24 September 2004

4th European Wood-Based Panel Symposium

From the 15th to the 17th of September 2004 the fourth European Wood-based Panel Symposium took place at the Maritim Grand Hotel in Hanover.  The Symposium was a successful event jointly organised by the European Panel Federation (EPF) and the Fraunhofer Institute for Wood Research (WKI). Nearly 300 participants from 29 countries attended 27 technical presentations. Besides of course from Germany, there were important delegations from Austria, the Baltic States, Belgium, Finland, France, Italy, Japan, Poland, Sweden Switzerland and the United Kingdom as well as some participants from countries like Brazil, Canada, Malaysia, … A truly world-wide audience sharing information about Technological Developments, Testing and Simulation, New Products and Products Developments and finally some Ecological Challenges.

A welcome party opened the Symposium on Wednesday evening 15 September in the Hotel, organised by iVTH, EPF and Industrial Partners. On Thursday evening, all participants were invited to the SasolWax Evening Reception, which took place in the Cavallo event house, a former royal indoor riding school.

Mr Kris Wijnendaele, Secretary General of EPF officially opened the Conference on Thursday 16 September by welcoming all participants to Hanover.

The President of EPF, Mr Ladislaus Döry, opened the Symposium with an overview of the current challenges and opportunities for the European wood-based panel industry.  He outlined the main actions EPF have been undertaking this year and stressed the importance of wood as a sustainable product.  Mr. Döry also summarised the ambitious Roadmap 2010 project which encloses four major strategic processes: living with wood, building with wood, wood products in sustainable development and wood in transport and packaging.

During his closing speech, Prof. Dr. Rainer Marutzky, Managing Director of WKI, expressed his pleasure with the attendance. He thanked all participants, all speakers and all involved in the organisation of the Symposium. Finally, Prof. Marutzky announced the intention of EPF and WKI to organise the fifth edition of the European Wood-Based Panels Symposium in September 2006.

Opening session

Dr. Arne Janssen of Jaakko Pöyry Consulting presented a survey focused on European wood-based panel producers at the centre of the supply chain and included their key suppliers and customers. The survey focused on understanding the level of development of various supply chain management processes. The results of the survey provide an overview of the development of the European wood-based panels supply chain as well as more specific insights into panel producers operations.

Professor Frühwald of the university of Hamburg gave a clear presentation about future potential of wood composites in the building sector.  The driving forces behind wood as the material for the future are according to the professor sustainable wood supply, economic competitiveness, environmentally sound and ecological competitiveness and last but not least a good image of environmental excellence.  Sustainability is a very important matter because experts assume that there could be a regional shortage of wood in the future that might cause an increase of wood costs by 25%.

Technological Developments (part 1)

Ms Ulrika Backlund spoke about thin board forming at high-speed-level. Ms Backlund works for Metso Panelboard that introduced in 1998 an innovative technology to the market.  Compared with the, at that time, traditional vacuum formers and mechanical formers, the Uniformer made a great step in reducing the customers operating cost in the MDF production and at the same time keep a high and consistent board quality.  For the first time it was showed that fibre mats could be formed by rollers actively working in the mat.  The development on the thin board and flooring market has moved the focus in forming technology to the area of thin panels produced at high line speeds. To be able to study the actual phenomena’s occurring in the forming process, Metso Panelboard has invested in and built a full scale, 4-feet wide forming station at the Metso Fibre Technology centre in Sundsvall, Sweden.  With the goal to examine and develop every section of the forming process the full-scale forming pilot was designed to have flexibility, full visibility, variable speed and variable line speed.

Mr Volker Gotsman of Binos Technologies discussed the actual developments of press technology for thin fibreboards.  After a comparison of the production process in wet press process and the producing of MDF thin boards with roller presses, Mr Gotsman presented a general overview of the construction development of roller presses.  Then a detailed demonstration of the spike-roll-system followed.  Particularly interesting was the final lecture about dry glue bending for MDF and its advantages.

New trends and developments in OSB technology where put on the agenda by Mr Günter Natus of Dieffenbacher. Mr Natus pointed out that more advanced structural strand products appear on the market and technology and equipment are nowadays ready for application. The speaker was also convinced that the new equipment helps to improve OSB production.

How to optimise natural gas use in the wood-based industry was a topic nicely presented by Mr Udo Jürgens from natGas. The production processes involved in manufacturing chipboard require large amounts of energy. Heating oil, natural gas and electricity are expensive, however. Mr Jürgens gave a possible option to optimise the generation of process heat.

