Encapsulated wood preservatives

Abstract

A method of incorporating biocides into wood or a wood product, the method including the steps of synthesising a plurality of capsules each having an outer shell of polymer and incorporating within each capsule an additive which includes an organic biocide, and then applying the capsules to the wood or wood product in a manner whereby the capsules penetrate the wood or wood product.

1 . An encapsulated organic biocidal composition when used to impregnate a wood or timber product resulting in retention of an effective amount of one or more biocides within the inner ninth core of said product wherein the composition comprises a plurality of capsules having a mean capsule size of between about 0.1 micron and about 20 microns and comprising a water immiscible solvent surrounded by a polymeric outer shell, the solvent containing said one or more organic biocides selected from fungicides, insecticides, mouldicides, bactericides, algaecides, and a combination thereof. 
     
     
         2 . The composition according to  claim 1  wherein the preferred mean capsule size is less than about 9.2 microns. 
     
     
         3 . The composition according to  claim 1  wherein the preferred organic biocide is at least one insecticide or fungicide. 
     
     
         4 . The composition according to  claim 1  wherein the one or more insecticide or fungicide is selected from the group consisting of an isothiazolone, a benzothiazole, a pyrethroid, a neonicotinoid, a halogenated carbamate, an azole, a chloronitrile, or a combination thereof. 
     
     
         5 . The composition according to  claim 1  wherein the one or more insecticide or fungicide is selected from the group consisting of 4,5-dichloro-2-n-octyle-4-isothiazoline-3-one (DCOIT), chlorothalonil, bifenthrin, and a combination thereof. 
     
     
         6 . The composition according to  claim 1  wherein the encapsulated organic biocide is applied to the wood or timber product with sufficient pressure to force the capsules to penetrate into the inner ninth core and resulting in a biocide retention within the inner ninth core exceeding 75% of the estimated average biocide retention. 
     
     
         7 . The composition according to  claim 1  further characterised in that the capsules are diluted in a fluid prior to being applied to the wood under industry standard vacuum and or pressure methods used to impregnate wood or timber products. 
     
     
         8 . The composition according to  claim 1  wherein the encapsulated organic biocide is made by dissolving the biocide in a water immiscible solvent containing a reactive oil soluble prepolymer. 
     
     
         9 . The composition according to  claim 8  wherein the oil is emulsified in an aqueous phase containing a reactive polymerisation initiator to create a capsule wall at the oil water interface. 
     
     
         10 . The composition according to  claim 1  wherein the encapsulated organic biocide further comprises one or more additional water soluble biocides and/or other penetrating adjuvants. 
     
     
         11 . The composition according to  claim 10  wherein other water soluble biocides are quaternary ammonium compounds metal or boron salts. 
     
     
         12 . The composition according to  claim 10  wherein the penetrating adjuvant is a fatty amine oxide. 
     
     
         13 . The composition according to  claim 1  when used in relation to wood or timber products formed from at least one of solid wood, orientated strand board, particle board, medium density fibrewood, plywood, laminated veneer lumber, and laminated strand lumber. 
     
     
         14 . A method for impregnating a wood or a timber product with an encapsulated organic biocidal composition according to  claim 1 , the method including the steps of:
 (i) synthesising a plurality of capsules each having a polymeric outer shell and a mean capsule size of between about 0.1 micron and about 20 microns,   (ii) incorporating one or more organic biocides within each said capsule and   (iii) then applying the resulting capsules to with sufficient force to impregnate the wood or timber product in a manner whereby the capsules penetrate the wood or timber product such that said biocide is retained within an inner ninth core of said product.   
     
     
         15 . A wood or timber product prepared by a process according to  claim 14 .