NZ624081B2 - Additives for use in wood preservation - Google Patents

Abstract

The present disclosure relates to a wood preservative formulation comprising a biocidal agent which is a copper or zinc ion complexed with an amino compound selected from the group consisting of ammonia, a water soluble amine or aikanoiamine and an aminocarboxyiic acid and a cationic polymer, as well as to aqueous treatment solutions comprising such a formulation and methods of treating wood or other cellulosic material utilising said formulation. Examples of a cationic polymer include compounds of formula (I), (II) and (III). l as to aqueous treatment solutions comprising such a formulation and methods of treating wood or other cellulosic material utilising said formulation. Examples of a cationic polymer include compounds of formula (I), (II) and (III).

Description

ADDITIVES FOR USE IN WOOD PRESERVATION Field of the Invention The present invention relates to wood preservative formulations and methods of treating wood and other cellulosic material. In particular it relates to formulations which contain a positively charged polymer which enhances the penetration of the active ingredients also present in the formulation into the wood or other cellulosic material.

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 common general knowledge in the field.

Many types of wood preservative treatments exist on the market today.

These can be applied directly to the surface, paint-on, or by vacuum pressure immersion treatments. During industrial application of preservatives, timber is typically impregnated with the treatment solution to achieve either shell or full cell type penetration into the substrate.

Depending on the wood species being treated and the end use, the depth of penetration of the preservative solution into the timber can have a significant bearing on the useful service life of the treated timber.

A typical industrial treatment plant will consist of a storage tank to hold the treatment solution and an autoclave. Timber is charged into the autoclave and this is then flooded with treatment solution. Combinations of vacuum and pressure are applied to achieve the required penetration of preservative into the timber.

During the treatment process, an amount of preservative solution is consumed by way of being absorbed into the timber. This typically represents a relatively small amount of the total volume of solution used to flood the autoclave.

This generates a scenario whereby treatment solution is repeatedly exposed to timber. The average treatment solution age increases as a function of solution refresh rates. This can extend from several days to many months. Therefore the solution is repeatedly exposed to timber.

It has been observed that the ability of the preservative to penetrate into the timber substrate as the solution is repeatedly exposed to timber can deteriorate very significantly. This can have significant consequences to the useful service life of the treated article.

Wood preservatives tend to be neutral or alkaline and the high pHs can solubilise chemical substances found in timber and during the impregnation process the timber generates anionic by-products. This combination of anionic by-products and timber extractives can then hinder penetration of the wood preservatives through the timber. , and Nikiforova et al. in the Russian Journal of Applied Chemistry (201 0) vol. 83, no 7, pp 1170-1175 describe formulations with one or more of the components of the formulations of the present invention, but they do not describe or suggest the formulations of the present invention or their ability to enhance uptake of biocides contained therein.

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.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be 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 embodied in many other forms.

Summary of the Invention According to a first aspect of the present invention there is provided a wood preservative formulation comprising a biocidal agent which is a copper or zinc ion complexed with an amino compound selected from the group consisting of ammonia, a water soluble amine or alkanolamine and an aminocarboxylic acid, and a cationic polymer selected from the group consisting of: (i) a compound of formula (I) (CH )n n (CH ) (CH )n 1 2 2 1 (I) (ii) a compound of formula (II) (II) ; and (iii) a compound of formula (III) n (CH ) N(R )n (III) in which: n = 3 to 5000; n = 0, 1 or 2; n = 0 or 1; n = 2 or 3 and when n = 3 the nitrogen atom carries a positive charge and a counter ion X is present; R groups, which can be identical or different, are hydrogen or a straight chain, branched or cyclic alkyl, alkenyl, alkynyl, alkanoxyl, aryl, -(C=O)H, -(C=O)R , -CO H -CO R , -CH CO H, -CH CO R , CH NR R , n 2 2 n 2 2 2 2 n 2 n n -(C=O)NR R , -CN, -(CH )n -O-R , in which; n n 2 4 n R groups, which can be identical or different, are hydrogen or a straight chain, branched or cyclic alkyl, alkenyl, alkynyl, alkanoxyl or aryl; n = 2 or 3; R is of the formula (IV) H O H H R R R z z z a b c d (IV) in which; R = H or OH; a = 0 to 10; b = 0 or 1; c = 0 to 10; d = 0 to 10; X is any anion selected from chloride, bromide, iodide, fluoride, sulphate, phosphate, carboxylate especially propionate and lactate, carbonate, bicarbonate, nitrate, nitrite, hydroxide, cyanide; and * represents the bonds connecting the repeating units within the backbone of the polymer.

