GB990834A - Improvements in or relating to the preservation of wood - Google Patents

Abstract

Wood is preserved by immersing the wood in a solution, at elevated pressure, of a preservative impregnating agent, such as pentachlorophenol in an aliphatic hydrocarbon and a cosolvent to assist said preservative impregnating agent, e.g. pentachlorophenol or copper quinolinolate into solution, said aliphatic hydrocarbon being gaseous at the process temperature and atmospheric pressure but liquid at the process temperature and said elevated pressure, and said cosolvent being soluble in the liquid aliphatic hydrocarbon and, at ambient temperature, less than 10% water-soluble and capable of dissolving at least 25% of the preservative impregnating agent. Specified cosolvents are nitrobenzene, di- and tri-chlorobenzenes, hydroxybenzenes, xylene, ethylene dichloride, diethyl ether, diisopropyl ether, vinyl ethyl ether, dibutyl ether, dibutyl ketone, diisobutyl ketone, methyl isobutyl ketone, benzonitrile, decalin, tetralin, butyraldehyde and isobutyraldehyde. Specified aliphatic hydrocarbons are liquefied petroleum gas, propane, n-butane, isobutane, n-pentane, isopentane or a mixture of two or more thereof. Water repellants, e.g. wax or paraffin, may be added to the solution for treating the wood. The wood may be impregnated by the full cell or empty cell process using air or nitrogen as the inert gas.