Particulate wood preservative and method for producing the same

Abstract

A wood preservative includes injectable particles comprising one or more sparingly soluble copper salts. The copper-based particles are sufficiently insoluble so as to not be easily removed by leaching but are sufficiently soluble to exhibit toxicity to primary organisms primarily responsible for the decay of the wood. Exemplary particles contain for example copper hydroxide, basic copper carbonate, copper carbonate, basic copper sulfates including particularly tribasic copper sulfate, basic copper nitrates, copper oxychlorides, copper borates, basic copper borates, and mixtures thereof. The particles typically have a size distribution in which at least 50% of particles have a diameter smaller than 0.25 μm, 0.2 μm, or 0.15 μm. At least about 20% and even more than 75% of the weight of the particles may be composed of the substantially crystalline copper salt. Wood or a wood product may be impregnated with copper based particles of the invention.

1 - 20 . (canceled) 
     
     
         21 . A wood preservative composition comprising:
 a plurality of milled particles comprising a sparingly soluble copper salt; and one or both of an alkanolamine and ammonia,   wherein the composition is suspended in an aqueous carrier; and   wherein the alkanolamine or ammonia, or both, are each in an amount less than 10% by weight of the composition and the aqueous carrier.   
     
     
         22 . The composition of  claim 21 , wherein the alkanolamine or ammonia, or both, are each in an amount less than 5% by weight of the composition and the aqueous carrier. 
     
     
         23 . The composition of  claim 22 , wherein the alkanolamine or ammonia, or both, are each in an amount less than 1% by weight of the composition and the aqueous carrier. 
     
     
         24 . The composition of  claim 21 , wherein the sparingly soluble copper salt is substantially crystalline. 
     
     
         25 . The composition of  claim 24 , wherein the sparingly soluble copper salt is selected from the group consisting of copper borate, basic copper borate, copper carbonate, basic copper carbonate, tribasic copper sulfate, copper oxychloride, alkaline copper nitrate, copper ferricyanate, copper fluorosilicate, copper thiocyanate, copper diphosphate, copper boride, copper phosphate, copper hydroxide and mixtures thereof. 
     
     
         26 . The composition of  claim 23 , wherein the alkanolamine or ammonia, or both, are each in an amount less than 0.1% by weight of the composition and the aqueous carrier. 
     
     
         27 . The compositions of  claim 23 , wherein the alkanolamine or ammonia, or both, are each in an amount less than 1% by weight of the copper. 
     
     
         28 . The compositions of  claim 21 , wherein the composition comprises at least one organic biocide. 
     
     
         29 . The composition of  claim 28 , wherein said organic biocide is an amine present in an amount which is not part of the amount of alkanolamine or ammonia present in the amount of less than 10% by weight of the composition and the aqueous carrier. 
     
     
         30 . The composition of  claim 28 , wherein at least a portion of the organic biocide is coated on the milled particles.