AU2015101281A4 - Preservative formulations for treating wood - Google Patents

Abstract

Abstract According to the present invention there is provided a preservative formulation for use in treating wood or other cellulosic materials, said formulation comprising: at least one preservative; and a carrier system comprising one or more low aromatic, or substantially low aromatic solvents. The invention also provides for a wood preservative formulation comprising such a carrier. In an embodiment, the carrier is selected from the commercially available range of Exxsol@ D and Isopar@ fluids.

Description

- 1 PRESERVATIVE FORMULATIONS FOR TREATING WOOD Field of the Invention The present invention relates to the treatment of wood products and other 5 cellulosic formulations with a preservative formulation. More specifically, the invention relates to developments in respect of carriers - agents that facilitate the penetration of the preservative/s into the wood. Although the invention will be described hereinafter with reference to this application, it will be appreciated that it is not limited to this particular field of use. 10 Background of the Invention Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field. 15 Wood is a staple construction formulation used throughout the world. However, it is prone to degradation from elements including the natural environment, weather events, insects, rot and fire. Accordingly, a range of chemical treatments has been developed to improve the durability and working lifetime of wooden structures. 20 To treat and prevent infestations, timber is often impregnated with a preservative such as a fungicide or insecticide. The preservative is typically present in a carrier, with the mixture being applied to the surface of the timber, for example by dipping, spraying, brushing or pressure treatment, such that the carrier and preservative are absorbed in to the timber. As such, the treatment of timber with 25 preservative compounds involves the introduction of stable chemicals into the cellular structure of the timber. This, in turn, protects the timber from hazards such as fungi, insects and other wood-destroying organisms. Preservative treatments may also include the introduction of chemicals that improve resistance to degradation by fire. 30 In Australia, the treatment of timber is governed by the Australian standard "AS 1604-2012". Hazard Class H3 is defined as being for protection against "moderate fungal decay and termite hazard" with examples of end uses being -2 decking, fascia, cladding, window reveals, and exterior structure timber. The timber is exposed to the weather or not fully protected. It is clear from the ground and the area is well drained and ventilated. H3 treatment is designed to prevent attack by insects, including termites, and decay. 5 Hazard Class H4 defines the requirements for "severe decay, borers and termites", fence posts, greenhouses, pergolas (in ground and landscaping timbers)". The timber to which H4 is applicable is in contact with the ground or is continually damp so there is a severe decay hazard. The treatment stops attack by insects, including termites, and severe decay. 10 "Penetration" is defined under the H3/H4 Standards as: "All preservative treated wood shall show evidence of distribution of the preservative in the penetration zone in accordance with the following requirements: (a) If the species of timber used is of natural durability class 1 or 2, the preservative shall penetrate all the sapwood. Preservative penetration of the heartwood is not required; (b) If 15 the species of timber used is of natural durability class 3 or 4, the preservative shall penetrate all of the sapwood and, in addition one of the following requirements shall apply; (b(i)) Where the lesser cross-sectional dimension is greater than 35 mm, the penetration shall be not less than 8 mm from any surface. Where the lesser cross-sectional dimension is equal or less than 35 mm, the penetration shall be not 20 less than 5 mm from any surface; and (b(ii)) Unpenetrated heartwood shall be permitted, provided that it comprises less than 20% of the cross-section of the piece and does not extend more than halfway through the piece from one surface to the opposite surface and does not exceed half the dimension of the side in the cross section on which it occurs". 25 As mentioned above, a carrier must be used in order to facilitate penetration of the preservative into the timber. As shown in the Australian Standards, the carriers presently available can be characterised broadly as "water-borne" or "solvent-borne" systems. A carrier must be capable of providing sufficient penetration of the 30 preservative into the wood, thereby to provide an effective barrier against infestation. Other considerations in the choice of carrier include the desired rate of penetration, cost, environmental, health and safety considerations. A carrier may -3 provide for a "complete penetration" formulation, or for an "envelope penetration" formulation in which a defined depth of penetration of one or more preservatives into the wood is achieved. The preservatives commonly used in timber treatment can be characterised 5 according to the carrier vehicle used to carry preservatives into the timber, and by the active ingredients protecting against the various hazards. Light organic solvent borne preservatives (LOSPs) comprise a light organic solvent, typically white spirits, to carry the preservative into the timber. The solvent is drawn out in the final stages of treatment, with the preservative remaining within the wood. Such 10 preservatives are typically fungicides, having copper, tin, zinc, azoles and pentachlorophenols (PCPs) as major toxicants. Insecticides such synthetic pyrethroids (e.g., permethrin, cypermthrin or bifenthrin) may be incorporated within the preservative composition if an insect hazard is also present. One principal advantage of LOSP and other hydrocarbon solvent-based 15 treatments is that the treated timber does not swell, making such treatment suitable for "finished" items such as mouldings and joinery. The majority of LOSPs used in wood treatment also contain mixtures of resin/waxes so as to give the surface water repellent properties. However, odour and exposure to VOCs (volatile organic compounds) can present some environmental/occupational health and safety issues. 20 The LOSP procedure does engender one significant advantage in that it does not add moisture back into the timber. Excessive moisture uptake can affect the dimensional stability of timber. It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. 25 The present invention thereby seeks to provide a wood treatment formulation that meets the industry-specific standards of active ingredient retention and penetration. The treated wood should preferably not require re-drying after treatment and have good dimensional stability. The advantages in obtaining an industrially-effective "low odour preservative" formulation may be both economic 30 and environmental. Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be -4 construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". Although the invention will be described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be 5 embodied in many other forms. Summary of the Invention According to the invention there is provided a preservative formulation for use in treating wood or other cellulosic materials, said formulation comprising: at 10 least one preservative; and a carrier system comprising one or more low aromatic, or substantially low aromatic solvents. In an embodiment, the one or more low aromatic, or substantially low aromatic solvents is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a 15 source that is naturally low in aromatics or mixtures thereof, or solvents that are equivalent or near equivalent in specification. In an embodiment, the carrier system comprises an aromatics content up to about 15% v/v. In an embodiment, the preservative comprises tebuconazole, propiconazole and permethrin as biocidally active agents. In an embodiment, the carrier system further comprises one or more 20 co-solvents to solubilise the biocidally-active agents. Low aromatic or dearomatised solvents are proposed herein as an alternative to LOSP/mineral spirits, kerosene, diesel - or indeed any other solvent based hydrocarbon carrier currently used throughout the wood preservation industry. For example, carriers according to the invention can comprise low odour 25 solvents or mixtures of solvents, which can be considered as dearomatised solvents or low aromatic solvents, that contain wood preservatives for the treatment of wood and wood products. Low odour solvents have been prescribed in, for instance, International patent publication WO 2000/066668. This document describes a composition 30 comprising: (a) a hydrocarbon component; and (b) an ester component; wherein the composition has: (i) less than 13% vol. of aromatic compounds relative to the total -5 volume of the composition; (ii) a distillation range situated within the range 135 260 'C; and (iii) a Kauri butanol value of 34 or more. For clarity, it will be appreciated by those of skill in the art that the low odour solvent or solvent mixture need not be free or even substantially free of 5 aromatics; an upper aromatics content of approximately 15% v/v is envisaged. As such - and for the avoidance of doubt, a solvent mixture comprising 85% v/v Exxsol® D40 (discussed below) and 15% v/v kerosene is considered "low odour" for the purposes of the present invention. 10 Table 1: Comparison of health factors using traditional LOSP carriers versus selected Exxsol@ D and Isopar@ fluids Properties Mineral Kerosene Diesel Exxsol Exxsol Isopar Isopar Isopar Spirit @ D40 @ D80 @ G @ L @ M Boiling 150-200 0 C 150-290 0 C, 180-365 0 C, 150- 200- 153- 182- 218 Range or wider or wider 196 0 C 250 0 C 180 0 C 205 0 C 257 0 C Flash Point 35-40 0 C 37-65 0 C > 55 0 C 40 C 75 C 40 C 62 C 80.5 C mm mm mm mm mm Composition: Aliphatics Aromatics x x x x x (up to 20+ (up to 20+ (up to 30+ (< 1 (< 1 (< 0.05 (< 0.05 (< 0.05 wt%) wt%) wt%) wt%) wt%) wt%) wt%) wt%) PNA 3 x x / x x x x 1200 1200 1200 1200 1200

