WO2013106566A1

WO2013106566A1 - Preservatives for wood

Info

Publication number: WO2013106566A1
Application number: PCT/US2013/021024
Authority: WO
Inventors: Sungmee Choi; Rahim Hani; Alex R. Valcke
Original assignee: Arch Wood Protection, Inc.
Priority date: 2012-01-10
Filing date: 2013-01-10
Publication date: 2013-07-18

Abstract

Disclosed herein is a wood preservative composition comprising (a) a 1-hydroxy-6-substituted pyridone or salts thereof and (b) an azole, wherein (a) plus (b) is present in an amount sufficient to impart antimicrobial efficacy to wood treated with the composition.

Description

PRESERVATIVES FOR WOOD

FIELD OF THE INVENTION

[0001 ] The present invention generally relates to preservative compositions for wood. More particularly, it relates to preservative compositions containing l-hydroxy-6-substituted pyridones and azoles. The present invention also relates to the method of treating wood and the wood treated with the preservative compositions.

BACKGROUND OF THE INVENTION

[0002] Azoles are well known wood preservatives. However, many azoles lack sufficient efficacy to control the bacteria commonly found in soil. As such, wood treated with these azoles are typically suitable for above ground use only. In addition, unexpected early failures have also been found in azole-treated wood even when the treated wood are used above ground, possibly due to azole tolerant fungi such as Antrodia spp.

[0003] l-hydroxyl-6-substituted pyridones are known and have been described in U.S. Patent No. 5,424,435. According to the '435 patent, l-hydroxyl-6-subsituted pyridine compounds are biocides and can be used in paints, adhesives, coatings, elastomers, sealants, shampoos, skin care medicaments and metalworking fluid. The '435 patent does not disclose using l-hydroxyl-6-substituted pyridine compounds in any wood preservative compositions.

[0004] Accordingly, in the wood preservation community, there is a continuing need for new preservative compositions that have broad spectrum efficacy against organisms found both in soil and above ground. The present invention is believed to provide an answer to that need.

SUMMARY OF THE INVENTION

[0005] In one aspect, the present invention relates to a wood preservative composition comprising (a) a l-hydroxy-6-substituted pyridone or salts thereof; and (b) an azoles for example, propiconazole and tebuconazole, and combinations thereof, wherein (a) plus (b) is present in an amount sufficient to impart antimicrobial efficacy to wood treated with the composition.

[0006] In another aspect, the present invention relates to a process for treating wood. The process includes contacting the wood with a composition containing (a) a l-hydroxy-6- substituted pyridone or salts thereof; and (b) an azole for example, tebuconazole, propiconazole, and combinations thereof.

[0007] In yet another aspect, the present invention relates to a wood treated with a composition containing (a) a l-hydroxy-6-substituted pyridone or salts thereof; and (b) an azole for example tebuconazole, propiconazole, and combinations thereof.

[0008] These and other aspects will become apparent upon reading the detailed description of the invention.

DETAILED DESCRIPTION

[0009] It has now been surprisingly found that l-hydroxy-6-substituted pyridones are efficient in controlling bacteria which cause fast degradation of azoles in ground exposure. In addition, it was found that l-hydroxy-6-substituted pyridones show good control of Antrodia sinuosa, which has caused an unexpected early failure of azole-treated wood products in above ground use. It has also been surprisingly found that the combination of azoles and l-hydroxy-6-substituted pyridones provides a synergistic effect against a broad spectrum of organisms, thus being suitable to treat wood for above ground use and ground contact use.

[0010] Accordingly, in one embodiment, the present invention provides a wood preservative composition containing a l-hydroxy-6-substituted pyridone or salts thereof and an azole, wherein the l-hydroxy-6-substituted pyridone or salts thereof and the azole are present in an amount sufficient to impart antimicrobial efficacy to wood treated with the composition. The amount required for preservative treatment depends on the ratio of the 1- hydroxy-6-substituted pyridone or salts thereof and the azole compound selected, the method of treatment employed, the wood species, the level of protection required and the nature and quantity of any other biocides present. In one embodiment, the combination of the 1- hydroxy-6-substituted pyridone or salts thereof and the azole is present in the wood preservative composition in an amount of from about 0.1% to about 30%, preferably from about 0.15% to about 20%, more preferably from about 0.35% to about 15%.

