“Although the European industry in general has performed well of late, it is important to recognise that competition within the industry and from other materials is still strong and is likely to remain so for the foreseeable future,” said Dr Hague. “Accordingly, the industry still needs to continually strive to innovate and improve its production processes in order to provide improved product quality at lower cost.” The key words here are “innovate” and “improve production processes” and that is what many of the papers were about. While it may seem a long way from examining wood fibres under a microscope, or developing a new resin in the laboratory, to feeding the hunger of that gargantuan continuous press on the factory floor, science has played a major part in developing the panels of today and will do so in the future; ignore the significance of today’s research at your peril, because it may provide the competitive edge you need tomorrow. The EPPS venue this year was, for the first time, the North Wales Conference Centre in Llandudno, rather than being hotel based. It ran over two and a half days in October and contained 24 presentations in seven sessions: Product Properties; Fundamental properties; Adhesion; Raw Materials; Process Technologies; Economics/Life Cycle Analysis (LCA); and Non-Destructive Testing (NDT). Peter Bonfield of the UK’s Building Research Establishment (BRE) gave the keynote address on the future, asking: “What can the wood based panels industry learn from the synthetic composites industry?” He said that synthetic composites present a serious threat to the industry and suggested there was potential in examining the range of products and processing techniques used in the synthetic composites industry and adapting these to apply to wood based panels. Dr Bonfield said synthetic composites range from glass reinforced materials, such as those used in motor car production, to ultra-high performance carbon fibre reinforced composites for aircraft. Wood based panels on the other hand are essentially in five major material types: OSB, plywood, fibreboards, particleboard and cement bonded boards. “Laminated veneer lumber is a start and a good example of enhanced performance by fibre orientation,” said Dr Bonfield. Although it is always looking at costs, he said that the construction industry was also now looking more closely at overall value and speed of construction. He suggested the following areas as avenues to be further explored: orientation of wood fibres and strands; increased use of recycled wood; developing better binding systems including cold cure resins; chemical modification of the wood constituent; and exploiting the attributes of different types of wood constituents. “Technical, innovative work is required to examine the potential that exists for wood based composites and to initiate and carry out work that enables the materials to be developed,” he concluded. He also warned that the challenges presented by the development of composites must be addressed if the wood based composite sector wishes to enhance its market share and fight competition from other sectors. ‘The wettability of medium density fibreboards’ was the topic for Dr Marius Barbu of Vienna University, Austria. “Knowledge about the wettability of the surfaces of wood products has become more important because of recent needs to coat wood products with water based acrylic paint systems, powders or plastic overlays,” he said. His research tested the wettability, surface density and roughness of commercially produced MDF boards. He concluded that lower surface tension and good wettability have important advantages, while too rapid and intensive absorption may cause too large a quantity of lacquer to penetrate the surface. The requirement is for good surface wetting with limited absorption and surface swelling. Dr Barbu suggested possible ways to achieve this would be the use of wood mixtures containing more beech, better consolidation of face layers by spraying water onto the fibre mat, utilising special glues, or increasing the amount of adhesive used. Dr Vic Kearley of TRADA Technologies in the UK reported on exploiting shear properties “to facilitate the increased use of wood based panels in applications where they are intended to carry shear forces, by developing a better understanding of shear test methods and properties and how they relate to the behaviour of components and structures.” This was a collaborative project supported by the European Commission’s FAIR programme. Drafts of the recommended new methods of measuring the panel and planar shear properties have been sent to CEN TC112 WG4, together with suggested quality control procedures, in the belief that they will provide more reliable design data for shear properties and therefore more exploitation of them. Jonathan Alexander of US-based company Jeld-Wen reported on research into the effect of resin type on OSB durability using accelerated ageing techniques on panels bonded with pMDI, powdered PF and liquid PF resins. The initial ranking of mechanical properties was in the above order. After boil/dry cycling and vacuum pressure soaking (VPS), mechanical properties of all three types decreased, but pMDI panels had the higher performance after treatment, said Mr Alexander. Chuck Yu of the UK Building Research Establishment reported on tests on formaldehyde emissions from various types of MF impregnated paper-coated wood panel products for indoor applications. His team used the environmental chamber test, but also the real-life situation of a new office building at the BRE headquarters. OSB durability in use is a major factor in its increased acceptance in building applications, and George Goroyias and Dr Mike Hale reported on work carried out at the University of Wales on Tanalith 3485-treated strandboards. They treated boards at various stages in their manufacture and found that those made from strands treated before manufacture, by either diffusion or vacuum methods, gave the best performance. Vacuum treatment gave the best results and had no significant impact on the board’s mechanical properties. Session Two, Fundamental Properties, was kicked off by Dr Mark Irle of the Forest Products Research Centre, High Wycombe, UK, on ‘Cell wall collapse and the pressing of particleboards’. He