Forintek Canada Corporation

Louis R Calve

Gilles G Brunette

Marcel Lefebvrc

Smooth surfaced panels e.g. of oriented strand board are prepared by producing a thin uniform mat of high density made from bonded wood particles, fibers or strands. The mat is produced by passing it between a pair of rollers one of which is heated to produce a smooth cured surface on the corresponding side of the mat, and the other of which is unheated, the corresponding side of the mat containing uncured adhesive. The mat is subsequently bonded to a panel, e.g. an oriented strand board core under conditions of heat and pressure to produce a composite panel having a smooth surface.

Method of making a smooth surfaced mat of bonded wood fines used in

Fast cure and 'pre-cure' resistance thermosetting adhesives and methods for their production useful for binding lignocellulosic materials together, are disclosed. A fast curing adhesive is obtained by cross-linking binary phenol-formaldehyde consisting of high average molecular weight phenolformaldehyde (PF) resin and low average molecular weight PF resin with lignin. A 'pre-cure' resistant adhesive is obtained by cross-linking a PF resin, such as binary phenol-formaldehyde, with a lignin with the addition of ammonia preferably in the form of an ammonium salt. The lignin may be obtained from different wood pulping waste materials including that recovered from the sulphite, kraft, organosolv or steam hydrolysed wood pulping processes. The adhesive can be produced as an aqueous solution of dispersion, and used in either a basic or acidic environment. The quick setting and 'pre-cure' resistant adhesive are inexpensive to produce and both display improved adhesion characteristics when compared with existing adhesives prepared from wood waste products. The adhesives also compare advantageously to a variety of existing commercial phenolic resin presently being used in the manufacture of wood composite products such as waferboards. These adhesives are capable of being spray dried more easily and produce higher yields, when compared with existing wood waste products which have been cross-linked with commercial PF resin or to a variety of existing commercial phenolic resins.

Fast cure and pre-cure resistant cross-linked phenol-formaldehyde

A low cost method of binding lignocellulosic materials utilizing a novel ammonium based spent sulphite liquor, with phenol and formaldehyde or phenol-formaldehyde thermosetting resin as the binder is disclosed. Phenol-formaldehyde which normally reacts with ammonium lignosulfonate under acidic conditions and is unstable under these conditions, can be dispersed or otherwise held in suspension and can be mixed direct with the material by spraying. The constituants of the novel binder can also be mechanically dispersed when in dry powder form. The binder has improved adhesion characteristics and a shorter cure time over existing binders using a spent sulphite liquor base when in combination with phenol-formaldehyde.

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Aylmer, Canada

Louis R Calve