NZ548674A - Combination of oxine copper and a quaternary ammonium salt in an acid solubilised system - Google Patents

Abstract

Disclosed is a biocidal composition consisting of at least: oxine copper, an acid or acids that at least in part solubilises the oxine copper, and at least one quaternary ammonium salt; wherein said at least one quaternary ammonium salt sufficient by itself, or said at least one quaternary ammonium salt is sufficient together with optional additives, to ensure the C10 corrosiveness (mg/L Fe) is less than 165.

Description

V 54 8674 *10056648008* NEW ZEALAND PATENTS ACT, 1953 No: 548674/551266 Date: 21 July 2006/10 November 2006 Intellectual Property Office of N.2. 12 JUL 2007 RECEI VEDj COMPLETE SPECIFICATION ANTISAPSTAIN COMPOSITIONS WITH IMPROVED WORKJNG PROPERTIES We, OSMOSE NEW ZEALAND, a New Zealand company of 14 Mayo Road, Wiri, Auckland, New Zealand, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 1 TECHNICAL FIELD The invention described herein relates to novel antisapstain compositions, their methods of manufacture and use as antisapstain products, for the protection of timber and other wood substrates against mould, sapstain and decay fungi.

BACKGROUND ART Oxine copper fungicidal products were first introduced to the NZ sawm.il.ling industry in the late 1970's for sapstain control, However die products were slow to be adopted by NZ mills because of corrosion concerns. Various early trials at NZ sawmills had shown elevated iron 10 levels in working solutions, indicative of corrosion of mild steel components, and dull grey streaks of iron staining on the wood. Iron stain is as significant as sapstain in the impairment of wood appearance and consequently is a major deterrent for usage of oxine copper products. Additionally, longer term corrosion effects related to maintenance costs and potential downtime of plant and equipment are negative cost factors.

Dark coloured solutions are possibly due to the presence of iron qumolinolate compounds, which are black. However it may be noted that working solutions are high in wood extractives and it is possible that other iron coordination compounds contribute to the presence of dark streaks, referred to as iron stain.

Experiences of various NZ mills using oxine copper products are that iron levels in 20 working solutions must exceed lOOmg/L before iron stain becomes noticeable on die wood.

Suppliers of oxine copper products have generally promoted "corrosion control" products based on phosphate compounds (either phosphoric acid or di-sodium hydrogen phosphate) to control iron stain. Although phosphates are known corrosion inhibitors for certain higher pH systems, diere is no reported evidence that phosphates reduce corrosion in acidic systems. Timber mill 25 experience shows that the addition of small amounts of phosphoric acid (e.g. 100 mg/L) may reduce iron stain although there is no accompanied reduction of iron levels in working solutions. It would appear that phosphate complex formation is able to keep the iron in soluble form so that iron stain is not evident. Thus phosphate addition produces a masking effect rather than inhibition of corrosion.

Addition of phosphates is only partially succcssful in controlling iron stain and overusage of phosphoric acid may actually accelerate corrosion, and cause a rise in iron levels of the working solution.

An alternative approach to corrosion minimization, practised in the USA, is die neutralisation of oxine copper solutions with borax. This procedure is carried out at the dip bath 35 stage (spray systems are not as common as in NZ) using less than 1% w/v borax and a fine 2 suspension of oxine copper is formed. This approach has not found favour in NZ, with the widely held view that formulations containing particulate oxine copper arc not as efficacious as acid solubilised versions.

Despite potential corrosion problems outlined above, oxine copper formulations, have 5 proved highly cost efficacious, and have continued to grow in popularity in NZ. From the early 1990's the chemical has been the major active used in NZ and many mills, especially those with spray systems, have been able to mitigate corrosion by (epoxy) coating steel surfaces or using stainless steel pumps, spray nozzles etc. Mills with automated dip bath systems, however, have lesser ability to use such corrosivc products, as high costs are associated with full protection of 10 plant and equipment, especially for moving plants such as outfeed chains and rollers.