pressed individual particles of 25mmx4.5mmx600micro-metres of Scots pine and lodgepole pine. Why? Because the information gained could be used to improve pressing cycles such that more stable panel products result. And CSC Forest Products felt it was important enough to provide funding for the research. Perhaps this is a classic case of ‘microscopic’ research having major implications for practice in the panel mill. On the basis that the mechanical properties of panels are strongly influenced by those of the components, Dr Les Groom of the USDA Forest Service has been working with the BioComposites Centre to investigate the effects of varying refiner pressure on the mechanical properties of loblolly pine fibres. They found that the refiner pressure does have a dramatic effect on the mechanical properties of both the fibre furnish and the MDF panel. Juvenility of the chip source is also important, with more mature fibres producing stiffer and stronger panels. Work is ongoing. Avril Egan from the University of Maine reported on ‘fracture and mechanics of fracture for resin coated single wood fibres’. The model produced will, it is claimed, enable “the prediction of how fibre/resin networks interact and influence gross wood composite properties”. Day two of the symposium began with session 3, Adhesion, and was opened by Manfred Dunky of Krems Chemie/Neste Resins/Dyno with a presentation on ‘Optimised bonding solutions for the new millennium’. Dr Dunky identified the main chemicals involved in resin production as formaldehyde, urea, melamine, phenol and resorcinol. He also identified the key issues in the development and production of glue resins as: shorter press times; amelioration of the hygroscopic behaviour of boards; cheaper and alternative raw materials; reduction of emissions during production and use of panels; and LCA, including re-use and recycling. Dr Dunky went on to illustrate how resins could contribute to addressing these issues now and in the future by different recipes, additives and cooking procedures for all the various panel types. The distribution of resin within a panel is a vital part of quality and cost control and Professor Fred Kamke of the Wood Based Composites Centre, Virginia Tech in the US suggested ways of visualising the resin in a panel in the factory. He pointed out that the distribution of liquid PF resin on OSB strands has already been shown to influence board properties. Colour video camera and macro lens, black and white video camera and fluorescent microscope, confocal laser scanning microscope, high resolution colour flat-bed scanners and an on-line video camera with fluorescence and a macro lens were all discussed as possible methods, together with their advantages and disadvantages – notably in terms of relative cost. Dr Kai Kruse of BFH, Hamburg, Germany, said that OSB is a young product with potential for improvement in terms of reduction of the press time factor, resins used and product diversification. Natural resins are a strong talking point these days and his paper was entitled ‘OSB glued with phenol and tannin resins’. It investigated the results of mixing quebracho tannins and phenol resins. Dr Kruse reported that OSB panels glued with tannins achieved OSB-3 quality for internal bond (IB) and wet IB but not for thickness swelling. Phenol glued OSB achieved OSB-4 quality for both parameters using press factors as low as 12sec/mm, while substitution of phenol by tannin enhanced IB and wet IB significantly and improved mattress moisture tolerance. It also resulted in slightly higher viscosity and significantly reduced gel time. Staying on the subject of OSB, the dark colour of phenolic resins can be a problem for producers and Ms Eleftheria Athanassiadou of ACM Wood Chemicals claimed to offer a solution with a ‘novel’ resin system for colourless OSB production. This is not an isocyanate resin but is a melamine-urea-phenol-formaldehyde (MUPF) resin with a hardener adapted to the specific needs of OSB, and ACM claims it can achieve OSB-4 requirements. Dr Chris Skinner of Huntsman Polyurethanes continued the OSB theme with a presentation on a ‘Novel fast-cure technology for the production of OSB with MDI based binders’. Dr Skinner said that the major use of pMDI is currently as a core resin in OSB. Phenolic resin is normally used in the faces because of release problems between press plate and panel when using pMDI adhesives. However, one way in which demands for higher speed production could be met is by using pMDI throughout the board.Dr Skinner said Huntsman has thus modified its isocyanate resin to produce a faster curing system called Suprasec 1482. He also claimed: “The combination of the fast curing resin technology with the internal release technology of Suprasec 1454 facilitates the production of panels at enhanced rates relative to standard pMDI, with excellent release performance.” The presenter of the next paper is destined to become even better-known to delegates as he takes over the helm of the BioComposites Centre from Jamie Hague who is taking up a new position in Australia. Dr Jeremy Tomkinson’s presentation was on ‘Organosolv lignin phenol formaldehyde resins as binders for particleboard’. The objective of the research was to investigate the potential for partially replacing phenol with organosolv lignin in a PF resin designed for use in particleboard production.It was found that boards bonded with up to 30% lignin content resins gave similar physical and mechanical properties to commercial PF resin, provided sufficient curing time and temperature were applied. Thus renewable resources such as lignin do have potential as a substitute for phenol in PF resin systems if a catalyst can be found to reduce press times. Raw materials were the subject matter for session 4 of the symposium and began with Professor Edmone Roffael of the Institute for Wood Biology and Wood Technology in Germany, comparing thermo-mechanical and chemo-thermo-mechanical pulps in MDF manufacture. An unusual presentation was given by Dr Joseph Tesha of the University of Dar-es-Salaam in Tanzania. He has been experimenting with production of particleboard from coffee husks using synthetic and natural resins and comparing it with conventional wood based boards and other non-wood based particleboards. The