According to a second aspect of the present invention there is provided a combined wood preservative product comprising (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12.

According to a third aspect of the present invention there is provided an aqueous wood preservative treatment solution comprising a wood preservative formulation as defined in claim 1 or claim 2 or any one of claims 6 to 11, said solution containing 10 to 1000 ppm of cationic polymer.

According to a fourth aspect of the present invention there is provided a method of preserving wood or other cellulosic material which comprises applying to the wood or other cellulosic material a formulation or solution as defined in any preceding claim or applying (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12; to the wood/material such that the wood/material effectively receives a formulation as defined in any one of the preceding aspects of the invention.

According to a fifth aspect of the present invention there is provided a wood treatment system comprising a storage tank adapted to receive the wood to be treated and in said tank a volume of treatment solution comprising (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12.

According to a sixth aspect of the present invention there is provided a substrate of wood or other cellulosic material containing: (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12.

According to a seventh aspect of the present invention there is provided a method of making a wood preservative formulation which comprises admixing: (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12.

According to an eighth aspect of the present invention there is provided the use of a cationic polymer as defined in any one of the preceding claims to enhance the penetration into wood or other cellulosic material of (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12 which is co-administered to the wood or other cellulosic material in a method of preservation.

It has been found that addition of certain highly cationic polymers to the wood preservative solutions can significantly improve preservative solution uptakes and penetration into the wood being treated.

Thus, in another aspect, the present invention provides a wood preservative formulation comprising a biocidal agent and a cationic polymer selected from the group consisting of: (i) a compound of formula (I) (CH )n (CH )n n (CH ) (ii) a compound of formula (II) (II) ; and (iii) a compound of formula (III) n (CH ) N(R )n (III) in which: n = 3 to 5000; n = 0, 1 or 2; n = 0 or 1; n = 2 or 3 and when n = 3 the nitrogen atom carries a positive charge and a counter ion X is present; R groups, which can be identical or different, are hydrogen or a straight chain, branched or cyclic alkyl, alkenyl, alkynyl, alkanoxyl, aryl, -(C=O)H, -(C=O)R , -CO H -CO R , -CH CO H, -CH CO R , CH NR R , n 2 2 n 2 2 2 2 n 2 n n -(C=O)NR R , -CN, -(CH )n -O-R , in which; n n 2 4 n R groups, which can be identical or different, are hydrogen or a straight chain, branched or cyclic alkyl, alkenyl, alkynyl, alkanoxyl or aryl; n = 2 or 3; R is of the formula (IV) H O H H R R R z z z b c d (IV) in which; R = H or OH; a = 0 to 10; b = 0 or 1; c = 0 to 10; d = 0 to 10; X is any anion selected from chloride, bromide, iodide, fluoride, sulphate, phosphate, carboxylate especially propionate and lactate, carbonate, bicarbonate, nitrate, nitrite, hydroxide, cyanide; and * represents the bonds connecting the repeating units within the backbone of the polymer.

R groups are preferably C , more preferably C , e.g. C alkyl, alkenyl, x 1-22 1-16 1-8 alkynyl or alkanoxyl, or C , more preferably C aryl. -22 6-10 Likewise R groups are preferably C , more preferably C , e.g. C alkyl, n 1-22 1-16 1-8 alkenyl, alkynyl or alkanoxyl, or C , more preferably C aryl. Aryl groups may -22 6-10 be heteroaromatic.

The molecular weight of the above polymers is typically up to 1,000,000, preferably up to 500,000, preferably at least 1,000, more preferably between 1,000 and 50,000.

As discussed in more detail below, many wood preservatives contain biocidal metal compounds, such as copper compounds, in which the metal ion acts as the primary fungicide. It is known in the art to use nitrogen containing compounds, such as monoethanolamine, as a complexing agent for the metal ion to enhance delivery of the metal into the wood. In such systems the complexing nitrogen compound is typically present at between 5 and 25% by weight of ingredients in the concentrated wood preservative formulation which is manufactured. In contrast, according to the present invention, where the cationic polymers are not included for the purposes of complexing a copper or other metal ion but to manage negatively charged extractives and by-products, the wood preservative formulation preferably contains 0.01 to 4%, more likely 0.05 to 2% by weight of a cationic polymer as defined above, more preferably 0.1 to 1%, most preferably 0.15 to 0.6%. These values refer to the amount of cationic polymer present in the wood preservative concentrate as manufactured and supplied to the treatment site. Such formulations are typically diluted with water to form treatment solutions which are 2-6% solutions on a m/v basis. The amount of cationic polymer applied to the wood will thus be correspondingly less in terms of the weight percentage of the impregnation solution.