In 1992, an emulsifiable concentrate product, Hylite Extra (Chemicca, 1989) containing oxine copper and carbcndaziin was introduced to NZ sawmills. Hylite Extra is based on solubilisation of oxine copper with dodecyl benzene sulphonic acid (DDBSA) with cosolvents and suffactants suitable to maintain carbendazi.ni solubility in the concentrate. The pioduct has 15 been used by many NZ mills without significant corrosion problems and is therefore a suitable yardstick for development of other potentially corrosive antisapstain products.

Until the late 1990's, DDBSA was the only acid used for solubilisation of oxine copper in commercial products, In 1998, oxine copper products based on solubilisation by phosphorous acid were registered in NZ (Maynard, W09953760 (PCT/NZ99/00045)). Cost and efficacy 20 advantages relating to the use of methane sulphonic acid (MSA) have also been revealed (Frazer, W005051618 (PCT/NZ2004/000303)). This patent disclosed that oxine copper products based on MSA are less corrosive than equivalent products based on phosphorous acid. However in the development of oxine copper products based on MSA, it is desired to produce products of similar or less corrosiveness to the Hylite Extra product.

SUMMARY OF THE INVENTION The present invention is directed to formulations of oxine copper having a quaternary ammonium salt presence that are efficacious (e.g. as antisapstains) and/or which have low corrosiveness of iron for such acid solubilised systems with the copper content. 30 In another aspect the invention is a biocidal composition (whether to be further diluted or not) consisting of at least oxine copper, an acid or acids that at least in part solubilises the oxine copper, and at least one quaternary ammonium salt.

Preferably said biocidal composition is an antisapstain composition. 3 A combination of oxine coppei and a quaternary ammonium salt in an acid solubilised system for the oxine copper opens up efficacy advantages whether with or without further additions. See, for example, Examples 10-13 hereinafter. The combination, irrespective of whether or not there arc such efficacy advantages, provide lower corrosiveness of iron.

Preferably said composition has a corrosion inhibiting presence of said at least one quaternary ammonium salt- Optionally said composition in addition includes at least one triazole, preferably a corrosion inhibiting triazole.

Preferably said acid or acids is a strong acid or strong acids.

Preferably said acid is one or more of MSA (methane sulphonic acid) or phosphorous acid, or a combination of both. Most preferably it is MSA.

Preferably said quaternary ammonium salt is selected from the group consisting of didecyl dimethyl ammonium chloride (DDAC) and benzalkonium chloride (BAC).

The preferred acid is MSA. We have also shown the corrosion reduction effect of the 15 quaternary ammonium salt (such as DDAC) with phosphorous acid. These arc dissimilar acids. Accordingly we believe that corrosion inhibition by DDAC is unrelated to the acid anion and that the corrosion inhibition provided by the presence of at least a quaternary ammonium salt (such as DDAC or BAC) is applicable to all acids (compatible with the composition components) capable of dissolving oxine copper. Examples of such acids include sulphuric acid, sulphamic 20 acid, nitric acid, phosphoric acid, substituted phosphonic acids and hydrochloric acid. This list may not be exhaustive and mixtures of any of the suitable acids can be contemplated.

By way of example of component incompatability, DDBSA has anionic surfactancy properties and is not compatible with DDAC.

Optionally said quaternary ammonium salt itself is a biocide (e.g. a fungicide) 25 Optionally a coactive is present or is added prior to use. Suitable co-actives include one or more triazole, benzimidazole, tri bromo-phenol and/or OPP (ortho-phenyl phenol). However this list is not limiting, and of the several thousand fungicidal!)' active compounds known to mankind, the only formulation requirement; is that the co-active be stable in the acidic environments of this invention.

Preferably a said optional benzimidazole is carbendazim.

Optionally OPP is present.

