Wood preservative composition and method of treating wood with same

Abstract

A wood preservative composition comprises a wood preservative such as a chromated copper arsenate-oil emulsion or an ammoniacal copper arsenate emulsion having about 0.1 to 15 percent chromated copper arsenate, ammoniacal copper arsenate, or ammoniacal copper zinc arsenate, about 1 to 20 percent oil and about 0.3 to 2.5 percent (based on total final emulsion) surfactant material. The first surfactant preferably has a hydrophilic lipophilic balance of about 7 to 9.5 and a second surfactant has a hydrophilic lipophilic balance of about 15 to 20. It is preferred that the first surfactant have an ethoxyl mole ratio less than about 5 and that the second surfactant have a mole ratio greater than about 15. The surfactant material may be composed of a first surfactant having an average mole ratio of about 1 to 5 and a second surfactant having an average mole ratio of about 20 to 100. The composition is storage stable for extended periods and provides a number of beneficial properties for wood products. A preferred group of surfactants for use in the present invention are ethoxylated alkylphenols or ethoxylated alkyl alcohols. A related method includes establishing an emulsion in oil of a first surfactant having an ethoxyl mole ratio less than about 5 and establishing in water a second surfactant having a mole ratio greater than about 15. The solutions are admixed and about 0.1 to 15 percent chromated copper arsenate, ammoniacal copper arsenate, or ammoniacal copper zinc arsenate is introduced into the mixed emulsions. The first and second surfactants may be emulsified in the oil which is subsequently admixed with the water, if desired. The chromated copper arsenate, ammoniacal copper arsenate or ammoniacal copper zinc arsenate bearing mixed emulsions are then introduced into wood. The composition and method are particularly useful with respect to wood products which will be used over prolonged periods in outdoor or other potentially hostile environments and are particulalry useful for utility poles, building products, and marine applications.

Dependencies are inferred from the claim text.