The wood preservative formulations of the invention may comprise one or more of the following active agents; boron containing biocides such as boric acid, oxides and salts thereof and organic fungicides including fungicidal amides such as prochloraz, penthiopyrad, dichlofluanid and tolylfluanid; anilide fungicides such as sedaxane and penflufen; anilinopyrimidine fungicides such as pyrimethanil, cyprodinil or mepanipyrim; fungicidal aromatic compounds such as chlorthalonil, cresol, dicloran, pentachlorophenol, sodium pentachlorophenol, 2- (thiocyanatomethylthio)-1,3-benzothiazole (TCMBC), dichlorophen, fludioxonil and 8-hydroxyquinoline; fungicidal heterocyclic compounds such as dazomet, fenpropimorph, bethoxazin and dehydroacetic acid; strobilurins such as azoxystrobin; quaternary ammonium compounds; azoles; isothiazolones; Potassium HDO (cyclohexylhydroxydiazene 1-oxide, potassium salt); pyrion compounds such as sodium pyrithione, zinc pyrithione, copper pyrithione, 1- hydroxypyridinone and pyrion disulfide and mixtures thereof. Particularly preferred organic fungicidal agents are quaternary ammonium compounds, azoles, and mixtures thereof.

Preferred quaternary ammonium compounds are trimethyl alkyl quaternary ammonium compounds such as cocotrimethyl ammonium chloride; dialkyldimethyl quaternary ammonium compounds such as didecyl dimethyl ammonium chloride, didecyl dimethyl ammonium carbonate, didecyl dimethyl ammonium bicarbonate, dioctyl dimethyl ammonium chloride and octyl decyl dimethyl ammonium chloride, or mixtures thereof; alkyl dimethyl or diethyl benzyl ammonium salts such as benzalkonium chloride and benzalkonium hydroxide; polyethoxylated quaternary ammonium compounds such as N,N-didecyl-N-methyl- poly(oxyethyl) ammonium propionate (Bardap 26) or N,N-didecyl-N-methyl-poly(oxyethyl) ammonium lactate; and N-substituted pyridinium compounds such as cetyl pyridinium chloride.

Particularly preferred quaternary ammonium compounds are benzalkonium chloride, didecyl dimethyl ammonium chloride and didecyl dimethyl ammonium carbonate, with didecyl dimethyl ammonium chloride and didecyl dimethyl ammonium carbonate being the most preferred.

The azole compound, i.e. a compound comprising an azole group, may be an imidazole or a 1,2,4-triazole and is preferably represented by the general formula (V) wherein X denotes CR or N; R denotes hydrogen or a linear, branched, cyclic, aromatic or any combination thereof, saturated or unsaturated, substituted or unsubstituted C to C group wherein any of the carbon atoms other than those bound to the nitrogen atom shown in formula (V) may be replaced with an optionally substituted hetero atom; R denotes hydrogen, C -C alkyl, C -C alkenyl, C -C aromatic, C -C 1 8 2 8 6 10 5 10 heteroaromatic or C -C alkyl carbamate; and R and R denote hydrogen; or 3 4 3 4 together R and R may provide a benzimidazole group (i.e. R and R may combine to form -(CH) -).

The formulations of the invention may contain one or more azole compounds, such as mixtures of an imidazole and a 1,2,4-triazole, or mixtures of two or more 1,2,4-triazoles. However, it is preferred to use 1,2,4-triazoles in the formulations of the invention.

The imidazole compound incorporates a five-membered diunsaturated ring composed of three carbon atoms and two nitrogen atoms at non-adjacent positions.

The imidazole compound may be a benzimidazole. Preferred compounds include thiabendazole, imazalil, carbendazim and prochloraz.

The 1,2,4-triazole compound incorporates a five-membered diunsaturated ring composed of three nitrogen atoms and two carbon atoms at non-adjacent positions.

Preferred triazole compounds include a triazole compound selected from compounds of formula (VI): R C C R (VI) wherein R represents a branched or straight chain C alkyl group (e.g. t- butyl) and R represents a phenyl group optionally substituted by one or more substituents selected from halogen (e.g. chlorine, fluorine or bromine) atoms or C alkyl (e.g. methyl), C alkoxy (e.g. methoxy), phenyl or nitro groups.

