A Wood Preservative Formulation

Abstract

According to the present invention there is provided the use of one or more low aromatic or substantially low aromatic solvents as a carrier, for efficacious use within a preservative formulation for treating wood or other cellulosic species. 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.

Claims

1-17. (canceled)

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

19. A formulation according to claim 18, wherein said low aromatic solvent is selected from the group consisting of degromatised hydrocarbon fluids, isoparaffinic fluids, and mixtures thereof.

20. (canceled)

21. A formulation according to claim 18, wherein the low aromatic solvent comprises a dearomatised hydrocarbon solvent having a boiling range of from 150° to 196° C. or from 200° to 250° C.

22. A formulation according to claim 18, comprising two said low aromatic solvents in a ratio from about 1:99 to about 99:1 w/w.

23. A formulation according to claim 22, wherein said ratio is about 50:50 w/w.

24. A formulation according to claim 18, wherein said one or more low aromatic solvents comprise an aromatics content up to about 15% v/v.

25. A formulation according to claim 18, wherein said preservative formulation has an uptake in the sapwood of less than about 150 L/m3.

26.-27. (canceled)

28. A formulation according to claim 18, wherein said preservative formulation has an uptake in the sapwood of less than about 50 L/m3.

29. (canceled)

30. A formulation according to claim 18, further comprising at least one biocidal metal compound.

31. A formulation according to claim 30, wherein said biocidal metal compound is a compound of copper.

32. (canceled)

33. A formulation according to claim 18, wherein said preservative is selected from the group consisting of: insecticides, termidicides, fungicides, mouldicides, or the like, and mixtures thereof.

34. A formulation according to claim 33, wherein said preservative is a triazole compound of formulae (I) or (II): ##STR00001## wherein R1 represents a branched or straight chain C1-5alkyl group; R2 represents a phenyl group optionally substituted by one or more substituents selected from halogen, C1-3alkyl, C1-3alkoxy, phenyl and nitro; R3 is as defined for R2; and R4 represents a hydrogen atom or a branched or straight chain C1-5alkyl.

35.-38. (canceled)

39. A formulation according to claim 33, wherein said preservative is a fungicide selected from azaconazole, tebuconazole, propiconazole, cyproconazole, hexaconazole, triadamefon, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-(DCOIT), didecyldimethylammonium chloride, didecyldimethylammonium carbonate/bicarbonate, benzalkonum 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, or pentachlorophenol,

40. A formulation according to claim 39, further comprising an insecticide.

41.-42. (canceled)

43. A formulation according to claim 33, comprising tebuconazole, propiconazole and an insecticide dissolved in a suitable co-solvent, diluted with a low odour solvent containing <15% aromatic components.

44.-52. (canceled)

53. A treated wood that has been treated with the formulation defined in claim 18, wherein said preservative penetration within said treated wood is by way of substantially complete penetration.

54.-60. (canceled)

61. A treated wood according to claim 53, comprising below about 10% w/w preservative content.

62.-69. (canceled)

70. A method of treating a substrate of wood or other cellulosic formulation which comprises applying to the substrate a preservative formulation as defined according to claim 18.

71. A method according to claim 70, wherein said step of contacting said wood is performed by means selected from the group consisting of: pressure application, spraying, dipping, rolling, painting, or any combination thereof.

72. (canceled)

73. A method according to claim 71, further comprising at least one vacuum step.

74. (canceled)

75. A method according to claim 71, further comprising at least one pressure step.

76.-86. (canceled)

87. 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 timber treated with said formulation remains less than 30% immediately after treatment.

88. A formulation according to claim 87, comprising at least one of surfactants/emulsifiers, other co-solvents, mouldicides, anti-foam agents, water repellent components, colour additives, adhesion promoters, or penetration marker compounds.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0098] A preferred embodiment of the invention will now be described with reference to the accompanying Figures, in which:

[0099] FIG. 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 results indicate a larger margin of safety when using Exxsol® D and Isopar®-type fluids.

[0100] FIG. 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 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.

[0101] FIG. 3 is relates to Example 2. 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).

[0102] FIG. 4 relates to Example 3. FIG. 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 assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14). FIG. 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).

