Fiberboard(redirected from fibreboard)
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a wood construction material prepared by crushing and splitting wood pulp or other vegetable raw materials to give a fibrous mass, which is processed by casting, pressing, and drying. The following varieties of fiber-board are distinguished: superhard, rigid, and semirigid, as well as insulation-finishing and insulation. The production of fiberboard is developing rapidly because of the abundance and low cost of the basic raw material: nonworkable wood (firewood), wood-processing wastes, waste paper, cane stalks, and agricultural waste (straw and bagasse). Additives such as hydrophobizing materials (paraffin or rosin), materials that increase strength (synthetic resins), and antiseptics are introduced into fiberboard to improve its service characteristics.
Two methods exist for the production of fiberboard: the wet method, without the addition of binders, and the dry method, which requires the introduction of 4-8 percent synthetic resin into the finely divided wood pulp. The dry method involves partial drying of the fibrous mass before molding.
Three methods for the preparation of the fibrous mass are being used: thermomechanical, in which pulp grinders and refiners are used; mechanical, in which the wood is pulverized in pulp grinders; and chemical-mechanical, in which the raw material is boiled in alkaline solutions before milling. Various emulsions (paraffin, resin, and oil) and mordants (aluminum sulfate) are added to the fibrous mass to increase its water resistance. The board is molded in casting machines. The moisture content of the cast board is as high as 70 percent; therefore, insulation board is dried, but rigid and intermediate fiberboard is pressed in hot multiplaten presses (at temperatures of 135°-180°C). The rigid and superhard fiberboard is then “quenched” at temperatures of 150°-170°C, with subsequent moistening to 5-7 percent (by weight). The superhard types have a density of not less than 950 kg/m3; the rigid types, not less than 850 kg/m3; the intermediate types, not less than 400 kg/m3; the insulation-finishing types, 250-350 kg/m3; and the insulation types, up to 250 kg/m3. The dimensions of the boards (in mm) are: length, 1,200-3,600; width, 1,000-1,800; and thickness, 3-8.
Composition board, which consists of combinations of several varieties of board (for example, ultraporous fiber-board with a density of 65-80 kg/m3 faced with rigid fiber-board), is produced abroad. Fiberboard may be finished on one side with finely ground wood pulp containing a filler and a dye, plastic paper, or polymeric films. The cross-breaking strength of superhard and rigid fiberboard is about 50 meganewtons per sq m (500 kilograms-force per sq cm).
Fiberboard is used in home and industrial construction for heat and sound insulation of roofs, walls, and the dividers between floors, and for the finishing of rooms. It is used especially frequently in the construction of low-rise housing, in agricultural construction, and in standard housing construction, as well as in the production of furniture and packaging. The production of fiberboard is one of the promising methods for the utilization of wood waste and nonworkable wood.
REFERENCESolechnik, N. la. Proizvodstvo drevesnovoloknistykh plit, 2nd ed. Moscow, 1963.
V. S. LEBEDEV