OEL

1 300 mg/m 3 200 mg/m 3 100 mg/m 3 mg/m 3 mg/m 3 mg/m 3 mg/m 3 mg/m 3 (50 ppm) (~40 ppm) (~20 ppm) (197 (165 (196 (171 (152 ppm) ppm) ppm) ppm) ppm) VHR2 -45 - 100 -150 13 1.4 12 4 0.6 "Low" Odour ____________ O Occupational exposure limit 2Vapour hazard ratio 15 3 Polynuclear aromatic hydrocarbons A non-limiting example of low aromatic solvents available in industry are those manufactured by ExxonMobil Chemical Company; the Exxsol@ D and Isopar@ fluid ranges. Such products are purported to give rise to improved health 20 benefits for the workplace by way of a low order of acute toxicity; not classified for skin irritation and does not cause skin sensitisation; lower aromatic leading to -6 increased worker comfort; and non-carcinogenic properties. These solvents also give rise to improved environmental performance such that they do not cause stratospheric ozone depletion. Moreover, Exxsol@ D and Isopar@ fluids meet certain US FDA Regulations (21 CFR), on an ex-plant basis. 5 Exxsol@ D and Isopar@ fluids are well defined solvents, with narrow boiling ranges that have been subjected to additional distillation and refining (cf. kerosene, etc.). When purified to this extent, they are found to be practically free of aromatics, which in turn brings forth perceptible advantages in that traditional aromatic hydrocarbons are associated with adverse health effects. 10 As can be seen from Table 1, above, mineral spirits, kerosene and diesel have wide boiling ranges; their composition varies significantly; and certain solvent behaviours can on occasion be difficult to predict. They may contain hazardous constituents such as naphthalene and/or ethyl benzene (naphthalene is classified as "Group 28" carcinogen, i.e., possibly carcinogenic to 15 Humans, by the International Agency for Research on Cancer, for effects seen at the nasal area of rodents; ethyl benzene carries the same classification given tumour growth in the kidneys of rodents). Table 2: Comparison of potential environmental classification using traditional 20 LOSP carriers versus selected Exxsol@ D and Isopar@ fluids Properties Mineral Kerosene Diesel Exxsol@ Exxsol@ Isopar@ G Isopar@ Spirit D40 D80 L Current EU R51/53 R51/53 R51/53 Not Not R53 Not classification classified classified classified Predicted GHS Acute II Acute II Acute II Chronic IV Chronic Acute III Not classification Chronic II Chronic II Chronic II CoIV I Chronic III classified 51/53: Toxic to aquatic organisms, may cause long term adverse effects in the aquatic environment R53: May cause long term adverse effects in the aquatic environment GHS: Globally harmonised system of classification and labelling of chemicals 25 Diesel, on the other hand, contains polynuclear aromatic hydrocarbons (PNAs). Certain PNAs have carcinogenic properties - and indeed, diesel is classified for carcinogenicity in Europe.

-7 By comparison, Exxsol@ D and Isopar@ fluids have a significantly higher Occupational Exposure Limit. Exxsol@ D and Isopar@ fluids are free of naphthalene and ethyl benzene. Further, the Vapour Hazard Ratio (VHR) for Exxsol@ D & Isopar@ fluids are significantly lower than the corresponding 5 measures for mineral spirits, kerosene or diesel, meaning that it is far easier to be "overexposed" to traditional wood preservative carriers. In fact, low aromatic solvents can be so gentle as to allow for their use within personal care products. To this end, the Isopar@ fluids are registered with the Personal Care Products Council (formerly, the CTFA). 10 According to a preferred form of the present invention there is provided the use of one or more low aromatic, or substantially low aromatic solvents as a carrier for a wood preservative. In an embodiment, the low aromatic solvent is selected from the group consisting of Exxsol@ D and Isopar@ fluids. 15 Preferably, the low aromatic solvent is selected from the group consisting of Exxsol@ D hexane; Exxsol@ D heptane; Exxsol@ DSP 80/100; Exxsol@ D30; Exxsol@ D40; Exxsol@ D60; Exxsol@ D80; Exxsol@ D110; Exxsol@ D130; Isopar@ C; Isopar@ E; Isopar@ G; Isopar@ H; Isopar@ L; Isopar@ M. In an embodiment, the use comprises two low aromatic solvents in a ratio 20 from about 1:99 to about 99:1 w/w. Preferably, the ratio is about 50:50 w/w. in an embodiment, the two low aromatic solvents are Exxsol@ D60 and Exxsol@ D80. In a preferred embodiment employing one solvent, the low aromatic solvent is preferably Exxsol@ D40, Exxsol@ D60 or Exxsol@ D80. According to another form of the present invention there is provided a 25 preservative formulation for use in treating wood or other cellulosic formulations, said formulation comprising: at least one preservative; and a carrier comprising one or more low aromatic, or substantially low aromatic solvents. 30 The low aromatic solvent is selected from the group consisting of Exxsol@ D and Isopar@ fluids. Preferably, the low aromatic solvent is selected from the group consisting of Exxsol@ D hexane; Exxsol@ D heptane; Exxsol@ DSP 80/100; - 8 Exxsol@ D30; Exxsol@ D40; Exxsol@ D60; Exxsol@ D80; Exxsol@ D110; Exxsol@ D130; Isopar@ C; Isopar@ E; Isopar@ G; Isopar@ H; Isopar@ L; Isopar@ M. In an embodiment, there are two low aromatic solvents in a ratio from about 5 1:99 to about 99:1 w/w. Preferably, the ratio is about 50:50 w/w. in an embodiment, the two low aromatic solvents are Exxsol@ D60 and Exxsol@ D80. In another preferred embodiment employing one solvent, the low aromatic solvent is preferably Exxsol@ D60 or Exxsol@ D80. In another embodiment, the formulation comprises one or more biocidal 10 compounds. In a preferred embodiment, the formulation contains biocides selected from the group consisting of: insecticides, termiticides, fungicides, mouldicides, or the like, and mixtures thereof. In a preferred embodiment, the fungicidal compound or compounds (in the case of mixtures) is a compound selected from the group consisting of: azoles or 15 triazoles, e.g., azaconazole, tebuconazole, propiconazole, cyproconazole, hexaconazole, triadamefon; isothiazolinones, e.g., 4,5-dichloro-2-n-octyl-4 isothiazolin-3-one (DCOIT); quaternary ammonium compounds, e.g didecyldimethylammonium chloride, didecyldimethylammonium carbonate/bicarbonate, N,N-didecyl-N-methyl-N-(polyoxyethyl) ammonium 20 propionate, benzalkonium chloride; and other fungicides such as penflufen, 3-iodo 2-propynyl-butylcarbamate (IPBC), copper naphthenate, copper oxine, copper octanoate, copper soaps, zinc naphthenate, zinc octanoate, zinc soaps, tributyltin naphthenate, chlorothalonil, pentachlorophenol. Preferably the insecticide or termiticide is selected from the group 25 consisting of: synthetic pyrethroids (such as allethrin, bifenthrin, cyfluthrin, cypermethrin, cyphenothrin, decamethrin, deltamethrin, permethrin, prallethrin, resmethrin, sumithrin, tetramethrin, tralomethrin, transfluthrin, imiprothrin), or other insecticides such as abamectin, chlorfenapyr, chlorpyifos, thiachloprid, etofenprox, fipronil, imidachloprid acetamiprid, clothianidin, dinotefuran, 30 nitenpyram, thiamethoxam and the like, and mixtures thereof.