[0103] FIG. 5 also relates to Example 3. FIG. 5a shows samples treated with a 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). FIG. 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).

[0104] FIG. 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=100*(quantity azoles leached from candidate carrier)/(quantity azoles leached from white spirit treatment).

[0105] FIG. 7 relates to Example 8. Shown are images of freshly cut ends of samples treated with a low odour/low aromatic wood preservative containing tebuconazole, propiconazole, permethrin and copper naphthenate (present as a penetration marker), taken after spraying with PAN indicator.

[0106] FIG. 7 relates to Example 9. Shown are end-sections of Pinaster pine Samples 1 (top) and 2 (bottom) after treatment with low odour/low aromatic solvent-based preservative and application of PAN indicator to cut ends.

[0107] FIG. 8 relates to Example 9. Shown is the end-section of Pinaster pine Sample 2 showing presence of blue-stain, prior to treatment with a low odour/low aromatic solvent-based preservative.

[0108] 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.

EXAMPLES

Example 1

[0109] An example of a wood preservative formulation containing a low odour solvent is given below in Table 5, below.

TABLE-US-00005 TABLE 5 Exemplary formulation Concentration Raw Material Function (g/L) Vacsol ® Azure Source of active ingredients, 81.8 Concentrate Wood tebuconazole, propiconazole, Preservative.sup.a permethrin and water repellent Green Solvent Pigment Colour additive 8 Pack Exxsol ® D80 Carrier Balance .sup.aVacsol Azure Concentrate Wood Preservative is a one-pack product containing the active ingredients tebuconazole, propiconazole, permethrin and various inert ingredients including a proprietary water repellent system.

[0110] 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.

Example 2

[0111] Radiata pine samples (90×35 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 after treatment and stored at ambient temperature.

[0112] 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 odour wood preservative.

[0113] 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.sup.3, 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.sup.3).

[0114] The individual specimen uptakes for the two sets of samples are shown in FIG. 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).

[0115] 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.

[0116] In each case, the person inspecting the samples commented that those 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

[0117] 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.

[0118] In this example, end-matched sets (70×35 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.sup.3, whereas the matching set treated with the low odour solvent (Exxsol® D60, boiling point range 185-199° C., typical aromatic content <0.5% w/w) had a mean uptake of 45.0 L/m.sup.3.

[0119] Comparing individual specimens, the uptakes were higher for the conventional kerosene solvent preservative, in seven out of ten replicates. 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.

[0120] In relation to the accompanying drawings, FIG. 4a shows samples treated with wood preservative formulated in low aromatic solvent (D60); the photograph shows the results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14); and FIG. 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).

[0121] 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 (FIG. 5a) or a dearomatised solvent D80 (FIG. 5b). The boiling point range for the D80 solvent (204-246° C.) matched that for the conventional kerosene very closely. The aromatic content in D80 is typically 0.4% w/w.

[0122] In both cases the product contained copper naphthenate as a penetration marker. The uptakes in each case were effectively identical.

[0123] Having regard to the accompanying drawings, FIG. 5a shows samples treated with wood preservative formulated in kerosene; the photograph shows the results of penetration assessment, after spraying freshly cut ends with PAN indicator (AWPA A3-08, Method 14); and FIG. 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).

Example 4

[0124] 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 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.

Example 5

[0125] 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 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.

[0126] Matched specimens of radiata pine sapwood measuring 50×20×20 mm were treated with a series of solvent-based formulations as summarised in Table 6, 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.

TABLE-US-00006 TABLE 6 Summary of preservative/carriers used in leaching study Aromatic Content of Solvent Actives.sup.a 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 .sup.aThe inert ingredients in each formulation were identical

[0127] After treatment the specimens were placed in polyethylene bags to allow the 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° C. for seven days, with regular changes of water. The leachate water was retained and analysed for the azoles tebuconazole and propiconazole by HPLC.

[0128] 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.

[0129] 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, unexpectedly the D80-treated samples gave reduced azole leaching.

[0130] The results are shown in FIG. 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.