[001 1 ] The optimum weight ratio of l-hydroxy-6-substituted pyridone or salts thereof to azole varies depending on the particular material or product to which the composition is applied and type of organism against which protection is required. Preferably, the ratio of 1- hydroxy-6-substituted pyridone or salts thereof to azole is between about 1 : 40 and about 40 : 1, more preferable between about 1 : 10 and about 10 : 1, more preferably between about 1 : 5 and about 5 : 1.

[0012] Suitable l-hydroxy-6-substituted pyridones are represented by structural Formula (I):

[0013] In connection with Formula (I), X is oxygen and R is substituted or

unsubstituted hydrocarbon radical having between 1 and 20 carbon atoms. Preferred hydrocarbon radicals are aliphatic hydrocarbons having between 3 and 15 carbons, more preferably a straight chain hydrocarbon having between 5 and 10 carbons. As used herein, the term "substituted hydrocarbon" is intended to include substituents such as halogen such as chloro, iodo, fluoro or bromo, alkoxy such as methoxy, ethoxy, propoxy or butoxy, nitro, thio, and the like. Illustrative hydrocarbon groups include n-octyl, 2,4,4-trimethylpentyl, 3,5,5-trimethylhexyl and the like. One preferred l-hydroxyl-6-substituted pyridone is 1- hydroxy-6-octyloxypyridine-2-(lH)-one.

[0014] The l-hydroxy-6-substituted-2 -pyridones can be prepared according to the method disclosed in US Patent No. 5,424,435, the content of which is incorporated herein by reference in its entirety. The method includes reacting 2,6-dichloropyridine N-oxide, a hydroxy-containing compound having between 1 and 20 carbon atoms such as n-octanol and a base such as sodium hydroxide, optionally in the presence of water or an organic solvent. [0015] In one embodiment, suitable azoles include the triazoles disclosed in U.S. patent No. 5,527,384, the content of which is incorporated herein by reference in its entirety.

Advantageously, the azoles are represented by Formula (II) and Formula (III).

[0016] In connection with Formula (II), Ri represents a branched or straight chain Ci to C₅ alkyl group such as tert-butyl, and R₂ represents a phenyl group optionally substituted by one or more substituents selected from halogen atoms (e.g. chlorine, fluorine or bromine), or Ci_3 alkyl (e.g. methyl), Ci_₃ alkoxy (e.g. methoxy), phenyl or nitro groups. A particularly preferred compound of Formula (II) is tebuconazole: a-[2-(4-chlorophenyl)ethyl]-a-(l,l- dimethylethyl)- 1H- 1 ,2,4-triazole- 1 -ethanol.

[0017] In connection with Formula (III), R₃ is as defined for R₂ above and R4 represents a hydrogen atom or a branched or straight chain Ci_₅ alkyl group such as n-propyl.

Particularly preferred compounds of formula (III) are: propiconazole (l-[[2-(2,4- dichlorophenyl)-4-propyl-l,3-dioxolan-2-yl]methyl]-lH-l,2,4-triazole) and azaconazole (1- [[2,4-dichlorophenyl)- 1 ,3-dioxolan-2-yl]methyl]- lH-1 ,2,4-triazole).

[0018] Hexaconazole and difenaconazole are examples of further azoles which may be used in the compositions of the invention.

[0019] Compositions may contain more than one azole. Suitable azoles are selected from the group consisting of cyproconazole, itraconazole, fluconazole, fenbuconazole, imidazole, triadimefon, triticonazole, ketoconazole, itraconazole, bifonazole, butoconazole, oxiconazole, 3-phenyl-4-allyl-5-mercapto-l ,2,4(H)-triazole, 3-o-chlorophenyl-4-allyl-5- mercapto-l,2,4(H)-triazole, flusilazole, myclobutanil, propiconazole, prothioconazole, tebuconazole, tetraconazole, 1, 2, 4-triazole, 1 -methyl- lH-l,2,4-triazole, lH-l,2,4-triazole-l- ylacetonitrile, 4,5-dimethyl-4H-l,2,4-triazole-3-thiol, 5-mercapto-4H-l,2,4-triazole-3-ol, 4- isopropyl-5-mercapto-4H-l,2,4-triazol-3-ol, 4-amino-5-methyl-4H-l,2,4-triazole-3-thiol, diclobutrazol, epoxiconazole, etaconazole, furconazole, ipconazole, simeconazole, uniconazole, amisulbrom, fluotrimazole, azaconazole, hexaconazole, difenaconazole, bitertanol, bromuconazole, diniconazole, fluquinconazole, flutriafol, imibenconazole, metconazole, penconazole, triadimenol, and combinations thereof.