-9 Preferably, the triazole compound is tebuconazole (a-[2-(4 chlorophenyl)ethyl] -a--(1, 1 -dimethylethyl) -1 H-1,2,4-triazole-1-ethanol) or hexaconazole (a-butyl-a-(2,4-dichlorophenyl)-1H-1,2,4-triazole- 1-ethanol). In a preferred embodiment, the triazole compound is propiconazole (1-[[2 5 (2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]methyl]-1H-1,2,4-triazole) or azaconazole (1-[ [2,4-dichlorophenyl) -1,3 -dioxolan-2-yl] methyl] -IH-1,2,4-triazole); or difenaconazole (1-[2-[2-chloro-4-(4-chlorophenoxy)phenyl]-4-methyl-1,3 dioxolan-2-ylmethyl]-1H-1,2,4-triazole). In a preferred embodiment, the preservative is a triazole compound selected 10 from the group consisting of: azaconazole, bromuconazole, cyproconazole, diclobutrazol, difenoconazole, diniconazole, diniconazole-M, epoxiconazole, etaconazole, fenbuconazole, fluquinconazole, flusilazole, flutriafol, furconazole, furconazole-cis, hexaconazole, imibenconazole, ipconazole, metconazole, myclobutanil, penconazole, propiconazole, prothioconazole, quinconazole, 15 simeconazole, tebuconazole, tetraconazole, triadimefon, triadimenol, triticonazole, uniconazole, and uniconazole-P. Most preferably, the triazole is a mixture of tebuconazole and propiconazole. In a preferred embodiment, the biocidal compound are present in 20 unmodified or modified forms. A modified form preferably comprises a chemical or physical modification providing relatively increased stability against environmental conditions such as heat and/or chemical degradation. A modified form may be a microencapsulated form and/or a micronised form. In a preferred embodiment, the formulation comprises below about 10% w/w 25 biocide content; preferably below about 5%, and more preferably below about 2%. The carrier can be any low aromatic solvent eliciting the health and safety benefits alluded to above. In a preferred embodiment, the carrier is Exxsol@ D60 or Exxsol@ D80. In other embodiments, the carrier may be a combination of one or more Exxsol@ D and Isopar@ fluids - and can even be a combination of low 30 aromatic and traditional LOSP solvents, as long as an appropriate efficacy is maintained within the resultant carrier mixture.

- 10 In a preferred embodiment, the preservative penetration within the treated wood is by way of substantially complete penetration. Preferably the substantially complete penetration is in accordance with Hazard Class H3 of the Australian Standard AS 1604-2012 series. 5 In a preferred embodiment, the treated wood is classifiable in the art as "dry after" (moisture content <15% w/w) following treatment with the treatment formulation comprising the low aromatic solvent carrier. In a preferred embodiment, the treated wood does not require a substantial subsequent drying operation. In an embodiment the formulation is applicable to hardwood and/or 10 softwood species. According to another form of the present invention there is provided a method of treating a substrate of wood or other cellulosic formulation which comprises applying to the substrate a preservative formulation as defined immediately above. 15 Preferably the step of contacting the wood is performed by means selected from the group consisting of: pressure application, vacuum application, spraying, dipping, rolling, painting, or any combination thereof. However, it will be readily appreciated that the invention is applicable to other types of timber, such as sawn logs and the like. 20 The method optionally comprises at least one vacuum step, more preferably being between about 0 and -50 kPa. The method optionally further comprises at least one pressure step, preferably being between about 0 and 100 kPa. Preferably each vacuum and/or pressure step is held for between about 0 and 10 minutes. In a preferred embodiment, the dimensional changes between the wood 25 prior to and post the treatment are no greater than about 2 mm in any or either cross-sectional dimension. In another preferred embodiment a final vacuum step is applied, the final vacuum step taking place when said wood is no longer exposed to the preservative formulation. Preferably the final vacuum step is between about 0 and -95 kPa and is held from about 0 to 60 minutes. 30 According to another form of the present invention there is provided treated wood, when so-treated by a method defined immediately above.

- 11 According to another form of the invention there is provided a method of preparing a formulation for treating wood, the method comprising the step of admixing a preservative mixture defined above, with a low aromatic solvent carrier. According to another form of the invention there is provided a formulation 5 for treating wood, when prepared by a method as defined immediately above. According to one preferred form of the invention there is provided the use of one or more low aromatic, or substantially low aromatic solvents in a carrier for a wood preservative. In an embodiment, the one or more low aromatic, or substantially low 10 aromatic solvents is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a source that is naturally low in aromatics or mixtures thereof, or solvents that are equivalent or near equivalent in specification. In another embodiment, the carrier comprises an aromatics content up to about 15% v/v. In another embodiment, the 15 wood preservative comprises tebuconazole, propiconazole and an insecticide as biocidally-active agents. In another preferred embodiment, the insecticide is permethrin. In another preferred embodiment, the carrier further comprises one or more co-solvents to solubilise the biocidally-active agents. According to another preferred form of the invention there is provided a 20 carrier system for use in a wood preservative formulation, said carrier system comprising one or more low aromatic, or substantially low aromatic solvents. In an embodiment, the low aromatic solvent is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a source that is naturally low in aromatics or 25 mixtures thereof, or solvents that are equivalent or near equivalent in specification. In another embodiment, the carrier system comprises an aromatics content up to about 15% v/v. In another embodiment, the preservative comprises tebuconazole, propiconazole and an insecticide as biocidally-active agents. In another preferred embodiment, the insecticide is permethrin. In another preferred embodiment, the 30 carrier system comprises one or more co-solvents to solubilise the biocidally-active agents.

