(12) Patent Application Publication (10) Pub. No.: US 2011/0039031 A1 Cobham Et Al
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US 2011 0039031A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2011/0039031 A1 Cobham et al. (43) Pub. Date: Feb. 17, 2011 (54) CARRIER, FORMULATION AND METHOD Publication Classification FOR THE TREATMENT OF TIMBER (51) Int. Cl. (75) Inventors: Peter Cobham, Queensland (AU); C09D 5/14 (2006.01) David Humphrey, Victoria (AU); BSD L/02 (2006.01) BOSD I/28 (2006.01) Brett Skewes, Victoria (AU) BSD L/18 (2006.01) Correspondence Address: (52) U.S. Cl. ........ 427/427.7: 106/18: 106/311; 427/440; BELL & ASSOCATES 427/428.01 58 West Portal Avenue No. 121 SAN FRANCISCO, CA 94127 (US) (57) ABSTRACT (73) Assignee: Arch Wood Protection Pty Ltd According to the present invention there is provided a carrier Appl. No.: composition for migration and/or redistribution of a preser (21) 12/989,417 vative formulation within wood or engineered wood prod (22) PCT Fled: Apr. 24, 2009 ucts, said carrier system comprising a drying oil and/or a semi-drying oil and an extender. There is also provided a (86) PCT NO.: PCT/AU09/00525 preservative formulation comprising Such a carrier composi tion and a method of treating wood comprising the step of S371 (c)(1), applying Such a preservative formulation to the wood or engi (2), (4) Date: Oct. 24, 2010 neered wood product. Patent Application Publication Feb. 17, 2011 Sheet 1 of 3 US 2011/0039031 A1 F.G. 3 F.G. 4 Patent Application Publication Feb. 17, 2011 Sheet 2 of 3 US 2011/0039031 A1 F.G. S F.G. 6 F.G. 8 Patent Application Publication Feb. 17, 2011 Sheet 3 of 3 US 2011/0039031 A1 F.G. () F.G. 12 US 2011/0039031 A1 Feb. 17, 2011 CARRIER, FORMULATION AND METHOD wood, thereby to provide an effective barrier against infesta FOR THE TREATMENT OF TIMBER tion. Other considerations in the choice of carrier include the desired rate of penetration, the cost and environmental and FIELD OF THE INVENTION health and safety considerations. 0001. The present invention relates to preservative treat 0009. The treatment of timber or timber products with ment of timber building materials and particularly, to carrier preservative compounds involves the introduction of stable compositions, formulations and methods for delivering a pro chemicals into the cellular structure of the timber. This, in tective envelope of said preservative to said timber. turn, protects the timber from hazards such as fungi, insects and other wood-destroying organisms. Preservative treat BACKGROUND OF THE INVENTION ments may also include the introduction of chemicals that improve resistance to degradation by fire. 0002 Any discussion of the prior art throughout the speci 0010 Preservative treatment of wood is usually carried fication should in no way be considered as an admission that out at increased pressure so as to force the liquid preservative Such prior art is widely known or forms part of common Solution into the pores of the wood. A vacuum may be applied general knowledge in the field. prior to the introduction of the treatment solution in order to 0003 Wood is a staple construction material used increase penetration. The active chemical agent is usually throughout the world. However, it is prone to degradation dissolved in a solvent and the Solutions generally are of rela from elements including the natural environment, weather tively low viscosity in order to facilitate the penetration of the events, insects, rot and fire. treatment solution. However, the preservative may also be 0004 For instance, in countries such as Australia, timber is especially susceptible to termite attack. This has been coun present in the carrier as an emulsion. teracted to some degree by the treatment of wood with pre 0011 Increased penetration of the preservative solution servatives in the form of insecticides. Accordingly, a range of can also be achieved by diffusion, which despite involving chemical treatments has been developed to improve the dura less expensive equipment does require a longer time period bility and available working lifetime of wooden structures. and greater levels of Stock holding. Diffusion time is also Application methods and approved chemicals vary signifi influenced by the initial wood moisture content and often cantly throughout the world. requires a pre-drying step so as to create a preferential diffu 0005 Softwood timbers such as pinus radiata, pinus sion gradient along which the preservative/carrier formula elliotti, and pinus carribea used as framing timber in Austra tion may migrate. lia are especially susceptible to termite attack. Changes in Government regulations have limited the use of soil poison 0012. In Australia, the treatment of timber is covered by ing agents (e.g. banning of organochloride insecticides). This the Australian standard AS 1604-2007. The present inven has unfortunately led to a higherincidence of termite attack in tion is especially applicable to Hazard classes