Abstract A wood preservative composition which substantially eliminates formation of pentachlorophenol crystals on the surface of the treated wood and results in increased paintability of the treated wood over compositions previously used consists of polypropylene glycol and a thermoplastic hydrocarbon resin derived from high temperature cracking of petroleum added to a solution of pentachlorophenol in a narrow boiling range mineral spirits solvent. Minor amounts of dioctylphthalate may be added which, along with the polypropylene glycol, prevent the formation of visible pentachlorophenol crystals on the surface of the treated product. Wood or other cellulosic materials are impregnated with the composition under pressure and the solvent carrier extracted and recovered from the wood before discharge of the wood from the treating chamber by a combination of heat and vacuum. The treated product, on removal from the treating chamber, is dry and clean to the touch with no ''''blooming'''' or formation of visible pentachlorophenol crystals on the surface of the wood.
The process of claim 1 wherein the treating solution includes 1 to 5 percent by weight polypropylene glycol, 0.06 to 0.5 percent by weight dioctylphthalate and 0.25 percent to 5.0 percent by weight thermoplastic hydrocarbon made up essentially of straight chain hydrocarbons containing substantially no aromatic structures, all percentages by weight based on the total weight of the treating solution.
Claim 2
Dependent Claim
28 words
The process of claim 1 wherein the solvent-carrier is an aliphatic hydrocarbon petroleum distillate containing a cosolvent for pentachlorophenol selected from the group consisting of xylene and cyclohexanone.
Claim 3
Dependent Claim
20 words
The process of claim 3 wherein the solvent-carrier is extracted from the wood at a temperature of 190*F. to 200*F.
Claim 4
Dependent Claim
236 words
A process for treating green wood to preserve it against attack from mold and microorganisms resulting in decay and stain, comprising: enclosing the wood in a confined treating chamber, submerging the wood in a treating solution of pentachlorophenol dissolved in a mineral spirits solvent-carrier having a distillation range of 300*F. to 360*F. Which forms an azeotrope with water at a temperature above about 80*F., heating the treating solution in the chamber under vacuum to a temperature sufficient to form a mineral spirits/water azeotrope with the water in the wood, withdrawing a vaporous mixture of the mineral spirits/water azeotrope from the treating chamber until the moisture content of the wood is reduced to a predetermined amount, releasing the vacuum in the treating chamber, impregnating the wood in the treating chamber with the treating solution by subjecting the wood to super atmospheric pressure and heat, removing the heated treating solution from the treating chamber, providing steam ejectors communicating with the treating chamber, extracting residual solvent-carrier from the wood as a vaporous solvent-carrier/steam azeotrope by feeding steam through the steam ejectors for evacuation of the treating chamber, the steam fed to the steam ejectors mixing with the solvent-carrier extracted from the wood to form a vaporous solvent-carrier/steam azeotrope, condensing the vaporous solvent-carrier/steam azeotrope, cooling the azeotrope below about 80*F. to allow separation of the solvent-carrier and water into two distinct phases, and recovering the mineral spirits solvent-carrier for reuse.
Claim 5
Dependent Claim
39 words
The process of claim 5 wherein the treating solution is heated to a temperature of 170*F. to 190*F. for removal of water from the wood and heated to 190*F. to 200*F. for extraction of residual solvent-carrier from the wood.