- 12 According to another preferred form of the invention there is provided a preservative formulation for use in treating wood or other cellulosic materials, said formulation comprising: at least one preservative; and a carrier system comprising one or more low aromatic, or substantially low aromatic solvents. 5 In an embodiment, the one or more low aromatic, or substantially low aromatic solvents is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a source that is naturally low in aromatics or mixtures thereof, or solvents that are equivalent or near equivalent in specification. In an embodiment, the carrier system 10 comprises an aromatics content up to about 15% v/v. In an embodiment, the preservative comprises tebuconazole, propiconazole and permethrin as biocidally active agents. In an embodiment, the carrier system further comprises one or more co-solvents to solubilise the biocidally-active agents. According to another preferred form of the invention there is provided a 15 method of treating a substrate of wood or other cellulosic materials which comprises applying to the substrate a preservative formulation comprising: at least one preservative in a carrier system comprising one or more low aromatic, or substantially low aromatic solvents. In an embodiment, the one or more low aromatic, or substantially low 20 aromatic solvents is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a source that is naturally low in aromatics or mixtures thereof, or solvents that are equivalent or near equivalent in specification. In an embodiment, the carrier system comprises an aromatics content up to about 15% v/v. In an embodiment, the 25 preservative comprises tebuconazole, propiconazole and an insecticide as biocidally-active agents. In another preferred embodiment, the insecticide is permethrin. In another preferred embodiment, the carrier system further comprises one or more co-solvents to solubilise the biocidally-active agents. According to another preferred form of the invention there is provided 30 treated wood or engineered wood products, when so-treated by a method which comprises applying to the substrate a preservative formulation comprising: at least - 13 one preservative in a carrier system comprising one or more low aromatic, or substantially low aromatic solvents. In an embodiment, the one or more low aromatic, or substantially low aromatic solvents is white spirit, kerosene, a dearomatised solvent, a paraffin 5 solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a source that is naturally low in aromatics or mixtures thereof, or solvents that are equivalent or near equivalent in specification. In an embodiment, the carrier system comprises an aromatics content up to about 15% v/v. In an embodiment, the preservative comprises tebuconazole, propiconazole and an insecticide as 10 biocidally-active agents. In an embodiment, the one or more insecticides comprise permethrin, bifenthrin, cypermethrin, deltamethrin, imidacloprid and thiacloprid. According to another preferred form of the invention there is provided a method of preparing a formulation for treating wood, said method comprising the step of admixing a preservative mixture, and a carrier system comprising one or 15 more low aromatic, or substantially low aromatic solvents. In an embodiment, the one or more low aromatic, or substantially low aromatic solvents is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a source that is naturally low in aromatics or mixtures thereof, or solvents that are 20 equivalent or near equivalent in specification. In an embodiment, the carrier system comprises an aromatics content up to about 15% v/v. In an embodiment, the preservative mixture comprises tebuconazole, propiconazole and an insecticide as biocidally-active agents. In another preferred embodiment, the insecticide is permethrin. In another preferred embodiment, the carrier system further comprises 25 one or more co-solvents to solubilise the biocidally-active agents. According to another preferred form of the invention there is provided a formulation comprising: tebuconazole, propiconazole and an insecticide diluted in a carrier system comprising one or more solvents such that the aromatic component of the carrier is less than about 15% v/v. 30 In a preferred embodiment, the insecticide is permethrin. In another preferred embodiment, the one or more solvents is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic - 14 solvent, a solvent derived from a source that is naturally low in aromatics or mixtures thereof, or solvents that are equivalent or near equivalent in specification. In another preferred embodiment, the formulation has a flash point equal to or greater than 61 0 C. In another preferred embodiment, the formulation optionally 5 further comprises mouldicides, anti-foam agents, water repellent components, fire retardants, colour additives, adhesion promoters, penetration marker compounds or other additives. In another preferred embodiment, the formulation optionally further comprises an amount of water, such that the moisture content of timber treated with said formulation remains less than 30% immediately after treatment. 10 According to another preferred form of the invention there is provided a method of treating a substrate of pinus radiata, pinus elliotti (including its hybrids), pinus caribaea (including its hybrids) or pinus pinaster timber which comprises applying to the substrate a preservative formulation comprising: at least one preservative in a carrier system comprising one or more low aromatic, or 15 substantially low aromatic solvents. In an embodiment, the formulation has a flash point of greater than about 61 0 C. In an embodiment, the formulation is applied at a rate or uptake sufficient to achieve penetration of the at least one preservative to the core of said substrate. In an embodiment, the penetration to the core of said substrate is compliant with 20 AS 1604 or NZS3640 series standards. In an embodiment, the one or more low aromatic, or substantially low aromatic solvents is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a source that is naturally low in aromatics or mixtures thereof, or solvents that are equivalent or near equivalent in specification; 25 and said carrier system comprises an aromatics content up to about 15% v/v. In an embodiment, the preservative formulation comprises tebuconazole, propiconazole and permethrin as biocidally-active agents dissolved in one or more co-solvents. The compositions according to the invention may be used to treat substrates such as wood or other cellulosic formulations (such as cotton, hessian, rope and 30 cordage). For convenience, the invention is described with reference to the treatment of wood, but it will be appreciated that the other formulations may be treated analogously.