Alternatively, the triazole compound is advantageously selected from compounds of formula (VII): (VII) 7 6 8 wherein R is as defined for R above and R represents a hydrogen atom or a branched or straight chain C alkyl group (e.g. n-propyl).

Particularly preferred triazoles include, but are not limited to, triadimefon, triadimenol, triazbutil, propiconazole, cyproconazole, difenoconazole, fluquinconazole, tebuconazole, flusilazole, uniconazole, diniconazole, bitertanol, hexaconazole, azaconazole, flutriafol, epoxyconazole, tetraconazole, penconazole, ipconazole, prothioconazole and mixtures thereof.

Particularly preferably the wood preservative formulation comprises a biocidal copper ion. The biocidal copper may advantageously be incorporated into the formulation in the form of inorganic copper salts, such as carbonate, bicarbonate, sulphate, nitrate, chloride, hydroxide, borate, fluoride or oxide.

Alternatively, the copper may be in the form of a simple organic salt, such as formate or acetate, or as a complex such as N-nitroso-N-cyclohexyl-hydroxylamine- copper (copper-HDO) or copper pyrithione (bis(2-pyridylthio)copper 1,1'-dioxide, CAS number 149158).

Preferably, the biocidal copper ion is a copper (II) ion. Preferred forms of copper (II) include basic copper carbonate (CuCO .Cu(OH) ), copper (II) acetate, copper (II) hydroxide, copper (II) oxide and copper (II) sulphate pentahydrate, with basic copper carbonate being the most preferred. Preferred copper (I) compounds that can be used are copper (I) oxide and copper-HDO.

Particularly preferred biocidal copper compounds are selected from basic copper carbonate, copper (II) acetate, copper (II) sulphate pentahydrate, copper (II) hydroxide, copper (II) oxide, copper (I) oxide, and copper-HDO.

In alternative preferred embodiments, the biocidal metal ion may be a biocidal zinc ion. The biocidal zinc may advantageously be incorporated into the formulation in the form of inorganic zinc salts, such as carbonate, bicarbonate, chloride, hydroxide, borate, oxide or phosphate. Alternatively, the zinc may be in the form of a an organozinc compound such as a simple organic salt, such as formate or acetate, or as a complex such as N-nitroso-N-cyclohexyl-hydroxylamine- zinc (zinc-HDO), zinc naphthenate or zinc pyrithione (bis(2-pyridylthio)zinc 1,1'- dioxide - CAS number 134637).

Preferred zinc compounds include zinc oxide, zinc carbonate, zinc chloride, zinc borate and zinc pyrithione, with zinc oxide, zinc carbonate and zinc borate being the most preferred.

The metal is present in the formulation of the invention as a solubilised metal ion. Suitable methods for solubilising metal ions such as copper and zinc are known in the art, for example from WO93/02557. Suitable complexing agents for the copper or zinc ion are ammonia; water soluble amines and alkanolamines capable of complexing with copper or zinc cations; and aminocarboxylic acids such as glycine, glutamic acid, ethylenediaminetetraacetic acid (EDTA), hydroxyethyldiamine triacetic acid, nitrilotriacetic acid and N-dihydroxy ethylglycine.

Where the complexing agents are acidic in nature they may be employed either as free acids or as their alkali metal or ammonium salts. These complexing agents may be used either alone or in combination with each other. Preferred complexing agents are selected from alkanolamines, such as monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, and tripropanolamine. Ethanolamines are preferred, with monoethanolamine being particularly preferred.

Formulations of the invention comprise a biocidal agent which is a copper or zinc ion complexed with an amino compound selected from the group consisting of ammonia, a water soluble amine or alkanolamine and an aminocarboxylic acid.

Preferred amino compounds are discussed herein and particularly preferred amino compounds are ammonia, monoethanolamine and primary, secondary or tertiary amines incorporating a C alkyl, preferably C alkyl, e.g. laurylamine or dimethyl 8-14 12 laurylamine.

Alternatively viewed, preferred formulations contain a zinc or copper compound and an amino compound selected from the group consisting of ammonia, a water soluble amine or alkanolamine and an aminocarboxylic acid.

The amino compound complexes with the metal ion to solubilise it.

In some embodiments, particularly where the formulation contains zinc, it may be advantageous to have two solubilising and/or complexing agents, for example an amino compound as discussed above and a gluconate salt such as sodium gluconate.