Technological Developments (part 2)

In the afternoon Mr Marco Krüzner of Siempelkamp informed about innovative dry gluing technologies for MDF. The conventional process of injecting glue onto MDF fibres in the so-called blowline, which is located just after the blow valve, has some disadvantages.  Besides the high resin consumption, it has long press curing times , formaldehyde contamination and extremely large exhaust air volumes from the dryer. In order to solve these problems a number of MDF plants have been equipped with glue blenders. Because this method did not solve all the problems, Siempelkamp developed a system which avoids the formation of glue spots after the fibres are treated with the resin.

In addition to the former speaker Mr Detlef Krug of the Institute of Wood Technology Dresden (ihd) presented some results of a joint research work between the Institute of Wood Biology and Wood Technology of the University of Göttingen, the Fraunhofer Institute of Wood Research (WKI) and ihd. MDF produced using the blender method are of higher internal bond strength and lower thickness swelling values compared to those made by the blowline technique. However, MDF made out of pine and beech wood fibres using the blowline method seems to have better dimensional stability at different climatic conditions. A direct comparison of different types of MDF made from beech and pine wood revealed that, generally, boards made from pine are dimensionally more stable. The overall results indicate that there is no clear-cut correlation between the physic-mechanical properties of the boards on the one hand and their long-term performance on the other hand.

The question: Is sawdust an attractive raw material source for the MDF-process? was raised by Mr Clemens Seidl of Andritz. The use of sawdust and other small wood residues becomes more and more important for MDF plants.  System adjustments and capital investment are required when more than 15% sawdust or fine residues need to be processed. Andritz recommends that future installations and refurbishments should be designed with future sawdust use in mind.

Mr Robert Loth of Maier Zerkleinerungstechnik informed the participants about high-speed flaking. The introduction of recycling wood to the particleboard factories increased the use of hammer mills to withstand excessive wear caused by impurities of recycling wood. The increasing wear costs, the influences on board quality during further processing and the higher wood and glue consumption often equalise the advantage of the reduced purchasing costs of the recycling wood. The development of a new knife ring flaker parallel to the better screening and cleaning systems has enabled the factories to use the knife ring flaker again. The new designed knife ring and the different applicable flaking speeds reduce the costs for flaking and with the produced flakes the board properties increase. Especially the high speed flaking offers a possibility to produce surface layer material at a lower cost. The separation of non-ferrous metallic parts and impurities from the flakes increases the lifetime during the board processing. The non-ferrous metal detector is not so often activated. That means an increase of capacity and quality. Thinner flakes are advantageous for the drying process. They bring more capacity, more regular final moisture and less refuses caused by damaged board surfaces. Thinner flakes can reduce the wood and glue consumption. Higher bending stress, internal bond as well as a higher screw holding forces are the result of a comparison with a standard board.

Testing and Simulation

Mr François Ravasse representing the French EPF member association UIPP discussed the characterisation of floor decking and more in particular the tests under concentrated point load in relation with EN 1195. Tests on 65 structural floor deckings from particleboards, OSB, MDF and plywood have been carried out at the French Technical Insitute for Wood and Furniture (CTBA) with the aim to confirm the results by tests against the span indicated for well known products included in Code of practice (DTU) and to validate new products. They concluded that there is 10% more deflection when putting the load mandrels on the Tongue&Groove joint than when putting it in the centre of the panel. Furthermore, the tests revealed that the square mandrel (50 x 50 mm applying a load of 1300 N) for tests according to the Eurocode (ENV 1991-2-1) results in a 25-50% higher ultimate load of rupture than with the round mandrel (25 x 25 mm) specified in EN 1995 (applying 2000 N). Mr Jean Marie Gaillard of CTBA complemented the presentation by showing interesting surface effects as a result of the loads in the area of placing the mandrels.

Status and future prospects of the on-line measurement technology for the wood-based panel industry was summarised by Messrs Ernst and Kai Greten of GreCon. The past ten years the presses built became longer and longer allowing production capacity to be increased further. Despite of these large innovations measuring technology with regard to optimal and less cost-intensive production is most often insufficiently used. From todays point of view many measuring systems unfortunately have shortcomings. GreCon has made it its task to change this situation. In order to do so, the company offers a measuring system with 100% reliability for operators to trust it. Cost savings are achieved by optimised operating modes.

Dr. Heiko Thömen from the University of Hamburg presented the virtual hot press, which is a simulation platform for process optimisation and training. Dr. Thömen presented the Virtual Hot Press as a software tool to simulate the hot pressing process of wood-based composites. Recent developments were presented, including new experimental techniques to determine material property input data, and a module to simulate the internal bond strength development of the panel. A new user-friendly interface makes the Virtual Hot Press an efficient tool for product development and process optimisation, as well as for research and training purposes.

