A New, Lightweight OSB-type Board

I-PAN stands for Innovative Poplar Low Density Structural Panel. It is the result of a three-year project co-financed by the European 7th Framework Programme of Research and Development. The programme aims at providing new and highly environmental-friendly solutions in the field of engineered wood based boards. A consortium of eight partners, from four different EU countries (Germany, Greece, Italy and Spain) was involved.

IMAL was the project co-ordinator; Italian company IBL, which specialises in poplar products and cultivation, was a partner; the resin specialists Chimar Hellas, the European Centre for Soft Computing, and the University of Milan were all involved.

The aim of the project was to design a breakthrough wood based panel, light in weight, using recycled material for about 50% of its volume and fresh poplar wood for the remaining 50%.

To manufacture it a novel process has been designed. Innovation has been applied to existing resins to use less energy during the drying and pressing process, minimising VOC emission and reducing the overall cost of production. The economic and environmental benefts of I-PAN can thus be considerable, says Imal.

Wood is one of the most valuable resources for humans and it has been an important construction material throughout human history. The scientific and industrial revolution delivered an engineered wood sector that is now substantially advanced, both in terms of higher quality wood based materials and in terms of production and manufacturing. Panels and plywood represent about 12% of total volume of timber use worldwide.

The woodworking industry in Europe consists of more than 100,000 companies employing between them about two million people and accounting for nearly 2% of value-added manufacturing. Ten years ago EU15 production totalled 45.6million m3.

Wood based panels therefore have a significant role in the economy; the I-PAN project, aimed at providing new and highly environmentally-friendly solutions in this field, may therefore have considerable impact.

The most important heavy engineered wood based panel in the market is the Oriented Strand Board (OSB), which in the last decades has replaced plywood in many sectors that use structural panels.

Some say that OSB has become the fundamental reference panel worldwide. Whenever lightness does not represent a critical advantage, OSB panels represent the material of choice, with well-regarded properties.

The main challenge for today’s panel industry is to engineer traditional wood based panels so that they can reach the higher functional characteristics (of strength, stability, durability, etc) of OSB, but at lighter weight.

The creation of a Lightweight Strand Board (LSB) calls for innovation in OSB manufacturing processes. It also calls for continuously increasing the efforts to manage and use valuable resources in a sustainable manner throughout the entire life-cycle of the product. Recovery and recycling of wood residues also forms an integral part of the eco-efficient utilisation of resources.

This was the thinking behind the I-PAN project: to boost the use of traditional wood based panels by engineering their properties to match lightweight application requirements. Manufacturing cost along the overall process should be reduced; at the same time a highly sustainable approach is required. The virtuous circle allowing a sustainable manufacturing process will range from a reduction of raw material process input to the use of re-cycled material and minimisation of waste, along with innovative technologies enabling savings in energy consumption and reduction of pollutant compound emissions.

The core research activities of the project focused on three areas of innovation. Each of them impacts on specific steps of the traditional OSB manufacturing process in order to reengineer them, with the main purpose of introducing innovative and greener technologies and final product subcomponents.

Resins, strand drying, handling and metering, blending and mat forming are some of the areas that were addressed. One aim was to use less energy during the drying and pressing process and to produce fewer volatile organic compound (VOC) emissions.

The main basic component of the final LSB were the slim strands of poplar. Poplar is plantation-grown in Italy, meaning that the source material is sustainable and that energy costs in transporting it to Italian-based manufacturers are low.

The characteristics required to be achieved from the poplar strands, after the initial steps of processing, were defined by IMAL and IBL by considering the particular properties of the selected poplar wood. That allowed them to define the characteristics of the drying plant innovations that needed to be developed.

An advanced blender system was also introduced, with the aim of respecting the structural properties of the slim strands and of achieving important savings in resin consumption through more effective and efficient distribution of resin over the surface of the strands.

Some of the strategic and technical aspects of the project are summarised below. With the state of the art as the starting point, the team proceeded with:

• Analysing and experimenting with new solutions to improve flake production by varying flaker knife angle;
• Improving the blending process: the experimental introduction of a high pressure resination system reduced resin consumption;
• Analysis of the layout and mat forming equipment to prevent flake break-up and to consequently produce a mat with the flakes remaining as integral as possible. Theoretical dimensions are 20-40mm wide, 80-100mm long and less than 0.5mm thick.
• Planning the implementation of an optical system at various points of the plant to continually monitor flake size and related shift, without flake breakage.
• Planning also specific algorithms to make an approximate calculation of the surface area passing through the process; this was then correlated to the concept of weight of material per unit weight of resin applied. Furthermore, by analysing flake break-up when the mat is being formed, it is possible to intervene in flake orientation, laying the flakes perpendicularly in the various layers to obtain technical characteristics with the same thickness.

The advanced solutions of the I-PAN project demonstrate considerable environmental benefits. They include:

• Reducing the pressure on forests from which the raw materials are derived. It optimises the use of selected poplar plantations to allow a seven- to eight year poplar growth cycle;
• Reducing the quantity of wood going into the overall process, thanks to using recycled wood for 50% of its volume, plus the upper parts of poplar trees, which are commonly under-used, for the remaining 50%;
• Reducing waste and consumption throughout the entire manufacturing process, starting from an optimal use of raw material (such as including the upper parts of the tree) through to the several steps needed for wood treatment and final product release;
• Reducing the quantity and presence of hazardous and volatile chemicals by developing a new formaldehyde-based resin;
• Reducing the carbon footprint b y innovation in the production process and decreasing the number of felled trees.
• Enhancing EU competitiveness in the eco-friendly global market.

These general objectives have been achieved through following specific goals. Saving energy in key production steps, to give a consistent reduction of CO2 emissions, was one of those goals.

Research on suitable existing glues t o be employed in the manufacturing phase, in order to reduce the use of harmful solvents and contaminants, was another.

Recycling about 50% of the wood without wastage was a third goal, in order greatly to reduce the pressure on primary raw materials.

The technology developed in the IPAN project has been replicated in six other production sites around the world. Results in these have equalled those obtained in the pilot line.

The project can therefore be claimed a success; it has produced a new type of panel, light in weight and environmentally friendly.

The team concluded that LSB poplar panel can be a credible substitute for existing products in both economic and environmental terms.