US 6,146,710 AGranted

Method of applying a powder coating to a length of a lignocellulosic material

AssigneeWindsor Technologies Limited

InventorMichael Windsor Symons

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Abstract

A method of applying a powder coating to a length of a lignocellulosic material. The method comprises impregnating the length of lignocellulosic material with an impregnating composition (i) a dicarboxylic anhydride or a tricarboxylic anhydride dissolved in non-aqueous solvent; (ii) an isocyanate thermosetting resin dissolved in a non-aqueous solvent; or (iii) a combination of (i) or (ii). Any excess impregnating composition is then removed from the lignocellulosic material. Non-aqueous solvent is also removed and the impregnated lignocellulosic material is placed in either an electrostatic field or in a fluidized bed and a powder coating composition is applied thereto so that the powder coating composition adheres to the lignocellulosic material. The impregnated and coated lignocellulosic material is then subjected to elevated temperatures to polymerise and/or cross-link the resin and cure the powder coating composition to form a powder coating. The length of lignocellulosic material may be a sheet of paper, wood or wood veneer. A typical solvent is dichloromethane or liquid carbon dioxide.

Claims13

Dependent claims

A method of applying a powder coating to a length of a lignocellulosic material includes the steps of:

(a) impregnating the length of lignocellulosic material with an impregnating composition comprising either;
(i) a dicarboxylic anhydride or a tricarboxylic anhydride dissolved in a suitable non-aqueous solvent;
or
(ii) an isocyanate thermosetting resin dissolved in a suitable non-aqueous solvent;
or
(iii) a combination of a dicarboxylic anhydride eor a tricarboxylic anhydride and an isocyanate thermo-setting resin dissolved in a suitable non-aqueous solvent;
(b) if necessary removing from the impregnated length of lignocellullosic material any excess of the impregnating composition;
(c) removing the non-aqueous solvent;
(d) placing the impregnated length of lignocellulosic material in an electrostatic field or in a fluidized bed and applying a powder coating composition thereto so that the powder coating composition adheres thereto;
and
(e) then subjecting the length of impregnated and coated lignocellulosic material to elevated temperatures to polymerise and/or cross-link the resin of step (a) in the length of lignocellulosic material and to cure the powder coating composition to form a powder coating.

8 more elements

Dependencies are inferred from the claim text.