- 15 The inventive compositions may contain more than one triazole compound for example, they may contain tebuconazole and propiconazole, or a mixture of tebuconazole, propiconazole and azaconazole. Compositions may contain more than one triazole compound. For example, they may contain tebuconazole and 5 propiconazole, or a mixture of tebuconazole, propiconazole and azaconazole. The compositions of the present invention may advantageously contain a biocidally-active quaternary ammonium compound or tertiary amine salt. The compositions in accordance with the invention comprise one or more low aromatic solvents as the carrier (or even as a constituent of the carrier). 10 Formulations can be prepared as concentrates intended to be diluted at the treatment facility, or the formulations can be prepared in the form of 'ready-to-use' treatment solutions. Optionally, separate solutions of preservatives and triazole compound can be provided, e.g., in the form of two concentrates intended to be mixed before or after dilution. 15 Compositions in accordance with the invention can optionally contain other additives conventionally employed in timber preservation such as water repellents, mouldicides, colour additives, adhesion promoters, corrosion inhibitors or penetration marker compounds. The latter refer to compounds that are included in the formulation to demonstrate the penetration of the active ingredients, in cases 20 where there are no known spot tests (AS 1605.2:2006; AWPA A3-08) for the active ingredients in question. Penetration markers used are commonly divalent metals, complexed with a suitable ligand to afford the appropriate solubility. The compositions of the invention may contain other organic compounds including fungicides, mouldicides, termiticides, insecticides and bacteriocides. 25 Such organic compounds include carboxylic acids such as naphthenic acids and branched aliphatic acids and their metal salts such as copper and zinc naphthenate, phenols and substituted phenols such as orthophenyl phenol and its alkali metal or ammonia salts; polyhalogenated phenols such as pentachlorophenol or tribromophenol and their alkali metal or ammonia salts; quaternary ammonium salts 30 and tertiary amine salts such as didecyl dimethyl ammonium chloride, octyl decyl dimethyl ammonium chloride, dodecyl dimethyl benzyl ammonium chloride, dodecyl benzyl trimethyl ammonium chloride, dodecyl dimethyl amine acetate, - 16 dodecyl dimethyl amine lactate, dodecyl dimethyl amine salicylate, didodecyl methyl amine chloride; isothiazolone derivatives such as 4,5-dichloro-2-(n-octyl)-4 isothiazolin-3-one or 2-methyl-4-isothiazolin-3 -one, 2n-octyl-4-isothiazolin-3 -one and mixtures of those and other related compounds; sulfamide derivatives such as 5 N,N-dimethyl-N-phenyl-(N-fluorodichloro-methylthio)-sulfonamide, N,N-dimethyl N-tolyl-N-(dichlorofluoro-methylthio)-sulfamide; azoles such as imidazole; MBT (methylene-bis thiocyanate); IPBC (3-iodo-2-propanyl-butyl-carbamate); carbendazim and chlorothalonil; N-nitrosophenylhydroxylamine and N-nitroso cyclohexyl hydroxylamine, either as their metal salts or as metal chelates; 10 pyrethroid type insecticides selected from the group consisting of cyano-(4-fluoro 3-phenoxyphenyl)-methyl-3-(2,2-dichioroethenyl)-2,2-dimethyl cyclopropanecarboxylate, (3-phenoxyphenyl)methyl-3-(2,2-dichloro-ethyenyl)-2,2 dimethyl-cyclopropanecarboxylate, cyano-(3-phenoxy-phenyl)-methyl-2-(4 chlorophenyl)-3-methylbutyrate, and mixtures thereof; organo -phosphorous, 15 carbamate and organochlorine insecticides such as lindane. Table 3: Exemplary "low odour" tebuconazole, propiconazole and permethrin formulations Producta,b Aromatic content "Low odour" wood preservative formulation prepared from Vacsol Azure Wood Preservative Concentrate 0.82% v/v (VAWPC) diluted with D80 "Low odour" wood preservative formulation in D80 from VAWPC, with a green colourant added at a rate in the 0.98% v/v range 0.01 to 0.1 %v/v "Low odour" wood preservative formulation in D80 from VAWPC, with green colour (as above) and metal tracer 1.30% v/v added at the appropriate addition rate. 20 aVacsol Azure Concentrate Wood Preservative is a proprietary one-pack product containing the active ingredients tebuconazole, propiconazole, permethrin and various inert ingredients including a proprietary water repellent system. bD80 refers to a dearomatised solvent with <0.5% w/w aromatics, boiling point range of approximately 200-250 'C, flash point of 80 'C. 25 Various "low odour" products containing tebuconazole, propiconazole and permethrin as ingredients could contain aromatic concentrations as summarised below.

- 17 According to a further form of the present invention there is provided a method of treating timber or another cellulosic substrate of the type hereinbefore described, which comprises applying to the substrate a composition as defined above. 5 The skilled person will be well acquainted with the various methods of treating the substrates with wood preservative solutions. For example, the compositions according to the invention may be applied to wood by dipping, spraying, deluging, brushing, vacuum impregnation, pressure impregnation, combinations thereof and/or any other applicable method. Other types of substrate 10 may be treated by analogous methods. Salient features of the formulations presented in Table 3 include: (a) that the "low odour" solvents may be derived by any known means, including hydrogenation of paraffinic, naphthenic and aromatic mixtures (dearomatisation, e.g., Exxsol@ D80), fractionation, liquid-liquid extraction, selective absorption 15 (e.g., with zeolites) or prepared from gas to liquid catalysis (as in the case of isoparaffins); (b) that different boiling point ranges of dearomatised/low aromatic solvents (e.g., D80 and D130) are used; (c) solvents that by nature of the crude oil they are derived from naturally contain low levels of aromatics, e.g., Enersol K; (d) include the substitution of dearomatised/low aromatic solvents by water (perhaps 20 10-30% v/v) within the formulation, such that the treated articles are still considered as "dry after" (moisture content < fibre saturation point -30%) and do not require re-drying; (e) the formulation may optionally include other solvents (generally described as "co-solvents"), to solubilise the preservative active ingredients or aid in formulating other additives; typical examples of co-solvents 25 include aromatics, alcohols, glycols, glycol ethers, carbonates, pyrrolidones, esters, ethers, amines, ketones, amides, sulfoxides, lactones, although in practice, some of these co-solvents may not be suitable for low odour products; (f) the dearomatised/low aromatic solvents can be flammable or combustible; (g) the low aromatic solvents may come from any one of numerous producers and suppliers; 30 some of which are given in the Table 4, below.