Example 6

[0131] Matched specimens of radiata pine framing timber, 90×35 mm in cross-section, were spray-treated with various permethrin-containing formulations (see, Table 7, below), with the objective to meet the penetration requirements of AS1604.1, Table H2.1.

[0132] 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.

[0133] It was found that the required depth of penetration could be achieved with formulations containing the low aromatic solvents Exxsol® D110 and Isopar® M, at lower uptake than with Tanalith® T, a product that contains a combination of a drying oil and kerosene as carrier. Exxsol® D110 is a dearomatised solvent (typical boiling point range 249-267° C.) with a typical aromatic content of 0.4% w/w. Isopar® M is an isoparaffin (typical boiling point range 225-254° C.) with a typical aromatic content of 0.01% w/w. The odour of the timber framing treated with D110 or Isopar® M formulations was considerably reduced over that treated with Tanalith® T.

TABLE-US-00007 TABLE 7 Summary of results from spray-treatment of framing timbers Mean Uptake Product/Formulation.sup.a (L/m.sup.3) Penetration.sup.b Tanalith ® T 11.2 5 mm penetration achieved Permethrin, blue pigment, 8.1 5 mm penetration achieved, zinc octanoate, Exxsol ® depth of penetration uniform D110 Permethrin, blue pigment, 5.9 5 mm penetration achieved, less zinc octanoate, Exxsol ® consistently than at higher D110 uptake. Presence of permethrin in the inner 3-5 mm zone confirmed by chemical analysis Permethrin, blue pigment, 10.1 Penetration somewhat variable. zinc octanoate, Isopar ® M Depth of penetration >5 mm in localised sections .sup.aFormulations contained zinc octanoate as a marker for determination of penetration. .sup.bPenetration determined by spraying freshly cut ends with PAN indicator (AWPA A3-08; Method 14).

Example 7

[0134] Table 8 shows the results from a laboratory bioassay carried out in accordance with recognised methods (see, Protocols for the Assessment of Wood Preservatives, Australasian Wood Preservation Committee, March 2007 Revision, Ensis, Clayton).

[0135] In this test, radiata pine sapwood (20×20×10 mm) specimens were treated with a preservative formulation containing tebuconazole, propiconazole and 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.

[0136] After drying, the specimens were saturated with water and leached in a shaking water bath at 35° 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 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%.

TABLE-US-00008 TABLE 8 Summary of results of laboratory decay test. Mass loss (%) in radiata pine sapwood specimens, after exposure to assorted decay fungi. Azole Mean mass loss (%) retention C. F. lila- G. P. (% oliva- cino- abie- A. tephro- Treatment m/m) cea gilva tinum xantha pora 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, 0.015 0.5 26.9 0.7 7.4 0.2 propiconazole, permethrin in a D80 carrier Tebuconazole, 0.030 −0.2 12.1 −0.4 −0.3 −0.6 propiconazole, permethrin in a D80 carrier Tebuconazole, 0.060 −0.1 0.5 −0.9 −0.2 −0.4 propiconazole, permethrin in a D80 carrier

[0137] In Table 8, 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 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 AS1604-2012 series specifies that timber or engineered wood products treated to Hazard Class 3 shall 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 8 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 the 0.060% m/m retention.

Example 8

[0138] In this Example the treatment of pinus radiata with a low odour/low aromatic wood preservative formulation is investigated. Extensive treatment trials have been carried out with end-sealed radiata pine samples of various end-sections. These samples were treated with a low odour/low aromatic (<1.0% w/v aromatics) formulation containing 4.5 g/L of tebuconazole, 4.5 g/L propiconazole and 3.3 g/L permethrin. The formulation also contained 10 g/L of copper naphthenate (6% w/w copper metal) as a penetration marker. The samples were weighed before and after treatment to determine preservative uptake. Several days after treatment, the specimens were cut and penetration assessed after spraying cut ends with PAN indicator (AWPA A3-08; Method 14). The penetration results are shown in FIG. 7.

[0139] Two adjacent sections were cut from various samples that were considered to be adequately treated based on the results of a spot test. The sections were analysed for the active ingredients tebuconazole, propiconazole and permethrin. One section was used to analyse the full cross-section, the second section was used to analyse the inner one-ninth (or core) of the samples. Some of the results are summarised in Table 9.