Preferably any optional said triazole is selected from a group typified by benzotrinzole, tolyltriazole, tebuconazole and propiconazole. 4 Tebuconazole and propiconazole are corrosion inhibitors. We have shown an additive effect where addition of both QAS (DDAC or BAC) and triazole has produced a lower corrosivity than either corrosion inhibitor individually.

Preferably the composition is and/or is to be diluted by a carrier liquid (e.g. water and/or 5 an organic liquid (e.g. a glycol such as ethylene glycol).

A preferred organic diluent is a glycol such as ethetyene glycol, however other compatible glycols can be used. Preferably some water is present.

In the concentrates as prepared, organic agents such as glycols or non-ionic surfactants may comprise none, part, or alJ of the carrier fluid. Usually water comprises at least part of the 10 carrier. The composition of the carrier is largely dependent on the solubilisation properties of the co-actives.

In the working solutions., by way of example, water comprises over 95% v/v of die mix.

In another aspect the present invention consists in a biocidal composition having oxine copper supported in a system that includes an oxine copper solubilising acid or acids and at least 15 one quaternary ammonium salt sufficient by itself (and with optional additives) to ensure the Ci0 corrosiveness (mg/L Fe) is less than 165.

Preferably the C)0 is less than 136.

Preferably the C10is less than 100.

Preferably die C10is less than 80.

Preferably the C,0 is less than 60.

Preferably said C,0.is less than 50 (more preferably less than 40).

Preferably said C10 is less than 30.

In still a further aspect the present invention consists in an antisapstain or biocidal composition (whether to be further diluted or not) consisting of at least oxine copper in the 25 presence of an acid or acids that at least Ln part solubilises die oxine copper, and at least, a sufficient presence of a suitable triazole or suitable triazolcs in conjunction with at least one quaternary ammonium salt so as to inhibit corrosion, (e.g. preferably by lowering (as a result of the presence of die triazole(s) and the at least one quaternary ammonium salt) the C)0 corrosivity as herein used below than that would otherwise be the case with the triazole or quaternary 30 ammonium salt alone).

Preferably said acid or acids is a system includes or consists solely of one or both of MSA and phosphorous acid.

In another aspect the invention consists in a "two pot" antisapstain composition (whether to be further diluted or not, and irrespective of whether dilution is post or premixing) 35 comprising or including, (I) as ilic first "pot": oxine copper, an acid 01: acids that at least in part solubilises the oxine coppei:, and at least one quaternary ammonium salt, and 5 C) as the second "pot": a fungicidal composition.

In a furcher aspect the invention consists in an antisapstain composition inclusive of an oxine coppet: at least in part solubilised in an acid or acids, wherein there is a corrosion inhibitory presence of at least one quaternary ammonium salt.

Preferably the C10 corrosivity is below that of the oxine copper were is solubilised only in MSA.

Preferably it is solubilised in MSA and has a C10 below 100 (preferably below 80 more preferably still below 60, 50 or 40 and most preferably below 30).

The invention also is an antisapstain composition or biocidal composition 15 comprising or including 1 to 25% oxine copper, 1 to 70% of oxine copper solubilising acid(s), 1 to 70% of quaternary ammonium salt(s), 0 to 10% of at least one triazole 20 0 to 80% organic cattier(s) 0 to 80% surfactant(s) 0 to 80% water (and optionally other content (e.g. one or more coactive, such as OPP).

The % are V„. Note % v/v x 10 is g/L.

In a further aspect the present invention consist in an antisapsttain composition (e.g. preferably as a concentrate suitable for dilution) comprising or including 1 to 25% oxine coppei 0 to 50% MSA 0 to 70% phosphorous acid 30 1 to 70% a quaternary ammonium salt(s) 0 to 10% of at least one triazole 0 to 80%organic carriet(s) 0 to 80%surfactant 0 to 80% water; ancl optionally other content (e.g. one or more coactive). 6 with the proviso that there is a presence of at least one of MSA ot phosphorous acid; and wherein the presence of at least the at least one quaternary ammonium salt has a corrosion inhibiting affect.