[0020] In one particular embodiment, the composition contains tebuconazole or propiconazole, or a mixture of tebuconazole and propiconazole.

[0021 ] It is appreciated that the l-hydroxy-6-substituted pyridone and the azole compound may be free in solution or may be present in the form of a salt or complex. For example, the azole compound could be present in the form of a complex with part of a biocidal metal ion. The l-hydroxy-6-substituted pyridone can be present in the form of a salt, such as an amine salt. Exemplary amine salts include monoethanolamine salts of 1-hydroxy- 6-substituted pyridones.

[0022] Optionally, the wood preservative composition of the invention contains elemental copper or a copper-containing compound. Suitable copper-containing compounds include water soluble copper compounds and water insoluble copper compounds. Exemplary water soluble copper compound include copper amine complexes. Exemplary water insoluble copper compound include copper carbonates, copper oxides, copper hydroxides, copper chlorides, copper aromatic or aliphatic carboxylates, and copper aminocarboxylates, and combinations thereof. The insoluble copper may be in the formed of micronized particles. Preferably, the copper compound is copper (I) and (II) oxide, and copper carbonate.

[0023] The wood preservative composition of the invention may, if desired,

additionally contain at least one co-biocide such as thiocarbamates, isothiazolinones, thiocyanates, sulfenamides, quaternary phosphonium compounds, quaternary ammonium compounds, and any other co-biocides that would be known to those skilled in the art.

Exemplary other suitable co-biocides include but not limited to:

(Thiocyanomethylthio)benzothiazole (TCMTB); Chlorothalonil; Dichlofluanid;

Isothiazolone: 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT); 5-chloro-2-methyl-4- isothiazolin-3-one; 2-methyl-4-isothiazolin-3-one (MIT); Benzisothiazolin-3-one (BIT); 2- octyl-3-isothiazolone (OIT); Imidacloprid; Iodopropynyl Butylcarbamate (IPBC); Bifenthrin; Cypermethrin; Permethrin; Chitin; Chitosan; Clorpyrifos; 4-(a-cumyl)phenol; Fipronil;

Carbendazim; Cyfluthrin.

[0024] The composition in accordance with the invention may contain water as solvent, or an organic solvent or a mixture of solvents. Formulations can be prepared as concentrates intended to be diluted at the treatment facility, or the formulations can be prepared in the form of dilute treatment solutions. Optionally, separate solutions of l-hydroxy-6-substituted pyridones and the azoles can be provided, for example, in the form of two concentrates intended to be mixed before or after dilution.

[0025] The compositions of the invention may be used to treat substrates such as wood or other cellulosic materials. For convenience, the invention is described with reference to the treatment of wood but it will be appreciated that the other materials may be treated analogously.

[0026] Accordingly, in one embodiment, the present invention is provided a wood treatment process. The process includes contacting wood with a composition containing a 1- hydroxy-6-substituted pyridone or salts thereof and an azole, wherein the l-hydroxy-6- substituted pyridone or salts thereof plus the azole is present in a total amount sufficient to impart antimicrobial efficacy to the wood.

[0027] Methods of treating wood are not particularly limited. For example, the compositions according to the invention may be applied to wood by dipping, spraying, brushing and by vacuum and/or pressure impregnation. Other types of substrate may be treated by analogous methods.

[0028] The retention of the preservative composition in the wood depends on a number of factors including but are not limited to the species of the treated wood, the composition of the preservative, the method of treatment, the desired level of protection, etc. Accordingly, the retention value can vary within a broad range. In one embodiment, the retention value of the azoles and the l-hydroxy-6-substituted pyridone or salts thereof in the wood is from about 0.02 to about 0.05 pcf. [0029] The following examples are intended to illustrate, but in no way limit the scope of the present invention. All parts and percentages are by weight and all temperatures are in degrees Celsius unless explicitly stated otherwise. All publications disclosed herein are incorporated by reference in their entireties.

EXAMPLES

[0030] Example 1 Determination of Minimum Inhibitory Concentrations (MICs)

[0031 ] Procedure: A 96-well microtiter plate Minimum Inhibitory Concentration (MIC) test was run in broth suitable for the test organisms. Stock solutions (0.125%) of all tested chemicals were prepared in DMSO, and the start-up concentration was adjusted to 312.5 ppm.

Data were collected at two days or one week of incubation. For decay fungi, 2% malt extract agar amended with test chemicals were prepared in Petri dishes.

[0032] The MIC results for a combination of tebuconazole and propiconazole in a 1 : 1 (weight) ratio and the MIC results for l-hydroxy-6-octylpyridine-2-(lH)-one ("HP-100") against various bacteria, mold/softrot, and decay fungi are reported in Table 1 below.