- 18 Table 4: Some commercially-available sources of "low odour " solvents Product name/tradenames Boiling range ("C) Aromatic content (% w/w) Exxsol@ Hexane 64-69 <0.01 Exxsol@ Heptane 94-98 <0.001 Exxsol@ DSP 80/100 79-103 0.1 Exxsol@ D30 141-159 <0.01 Exxsol@ D40 167-193 <0.1 Exxsol@ D60 185-199 <0.5 Exxsol@ D80 204-246 0.4 Exxsol@ D110 249-267 0.4 Exxsol@ D130 279-313 1.1 Isopar@ C 98-104 <0.001 Isopar@ E 115-140 <0.005 Isopar@ G 167-176 <0.005 Isopar@ H 179-188 <0.001 Isopar@ L 185-199 <0.01 Isopar@ M 225-254 0.01 ISANE IP 185 -185-212 <0.0001 ISANE IP 175 -180-195 <0.0001 ISANE IP 165 -165-195 <0.0001 ISANE IP 155 -160-173 <0.0001 ISANE IP 130 -130-160 <0.0001 Hydroseal G 400H -305-350 0.001-0.01 Hydroseal G 3H -278-320 0.001-0.01 Hydroseal G 250H -255-325 0.001-0.01 Hydroseal G 240H -240-285 0.001-0.01 Hydroseal G 232H -232-265 0.001-0.01 Ketrul D100 -230-270 0.001-0.01 Ketrul 220 -220-240 <0.0001 Ketrul 212 -220-255 1-20 Ketrul 211 -210-260 1-20 Ketrul D85 -205-240 0.001-0.01 Ketrul D80 -198-240 0.001-0.01 Ketrul D75 -190-275 0.01-1.0 Ketrul D70 -185-240 0.001-0.01 Ketrul HT -185-260 1-20 Kerdane -190-255 0.001-0.01 Spirdane D66 -178-220 0.001-0.01 Spirdane K2 -180-215 1-20 Spirdane D60L -180-195 0.001-0.01 Spirdane D60 -180-210 0.001-0.01 Spirdane D40K -160-200 0.01-1.0 Spirdane D40 -140-170 0.001-0.01 Enersol H -125-195 <10 Enersol K -185-300 <10 Recosol 78 198-250 < 0.03% Shellsol TD 172-185 0.01 Shellsol T 187-213 0.01 Shellsol TK 185-199 0.001 Shellsol TM 215-260 0.001 Shellsol D40 166-192 0.01 Shellsol D60 187-211 0.02 - 19 Shellsol D70 198-250 0.03 Shellsol D90 225-275 <0.02 Shellsol D100 238-257 0.05 Cypar 7 98-114 <0.2 Cypar 9 138-164 <0.01 YK-D80 -200-243 <0.1 a The preservative compositions according to the present invention are primarily the azole fungicides tebuconazole and propiconazole, with permethrin 5 included as an insecticide. The insecticide could be substituted for other suitable insecticides. Another alternative to the azoles tebuconazole and propiconazole would be copper naphthenate, although the latter can be problematic when the timber is to be painted in service with light coloured paints. 10 It may not be essential to use a co-solvent if the product is supplied as a "ready-to-use" solution without water repellent. However, in other embodiments, the use of a co-solvent can be advantageous. For instance, another form of the present invention relates to a formulation comprising: tebuconazole, propiconazole and permethrin dissolved in a suitable co 15 solvent, diluted with a low odour solvent containing <15% aromatic components and an amount of water, such that the moisture content of timber treated with said formulation remains less than 30% immediately after treatment. In a preferred embodiment, such a formulation optionally comprises surfactants/emulsifiers, other co-solvents, mouldicides, anti-foam agents, water repellent components, colour 20 additives, adhesion promoters, penetration marker compounds or other additives. In an especially preferred embodiment, the low odour solvent is Exxsol@ 60 or Exxsol@ D80. The application process by which the inventive carrier and preservative mixture can be applied to the timber is any suitable treatment method - for 25 instance, spraying, dipping, deluging, rolling and pressure/vacuum treatment. In a preferred embodiment, the method of application is vacuum-pressure treatment in an autoclave/treatment cylinder. For the avoidance of doubt, any application process that gives penetration and retention compliance with AS 1604, - 20 NZS 3640, or other equivalent national standards is applicable to the present invention. In other especially preferred embodiments, the carrier formulation, incorporating the preservative/s may be applied at elevated temperature. 5 Another salient feature of the present invention is the uptake of preservative formulation (preservative plus carrier) that can be achieved in practice; uptakes will be somewhat low, generally less than 50 L/m 3 . A range of other actives are theoretically possible, for instance those included in Table 5, below. 10 Table 5: Some exemplary formulations according to the invention Composition A formulation comprising one of more fungicides selected from azaconazole, tebuconazole, propiconazole, cyproconazole, hexaconazole, triadamefon, 4,5-dichloro-2-n-octyl-4 isothiazolin-3-one (DCOIT), didecyldimethylammonium chloride, didecyldimethylammonium carbonate/bicarbonate, N,N-didecyl-N-methyl-N-(polyoxyethyl)ammonium propionate, benzalkonium chloride, penflufen, 3-iodo-2-propynyl-butylcarbamate (IPBC), copper naphthenate, copper oxine, copper octanoate, copper soaps, zinc naphthenate, zinc octanoate, zinc soaps, tributyltin naphthenate, chlorothalonil, pentachlorophenol and an insecticide, formulated in such as way as to enable dilution with a low odour solvent containing <15% aromatic components. A formulation comprising tebuconazole, propiconazole and an insecticide dissolved or suspended [in the case of finely ground (micronized) or precipitated active ingredients] in a suitable co-solvent, diluted with a low odour solvent containing <15% aromatic components. The formulation may optionally contain mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. A formulation comprising tebuconazole, propiconazole and an insecticide dissolved in a suitable co-solvent, diluted with a low odour solvent, where the low odour solvent is D40, D60 or D80. The formulation may optionally contain mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. A formulation comprising tebuconazole, propiconazole and permethrin dissolved in a suitable co-solvent, diluted with a low odour solvent containing <15% aromatic components. The formulation may optionally contain mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. A formulation comprising tebuconazole, propiconazole and imidacloprid dissolved in a suitable co-solvent, diluted with a low odour solvent containing <15% aromatic components. The formulation may optionally contain mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives.

- 21 A formulation comprising tebuconazole, propiconazole and permethrin dissolved in a suitable co-solvent, diluted with a low odour solvent containing <15% aromatic components and an amount of water, such that the moisture content of the timber treated with such a formulation remains less than 30% immediately after treatment. The formulation may optionally contain surfactants/emulsifiers, extra co-solvents, mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. A formulation comprising tebuconazole, propiconazole and permethrin dissolved in a suitable co-solvent, diluted with a low odour solvent containing <15% aromatic components, with a flash point equal to or greater than 61 'C. The formulation may optionally contain mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. A formulation comprising tebuconazole, propiconazole and permethrin dissolved in a low odour solvent containing <15% aromatic components. The formulation may optionally contain mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. A formulation comprising tebuconazole, propiconazole and permethrin dissolved in a low odour solvent containing <15% aromatic components and an amount of water, such that the moisture content of the timber treated with such a formulation remains less than 30% immediately after treatment. The formulation may optionally contain surfactants/emulsifiers, extra co-solvents, mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. A formulation comprising copper naphthenate and an insecticide dissolved in a low odour solvent containing <15% aromatic components. The formulation may optionally contain mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. A formulation comprising copper naphthenate and permethrin dissolved in a low odour solvent containing <15% aromatic components. The formulation may optionally contain mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, penetration marker compounds or other additives. The treated timber can include engineered wood products (EWPs), along with softwoods including (but not limited to), Radiata pine (P. radiata), slash pine 5 (P. elliottii), Caribbean pine (P. caribaea), the hybrid, maritime pine (P. pinaster), Southern yellow pine (including sub-species); and other Asian pinus species. The invention is also applicable to the treatment of hardwoods and exotic species. Brief Description of the Figures 10 A preferred embodiment of the invention will now be described with reference to the accompanying Figures, in which: Figure 1 is graph showing comparative VHR values for the presently-used mineral spirits, kerosene and diesel LOSP carriers versus selected Exxsol@ D and Isopar@ fluids. VHR reflects the ability of a solvent to evaporate to its OEL. The 15 results indicate a larger margin of safety when using Exxsol@ D and Isopar@-type fluids.

- 22 Figure 2 is a graph showing comparison of odour between mineral spirits and selected Exxsol@ D and Isopar@ fluids. ED50 is a measure of odour threshold - and indicates the dilution factor at which half a test population can no longer detect odour. Higher ED50 values are indicative of a stronger, more penetrating 5 odour. The data show that mineral spirits containing a significant aromatic content has a greater than 30-fold higher ED50 than either Exxsol@ D40 or Isopar@ G fluids. Figure 3 is relates to Example 2. Individual sample uptakes for radiata pine specimens treated with (a) an azole-containing wood preservative formulation 10 utilising D80 as the carrier (red) and (b) a similar preservative where a conventional kerosene solvent was used as the carrier (blue). Figure 4 relates to Example 3. Figure 4a shows samples treated with wood preservative containing a copper naphthenate penetration marker, formulated in low aromatic solvent (D60); the photograph shows the results of penetration 15 assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14). Figure 4b shows samples treated with the same wood preservative formulated in kerosene; the photographs show the results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14). Figure 5 also relates to Example 3. Figure 5a shows samples treated with a 20 wood preservative containing tebuconazole, propiconazole, permethrin and zinc naphthenate as a penetration marker, formulated in kerosene; the photograph shows the results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14). Figure 5b shows samples treated with wood preservative formulated in low aromatic solvent, D80; the photograph shows the 25 results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14). Figure 6 relates to Example 5. It depicts results from accelerated leaching study comparing the leaching of the azoles, tebuconazole and propiconazole, from radiata pine as a function of different solvent carriers. Leachability index = 30 100*(quantity azoles leached from candidate carrier)/(quantity azoles leached from white spirit treatment).