The present invention also includes a "two pot" biocidal or antisapstain composition where addition of one pot to the other provides a composition of any previous aspect of the invention.

One pot can include acid(s) and the oxine copper.

The other pot can include one or more coactive. Best anticorrosion results from the 10 quaternary ammonium salt(s) and any optional triazole(s) being present whenever the acid solubilised oxine copper is likely to encounter a metal that might corrodc.

In a further aspect the present invention consists in a method of treating a substrate (preferably wood or timbers) which involves coating and/or impregnating with a composition of any of the kinds of die present invention.

In yet a further aspect die present invention consists in a substrate treated by a composition in accordance with the present invention, e.g. treated woods or timbers.

In the present invention, quaternary ammonium salts, such as didecvl dimethyl ammonium chloride (DDAC), may be incorporated in oxine coppei: formulations, solubilised in strong acids such as MSA or phosphorous acid, to produce antisapstain products of relatively low 20 corrosivity.

Furthermore in the present invention combinations of quaternary ammonium salt plus triazole, when added to acid oxine copper formulations, have favourable corrosion profiles compared to established commercial oxine copper products.

The present invention shows incorporation of quaternary ammonium salts in acidic oxine 25 copper formulations can be used advantageously to produce antisapstain products with enhanced fungicidal activity. Such combinations have not been previously reported.

Examples, not confining of the invention, of how oxine copper plus quaternary ammonium salt combinations may be employed with other actives in a single formulation or combined with suspension concentrates and added as two - pot mixtures to antisapstain 30 application systems are disclosed hereinafter.

As used herein the term "and/or" means "and" or "or", or both.

As used herein the term "(s)" following a noun includes, as might be appropriate, the singular or plural forms of that noun.

As used herein the term "pot" includes an already mixed component. 35 As used herein the term "Cu8" means or includes oxine copper. 7 Corrosion of Ferrous Metals in Acid Systems Corrosion involves a flow of electrons from the anode to the cathode. In the case of an iron metal anode, the reaction is Fe — 2e Fe2+ and the ferrous ions formed are soluble in the 5 acidic media (pH < 3) of the acid solubilised oxine copper products of this study.

In acidic solutions, two cathodic reactions may occur: (a) Reduction of (dissolved) oxygen: V2 02 +2 H30+ + 2e 3 H20 (la) Reduction of hydrogen (hydronium) ions to hydrogen: 2 HjO+ + 2e H2 + 2 OH ~ The reduction of oxygen reaction is relatively independent of pH, whereas the hydrogen 10 evolution reaction is strongly favoured as the pH decreases.

A wide range of physical factors, such as temperature, fluid flow rate, physical imperfections and surface area of the metal affect corrosion rates of iron and steel. Chemical factors influencing corrosion rates include the nature of the acid anion, composition of the ferrous metal, and the presence of other anions and cations.

Numerous studies have been carried out on the corrosion protection of ferrous metals in the presence of acids, mainly related to steel pickling compositions.

In the I9,h and early 20<h centuries corrosion inhibition additives used for pickling acids, such as hydrochloric acid and sulphuric acid, included flour, molasses, vegetable oils, alkaloids and other plant and animal extracts.

The most commonly used corrosion inhibitors used today for iron and steel in acid media are various heterocyclic compounds (particularly triazoles and imidazolines), quaternary ammonium salts, amine derivatives, organic phosphates, and succinimides (Abdel Hamid et al, 1998).

Heterocyclic compounds are ferrous metal corrosion inhibitors. Use of triazoles to 25 inhibit acid corrosion of steel has been repotted by Al-Farkh (1980); Tadtos (1988); Muralidharan (1995); Bentiss ct al, (1999); Green (1998); Kravitz (2003), and Chebabe ct al, (2003). Use of oxadiazoles is reported by Bentiss, (2003) and thiazolc compounds by Athar, (2002).