Preferred wood preservative formulations of the invention are known as alkaline copper quaternary systems, comprising a copper compound and a quaternary ammonium compound, for example as defined above. Further preferred wood preservative formulations contain an azole as defined above. More preferred formulations contain a copper compound and a triazole, preferably together with an alkanolamine. Particularly preferred formulations contain copper carbonate present as an ethanolamine complex and tebuconazole, e.g. as sold under the Tanalith brands.

Preferred cationic polymers for use in the formulations of the invention include: Poly vinyl formamides, Poly amides, Poly vinyl amides, Polyamines, branched and linear, specifically polyamines derived from epihalohydrin, Poly vinyl amines (PVAm), Poly DADMAC’s, Poly allyl amines (PAAm), Poly DADMAC Sulphones, and Vinyl amine/ vinyl formamide copolymers.

Particularly preferred are polyvinylamines, poly DADMAC and poly DADMAC-sulphone and polyamines (both high and low MW polyamines). Most preferred is a polyamine, in particular a polyamine with a molecular weight of about 1,000 to 10,000, for example 2,000 to 4,000.

In some instances it is preferable to prepare the wood preservative formulation from two or more products shortly before administration, thus in a further aspect, the present invention provides a combined wood preservative product comprising, (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined herein.

The product will typically contain a first compartment or container containing a formulation comprising (a) and a second compartment or container containing the polymer (b). The product may be supplied with written instructions for mixing and diluting (in any order) the two parts.

The formulation or product is typically diluted prior to application to the timber as an impregnation or treatment solution, the copper or zinc biocidal agent containing part may be diluted first before addition of the polymer. Dilution is preferably with water, e.g. at a ratio of water:concentrate v/v of 10:1 to 200:1, preferably 20:1 to 100:1, more preferably 20:1 to 50:1.

The treatment solution will preferably contain 10 or 50 to 1000 ppm of cationic polymer, more preferably 50 or 100 to 500 ppm (ppm = parts per million by weight).

In a further aspect, the invention provides a method of preserving wood or other cellulosic material which comprises applying to the wood or other cellulosic material a formulation of the invention as described above or applying the individual components to the wood/material such that the wood/material effectively receives a formulation of the invention.

Reference to "individual components" is not to be understood as requiring separate application of each active ingredient but as indicating that the whole complement of active and other ingredients are not simultaneously applied. Thus, the material is treated in such a way which means that it effectively receives a wood preservative formulation of the invention.

Types of wood which can benefit from treatment with the formulations of the invention include sawn timber, logs, glulam, plywood, laminated veneer lumber (LVL), wood based composite products such as oriented strand board (OSB), medium density fibreboard (MDF), fibreboard, hardboard and particle board.

It will be understood that "wood" in the context of this invention does not encompass living trees or other plants.

Other cellulosic materials which can benefit from treatment with the formulations of the invention are lignocellulosic substrates, wood plastic composites, cardboard and cardboard faced building products such as plasterboard, and cellulosic material such as cotton. Also, leather, textile materials and even synthetic fibres, hessian, rope and cordage as well as composite wood materials. For convenience, the invention is described with reference to the treatment of wood but it will be appreciated that other cellulosic materials may be treated analogously. The reference to treatment of "wood" or "timber" applies mutatis mutandis to such substrates, unless it is clear from the context. Preferably, though not exclusively, the formulations are applied to sawn timber, logs or laminated veneer lumber, OSB or MDF. Most preferably, the formulations are applied to unseasoned timber.

Conveniently, the formulations of the present invention are applied as a liquid composition. They may also be applied as a solid implant or paste.

Preferably, the formulations are applied as a liquid composition, e.g. in the form of an emulsion made up of solubilised liquid droplets. Preferably, the emulsions are in the form of a micro-emulsion. The person skilled in the art of making emulsions knows how to make an emulsion according to the invention by the use of suitable solvents and emulsifying agents.

Preferably, when applied in liquid form, this is in an aqueous solution, but one or more organic solvents or a mixture of water and an organic solvent could also be used. Suitable organic solvents include both aromatic and aliphatic hydrocarbon solvents such as white spirit, petroleum distillate, kerosene, diesel oils and naphthas. Also, glycol ethers, benzyl alcohol, 2-phenoxy ethanol, methyl carbitol, propylene carbonate, benzyl benzoate, ethyl lactate and 2-ethyl hexyl lactate.

The application of these formulations may be by one or more of dipping, deluging, spraying, brushing or other surface coating means or by impregnation methods, e.g. high pressure or double vacuum impregnation into the body of the wood or other material, all being techniques well known to the man skilled in the art.