- 23 The following Examples are intended to be illustrative of the present invention; they are not to be considered limiting. Indeed, the person skilled in the art will readily appreciate that numerous modifications are possible without departing from the spirit and scope of the present invention. 5 Examples Example 1 An example of a wood preservative formulation containing a low odour solvent is given below in Table 6, below. 10 Table 6: Exemplary formulation Raw Material Function Concentration (g/L) Vacsol@ Azure Concentrate Source of active ingredients, 81.8 Wood Preservative a tebuconazole, propiconazole, permethrin and water repellent Green Solvent Pigment Pack Colour additive 8 Exxsol@ D80 Carrier Balance aVacsol Azure Concentrate Wood Preservative is a one-pack product containing the active ingredients tebuconazole, propiconazole, permethrin and various inert ingredients including a 15 proprietary water repellent system. The formulation was shown to be adequately stable and suitable for use as a solvent-based preservative to treat timber for use in outdoor, above-ground end uses. The low odour wood preservative was used to treat softwood timbers. 20 Example 2 Radiata pine samples (90 x 35 mm in cross-section, 220 mm long and end sealed with two-part epoxy resin) were treated with the low odour wood preservative described in Example 1 were wrapped in plastic bags immediately 25 after treatment and stored at ambient temperature. At the same time, matched samples were treated with a conventional solvent-based preservative, Vacsol@ Azure Green C, which uses an aromatic containing solvent. These samples were also wrapped in plastic bags immediately after treatment and stored under the same conditions as those treated with the low 30 odour wood preservative.

- 24 In the case of the samples treated with the formulation described in Example 1, the mean uptake for eight replicates was 50.2 L/m , which was similar to that for the samples treated with Vacsol@ Azure Green C (mean uptake for eight matched replicates was 52.0 L/m 3 ). 5 The individual specimen uptakes for the two sets of samples are shown in Figure 3 of the accompanying drawings; individual sample uptakes for radiata pine specimens treated with (a) an azole-containing wood preservative formulation utilising D80 as the carrier (red) and (b) a similar preservative where a conventional kerosene solvent was used as the carrier (blue). 10 After storage for 4 to 8 weeks, the two sets of samples were periodically unwrapped and shown to various interested persons in a blind test, where the identity of the preservative used to treat the specimens was unknown to the person inspecting the samples. In each case, the person inspecting the samples commented that those 15 treated with the wood preservative formulation described in Example 1, containing a low aromatic solvent, smelled less noticeably than those treated with the conventional preservative, Vacsol@ Azure Green C. Example 3 20 It was surprisingly found that the low odour solvent penetrated timber more readily than conventional solvents. It has been postulated previously that solvents with low aromatic content do not penetrate timbers as readily as conventional solvents that contain approximately 15-20% aromatics, particularly in the case of timbers than have naturally high levels of resin. 25 In this example, end-matched sets (70 x 35 mm cross-section) of end-sealed slash pine samples were treated with identical preservatives containing a metal naphthenate tracer, formulated in two different solvents. The mean uptake for the set treated with the conventional solvent (kerosene) was 49.6 L/m , whereas the matching set treated with the low odour solvent (Exxsol@ D60, boiling point range 30 185-199 0 C, typical aromatic content <0.5%w/w) had a mean uptake of 45.0 L/m . Comparing individual specimens, the uptakes were higher for the conventional kerosene solvent preservative, in seven out of ten replicates.

- 25 Therefore, it was surprising that the metal penetration in the set treated with the low odour solvent was equal to or better in nine of the ten replicates. In relation to the accompanying drawings, Figure 4a shows samples treated with wood preservative formulated in low aromatic solvent (D60); the photograph 5 shows the results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14); and Figure 4b shows samples treated with wood preservative formulated in kerosene; the photographs show the results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14). 10 A similar observation has also been made in the treatment of radiata pine samples, with an azole containing product where the carrier was either a conventional kerosene with -20% aromatics (Figure 5a) or a dearomatised solvent D80 (Figure 5b). The boiling point range for the D80 solvent (204-246 0 C) matched that for the conventional kerosene very closely. The aromatic content in D80 is 15 typically 0.4% w/w. In both cases the product contained copper naphthenate as a penetration marker. The uptakes in each case were effectively identical. Having regard to the accompanying drawings, Figure 5a shows samples treated with wood preservative formulated in kerosene; the photograph shows the 20 results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14); and Figure 5b shows samples treated with wood preservative formulated in low aromatic solvent, D80; the photograph shows the results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14). 25 Example 4 A soil block test was undertaken to compare the anti-fungal activity of the azoles (tebuconazole and propiconazole) when applied from different solvents, i.e., aromatic-containing solvents, and dearomatised/low aromatic solvents. The results 30 suggest that the azoles applied to wood specimens in a low odour carrier are at least as efficacious as those applied from conventional hydrocarbon solvents containing an appreciable portion of aromatic compounds.

- 26 Example 5 The performance of a given preservative is dependent upon a number of factors. For timber that is to be exposed outdoors, one of the most critical factors is 5 the permanence of the fungicidal active ingredients in the wood substrate. In general terms, the more permanent the active ingredients, the better the preservative performance. The azoles tebuconazole and propiconazole are commonly used fungicides in wood preservatives. A comparison of their permanence in timber as a function of different solvent carriers was carried out. 10 Matched specimens of radiata pine sapwood measuring 50 x 20 x 20 mm were treated with a series of solvent-based formulations as summarised in Table 7, below. The same process was used to treat the specimens in each case and the uptakes were similar, resulting in similar azole retentions in the treated specimens. 15 Table 7: Summary of preservative/carriers used in leaching study Actives* Solvent Aromatic Content of Solvent (%) Tebuconazole, propiconazole, permethrin White spirit 20 Tebuconazole, propiconazole, permethrin Kerosene 18 Tebuconazole, propiconazole, permethrin Exxsol@ D60 <0.5 Tebuconazole, propiconazole, permethrin Exxsol@ D80 <0.5 Tebuconazole, propiconazole, permethrin Exxsol@ D130 <0.5 *The inert ingredients in each formulation were identical After treatment the specimens were placed in polyethylene bags to allow the 20 solvent to evaporate slowly. Once the majority of the solvent had evaporated, the specimens were aired in the open for a further two weeks. The specimens were then subjected to an accelerated leaching study, whereby the specimens were leached in a shaking water bath at 35 0 C for seven days, with regular changes of water. The leachate water was retained and analysed for the azoles tebuconazole and 25 propiconazole by HPLC. From the results of the azole analysis, the Leachability Index (LI) was calculated for each solvent. The LI for each solvent carrier is defined as the percentage of azoles leaching from the timber specimens, relative to that leached from the specimens treated with the white spirit formulation.