Cationic surfactants, particularly quaternary ammonium salts, have been shown to be efficient corrosion inhibitors for acid solutions in contact with ferrous metals (Abdel Hamid et al, 30 1998; El Dalian et al, 1999). Bereket and Yurt, (2002) in a study of nine cationic surfactants, including six quaternary ammonium salts, concluded that inhibition efficiency increased with increasing chain length of the hydrophobic group and the presence of an aromatic group. 8 Corrosion of Ferrous Metals in Acid Systems which Contain Copper Ions The presence of copper ions in acid systems presents a further complexity due to t.he presence of a third competing cathodic reaction, related to the reduction of copper ions to copper metal: Cu2+ + 2e Cu The presence of copper ions in acid solutions has been shown to enhance corrosion of steel (Subrahmanyam and Hoey, 1975: Scheers, 1992). However, Singh and Singh, (1987) report that ppm quantities of copper ions reduce the corrosion rate of mild steel in sulphuric acid. Also a Japanese patent (Hatsutod et al, 1995) relates to addition of coppcr ions to reduce corrosion of 10 stainless steels in contact with organic sulphonic acids.

Corrosion of steel may be enhanced or reduced by copper ions in conjunction with corrosion inhibitors. Wahden et al (1997) report that 10"4 M quantities of copper in conjunction with imidazole strongly inhibited corrosion of steel by sulphuric acid. However higher copper-ion concentrations (10"3 N't) caused an increase of corrosion rate. Gomaa (1998) reports corrosion 15 of steel in 0.1M sulphuric acid is significantly reduced by a combination of benzotriazole and 10'3 M copper ions. At higher copper ions concentrations corrosion rates arc enhanced. The use of heterocyclic compounds to reduce corrosion of steel in the presence of coppcr ions has been reported by Gomaa, (2000), who studied the effect of copper ion concentration on the corrosion of steel by sulphuric acid in the presence of tolyltriazole. The inhibition efficiency of tolyltriazole 20 was greater with increasing copper ion concentrations in the range 10"4 to 10"' M.

Measurement of Corrosion The two main laboratory corrosion methods used in the above referenced studies ate potentiodynamic methods and coupon corrosion tests.

Apparatus for potentiodynamic methods comprises a three electrode system widi a polished mild steel anode, a platinum counter electrode and a saturated calomel reference elcctrode. The method, described for example by Neufeld, (1989), involves initial immersion of the iron electrode to measure the free corrosion potential before the polarization curves are recorded. The cathodic polarization measurements are yielded by constantly scanning to higher 30 negative potentials and recording the resultant corrosion currents. Similarly anodic measurements may be recorded by moving to higher positive potentials. Inhibition efficiencies are determined from corrosion currents by the Tafel extrapolation method. Measurements are repeated for different concentrations of the corrosion inhibitor and the resulting changes in Tafel slopes in the cathodic and anodic regions are indicative of whether the inhibitor affects 35 predominant.])' the cathodic or anodic reaction. 9 Alternatively, corrosion rates may be determined by weight loss measurements of immersed test specimens (coupons) of known composition for various periods in the corrosive solutions. Prior to immersion, the coupons should be polished to remove oxide and cleaned to remove any surface contamination. After immersion the coupons are carefully removed, dried 5 and weighed.

Although these methods have found widespread application in measuring corrosion of steel in acid media, we have discovered difficulties in obtaining meaningful results in our antisapstain product systems containing copper ions. Problems may be caused by copper plating on the steel surface, which in some cases forms a dense tenacious coating on the steel surface which inhibits further corrosion. In other cases copper is formed with little affinity to the steel and is easily flaked off to form a fresh steel sutface for continued corrosion. In the potentiodynamic method, described above, it is essential to have a constant anode surface to make meaningful measurements of corrosion currents. Also in coupon corrosion tests the effect of copper plating on the steel surface causes a weight gain, rather than a weight loss.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents arc deemed to be incorporated herein as if individually set forth.