Impregnation under pressure is particularly advantageous when the substrate is wood or a wood composite material which is made to become wet during its life, for example, wood for window frames, timber used above ground in exposed environments such as decking and timber used in ground contact or fresh water or salt water environments.

The formulations of the invention are preferably used in immersion treatments of wood, in particular immersion treatments which utilise a vacuum and/or pressure. Thus, in a further aspect, the present invention provides a wood treatment system comprising a storage tank adapted to receive the wood to be treated and in said tank a volume of treatment solution comprising a biocidal agent comprising a copper or zinc ion as defined herein and a cationic polymer as defined herein. Optionally the system further comprises an autoclave. Optionally the system comprises means to apply a vacuum or pressure, e.g. 25-95% of a full vacuum and 8-12 Bar pressure.

Substrates made of wood or cellulosic material which have been treated with a formulation or product or by a method according to the invention as described herein, comprise further aspects of the present invention. Additionally, substrates made of wood or other cellulosic material containing a biocidal agent comprising a copper or zinc ion as defined herein and a cationic polymer (e.g. a formulation) according to the invention comprise a further aspect of the present invention.

Also described is the use of formulations and products of the present invention in the treatment or preservation of wood or other cellulosic material.

In yet a further aspect, the invention provides a method of making a wood preservative formulation which comprises admixing a biocidal agent comprising a copper or zinc ion as defined herein and a cationic polymer as defined herein.

As described above, the cationic polymers defined herein improve the penetration of biocidal agents into the treated wood; thus in a further aspect, the present invention provides the use of a cationic polymer as defined herein to enhance the penetration into wood or other cellulosic material of biocidal agents comprising a copper or zinc ion as defined herein which are co-administered to the wood or other material in a method of preservation. "Preservation" (and preserving) refers to the protection of wood or other material against fungal decay, borers and termites. Also described is the use of a cationic polymer as defined herein to ameliorate the impact on penetration into wood (or other cellulosic material) of biocidal agents which is caused by anionic by-products and timber extractives, as part of a method of preserving wood or other cellulosic material. Preferred methods of application and biocides are described above.

The invention will now be further described with reference to the following non-limiting Examples and Figures in which: Figure 1 is a graph showing % gains in solution uptake achieved during impregnation of a copper MEA solution into Pinus sylvestris with various cationic polymer additives of the invention.

Figure 2 is a graph showing % gains in solution uptake achieved during impregnation of a copper MEA solution into Pinus sylvestris with various concentrations of a cationic polymer additive of the invention.

Figure 3 is a graph showing % gain in solution uptake achieved during impregnation of a zinc/gluconate/MEA solution into Pinus sylvestris with a cationic polymer additive of the invention.

Example 1 Materials and methods An aqueous solution of copper 2 ions was prepared by reacting basic copper carbonate with mono ethanolamine (MEA) to give a copper concentration of %w/w and MEA concentration of 19.2%w/w, equivalent to an MEA:Copper molar ratio of 4:1. 3%w/v aqueous solutions of the copper amine complex were prepared with separate solutions dosed with 200ppm of the cationic polymeric additives of the present invention. Additives 1 to 6 as incorporated are as follows: Product Physical Properties Viscosity, Additive Chemical Solution Approximate CAS No. cps, 22°C S.G., Freeze Flash No. Group Strength, Mw Sp 2, Sp 60 g/cm point, °C point, °C Poly vinyl 913068 1 24 10 1,000-4,000* 4 - 6 1.12 - 1.14 < 0 N/A amine 7 Low Mw Poly 2 259880 50 12 2,000-4,000* 4 - 7 1.12 - 1.16 -3 >100 amine High Mw Poly 500,000- 3 259880 55 147 4 - 7 1.12 - 1.16 -3 >100 amine 1,000,000* ,000- 4 poly DADMAC 260623 40 45 3 - 4 1.1 -3 N/A 50,000 poly DADMAC 264706 40 6 4,000 3 1.14 -5 N/A Sulphone Poly allyl 6 305514 20 15 3,000 12 1.03 -5 N/A amine * are estimates based on viscosity Additive 1 Polyvinylamine, CAS 9130687, 2-propenaminium, N,N-dimethyl-N propenyl-, chloride (1:1), polymer with 2-propenamide, decarboxylated, hydrochlorides Additive 2 Polyamine, Poly(2-hydroxypropyldimethylammonium chloride) CAS 25988- 97-0, low MW Additive 3 Polyamine, Poly(2-hydroxypropyldimethylammonium chloride) CAS 25988- 97-0, High MW Additive 4 PolyDADMAC (Diallyldimethylammoniumchloride), CAS 260623 Additive 5 PolyDADMAC-Sulphone, CAS 264706 Additive 6 Polyallylamine, CAS 305514 The 3%w/v aqueous solutions of the copper amine complex containing active substance were aged, to replicate commercial treatment plant solutions, by the addition of Pinus Sylvestris sapwood sawdust, 3.5%w/v, and stirred for 1 hour.

