FIBIC EffNet programme report


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

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FIBIC EffNet programme report

  1. 1. Ohjelmatunnukset Efficient Networking Towards Novel Products and Processes Programme Report 2010–2013
  2. 2. 13 Ohjelmatunnukset Efficient Networking Towards Novel Products and Processes Programme Report 2010–2013
  3. 3. 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. This publication includes materials protected under copyright law, the copyright for which is held by FIBIC or a third party. The materials appearing in publications may not be used for commercial purposes. The contents of publications are the opinion of the writers and do not represent the official position of FIBIC. FIBIC bears no responsibility for any possible damages arising from their use. The original source must be mentioned when quoting from the materials. ISBN 978-952-67969-0-1 (paperback) ISBN 978-952-67969-1-8 (PDF) Layout: Brand United Ltd Printing: Kirjapaino Lönnberg
  4. 4. 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
  5. 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.
  6. 6. 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
  7. 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
  8. 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
  9. 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
  10. 10. 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
  11. 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 ( • 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
  12. 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
  13. 13. High consistency forming of microfibrillated composite webs c o n ta c t p e r s o n Thad Maloney, pa r t n e r s Aalto University Metso Paper Metsä Board 14
  14. 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
  15. 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-
  16. 16. 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
  17. 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
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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
  23. 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
  24. 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
  25. 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
  26. 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
  27. 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
  28. 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- Rantanen, J., Lahtinen, P. and Maloney, T. 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 Rantanen, J., Lahtinen, P. and Maloney, T. (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
  29. 29. Foam Forming c o n ta c t p e r s o n Petri Jetsu, pa r t n e r s VTT Metso Paper Metsä Board Stora Enso UPM-Kymmene 30
  30. 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
  31. 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
  32. 32. 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
  33. 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
  34. 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
  35. 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
  36. 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
  37. 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
  38. 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
  39. 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
  40. 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
  41. 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
  42. 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
  43. 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
  44. 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 Demo products specifications, concept evaluation, commercialization perspective UPM-Kymmene Demo products specifications, concept evaluation, commercialization perspective SP Technical Research Institute of Sweden (former YKI) Foam chemistry research, understanding of basic mechanisms related to fibre-foam chemistry, foamability and stability 45
  45. 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.
  46. 46. 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
  47. 47. Fibre-based products for new applications c o n ta c t p e r s o n Erkki Hellén, pa r t n e r s VTT Aalto University Helsinki University Kemira Stora Enso Tampere University of Technology UPM 48 effnet Programme report
  48. 48. 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 effnet Programme report 49