Welcoming the delegates, Rob Elias, marketing manager of organisers the BioComposites Centre, University of Wales, Bangor, thanked the sponsors of the symposium who were ATR, F-Stop, Habasit, Dieffenbacher, Dow Chemicals, Dynea, Huntsman Polyurethanes, Kronospan, Nexfor, TECO and Wood Based Panels International. He said that the Centre’s website, and exposure in WBPI, had both made a major contribution to the good turnout at this event. “We appreciate that taking time away from work is difficult, but we hope that this symposium offers the opportunity for a respite to learn, think and look to the future, to gain new information and to have social interaction,” said Dr Elias. The keynote speaker for the symposium was Professor Tony Pizzi of the University of Nancy, France. This man has a long list of published works to his credit and enormous experience in the field of resins. He traced the recent history of resins used in panel production and outlined the problems associated with the cost and availability of urea and melamine as raw materials. He also looked at market trends and highlighted the increase in OSB production, the movement towards on-site production of resins at the larger panel manufacturing complexes, and the interchangeability of resins which means that the best resin at the best price at a particular point in time is the one selected. “It is no longer the case that melamine formaldehyde (MF) resins can do this and phenol formaldehyde (PF) resins can do that,” said Professor Pizzi. “We can now produce melamine urea formaldehyde (MUF) resins with better properties than PF resins.” Kicking off session one, Dr Les Groom of the USDA Forest Service reported on a five year project on the ‘relationships between wood quality, refiner pressure and resin distribution and their influence on MDF panel properties’. He concluded that the most important variable in the stiffness and strength of MDF is the pressure at which the fibre is refined, with optimal pressure for minimising fines and maximising fibre length being 8.1 and 7.7 bar, respectively. The maturity of the fibres also had an effect on final panel properties. The second paper in this session was presented by Steffen Tobisch of the Institute für Holztechnologie (IHD) in Dresden, Germany. His subject was ‘Influence of the fibre pulping conditions and the resin type on the weather resistance of MDF in exterior use’. He pointed out that over-capacity in MDF had resulted in the need for extension of the product range, such as in weather resistant board and HDF used in laminate flooring production. Again, higher pulping pressures, and the use of MUF resins, were found to give improved performance in terms of thickness swelling and weather resistance, although other factors such as energy requirement (for pulping), wood yield and bending strength need to be taken into account. ‘Interaction of wax and UF resin in MDF’ was the subject of Armin Thumm of Forest Research in New Zealand. Wax is necessary to enhance the water repellent properties of MDF fibre but, according to Mr Thumm, how wax and resin influence each other’s movement, and their interactions in the final panel, were unknown. Accordingly, he developed a method to visualise the wax and resin simultaneously by labelling and the use of confocal laser scanning microscopy and found evidence that wax may reduce the movement of resin into fibre walls. So far, MDF had taken centre stage at the symposium, but Ismail Aydin of Karadeniz Technical University in Turkey changed all that with his paper on ‘The effects of veneer drying temperature on wettability, surface roughness and some properties of plywood’. Beech, alder and spruce veneers were tested and beech was found to have the highest shear and bending strengths, while spruce gave the lowest values. Wettability and formaldehyde emissions also varied between species. Concluding the first session, Dr Mizi Fan reported on his work on a non-destructive system for stress determination for long-term creep loading of wood based panels. This was funded by the EU as part of a FAIR project investigating long term performance of panels in roof and floor construction. Samples of OSB, MDF, hardwood plywood, particleboard, hardboard and cement bonded particleboard were tested and it was found that the research team’s NDT testing procedures could accurately predict stress levels and helped minimise the variability between creep test results. Session two looked at new products and was opened by Ms Emma Thacker of furniture manufacturer Moores Furniture Group who said that particleboard, MDF and hardboard were the main panels used in cabinet furniture production. She said that the important characteristics for these raw materials are surface density, dimensional stability and suitability for surfacing and outlined some problems which her company had experienced. Ms Thacker said that a problem with grit or sand content of MFC panels was highlighted recently by increased tool wear, while in MFC and MDF boards, paper or pressing faults had occurred in melamine surfaces and colour matching to samples had also been an issue. Difficulties for her MFC suppliers relating to decor paper stocks had also caused problems. Future challenges for both Moores and its customers mainly concern delivery and