The sawdust was filtered from of the aqueous the copper amine solution prior to treatment of matched blocks being undertaken.

Sections of kiln dried Pinus Sylvestris (12cmx12cmx2.75cm) were then impregnated with a 3%w/v solution of the copper amine complex, using a double vacuum process.

Treatment Process:  Weigh timber sample prior to treatment.

 Place timber sample in vacuum desiccator, apply vacuum to timber, 760 mm Hg, hold under vacuum for 20 minutes.

 Flood vessel under vacuum.

 Release vacuum, and soak at atmospheric pressure for 1 hour.

 Remove sample from solution, remove residual surface solution, then re-weigh timber sample.

Uptakes were determined and these expressed as a weight gain for the timber section. Retentions were also calculated as Kg/m3, (Weight of treatment solution per m3 of pine sapwood).

The depth of penetration was observed by cross cutting the samples and spraying with a reagent that reacts with copper to generate a dark coloration (dark blue to black).

Copper Spray reagent: % Sodium acetate solution 0.5% Alcoholic Rubianic acid (Dithio-oxamide) solution Dissolve 5g of sodium acetate in 100ml of deionised water.

Dissolve 0.5g of Rubianic acid in 100ml of ethanol or methanol.

The sodium acetate solution was sprayed onto a fresh cross cut face of timber and then the Rubianic acid solution was sprayed onto the fresh cross cut face of timber. The copper penetrated timber turns a dark blue to black colour instantly.

Results Chemical Pre Post Uptake % Uptake Uptake/g Group Treatment Treatment Kg/m vs no Wt, g wt/g additive No additive 162.83 225.85 63.02 204.0 0 Polyvinylamine 161.09 348.05 186.96 605.3 197 Polyamine 156.37 286.96 130.59 422.8 107 Polyamine 161.83 246.19 84.36 273.1 34 PolyDADMAC 156.46 295.36 138.9 449.7 120 PolyDADMAC- 158.29 282.61 124.32 402.5 97 Sulphone Polyallylamine 158.62 243.70 85.08 275.4 35 For all products tested, gains in solution uptake (also reflected in the depth of penetration of the preservative in the timber) increased ~20-200% vs a solution with no additive. Results are also shown in Figure 1.

Example 2 The copper MEA solution, with 5%w/w copper concentration and an MEA:Copper molar ratio of 4:1 was prepared in accordance with the method in example 1.

Six 3%w/v aqueous solutions of the copper amine complex were prepared, with separate solutions dosed with 0, 10, 20, 30, 50 and 200 ppm of the cationic polymeric additive, additive no. 1 of the present invention, respectively.

The methods for aging the solution and treating matched blocks of Pinus Sylvestris was in accordance with those given in example 1.

Results are shown in Figure 2.

Example 3 An aqueous solution of zinc ions was prepared by reacting zinc chloride with sodium gluconate and mono ethanolamine to give a zinc concentration of 0.50%w/v and a Gluconate:Zn molar ratio of 2:1, and an MEA:Zn molar ratio of 2:1.

To separate aqueous solutions of the zinc gluconate/amine complex prepared was dosed 0 and 200 ppm of the cationic polymeric additive, additive no. 1 of the present invention, respectively.

The methods for aging the solution and treating matched blocks of Pinus Sylvestris was in accordance with those given in example 1.

Results are shown in Figure 3.