- 27 If LI is greater than 100, it implies that more azoles were leached from the timber specimens than occurred for white spirit, while if LI is less than 100, it implies that less azoles were leached. The smaller the LI, the more desirable the result, i.e., less azoles leached from the timber. In the experiment described here, 5 unexpectedly the D80-treated samples gave reduced azole leaching. The results are shown in Figure 6 of the accompanying drawings. The results show the significant and unexpected results for the dearomatised solvent carriers with D80 giving a particularly surprising result. 10 Example 6 Matched specimens of radiata pine framing timber, 90 x 35 mm in cross section, were spray-treated with various permethrin-containing formulations (see, Table 8, below), with the objective to meet the penetration requirements of AS 1604.1, Table H2.1. 15 In the case of permethrin, the penetration zone is 5 mm and the minimum active retention in the penetration zone is 0.02 %m/m. Table 8: Summary of results from spray-treatment of framing timbers Product/Formulation' Mean Uptake (L/m 3 ) Penetrationt Tanalith@ T 11.2 5 mm penetration achieved Permethrin, blue pigment, zinc 8.1 5 mm penetration achieved, octanoate, Exxsol@ D1 10 depth of penetration uniform 5 mm penetration achieved, less Permethrin, blue pigment, zinc consistently than at higher octanoate, Exxsol@ DI110 5.9 uptake. Presence of permethrin in the inner 3-5 mm zone confirmed by chemical analysis Permethrin, blue pigment, zinc Penetration somewhat variable. octanoate, lsopar@ M 10.1 Depth of penetration > 5 mm in localised sections 20 aFormulations contained zinc octanoate as a marker for determination of penetration. bPenetration determined by spraying freshly cut ends with PAN indicator (AWPA A3 -08, Method 14). It was found that the required depth of penetration could be achieved with 25 formulations containing the low aromatic solvents Exxsol@ D 110 and Isopar@ M, at lower uptake than with Tanalith@ T, a product that contains a combination of a - 28 drying oil and kerosene as carrier. Exxsol@ Dl10 is a dearomatised solvent (typical boiling point range 249-267 0 C) with a typical aromatic content of 0.4% w/w. Isopar@ M is an isoparaffin (typical boiling point range 225-254 0 C) with a typical aromatic content of 0.01% w/w. The odour of the timber framing treated 5 with D 110 or Isopar@ M formulations was considerably reduced over that treated with Tanalith@ T. Example 7 Table 9 shows the results from a laboratory bioassay carried out in 10 accordance with recognised methods (see, Protocols for the Assessment of Wood Preservatives, Australasian Wood Preservation Committee, March 2007 Revision, Ensis, Clayton). In this test, Radiata pine sapwood (20 x 20 x 10 mm) specimens were treated with a preservative formulation containing tebuconazole, propiconazole and 15 permethrin, formulated in a low aromatic solvent carrier (D80). Three sets of specimens were treated to three different azole retentions, i.e., 0.015, 0.030 and 0.060 %m/m total azole (tebuconazole plus propiconazole, with the tebuconazole/propiconazole ratio ~1:1). A further group of specimens were treated with the solvent only, as a control. 20 After drying, the specimens were saturated with water and leached in a shaking water bath at 35 0 C for seven days, with daily changes of water. After leaching, the specimens were vacuum oven dried, before being sterilised in readiness for the fungal bioassay. The specimens were then placed in the soil jars, which had previously been inoculated with the chosen decay fungus, and the jars 25 were incubated under conditions ideal for decay for a period of approximately 12 weeks. After incubation the specimens were cleaned, weighed and their mass loss determined. Mass loss, expressed as a percentage, was used to determine the effectiveness of the preservative treatment. Decay is deemed to have been prevented if the mass loss is less than 3%. 30 In Table 9 the mass loss for the water- and solvent-treated controls are shown. In each case the mass loss was in excess of 35%, illustrating the viability of the organisms and their capability to decay the radiata pine sapwood. The lowest - 29 azole retention tested (0.015% m/m) was able to prevent decay of the treated specimens by three of the five fungi, while for the middle retention (0.030% m/m) four of the five decay fungi were controlled. In Australia the AS 1604-2012 series specifies that timber or engineered wood products treated to Hazard Class 3 shall 5 contain a minimum total azole retention in the penetration zone of 0.060% m/m, where the total azole retention equals the sum of the respective propiconazole and tebuconazole retentions. The results (mean percentage mass loss) in Table 9 show that the azole-containing preservative formulated in a low aromatic hydrocarbon carrier is highly efficacious, with all five decay fungi controlled (mass loss < 3%) at 10 the 0.060 % m/m retention. Table 9: Summary of results of laboratory decay test. Mass loss (%) in radiata pine sapwood specimens, after exposure to assorted decay fungi. retention Mean mass loss (%) Treatment C. F. lilacino- G. A. P. olivacea gilva abietinum xantha tephropora Water 0 59.9 62.4 38.1 55.9 42.5 D80 0 50.5 56.8 38.4 35.4 43.3 Tebuconazole, propiconazole, 0.015 0.5 26.9 0.7 7.4 0.2 permethrin in a D80 carrier Tebuconazole, propiconazole, 0.030 -0.2 12.1 -0.4 -0.3 -0.6 permethrin in a D80 carrier Tebuconazole, propiconazole, 0.060 -0.1 0.5 -0.9 -0.2 -0.4 permethrin in a D80 carrier 15 Although the invention has been described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. Reference throughout this specification to "one embodiment" or "an 20 embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an - 30 embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more 5 embodiments. In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an 10 understanding of this description. Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognise that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, 15 any formulas given above are merely representative of procedures that may be used. Steps may be added or deleted to methods described within the scope of the present invention. It will be appreciated that the above-described invention provides for a low aromatic, or substantially low aromatic solvent carrier for a wood preservative 20 formulation, wherein the carrier provides for efficacious penetration of the preservative into the wood - but does not bear the undesirable odour, toxicity and environmental disbenefits that characterise the more "traditional" LOSP solvent carriers such as mineral spirits, kerosene and diesel. The prior art is characterised by the use of odoriferous solvent carriers for 25 use in timber preservative formulations; the present invention addresses some of the drawbacks relating to the issue of odour.

Claims (5)

1. A preservative formulation for use in treating wood or other cellulosic materials, said formulation comprising: 5 at least one preservative; and a carrier system comprising one or more low aromatic, or substantially low aromatic solvents.

2. A preservative formulation according to claim 1, wherein said one or 10 more low aromatic, or substantially low aromatic solvents is white spirit, kerosene, a dearomatised solvent, a paraffin solvent, an isoparaffin solvent, a naphthenic solvent, a solvent derived from a source that is naturally low in aromatics or mixtures thereof, or solvents that are equivalent or near equivalent in specification. 15

3. A preservative formulation according to claim 1 or claim 2, wherein said carrier system comprises an aromatics content up to about 15% v/v.

4. A preservative formulation according to any one of the preceding claims, 20 wherein the preservative comprises tebuconazole, propiconazole and an insecticide as biocidally-active agents.

5. A preservative formulation according to claim 4, wherein the carrier system further comprises one or more co-solvents to solubilise the 25 biocidally-active agents. Dated this 20th day of August 2015 Shelston IP 30 Attorneys for: Arch Wood Protection Pty Ltd.