The annual April ‘Pullman Symposium’ drew 200 panel people from 11 countries to Washington State University in early April.Where once particleboard ruled the event, this year’s session centred on the wood-plastic combinations that are drawing so much interest. Powder surface coatings and integral panel colouring also drew attention as well as air quality control.
WSU’s Bob Tichy and Vikram Yadama co-chaired the 39th annual session.
Michael Ainsworth, executive vice president of Canada’s Ainsworth Lumber Co Ltd, Vancouver, BC was keynote speaker. His company started a switch to OSB some years ago and is now North America’s fourth largest producer, with mills in BC, Alberta and Ontario in Canada, and Minnesota in the US.
Mr Ainsworth told attendees: “Market forces shape where we go as an industry.We have been running at capacity for the last several years with a tremendous growth in the US market.”
He said construction remains the largest market for panels, continuing: “The boom has subsided, but it [the market] is still solid. Pricing has been very strong for the past seven quarters.”
Mr Ainsworth said plywood imports continue to increase. Agreeing with most industry sages, he said: “China is the wild card.” Looking ahead, he said 2007 will be a “very great year” for additional capacity.
He judged two OSB industry thorns as higher resin and transportation costs. He said these are products of sky-rocketing oil prices and railroads failing to invest in new equipment.
On resin, he predicted changes in PF resins with the move towards thicker panels and the trend towards continuous pressing.
He asked rhetorically: “Will OSB finally evolve into oriented strand lumber?”
Maximum achievable control technology (MACT), is absorbing much US time and resources in panel industry pollution control and enforcement will begin next year.
Dave Smith, Evergreen Engineering Inc, Eugene, Oregon said the main focus is on dryers and presses. The regulations allow for a ‘low risk’ listing for mills already passing the mandated control standards. He estimated some 200 plants would be in this class with 30 to 50 of them finally certified.
Gary Heroux, Composite Panel Association, Gaithersburg, Maryland, commented on indoor air quality in relation to composite panels. He declared that the industry has reduced formaldehyde emissions from panels by more than 80% over the past 20 years.
Mr Heroux said most consumer products made with composite panels are not used in raw form, but have some type of surface finish over the substrate acting as a barrier to off-gassing, thus reducing emissions.
The conference next turned its attention to recycling. ‘Green’ mills based on recycled wood have had varying success. However there is apparently a growing market from some who want to make an environmental point.
Reinhard Kessing, Keskon Engineering, Miami, Florida, described GreenTech Panels in Minden, Louisiana, as the first North American particleboard plant to operate successfully with 100% recycled post-consumer waste wood. Annual input is 35,000 tons.
The mill uses pallets, crates, cable reels, construction and industrial wood. One of the keys is compaction of the residues, such as pallets and reels, to allow more material per truck load and consequent lower raw material transportation costs. Pallets come from within a 150-mile radius. Another key is a stringent cleaning process with nine points where debris and metal are removed from the raw material.
Keskon designed and engineered the plant. Crushing, cleaning, metal and debris removal were by Pal srl of Italy. Drying, conveying, blending and pressing with continuous Berndorf bands and sanding were by Modul Systeme of Germany.
Drying is fairly conventional except for two more wind sifters after drying – one for core and the other for surface. The objective is to remove the last bit of ash and other contaminants from the furnish.
Drying costs are lower because the wood is generally at or below 20% moisture content. However, the material requires about 1% higher resin content.
Inge Larsson, Metso Panelboard, and Steve Bruntlett Jr, Masonite International, Laurel, Mississippi, described a steam cleaning system used by Masonite for removing VOCs before the dryer.
Their solution was to separate the dirty steam coming from the refiner, together with most of the volatiles from fibre processing. The dirty steam is condensed and treated in a conventional water treatment plant. The fibres are then conveyed from the steam separator, helped by fresh steam to allow for conventional blow line blending in a secondary blow line ahead of the dryer. Dryer emissions are mainly volatiles from the resin added in the blow line and are managed by control devices such as RTOs.
Rolf Hagner and Cole Martin of Dieffenbacher outlined the growing market for high precision in-register embossing in producing finished composite panels used in such products as laminate flooring and furniture components. Patterns and surface structures are matched to bring authenticity to appearance and touch.
Fred Kurpiel, president of Imeas, Peachtree, Georgia, substituted for Michele Pagnoni, Pagnoni Impianti of Monza, Italy, in describing the growing switch to continuous pressing for surface laminating.
Pagnoni has eight Easylam presses in Europe, handling glued overlaid veneer and laminates bonded to veneer-based and composite panel substrates.
The system can use low pressures and temperatures. It feeds flooring at up to 30m/min. No heat passes through the thickness of the material. A separate hardener provides for the necessary heat to support glue line curing.
Hartmut Pallmann, of Pallmann Maschinenfabrik, Germany, outlined his new double-belt system for bonding natural fibres, plastics and additives in which computer-controlled gravity feeding requires bins and hoppers able to work reliably with sticky materials and bridging in the line. A Palltruder applies friction heat and high pressure to the raw materials. The pressure forces the plastic into the natural fibre bundles, encapsulating the individual fibres and forming a free-flowing agglomerate.
Steam released from the fibres is handled by a vacuum exhaust system.
Professor Mike Wolcott,Washington State University Wood Materials and Engineering Laboratory, then outlined the state of the wood-plastic composite industry, citing Trek decking as probably the best known of the genre in the US.
One particular advantage, he noted, is the ability to do shape and form. Door and window components are typically extruded. Polymer applications go more into durable applications such as house siding.
Dr Wolcott said a new generation of composites is coming about with woodplastic merging into vinyl polymer.
Raw material is largely wood flours in the 20 to 60-mesh range in North America. Pine, oak, and maple are the main species.
Costs of many of these products are higher than wood, but they have real advantages, according to Dr Wolcott. Life cycles are better than pressure treated wood and colour  stability is better; he said consumers demand a high level of colour stability.
Karl Englund, research associate, Washington State University Wood Materials and Engineering Laboratory, explained: “The wood cavities and cells are filled with plastic. You can determine success by checking density.”
He broke down production into raw material preparation, getting it into extrudable form, blending, incorporating plastic into the wood, profile extrusion, cooling, cutting to size and surfacing, if desired.
Changing the subject to press protection and quality control matters, Kai Greten, technical director of GreCon Inc, Tigard, Oregon, described his company’s SuperScan and Dieffensor systems.
Dieffensor is x-ray inspection of the mat between the pre-press and hot press. It detects foreign bodies or high density spots in the mat which might damage the steel belts of the press. It also provides continuous measurement of weight per unit area for rapid response.
SuperScan is an optical inspection of panel surfaces in print, paint, paper lamination and melamine. It is located where the operator can make immediate adjustments in response to the optical inspection.