forming.
Similar structures were also shown to perform well as lightweight, sustainable
sound absorption materials at challenging low frequencies (~500Hz). The best
structures were comparable to commercial sound insulation materials with
a density as low as 20 kg/m3. Finally, it was demonstrated that a new type of
microcellulose, namely carboxymethyl cellulose grafted microcrystalline cellulose, can act as an efficient strength additive in paper.
Foam forming clearly has the highest value creation potential of the concepts
studied in this section. Foam forming opens the way for a new manufacturing
platform for fibre-based products, as it 1) enables exploitation of unprecedented
raw material combinations 2) offers a sustainable solution for the manufacture
of a wide range of products like paper, board, tissue, hygiene products, insulation
materials, filters and other added value products from bio-based, long fibres, and
3) offers possibilities for both large companies and SMEs to create novel value
chains. The substrate for printed electronics also shows good value creation potential but, although the market potential for printed electronics is high, the market itself is still most probably too small for large companies to enter. The same
applies to the other demonstrations, which, however, may offer viable market opportunities for small and medium size enterprises. Overall, these demonstrations
show that it is possible to manufacture value-added products from wood fibres.

Keywords
printed electronics, MFC, foam forming, sound absorption, lightweighting, thermal insulation

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