TABLE-US-00009 TABLE 9 Summary of results for Example 8 Uptake Full cross section (% m/m) Inner one-ninth (% m/m) Sample (L/m.sup.3) Teb Prop Perm Teb Prop Perm 1 39.0 0.057 0.043 0.036 0.035 0.033 0.025 2 39.0 0.050 0.044 0.031 0.030 0.030 0.023 3 39.0 0.061 0.055 0.036 0.033 0.030 0.021 4 41.6 0.063 0.063 0.042 0.033 0.033 0.026

[0140] The samples all contain >0.06% m/m total azole (tebuconazole/propiconazole) and >0.02% m/m permethrin in the full cross-section, as expected on the basis of piece uptakes recorded for individual samples. The inner one-ninth analyses revealed that, on average, 59% of the full cross-section retention was found in the core, demonstrating the ease with which the low odour/low aromatic formulations are able to penetrate species such as radiata pine.

Example 9

[0141] In this Example, the treatment of pinus pinaster (maritime pine) with a low odour/low aromatic wood preservative formulation was investigated. End-sealed pinaster samples (90×35 mm end section) were treated with a low odour Vacsol Azure formulation containing 4.5 g/L of tebuconazole, 4.5 g/L propiconazole and 3.3 g/L permethrin, where the aromatic content of the formulation was less than 1% w/v. The formulation also contained 10 g/L of copper naphthenate (6% w/w copper metal) as a penetration marker. The samples were weighed before and after treatment to determine preservative uptake. Several days after treatment the specimens were cut and penetration assessed after spraying cut ends with PAN indicator (AWPA A3-08; Method 14). The results of treatment are summarised in Table 10.

[0142] The sapwood of each of the samples was penetrated fully, as judged by the colour development on the end-grain upon application of the PAN indicator (see, e.g., FIG. 8). Samples 3 and 4 were typical of high density pinaster pine, with 5-7 growth rings/10 mm. The sapwood was penetrated fully, and the envelope on the heartwood was sufficient to meet the penetration requirements of AS1604.1-2012.

TABLE-US-00010 TABLE 10 Treatment of pinaster pine with low odour/low aromatic wood preservative formulation Density Uptake Sapwood Heartwood Sample (kg/ Heartwood Blue- (L/ penetration penetration Number m.sup.3).sup.a (%).sup.b stain.sup.c m.sup.3).sup.d (%).sup.e (P/F).sup.f 1 517 0 N 36.0 100 N/a 2 478 0 Y 38.6 100 N/a 3 584 70 N 34.8 100 P 4 615 80 N 33.2 100 P .sup.aDensity .sup.bHeartwood content determined by spot test; AS/NZS1605.1:2006. .sup.cVisual detection of blue-stain (Y = yes, N = no). .sup.dUptake determined by weighing samples before and after treatment. .sup.eAWPA A3-08; Method 14. .sup.fPass (P) or Fail (F) as judged by penetration criteria in AS1604.1-2013 for Hazard Class 3

[0143] Sample 2 was a lower density sample that was free of heartwood. Although blue-stain was readily visible in this sample (see, FIG. 9), the uptake was not appreciably different to that for Sample 1; this finding was surprising. The presence of sapstain or blue-stain in kiln-dried timber frequently gives rise to increased uptakes upon preservative treatment, especially when treating with light organic solvent-based preservatives where increases in uptake of up to 100% are regularly seen, that cannot be reduced even with extended vacuum schedules. Hence, the presence of blue-stain gives rise to increased treatment costs. It would appear that the low aromatic carrier is less susceptible to exhibiting high uptakes when blue-stain is present in the substrate.

Example 10

[0144] In this Example, the influence of carrier on uptake in sapstained timber is investigated. As discussed above, the presence of sapstain or blue-stain in kiln-dried timber frequently gives rise to increased uptakes upon preservative treatment. In a further trial investigating the treatability of radiata pine with a low odour, solvent-based formulation, blue-stain was visibly present in a number of the samples. Upon treatment with a low odour solvent-based formulation it was found that uptakes were only slightly higher than may have been expected, with charges uptakes in the range 46-49 L/m.sup.3 over several end-sections (90×35 mm, 90×45 mm and 140×45 mm). What was surprising was the absence of very high uptakes that are typically observed when blue-stain is present, resulting in charge uptakes that are substantially higher than normal. In blue-stain free samples, uptakes were in the range 42-45 L/m.sup.3 for the same end-sections.