Table 1

Antrodia sinuosa Field isolate 31.25 ppm 7.81 ppm

Decay fungi Gloeophyllum trabeum Mad 617 <0.98 ppm 7.81 ppm

Postia placenta Mad 698 1.95 ppm 7.81 ppm

Trametes versicolor Mad 697 7.81 ppm 500 ppm

[0033] Example 2 Interactions of l-hydroxy-6-octylpyridine-2-(lH)-one with azoles

[0034] A checkboard titration was used to evaluate the interactions between 1-hydroxy- 6-octylpyridine-2-(lH)-one and azoles. For decay fungi, 2% malt extract agar amended with two combined actives were prepared in Petri dishes. The Fractional Inhibitory

Concentration (FIC = concentration of biocide in an inhibitory mixture divided by the MIC of the pure biocide) was determined, and the FIC Index (sum of the two FIC's) was calculated. The interaction was categorized according to the magnitude of the Index: Synergistic (<1), Indifference (>1, <2), or Antagonistic (>2).

[0035] Results: The data in Tables 2 and 3 show synergism between l-hydroxy-6- octylpyridine-2-(lH)-one ("HP 100") and wood preservatives such as azoles and copper. As shown in Tables 2a, 2b and 2c, when l-hydroxy-6-octylpyridine-2-(lH)-one was used with tebuconazole/propiconazole (1 : 1), synergy was observed against bacteria, mold and azole tolerant decay fungi. As shown in Tables 3a and 3b, when l-hydroxy-6-octylpyridine-2- (lH)-one was used with copper (in the form of basic carbon carbonate), synergy was observed against bacteria and soft rot fungi.

[0036] Table 2a Interactions between ΗΡ100 and TebrProp (1:1)

against Staphylococcus aureus

[0037] Table 2b Interactions between HPlOO and TebrProp (1:1) against

Aspergillusniger

[0038] Table 2c Interactions between HPlOO and TebrProp (1:1) against Antrodia sinuosa

[0039] Table 3a Interactions between HPlOO and Cu against Staphylococcus aureus

[0041 ] While the invention has been described above with references to specific embodiments thereof, it is apparent that many changes, modifications and variations can be made without departing from the invention concept disclosed herein. Accordingly, it is intended to embrace all such changes, modifications, and variations that fall within the spirit and broad scope of the appended claims.

Claims

What is claimed is:

1. A wood preservative composition comprising (a) a l-hydroxy-6-substituted pyridone or salts thereof and (b) an azole, wherein (a) plus (b) is present in an amount sufficient to impart antimicrobial efficacy to wood treated with the composition.

2. The wood preservative composition according to claim 1 , wherein said l-hydroxy-6- substituted pyridone is l-hydroxy-6-octyloxypyridine-2(lH)-one.

3. The wood preservative composition according to claim 1 , wherein said azole is selected from the group consisting of cyproconazole, itraconazole, fluconazole, fenbuconazole, imidazole, triadimefon, triticonazole, ketoconazole, itraconazole, bifonazole, butoconazole, oxiconazole, 3-phenyl-4-allyl-5-mercapto-l ,2,4(H)-triazole, 3-o-chlorophenyl-4-allyl-5- mercapto-l ,2,4(H)-triazole, flusilazole, myclobutanil, propiconazole, prothioconazole, tebuconazole, tetraconazole, 1 , 2, 4-triazole, 1 -methyl- lH-l ,2,4-triazole, lH-l ,2,4-triazole-l- ylacetonitrile, 4,5-dimethyl-4H-l ,2,4-triazole-3-thiol, 5-mercapto-4H-l ,2,4-triazole-3-ol, 4- isopropyl-5-mercapto-4H-l ,2,4-triazol-3-ol, 4-amino-5-methyl-4H-l ,2,4-triazole-3-thiol, diclobutrazol, epoxiconazole, etaconazole, furconazole, ipconazole, simeconazole, uniconazole, amisulbrom, fluotrimazole, azaconazole, hexaconazole, difenaconazole, bitertanol, bromuconazole, diniconazole, fluquinconazole, flutriafol, imibenconazole, metconazole, penconazole, triadimenol, and combinations thereof.

4. The wood preservative composition according to claim 1 , wherein said azole is selected from the group consisting of tebuconazole, propiconazole, and combinations thereof.

5. The wood preservative composition according to claim 1 , further comprising (c) elemental copper or a copper compound.