mode of supply issues. Referring to the need to reduce both waste and stock levels, Ms Thacker said: “New manufacturing methods are under consideration and this may lead to a requirement for board manufacturers to provide bespoke board sizes rather than just full or half size sheets.” On the supply side, making suppliers responsible for controlling and monitoring Moores’ stock levels is also being considered. ‘The future of long strand reconstituted lumber’ was the title of the paper presented by Geoffrey Sanderson of Ausply Ltd, a plywood producer in ‘the other Wales’ – New South Wales, Australia. He began by tracing the history of reconstituted fibre products from Egyptian plywood in the days of the Pharaohs to the LVL and PSL products of the 80s and 90s. First developed in 1973 in Australia, a product called scrimber failed to achieve full production at that time. It was made from crushed thinnings, thus producing long intertwined fibres, which were pressed into billets for use as rafters, beams or joists. However, Mr Sanderson was able to report that Timtek in Australia has revived and greatly improved the manufacturing process and is building a new pilot line with the promise of success for scrimber, or ‘long fibre lumber’. He sees its strong advantage being the fact that it uses short rotation feed stock. The catastrophic fire seasons of 2000 and 2002 in the US formed the backdrop to the presentation by John Hunt of the USDA Forest Service. He pointed out that the removal of debris and forest undergrowth would reduce the fire risk and suggested that 3-D moulded engineered fibreboard could provide a useful outlet for such residues. The tests so far carried out by the USDA suggest that these products could be load-bearing, particularly where bending properties are important, said Mr Hunt. The next speaker, Dr Morwenna Spear, described her work in natural fibre reinforced polypropylene composites, assessing the potential of hemp and thermo-mechanically pulped (TMP) fibre to produce extruded sections for building products with limited structural requirements. Something for nothing, surely not? But yes, Dr Fred Kamke of Virginia Tech, US, was offering just that with his ‘web-based problem solving environment for wood based composite applications’. This freely available website offers a Problem Solving Environment (PSE) called WBCSim for dealing with wood based composite design and manufacture. As Dr Kamke pointed out, the increasingly complex technology involved in panel production today is often beyond the understanding of even the most experienced production operator, hence the need for this PSE. Simulation models currently available on WBCSim are for the rotary dryer, oriented strand mat, hot pressing, composite material analysis, and radio frequency pressing processes. To give one example, in the rotary dryer simulation (RDS), the user inputs the inlet conditions of the wet wood particles and hot gases, as well as the physical dimensions of the drum and lifting flanges, flow rates and thermal loss factor for his dryer. The RDS model then predicts the particle moisture content, temperature, gas composition and energy consumption of that dryer.Moving 3-D animations form part of the WBCSim service, which is under continual development and expansion to increase its sophistication and usefulness as a manufacturing tool, while remaining usable by anybody, without the need for specialist knowledge. The second day’s keynote address was given by Irvine Flett, a consultant formerly employed by UK panel maker Nexfor, who gave ‘A short history of oriented strand board’. The man credited with the invention of OSB’s predecessor, waferboard, was James D’Arcy Clark, who built a mill in Sandpoint Idaho in 1955. Mr Flett went on to look at improvements in binder and strand orientation systems over the years and considered the future improvements which could be made on both sides of the Atlantic. He also emphasised the importance of people to any manufacturing process. Session 3, Environmental and Process Control, started off with three presentations concerning recycled wood. The first was by Gareth Mayhead of The Mersey Forest concerning the resource and its utilisation in the UK with particular reference to the north west of England.A regular columnist in WBPI, Dr Mark Irle then offered a review of his ongoing report, ‘A sampling protocol for the determination of contaminant levels in wood raw materials for finished board products’. His research is funded by the Waste and Resources Action Programme (WRAP), with contributions in kind from Egger (UK), Kronospan (UK), Nexfor UK, Sonae Tafibra (UK), Spanboard Products Ltd and the Wood Panel Industries Federation of the UK (WPIF). The aim of this project, said Dr Irle, is “to provide manufacturers with the information they need to enable them to make particleboard with a high proportion of recycled wood and to assure customers that such panels are safe.” The need for an industry standard was recognised by the European Panel Federation (EPF) and its recommendations were incorporated in the WPIF’s code of practice on chain of custody. “That is very laudable but some of the limits in the standard are very low,” said Dr Irle, pointing out that one tiny sliver of copper in a panel could trigger a failure. The