Dr. Darius Gailius from the Kaunas University of Technology presented an ultrasonic method of hardboard testing.  Ultrasonic strength measurement method may be used for an effective hard board strength testing and in assessing its distribution in a panel.  Although the main investigation was carried out on the basis of hardboard, this ultrasonic method may be applied also to other panels. This was proven by initial experiments with wood particleboard.

New Products and Product Developments

The second day of the symposium started with a presentation by professor Andreas Michanickl (University of Applied Sciences, Rosenheim) about light wood-based panels. Since about two years lightwood based panels and other lightweight wooden composites are in the focus of discussions. Especially sandwich constructions with paper based honeycomb core layer have found big attraction as they are produced for the first time in big quantities for the furniture industry. Nevertheless there is a wide range of lightweight materials manufactured totally or partly from wood or wooden products. The field of applications ranges from interior fitments for aircrafts, yachts, ocean liners, public and private houses to mass and high-end furniture. The technical properties of the used materials are very different. There are still a lot of challenges to improve the existing materials and their production techniques. Light wood-based materials will not replace the classical wood based panels in their major application areas. They widen the scope of materials available for the production of furniture, interior fitments and houses. The amount of panel types produced will continue to increase, although many of them could disappear very soon. Prof. Michanickl was of the opinion that only some materials have the potential for a production on industrial scale or to be used in niche markets.

A very lively speech was given by Dr. Michael Müller of Glunz about coloured MDF.  Until the year 1998 dye for MDF products has only been used for marking purposes. Red was used for marking fire-retardant MDF whereas green dye marked moisture-resistant MDF products. At Glunz the development of dye as a design feature for MDF began in late 1998 with black-dyed MDF as a response to a customer request. The customer intended to manufacture veneered desktops leaving the black core as a visible and decorative element. Since that starting point, improvements in the pigments and the bonding enabled Glunz to introduce in 2003 a whole range of colours for MDF.  Design MDF is still a niche product. With additional colours such as white and light grey, as well as additional properties such as improved conductivity, new markets could be conquered. Design MDF will help to promote MDF as a wood-based panel with unlimited possibilities.

Wood-polymer-composites (WPC) was an interesting topic outlined by Prof. Volker Thole of WKI. WPC is a new type of wood-based material in Europe, consisting of thermoplastic material and wood chips and/or wood fibres. The combination of a thermoplastic plastic with wood particles is offering new processing methods and new utilisation opportunities for materials on the basis of wood. The plastic characteristics of a heated wood polymer enables the production of formed semi-finished materials, of structural part rods and flat pressed structural parts. The possible use of WPC results from the components characteristics, the manufacturing costs; the different manufacturing methods and the very variable shaping.

How to coat wood fibres and particles with plastics, was explained by Mr Hans Dieter Hullmann of Lödige Process Technology. In his opinion there are a lot of advantages to coat wood with plastics. Firstly it is possible to make very complex profiles.  Secondly one is able to do it in only one operation with no material loss. Thirdly it is not necessary to do subsequent profile work.  Furthermore there is a reduction of heaviness. Besides all these advantages, there are also some new characteristics added to the coated product: non-decomposable, protected against insect attack and fungal decay, applicable for ground contact and water contact. Mr Hullmann estimated the market potential for wood based composites to be 25,000 tons per year.

A rather complicated but interesting topic about rheological and mechanical characterisation of extrudable wood/melamine resin composites was discussed by Dr. Uwe Müller (Kompetenzzentrum Holz). Highly filled wood/melamine resin compounds show a very complex processing behaviour. High-pressure capillary rheometry with slit dies is proven to be a suitable method to characterise rheological behaviour of highly filled wood/melamine resin compounds. The combination of the special melamine resin, polymer additives and slipping agents gave promising results in terms of processing behaviour in the extrusion step of wood/melamine resin composites. The obtained viscosity shear rate behaviour is similar to wood/polypropylene composite. Moreover, this study investigated also composition processing properties relationships of wood/melamine resin composites. Dr. Müller and his team found, that especially the addition of thermoplastic processing aids leads to negative effects on the mechanical properties. Determining factors for the material properties are the optimisation of the cross-linking temperature and processing time. A too low degree of cross-linking as well as over-hardening of the material leads to material failure.

Dr. Wolfgang Kantner of Dynea Austria presented resol-emulsions as adhesives for wood-based panels. Resol emulsions are light coloured phenolic adhesives. After curing such resins give a light colour, both in a glue line or on the surface layer of a particleboard or OSB. The light colour is caused by neutralization in the resol. Thus, the emulsification process offers apart of the neutral colour also a non-caustic resin. However, resol-emulsions suffer from drawbacks like reduced reactivity and low boiling strength. Addition of small amounts of pMDI is able to overcome these deficits. Dynea Austria are continuing their efforts to solve these problems as pMDI addition is not always feasible or cost efficient.

