US 20060257578A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2006/0257578 A1 Zhang et al. (43) Pub. Date: Nov. 16, 2006 (54) MICRONIZED WOOD PRESERVATIVE (60) Provisional application No. 60/570,659, filed on May FORMULATIONS COMPRISING BORON 13, 2004. Provisional application No. 60/565,585, COMPOUNDS filed on Apr. 27, 2004. Provisional application No. 60/461,547, filed on Apr. 9, 2003. Provisional appli (76) Inventors: Jun Zhang, Getzville, NY (US); cation No. 60/518,994, filed on Nov. 11, 2003. Wenjin Zhang, Tonawanda, NY (US); Robert M. Leach, Grand Island, NY Publication Classification (US) (51) Int. Cl. Correspondence Address: BOSD 3/02 (2006.01) HODGSON RUSS LLP C09D 5/18 (2006.01) ONE M & T PLAZA BSD L/18 (2006.01) SUTE 2000 B27K 3/5 (2006.01) BUFFALO, NY 14203-2391 (US) (52) U.S. Cl. ................... 427/393.3; 427/430.1; 428/541; 106/18.13 (21) Appl. No.: 11/354,726 (22) Filed: Feb. 15, 2006 (57) ABSTRACT Related U.S. Application Data The present invention provides wood preservative and flame retardant compositions having low leachability comprising (63) Continuation-in-part of application No. 11/126,839, micronized boron compounds and, optionally, one or more filed on May 11, 2005, and which is a continuation organic biocides which may be micronized. Also provided is in-part of application No. 10/970,446, filed on Oct. a method for applying the composition to wood and wood 21, 2004, and which is a continuation-in-part of products comprising impregnating the wood with the com application No. 10/821,326, filed on Apr. 9, 2004. position. Patent Application Publication Nov. 16, 2006 Sheet 1 of 3 US 2006/0257578A1 o sO O 9 9 H g w O O) D 1. S. A O 5 w 1 d CD n Boric Acid Micronized Zinc Borate Patent Application Publication Nov. 16, 2006 Sheet 2 of 3 US 2006/0257578A1 Con tracheids it airs ray cells Figure 2 Patent Application Publication Nov. 16, 2006 Sheet 3 of 3 US 2006/0257578 A1 pit US 2006/0257578 A1 Nov. 16, 2006 MCRONIZED WOOD PRESERVATIVE time periods. In an effort to reduce the high leachability of FORMULATIONS COMPRISING BORON boron compounds from treated wood in a moisture environ COMPOUNDS ment, many efforts have been directed by researchers in the 0001. This application is a continuation-in-part of U.S. wood preservation area to fix the boron in the treated wood. Nonprovisional application Ser. No. 11/126,839, filed on U.S. Pat. No. 6,821,631 discloses a two step treatment May 11, 2005, which claims priority to U.S. Provisional process for preventing leaching of boron compounds from Application No. 60/570,659, filed on May 13, 2004. This wood. Wood is treated with an alkali silicate solution fol application is also a continuation-in-part of U.S. Nonprovi lowed by treatment with an alkali borate solution. It is sional application Ser. No. 10/970,446, filed on Oct. 21, thought that the silicate and borate forms a borate-silicate 2004, which claims priority to U.S. Provisional Application polymer within the wood Substrate, imparting leach resis No. 60/565,585, filed on Apr. 27, 2004, and which is a tance to wood treated with boron compounds. However, due continuation-in-part of U.S. Nonprovisional application Ser. to the incompatibility of the silicate and borate solutions, No. 10/821,326, filed on Apr. 9, 2004, which in turn claims this method is likely to create a cross contamination problem priority to U.S. Provisional Application No. 60/461,547, in commercial wood treating plants. In addition, the two filed Apr. 9, 2003, and U.S. Provisional Application No. step treating process is expensive and time consuming. 60/518,994, filed Nov. 11, 2003. The disclosures of all of 0006 U.S. Pat. No. 6,896.908 discloses a leach resistant these applications are incorporated herein by reference. borate preservative containing borate, copper or Zinc, and organic acids. FIELD OF THE INVENTION 0007 Aqueous ammonia-based solutions have been 0002 The present invention is related generally to the widely used to solubilize metal borates, such as copper field of wood preservatives and wood flame retardants, and borate, Zinc borate and calcium borate in an attempt to fix more particularly to such compositions which comprise borates in wood. U.S. Pat. No. 5,207,823 describes a boron micronized boron compounds. fixation method which includes dissolving copper borate or Zinc borate in ammonia or other volatile agents. When the BACKGROUND OF THE INVENTION boron containing formulation is impregnated into wood, the 0003 Wood and other cellulose based products exposed Volatile agents evaporate, leaving water-insoluble copper or in an outdoor environment are biodegradable, primarily Zinc borate residue on the interstices of the wood. U.S. Pat. through attack by microorganisms and insects. As a result, No. 2,194,827 discloses a boron wood preservative contain they will decay, weaken in strength, and discolor. Microor ing an aqueous ammoniacal