Claims (20)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: -

1. A wood preservative formulation comprising a biocidal agent which is a copper or zinc ion complexed with an amino compound selected from the group 5 consisting of ammonia, a water soluble amine or alkanolamine and an aminocarboxylic acid, and a cationic polymer selected from the group consisting of: (i) a compound of formula (I) (CH )n (CH )n n (CH ) 10 (I) (ii) a compound of formula (II) (II) ; and (iii) a compound of formula (III) n (CH ) N(R )n (III) in which: n = 3 to 5000; n = 0, 1 or 2; n = 0 or 1; n = 2 or 3 and when n = 3 the nitrogen atom carries a positive charge and a 5 counter ion X is present; R groups, which can be identical or different, are hydrogen or a straight chain, branched or cyclic alkyl, alkenyl, alkynyl, alkanoxyl, aryl, -(C=O)H, -(C=O)R , -CO H -CO R , -CH CO H, -CH CO R , CH NR R , n 2 2 n 2 2 2 2 n 2 n n -(C=O)NR R , -CN, -(CH )n -O-R , in which; n n 2 4 n 10 R groups, which can be identical or different, are hydrogen or a straight chain, branched or cyclic alkyl, alkenyl, alkynyl, alkanoxyl or aryl; n = 2 or 3; R is of the formula (IV) H O H H R R R z z z b c d 15 (IV) in which; R = H or OH; a = 0 to 10; b = 0 or 1; 20 c = 0 to 10; d = 0 to 10; X is any anion selected from chloride, bromide, iodide, fluoride, sulphate, phosphate, carboxylate especially propionate and lactate, carbonate, bicarbonate, nitrate, nitrite, hydroxide, cyanide; and 25 * represents the bonds connecting the repeating units within the backbone of the polymer.

2. A wood preservative formulation according to claim 1, wherein the polymer has a molecular weight between 1,000 and 100,000.

3. A wood preservative formulation according to claim 2, wherein the polymer has a molecular weight between 1,000 and 50,000.

4. A wood preservative formulation according to any one of the preceding claims, wherein the formulation contains 0.01 to 4% by weight of the cationic 5 polymer.

5. A wood preservative formulation according to claim 4, wherein the formulation contains 0.1 to 1% by weight of the cationic polymer. 10

6. A wood preservative formulation according to any one of the preceding claims, wherein the amino compound is monoethanolamine or ammonia.

7. A wood preservative formulation according to any one of claims 1 to 4, wherein the amino compound is laurylamine or dimethyl laurylamine.

8. A wood preservative formulation according to any one of the preceding claims, further comprising an azole compound.

9. A wood preservative formulation according to any one of the preceding 20 claims, further comprising didecyl dimethyl ammonium chloride or carbonate.

10. A wood preservative formulation according to any one of the preceding claims, wherein the cationic polymer is selected from the group consisting of: poly vinyl formamides, 25 poly amides, poly vinyl amides, polyamines, poly vinyl amines (PVAm), poly DADMAC’s, 30 poly allyl amines (PAAm), poly DADMAC sulfones, and Vinyl amine/ vinyl formamide copolymers.

11. A wood preservative formulation according to claim 10, wherein the cationic 35 polymer is a polyamine, preferably with a molecular weight of 2,000 to 4,000.

12. A wood preservative formulation according to claim 11, wherein the cationic polymer is a polyamine, preferably with a molecular weight of 2,000 to 4,000. 5

13. A combined wood preservative product comprising (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12.

14. An aqueous wood preservative treatment solution comprising a wood preservative formulation as defined in claim 1 or claim 2 or any one of claims 6 to 11, said solution containing 10 to 1000 ppm of cationic polymer.

15 15. A wood preservative treatment solution according to claim 14, which contains 50 to 1000 ppm of cationic polymer.

16. A method of preserving wood or other cellulosic material which comprises applying to the wood or other cellulosic material a formulation or solution as defined 20 in any preceding claim or applying (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12; 25 to the wood/material such that the wood/material effectively receives a formulation as defined in any one of the preceding claims.

17. A wood treatment system comprising a storage tank adapted to receive the wood to be treated and in said tank a volume of treatment solution comprising 30 (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12.

18. A substrate of wood or other cellulosic material containing: (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and 5 (b) a cationic polymer as defined in any one of claims 1 to 12.

19. A method of making a wood preservative formulation which comprises admixing: (a) a biocidal agent which is a copper or zinc ion complexed with an 10 amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12.

20. The use of a cationic polymer as defined in any one of the preceding claims 15 to enhance the penetration into wood or other cellulosic material of (a) a biocidal agent which is a copper or zinc ion complexed with an amino compound wherein said amino compound is as defined according to any one of claims 1, 6 or 7; and (b) a cationic polymer as defined in any one of claims 1 to 12 20 which is co-administered to the wood or other cellulosic material in a method of preservation. 25 Dated this 20 day of October 2015 Shelston IP Attorneys for: Arch Timber Protection Limited