6. The wood preservative composition according to claim 5, wherein said copper compound is selected from the group consisting of copper oxide, copper hydroxide, copper salts and combinations thereof.

7. The wood preservative composition according to claim 4, wherein said l-hydroxy-6- substituted pyridone is l-hydroxy-6-octyloxypyridine-2(lH)-one.

8. A process of treating wood, said process comprising contacting wood with a composition comprising (a) a l-hydroxy-6-substituted pyridone or salts thereof and (b) an azole, wherein (a) plus (b) is present in a total amount sufficient to impart antimicrobial efficacy to said wood.

9. The process according to claim 8, wherein said l-hydroxy-6-substituted pyridone is 1- hydroxy-6-octyloxypyridine-2( lH)-one .

10. The process according to claim 8, wherein said azole is selected from the group consisting of cyproconazole, itraconazole, fluconazole, fenbuconazole, imidazole, triadimefon, triticonazole, ketoconazole, itraconazole, bifonazole, butoconazole, oxiconazole, 3-phenyl-4-allyl-5-mercapto- 1 ,2,4(H)-triazole, 3-o-chlorophenyl-4-allyl-5-mercapto- l ,2,4(H)-triazole, flusilazole, myclobutanil, propiconazole, prothioconazole, tebuconazole, tetraconazole, 1 , 2, 4-triazole, 1 -methyl- lH-l ,2,4-triazole, lH-l ,2,4-triazole-l-ylacetonitrile, 4,5-dimethyl-4H-l ,2,4-triazole-3-thiol, 5-mercapto-4H-l ,2,4-triazole-3-ol, 4-isopropyl-5- mercapto-4H-l ,2,4-triazol-3-ol, 4-amino-5-methyl-4H-l ,2,4-triazole-3-thiol, diclobutrazol, epoxiconazole, etaconazole, furconazole, ipconazole, simeconazole, uniconazole,

amisulbrom, fluotrimazole, azaconazole, hexaconazole, difenaconazole, bitertanol, bromuconazole, diniconazole, fluquinconazole, flutriafol, imibenconazole, metconazole, penconazole, triadimenol, and combinations thereof.

1 1. The process according to claim 8, wherein said azole is selected from the group consisting of tebuconazole, propiconazole, and combinations thereof.

12. The process according to claim 8, wherein said composition additionally comprises (c) elemental copper or a copper compound.

13. The process according to claim 12, wherein said copper compound is selected from the group consisting of copper oxide, copper hydroxide, copper salts and combinations thereof.

14. Treated wood comprising wood containing a preservative composition comprising (a) a l-hydroxy-6-substituted pyridone or salts thereof and (b) an azole applied to the wood, wherein (a) plus (b) is present in an amount sufficient to impart antimicrobial efficacy to said treated wood.

15. The treated wood according to claim 14, wherein said 1 -hydroxy-6-substituted pyridone is 1 -hydroxy-6-octyloxypyridine-2( lH)-one.

16. The treated wood according to claim 14, wherein said azole is selected from the group consisting of cyproconazole, itraconazole, fluconazole, fenbuconazole, imidazole, triadimefon, triticonazole, ketoconazole, itraconazole, bifonazole, butoconazole, oxiconazole, 3-phenyl-4-allyl-5-mercapto- 1 ,2,4(H)-triazole, 3-o-chlorophenyl-4-allyl-5-mercapto- l ,2,4(H)-triazole, flusilazole, myclobutanil, propiconazole, prothioconazole, tebuconazole, tetraconazole, 1 , 2, 4-triazole, 1 -methyl- lH-l ,2,4-triazole, lH-l ,2,4-triazole-l-ylacetonitrile, 4,5-dimethyl-4H-l ,2,4-triazole-3-thiol, 5-mercapto-4H-l ,2,4-triazole-3-ol, 4-isopropyl-5- mercapto-4H-l ,2,4-triazol-3-ol, 4-amino-5-methyl-4H-l ,2,4-triazole-3-thiol, diclobutrazol, epoxiconazole, etaconazole, furconazole, ipconazole, simeconazole, uniconazole,

17. The treated wood according to claim 14, wherein said azole is selected from the group consisting of tebuconazole, propiconazole, and combinations thereof.

18. The treated wood according to claim 14, wherein the preservative composition additionally comprises (c) elemental copper or a copper compound.

19. The treated wood according to claim 18, wherein said copper compound is selected from the group consisting of copper oxide, copper hydroxide, copper salts and combinations thereof.