H1, H2,H3 and timber-framed houses. Accordingly, many countries continue H2F. Of these, Hazard class H2 is defined for the biological to seek suitable cost-effective methods to combat this ever hazard borer and termites and Hazard Class H3 is defined as increasing risk of termite attack. being for protection against “moderate fungal decay and ter 0006. One of the strategies to combat termite attack of mite hazard for decking, fascia, cladding, window reveals, softwood frames is the treatment of the timber with insecti and exterior structure timber. Although the present invention cides or more broad-spectrum wood preservatives. To this is exemplified with respect to H2 and H3 requirements, it will end, timber is often impregnated with a preservative such as a be readily appreciated by those skilled in the art that the fungicide or insecticide. The preservative is typically present invention is equally applicable to H1 and H2F requirements in a carrier, with the mixture being applied to the surface of the timber, for example by dipping, spraying or brushing, and penetration standard. such that the carrier and preservative are absorbed in to the 0013 The approved chemicals are shown in the following timber. table (retention is measured in w/w % m/m). 0007 Examples of commonly used insecticides include synthetic pyrethroids. These are axonic poisons that work by TABLE 1 keeping the Sodium channels open in the neuronal mem branes of insects. The Sodium channel is a small hole through Minimum Preservative Retention in the which sodium ions are permitted to enter the axon and cause Penetration Zone - Hazard Class 2 (H2) excitation. As the nerves cannot then de-excite, the insect is rendered paralysed. However, as preservatives in an aqueous Waterborne solvent for the treatment of timber, such components are still susceptible to leaching from the timber after treatment. More Copper chrome Ammoniacal copper Light organic solvent preservatives over, swelling of the timber after treatment due to water retention is a significant detriment. Examples of commercial arsenic (CCA) quaternary Per- Cyper- Delta pyrethroids include allethrin, bifenthrin, cypermethrin, cyphenothrin, deltamethrin, permethrin, prallethrin, res (Cu + Cr + As) (Cu + DDAC) methrin methrin methrin methrin, Sumithrin, tetramethrin, tralomethrin, transfluthrin and imiprothrin. O.32O O3S O.O2O O.O3O O.OO2O 0008. A selected carrier is required to be capable of pro viding sufficient penetration of the preservative into the US 2011/0039031 A1 Feb. 17, 2011 TABLE 2 Minimum Preservative Retention in the Penetration Zone - Hazard Class 3 (H3) Waterborne Light organic solvent preservatives TBTN Cu + Copper or Propiconazole + Copper Synthetic CCADDAC azole Creosote TBTO Tebuconazole naphthenate Pyrethroids O.380 Soft: O.229 8.OO 0.080 Soft: 0.06 O.100 0.02 Permethrin O3S 0.160 Hard: 0.03 Cypermethrin Hard: 0.002 Deltamethrin O.39 0.0047 Bifenthrin 0014 “Penetration' is defined under the standard as: “all 0024. By comparison, solvent-borne preservatives do not preservative-treated wood shall show evidence of distribution raise the moisture content and hence do not swell the wood of the preservative in the penetration Zone inaccordance with because they are non-polar. Thus, the process sequence is: the following requirements: (0.025 Dry wood->Solvent treat 0015 (a) If the species of timber used is of natural 0026. Although the use of solvent-borne preservatives durability class 1 or 2, the preservative shall penetrate all mitigates against the need for the re-drying step, the principal the sapwood. Preservative penetration of the heartwood disadvantages of this treatment system are the relatively high is not required. cost of solvents (cf water) and the potential environmental 0016 (b) If the species of timber used is of natural concerns with, e.g. Volatile organic compounds being durability class 3 or 4, the preservative shall penetrate all released into the atmosphere. of the sapwood and, in addition one of the following 0027. As mentioned above, the application of the preser requirements shall apply: vative/carrier to the wood is often carried out by a batch 0017 (i) Where the lesser cross-sectional dimension process involving a pressure vessel. For water-borne preser is greater than 35 mm, the penetration shall be not less vatives, a vacuum pressure process (Bethell or MI cell) is than 8 mm from any surface. Where the lesser cross used. This ensures, providing the wood is dry, complete sap sectional dimension is equal or less then 35 mm, the wood penetration and adequate heartwood penetration if penetration shall be not less than 5 mm from any required. Surface. 0028 Copper, chromium and arsenate (HASO), 0018 (ii) Unpenetrated heartwood shall be permit “CCA, is a leach-resistant wood preservative that has been ted, provided that it comprises less than 20% of the used for some time to treat Solid wood in external applica cross-section of the piece and does not extend more tions.