CLEAR project aims to develop a fair and practicable protocol for testing finished products and incoming recycled raw material. Turning surfaced MDF furniture components back into raw MDF panels is the objective of the Fibresolve Process, as outlined by Stephen Riddiough of TRADA Technology of the UK. Initial tests were carried out using a domestic pressure cooker and this led to the autoclave-based reactor which is at the heart of the Fibresolve Process. The inventors claim that it is possible to recover good quality wood fibre, free of the original coating material, from the autoclave and that small panels of “reasonably good quality MDF” can be made from it. Scaling-up of the process is currently under way. Lars-Erik Bergquist of Metso Panelboard described ‘On-line monitoring of fibre quality in the MDF process’. The system uses near infra-red spectroscopy at the forming head to analyse the fibre, in combination with multivariate analysis to predict final board quality. The fifth presentation in session 3 was by Dr Justin Marchant of Esmil Process Systems on wood pulp effluent treatment and recovery. Dr Marchant described Esmil system’s improvements since it was first presented at EPPS in 1998. The system uses modular design and systematic steps for refinement of the effluent which is always of varying content, even in the same MDF plant, he said. George Goroyias of the BioComposites Centre presented a paper co-authored by Earl McCarthy of McCarthy Products Co of Seattle, US on the assessment of fibre properties and optimisation of refining parameters in MDF manufacture. The QualScan, developed by McCarthy Products, uses image analysis to measure fibre geometry and to correlate fibre properties with refining stage process parameters. The objective is to produce better fibres and therefore better boards, and to optimise energy and resin consumption. Mat spraying prior to the hot press with its proprietary products has several claimed advantages for the finished board, according to Keith Godber of the Chemical Release Company Ltd. These include: increased vertical tensile strength; reduced water absorption; no blisters or blows; reduced press factor; reduction in sanding tolerances; higher fibre compression, reduced paint consumption; reduced formaldehyde content; and reduced overall board density while maintaining high surface density. Mr Godber reported on tests carried out on PAT-529/S and PAT-2529/JA3X on MDF and HDF to substantiate these claims. The next presentation was on the process control technology offered by ATR, a Siempelkamp subsidiary specialised in this field. It covered that company’s Statistical Process Optimisation and Control (SPOC), Production Line Maintenance (PLM) and Production Management and Control System (PROMACS). The aim of all these systems is to optimise technological, technical and organisational processes within a panel mill. There has been increasing emphasis on certification of panel products as being fit for purpose over the years and the new European CE marking for wood based panels used in construction is a good example of this. Certification and grade stamping of panels is the speciality of TECO and its executive vice president, Steve Winistorfer came from Madison, Wisconsin, to explain its role in the quality assurance of wood based structural-use panels in North America to the delegates. TECO has developed a range of four panel testing machines which can be used at the point of production rather than relying on after-the-event product sampling and testing. The final day of EPPS6 still had a strong attendance and was opened by a keynote speech by Dr Peter Bonfield of the UK’s Building Research Establishment on the subject of sustainability, with particular reference to the UK. He concluded: “The contribution that the forestry and wood products industry can make to sustainability has been recognised by the UK government and by the wood processing industries. The wood panels industry has produced a Sustainability Strategy … which addresses three main elements of sustainability which include economic, environmental and social aspects.” Session four was entitled ‘Resins’ and comprised two presentations. The first was by Professor Pizzi and addressed buffer upgrading of MUF panel adhesives at lower melamine content. He said that the buffer ‘hexamine sulphate’, as it is known, markedly improves the water, weather resistance and wet IB strength performance of hardened MUF resins. “You can take a cheap resin and add hexamine sulphate and bring it up to the performance of a more expensive resin, or you can reduce the melamine content to 40% of what you use today and keep the same performance, or leave the melamine content as it is and have better performance than you would get with phenolic resin,” said Professor Pizzi. Wolfgang Kantner of Dynea Austria had the unenviable task of being the last speaker of EPPS6. He spoke about the ‘Reactivity of amino resins for wood based panels’ and described the new resin system developed by his company which employs an accelerator to enhance the resin’s reactivity without exceeding the F/U molar ratio above the commercially acceptable value. The result, he said, was a UF system with significantly higher reactivity than that of commercially used resin materials.
