Improved stabilization of wood preservative solutions and preservation of wood by such solutions
AssigneeBell Canada
InventorsWilliam P. Trumble, Cheryl M. Maritan
Life of this patent
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Abstract
A wood preservative solution comprising water, hexavalent chromium, copper and arsenic can be stabilized against precipitation by the addition of fluorine ion, thereby enhancing the useful life and safety of the solution. Fluoride salts like cerium fluoride, sodium fluoride and calcium fluoride are suitable sources for fluorine ion in such a solution. Wood treated with the preservative solution displays increased penetration, distribution and retention of chromium, copper and arsenic.
Claims53
An aqueous wood preservative solution comprising a CCA-type formulation consisting essentially of 33% to 69.3% hexavalent chromium, calculated as Cr.sub.2 O.sub.3 ;
- 16% to 22% bivalent copper, calculated as CuO;
- and 14.7% to 48% pentavalent arsenic, calculated as As.sub.2 O.sub.5 ;
- diluted with water, and an amount of F.sup.- ion sufficient to stabilize said solution against precipitation of at least said chromium without retarding conversion of hexavalent chromium to trivalent chromium in a wood matrix.
A method of treating wood, comprising the step of exposing wood to an aqueous wood preservative solution comprising a CCA-type formulation consisting essentially of 33% to 69.3% hexavalent chromium, calculated as Cr.sub.2 O.sub.3 ;
- 16% to 22% bivalent copper, calculated as CuO;
- and 14.7% to 48% pentavalent arsenic, calculated as As.sub.2 O.sub.5 ;
- diluted with water, and an amount of F.sup.- ion sufficient to stabilize said preservative solution against precipitation of at least said chromium and insufficient to retard the conversion of hexavalent chromium to trivalent chromiumin a wood matrix.
An article of manufacture produced by a process comprising the step of treating wood with a wood preservative solution comprising a CCA-type formulation consisting essentially of 33% to 69.3% hexavalent chromium, calculated as Cr.sub.2 O.sub.3 ;
- 16% to 22% bivalent copper, calculated as CuO;
- and 14.7% to 48% pentavalent arsenic, calculated as As.sub.2 O.sub.5 ;
- diluted with water, and an amount of F.sup.- ion sufficient to stabilize said preservative solution against precipitation of at least said chromium without retarding conversion of hexavalent chromium to trivalent chromium in a wood matrix.
A method for stabilizing a wood preservative solution comprising a CCA-type formulation consisting essentially of 33% to 69.3% hexavalent chromium, calculated as Cr.sub.2 O.sub.3 ;
- 16% to 22% bivalent copper, calculated as CuO;
- and 14.7% to 48% pentavalent arsenic, calculated as As.sub.2 O.sub.5 ;
- diluted with water, comprising the step of adding a source of F.sup.- ion to said preservative solution in an amount sufficient to stabilize said preservative solution against precipitation of at least said chromium.
Dependencies are inferred from the claim text.