Example 11

[0145] In this Example, the influence of carrier on treatment of different end-sections was investigated. When treating structural timber with light organic solvent preservatives it is often observed that using the same schedule on different end-sections results in different mean uptakes, and as a consequence different penetration patterns. For example, treatment of a particular radiata pine resource of 90×35 mm end-section with Vacsol® Azure C (that uses a traditional kerosene carrier containing approximately 17% aromatics) using a modified Lowry process (+50 kPa/40 sec; -90 kPa/15 min) resulted in a mean uptake of 40.4 L/m.sup.3 (and satisfactory penetration), whereas the same schedule on 140×45 mm end-section radiata pine gave a mean uptake of 33.5 L/m.sup.3, and unsatisfactory penetration.

[0146] Satisfactory penetration of the 140×45 mm end-section was achieved with a heavier schedule delivering a mean uptake of 43 L/m.sup.3. The implications are that if the mixed end-sections are treated in the same charge, either (i) unsatisfactory treatment quality for the larger end-section will result, or (ii) the smaller end-section will be over-treated. Treatment quality and preservative consumption may be optimised by treating the different end-sections in different charges, however may not always possible. For example, when insufficient timber of a particular end-section is available to make a full charge the efficiency of the plant decreases, which is also undesirable.

[0147] An additional feature of the low odour/low aromatic wood preservative formulation is that different end-sections of the same radiata pine resource gave relatively consistent uptakes. The results are summarised in Table 11. In this trial a formulation containing the active ingredients tebuconazole, propiconazole and permethrin formulated in a low aromatic carrier (<1.0% w/v aromatics) was used to treat end-sealed radiata pine samples of different end-section, sourced from the same mill. The same treatment schedule was used in each case, and the uptakes were similar across the three end-sections.

TABLE-US-00011 TABLE 11 Treatment of radiata pine with a low odour/low aromatic wood preservative formulation End-section (mm) Mean uptake (L/m.sup.3).sup.a 90 × 35 47.5 90 × 45 47.1 140 × 45  47.4 .sup.aMean of 20 boards for 90 × 35 and 140 × 45 mm, and 30 boards for 90 × 45 mm

Example 12

[0148] In this Example, the influence of the carrier on the penetration of heartwood was examined. An additional unexpected benefit of the low odour/low aromatic wood preservative was the improvement in penetration of radiata pine heartwood. Light organic solvent preservatives typically treat radiata pine sapwood somewhat inconsistently, in that samples with heartwood typically display lower uptakes than those without heartwood. Envelope penetration on heartwood is sometimes observed, but it can be inconsistent. End-sealed radiata pine samples either 90×45 or 140×45 mm in end-section, that contained various amounts of heartwood were treated with the low odour/low aromatic formulation used in Example A4. After airing the specimens they were cut and penetration assessed via PAN spot test indicator. The preservative penetration in the heartwood containing samples was surprisingly good, with at least 90% of the heartwood penetrated, as judged by positive response to the spot test indicator.

TABLE-US-00012 TABLE 12 Treatment of radiata pine with low odour/low aromatic wood preservative formulation End-section Heartwood Piece uptake Preservative (mm) content (%) (L/m.sup.3) penetration  90 × 45 50 42.0 100 140 × 45 25 48.7 90 140 × 45 20 40.9 90 140 × 45 25 45.5 100 140 × 45 25 49.4 >95

[0149] Reference throughout this specification to “one embodiment” or “an 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. 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 embodiments.

[0150] In the description provided above, 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, 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.

[0151] It will be appreciated that the above-described invention provides for a low aromatic, or substantially low aromatic solvent carrier for a wood preservative 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.

[0152] The prior art is characterised by the use of odoriferous solvent carriers for use in timber preservative formulations; the present invention addresses some of the drawbacks relating to the issue of odour.