Solution of copper or Zinc ganisms causing wood deterioration include brown rots Such borate. Similarly U.S. Pat. No. 2,573.253 discloses a process as Postia placenta, Gloeophyllum trabeum and Coniophora for treating wood with a solution of copper borate in puteana, white rots such as Irpex lacteus and Trametes ammonia. However, current processes generally require the versicolor, dry rots such as Serpula lacrymans and Meruli dissolution of the boron compound in a solvent, usually poria incrassata and Soft rots Such as Cephalosporium, ammonia, which can be difficult and dangerous to work with Acremonium, and Chaetonium. Insects which can destroy due to its noxious fumes. wood include termites, beetles, ants, bees, wasps, etc. Wood 0008. In addition to boron-containing biocides, existing preservatives are used for preserving wood and other cellu wood preservatives can also contain other types of biocides, lose-based materials, such as paper, particleboard, textiles, Such as organic biocides. However, many organic biocides rope, etc., against organisms responsible for the deteriora have limited water-solubility. Therefore, solubilizing agents, tion of wood. Surfactants and wetting agents are often added to either 0004 Wood is also subject to destruction or degradation solubilize or form emulsions of the organic biocide to through other destructive agencies. In particular, wood is formulate a product that is suitable for the treatment of wood generally highly flammable, which can limit its usefulness in or other cellulosic substrates. applications involving high temperatures or proximity of 0009. However, the solubilizing agents, surfactants, and flames or flammable materials. Boron compounds have been wetting agents are costly and the use of these products can widely used to provide wood with broad spectrum protection result in enhanced leaching of the biocides when the treated against most wood destroying organisms, such as fungi, material comes into contact with moisture, giving rise to termites, ants, bees, beetles, etc. Boron compounds, particu field performance problems and environmental issues. Such larly inorganic compounds, are also known to have a flame enhanced leaching is considered to be the result of the retardant effect. An advantage of boron compounds over solubilizing agents, Surfactants and wetting agents which other wood preservatives and flame retardants is their low remain in the wood after treatment. mammalian toxicity and minimal environmental impact. 0010 Despite many efforts to address these deficiencies 0005 Water-soluble boron compounds, such as boric in existing wood preservatives, there is an unmet need for acid, Sodium borate and disodium octaborate tetrahydrate aqueous boron-based wood preservatives which, upon con (DOT) have been widely used on wood based products for the past few decades. Several boron-containing wood pre tact with moisture, exhibit only minimal leaching into the servative systems, such as copper-chromium-boron (CCB) environment. and copper-boric acid-azole (CBA), have been developed. 0011. A few inorganic boron compounds, such as for However, a major limitation of these commercially available example, Zinc borate, have been employed as flame retar preservatives is that the boron compounds readily leach dants in wood applications. Generally, the compounds have from wood when exposed to environmental moisture, result been used by as a powder incorporated into a matrix. For ing in a diminished bioefficacy, especially over extended example, the boron compound is incorporated into plastic by US 2006/0257578 A1 Nov. 16, 2006 blending a polymer material with boron compounds. In an sition generally exhibits minimal leaching of boron com exemplary use of boron compounds in wood applications, pounds. It has been observed for micronized particles that in Zinc borate is mixed with wood particles, chips fibers or most cases at least 10 wt % of the micronized particles sawdust and a glue or adhesive matrix to form a wood present in the wood Substrate after impregnation have pen composite product such as, for example Oriented Stand etrated to a depth of 0.3 millimeters or greater. In other Board (OSB), or particle board. In another example, a boron embodiments, at least 20 or 35 wt % of the micronized compound-containing glue or adhesive matrix is used to join particles present inside the wood substrate after treatment wood plys or veneers together (so-called “glue-line' use) to have penetrated to a depth of 0.3 mm or greater. form plywood. 0018. Also provided is wood through at least a portion of 0012 However, the above methods for incorporating the volume of which is distributed micronized particles of a flame retardant boron-containing compounds into wood or boron compound, and optionally, an inorganic biocide, wood products is only applicable to composite wood prod which may or may not be micronized.