Particleboard

The expanding economy of the 1960s, the increasing availability of suitable raw material and the high acceptability of the product led to more new plants and a very high annual growth rate, some of it at the expense of hardboard and plywood. In the 1970s this tapered off as building industry activity slackened but new plants continued to be built, so that by 1978 capacity utilization was down to about 60 per cent. Currently there are 14 plants in operation, the last two to be built -Softwood Holdings Ltd. at Portland, Vic. and Westralian Forest Industries Ltd. at Bunbury, WA -being large by world standards.

The industry has been innovative in raw material, process and product, principally by adapting overseas developments to local conditions. It has made extensive use of sawmill residues, which now amount to over 50 per cent of its raw material. While multi-daylight pressing has been normal practice, single-daylight pressing, with the sheet carried on an endless belt, was introduced by Softwood Holdings at a new plant in Mt. Gambier in 1981 to make sheets up to 20 m long.

Wood-veneered particleboard was first introduced in 1961, by Westralian Forest Industries. In the early 1970s particleboard surfaced with plastic laminates was introduced and in the mid-1970s, after much joint development with resin suppliers and CSIRO Division of Building Research, a flooring grade was developed using water-resistant phenol- or tannin-formaldehyde resin. This led to other potential structural applications which were explored by the industry with help from the Wood Technology Division of the NSW Forestry Commission and the Capricornia Institute of Advanced Education.

Oriented strand board (OSB), a particleboard variant in which somewhat elongated particles are used and oriented to increase longitudinal strength, has very recently been introduced by Pyneboard at their Tumut, NSW plant. The process has been in use overseas for some years where it competes with structural plywood.

The particleboard industry has become an important factor in the overall economics of softwood plantation forestry because of its use of thinnings, tops and sawmill residues. It has also reduced the demand for solid wood and plywood, although its expected market penetration in flooring and general structure use does not yet appear to have been achieved.

Scrimber

Apart from the methods already described there are other ways in which wood can be sub-divided before being reconstituted. In a recent Australian innovation -Scrimber -small logs (e.g. radiata pine thinnings) are crushed between rollers to form long inter-connected strands, dried and then reconstituted as long sections after addition of a binding resin and hot pressing. This process, invented by Coleman in CSIRO[81] and developed in conjunction with Repco Corporation Ltd., is currently being established on a commercial scale by the South Australian Timber Corporation.[82] It has the potential to produce strong, large cross-section beams to meet a need at present met largely by imports and to provide a valuable outlet for both pine and eucalypt thinnings.

Australian Academy of Technological Sciences and Engineering