availability of synthetic resins in Tanzania is extremely poor so Dr Tesha wanted to minimise their use in his panels. From his research he concluded that coffee husks can be used to make particleboard using synthetic resins such as urea and phenol formaldehyde and natural resins such as hydrolysed tannin (tannin mixed with cashew nut shell liquid, a natural phenol based resin). In fact, the use of tannin as a binder with coffee husk resulted in panels with superior mechanical and physical properties compared with UF bonded panels, although properties were typically poorer than wood based boards. Tanzania produces around 4-6,000 tonnes of coffee beans annually and 20% of this is husks. The country also produces about 32 tonnes of tannin per day, 95% of which is currently exported for leather tanning. Kelvin Chapman of MDF-Tech Ltd, New Zealand discussed the importance of fibre moisture control in MDF manufacture. He was the first speaker to introduce the concept of ‘feed-forward’ control as opposed to ‘feed-back’ control. He likened the latter to a guided missile with continuous path adjustment as it travels towards its target; while feed-forward (also known as a neural network) would be an artillery shell or an unguided missile. The point of Mr Chapman’s presentation was that reducing fibre moisture variation is a valuable goal as such variation has a very significant effect on the operation of the press and that the delay inherent in measuring moisture content after the dryer is too long for effective control. “Feed-forward control offers the possibility of moving the dryer to a new operating condition as the change is coming from the refiner, and thus offers the possibility of reduced moisture variation,” he reported. Session 5 – and day two – began with a presentation by Thomas Olofsson of Valmet Fibre AB, Sweden, on ‘Revolutionary forming technology for the MDF industry’. He described the principle and operation of the new Valmet Uniformer. Advantages claimed included: no mat scalping required; width adjustment carried out within the former; a good structural integrity for the mat; and a forming accuracy of more than +/-2% in length and width. He claimed the new system reduces recirculated fibre flow and would also reduce operating costs and give high and consistent board quality compared to traditional vacuum and mechanical formers. Life Cycle Analysis was the second subject for Peter Bonfield of the BRE. His paper described the methods used to generate environmental profiles for UK production of particleboard, MDF and OSB and is seen to have wider implications for the international panel industry. “You will be asked for environmental impacts of your products,” warned Mr Bonfield. Arne Janssen of Hamburg University, Germany, presented a mathematical model for evaluating the production process under varying machinery configurations and cost structures and the cost sensitivity of changing parameters, such as the length of a continuous press, or raw material prices. The model is designed to assist managers and operational staff when making decisions for investments or identifying potential cost savings. The final session, on non-destructive testing (NDT), was opened by Professor R W Kessler of the University of Reutlingen, Germany. His process, now patented, involves the use of high level spectroscopic on-line control in the adaptive processing of wood for fibreboards. The concept of feed-back and feed-forward control was again a feature of this presentation, concerned mainly with wet process fibreboards for specific end-uses such as moulded car parts. The idea is that the use of a great variety of different raw materials and special processing steps offers the option to produce tailor-made boards. Having determined all the major parameters affecting board quality, Dr Kessler’s team developed new measuring systems to quantify and qualify raw material, with resulting information being fed into a knowledge-based process management system. The result, said Dr Kessler, is a practical system which can be used on the line to optimise production. The next speaker returned to the theme of OSB manufacture and presented a system to monitor the fibre orientation during production, using filtered image analysis (FIA). Dr Nishimura of the University of Bath pointed out that the strength of OSB in bending is related to fibre orientation of the strands. His aim was to enable monitoring and control of this orientation. He concluded that the FIA method works under production line conditions and that the information gained could be used to increase maximum MOE and MOR in the longitudinal direction of the board without overly reducing them in the cross-wise direction. It is never easy being the final speaker, but Hans Peter Kleinschmidt of Electronic Wood Systems (EWS) of Hameln, Germany gave an informative account of his equipment for quality control in LVL and panel production. His company has considerable experience in the manufacture of sophisticated on-line quality control equipment such as delamination/blister/blow detectors. The original method of detecting such defects, he said, was with a hammer and the human ear to detect hollows within the board – still common practice in many plywood mills. The brush method mechanised the same sound-based principle and the ultrasonic system, with results viewed on a screen, took things a stage further. However, external noise from saws, air nozzles and other production equipment could confuse these methods. Mr Kleinschmidt’s answer is his Ultrasonic Resonance Method which, he claimed, produces a 30-fold higher signal than conventional systems. He also claimed penetration of panels up to 40mm thick. The unit combines a thickness gauge and operates accurately even in ‘hostile’ production line environments, he said. The new venue for EPPS appears to have been a success, with a well-equipped lecture theatre offering problem-free sound and visual presentation in an air-conditioned atmosphere. A large ‘lounge’ also provided ample space for the event’s first trade show and the poster displays. Copies of the full proceedings of EPPS4 and EPPS3 are available now. Contact Sue Griffiths at the BioComposites Centre, University of Wales, Bangor, Gwynned LL57 2UW, UK, Fax: +44 (0) 1248 370594. Email: r.s.griffiths@bangor.ac.uk
