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US 4,466,998 AGranted
Wood impregnation
AssigneeKoppers Company, Inc.
InventorsCraig R. McIntyre, Daniel A. Eakin
Life of this patent
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Abstract
Water-borne preservative salts are used to impregnate wood by the empty-cell pressure impregnation method without the precipitation of water-borne salts such as chromium, copper and arsenic when wood sugars enter the treating solution during the kickback or pressure release phase of the empty-cell cycle. The lack of precipitation is obtained by maintaining the preservative salts solution at a temperature between about 40.degree. F. and about 70.degree. F.
Claims10
A wood pressure impregnation method comprising:
- (a) placing wood in a treating vessel and subjecting the wood to a vacuum 1/2 of 25 in. Hg to a pressure above atmospheric of up to 100 psig for a period up to 2 hours
- (b) filling the vessel with a water-borne preservative salts treating solution that reacts at elevated temperatures with wood constituents to form difficulty soluble precipitates, said treating solution having a temperature of between about 40.degree. F. and about 70.degree. F. while maintaining the pressure of (a),
- (c) adjusting the full treating vessel to a positive pressure of between atmospheric and 200 psig, and holding this pressure until a predetermined amount of treating solution has been injected into the wood,
- (d) releasing the pressure and returning the treating solution to a storage vessel, whereby the precipitation of preservative salts is obviated or reduced,
- (e) removing the excess solution from the wood at a pressure of from atmospheric to 26 in Hg, and
- (f) recovering the wood.
3 more elements
Dependencies are inferred from the claim text.