Prof. Edmone Roffael (Göttingen University) presented the advances in sizing of wood-based panels. The chemical composition of waxes used as a hydrophobing agent in wood-based panels exerts a significant influence on their sizing potential. Linear chain hydrocarbons (n-paraffins) increase in effectiveness with increasing molecular weight. Moreover, the sizing potential of linear chain paraffins (n-paraffins) is, in general, higher than that of iso-paraffins with equivalent chain length. Mainly linear chain high molecular weight paraffins of high melting point are formed by the Fischer-Tropsch-Synthesis (FT-waxes). This process is used in some countries for the production of liquid fuels, lubricants, waxes and other hydrocarbon based chemicals. Due to the use of coals or natural gas as an alternative source to crude oil for the production of petrochemicals the Fischer-Tropsch-Technology became more and more important in recent years. The use of FT-waxes as a component in different formulations increases the sizing potential of paraffin substances as dispersion and in the molten state. FT-waxes have, when added in optimised amounts, no negative effect on the strength properties of wood-based panels. Moreover, they decrease the volatility of waxes, a desired property in technical processes.

Ecological Challenges

Professor Marutzky of WKI opened the section on Environmental challenges by explaining the VOC (Volatile Organic Compounds) regulations for wood products in Europe and in other regions. Wood-based panels are important materials for the manufacture of buildings, furniture and other products. Particularly challenging for the wood-based industries are the trials of different European states to regulate the emissions of building products. There has been much progress in reduction of formaldehyde emissions of wood-based panels and other wood products during recent years. The average formaldehyde release of most panel products has been reduced by a factor of more than 30. The release of natural volatile organic compounds from building products concerns especially wood-based panels and other wood products made from softwoods. The undifferentiated incorporation of natural volatile organic compounds, ingredients of all wood species, as regulated substances into horizontal standards for construction materials would become a threat for softwood-based products. The implementation of fair regulations taking into consideration the natural origin and composition of wood is a question needing the full commitment of the forest and wood chain.

Mr Christophe Yrieix (CTBA) spoke about a French study on the determination of VOC emissions from wood products.  In order to improve indoor air quality it appears to have analytical protocol for the measurement and evaluation of building product emissions. In this context, the CTBA (French Wood Technical Centre) and the CSTB (French Building Technical Centre), set up and tested a methodology to characterize emissions of Volatile Organic Compounds from wood building materials. This methodological tool called ‘Bench of Quality’, consists to measure VOC emissions from building products with laboratory emission test chamber method (Draft European Standard prEN 13419), which is however still under development. In all, 15 wood building products were tested: solid wood, wood-based panels (particleboards, melamine faced chipboards, unsanded and painted plywood), glulam, laminate flooring. Results showed that prEN 13419 could be applied to solid wood products. CTBA is now developing this method further with French wood manufacturers could be able to determine VOC emissions from their products with a view to comparing them with other building products.

Dr. Kohta Miyamoto of the Forestry and Forest Products Research Institute in Japan presented some measurements of aldehydes and VOC emissions from various wood-based materials.  Volatile organic compounds emissions from various wood-based materials such as particleboard, medium density fiberboard (MDF), flooring, glued-laminated timber, plywood and solid wood, were measured by the small chamber method (20L) of Japanese Industrial Standard (JIS A 1901) (at 28 degree centigrade, 50% relative humidity and 0.5 times/hour ventilation). Formaldehyde emission from most of the wood-based materials used in this study gradually decreased to close the limit of quantitation (2µg/m2 h) after 21 days in the chamber. However, formaldehyde emissons form particleboard and MDF were found not to decrease in long time, but if the absorbed coefficients of the materials are included in the calculation of the emission factor, the real emission factors of particleboard and MDF can be estimated at a much smaller factor than the values measured. In addition, hexanal was detected particularly as a predominant VOC in the particleboard samples. Remarkable amounts of acetaldehyde and phenol were detected in a glued-laminated timber bonded with resorcinol adhesives although the origins of acetaldehyde are unclear. Some organic solvents contained in the top coating paint obviously affected the VOCs emission from complex flooring and overlay plywood. In several domestic and imported solid wood species natural VOC emissions were also measured. Both the variety and amount of VOCs depend on the wood species.

Finally, Mr Sandro Ciroi of the Italian institute CATAS presented the results of comparative formaldehyde emissions testing with European and Japanese methods. The tests were carried out in co-operation with WKI. The researchers found that the Japanese methods correlates quite well with the European emission test methods. This correlation could be enhanced if the influence of the density is taken into consideration.

Source: holz.net vom 2004-09-24.

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