BRIEF DESCRIPTION OF DRAWINGS A preferred form of the present invention will now be described with reference to the accompany non limited examples and drawings in which Figure 1 is a plot in respect of Example 6 of Fe (mg/L) against Time evaluating Tolyltriazole and DDA (as Corrosion Inhibitors, and Figure 2 is a plot in respect of Example 7 of Fe (mg/L) against Time evaluating Tebuconazole and Propiconazole as Additives.

DETAILED DESCRIPTION In recognition of the difficulties of corrosion testing acidic copper solutions we developed a corrosion test method based primarily on the reactivity of iron in the corrosive solution, without: the major influence of copper plating.

In our method a measured weight of cast iron filings is added to a stirred volume of the test solution. At specified time intervals, aliquots of the test solution are removed and immediately filtered to remove any iron filings, the filtrate being retained for analysis of iron. The iron content, of the filtrate is recorded as a measure of the corrosiveness of the test solution.

The apparatus consisted of a variable speed stirrer (rotation speed 400rpm) fitted with a Quickfk glass stirrer shaft and matching 40mm segment blade. The apparatus settings were 5 designed to allow some movement of the iron particles in die stirred solution but the fluid movement was not sufficient to create a large vortex and thus create major air entrapment in the fluid. A selected iron filings fraction of particle size of -355 + 106 microns was used for the corrosion studies.

Using 500mL of the test solution in the beaker and with the stirrer turned on, l.OOg of 10 cast iron filings is added to the solution. At time periods 2, 4, 8,12, and 16 minutes, 10 mL aliquots were removed from the solution and immediately filtered to remove any iron particles. Filtrates were retained for iron analysis by atomic absorption spectroscopy.

The relationships between solute iron contents and reaction times may be presented graphically. For comparisons between samples it has been found convenient to have a single 1 5 measure of corrosivity. In this study the iron content at 10 minutes reaction time was chosen (denoted as C1Q), interpolated from the best (polynomial) fit to the graph.

Repeatability tests indicated a standard deviation of 7% around a mean value for a single point of time analysis, which is sa as factory for our range of corrosivities encountered.

The main advantage of this corrosion method is that the presence of a large surface area 20 of highly reactive iron minimises the copper plating inhibition effect and thus is a better reflection of the reactivity of the metal surface to the corroding solution. I t may be argued that, copper plating of steel surfaces is also seen in the industrial environment and so this effect should also be an integral part of the laboratory method. However it should be noted in relation to industrial plant and equipment, that the tenacity of die copper coating depends on a number of 25 physical factors (cavities, local flow rates, weld defects, etc) not necessarily represented by the polished steel surfaces of the laboratory specimens.

The development of experimental mediod for determining corrosion as detailed above has permitted an understanding of the nature of corrosion of die various oxine copper based antisapstain products of interest. Fundamental to understanding these systems is knowledge of 30 whether corrosion was essentially due to the acid nature of these systems or due to the presence of copper ions in solution. In the former case, where corrosion is dependent on the reduction of hydrogen ions (hydrogen evolution reaction), previous research by other workers into corrosion inhibition of the hydrogen evolution reaction, discussed above, may also be applicable to our antisapstain systems. Alternatively if the corrosion was related mainly to the cathodic reduction 35 of copper ions to copper, it would be apparent that there would be little useful existing 11 information available as corrosion inhibition of similar systems have not been widely studied. In fact, timber treatments may be the only commercial applications of acid systems containing appreciable concentrations of copper ions, where corrosion is of major importance.

Although it is visually apparent that copper plating occurs on steel surfaces in contact 5 with antisapstain solutions it is not obvious if the copper reaction is a minor or major contributor to the total corrosion. Therefore the first two examples have been designed to quantify the relative contributions of the various competing cathodic reactions.

Example 1. Corrosion Properties of Oxine Copper Products Solubilised by Various Acids.

Six products were prepared as aqueous concentrates with the following ratios (w/w) of acid to oxine copper; DDBSA = 10.7:1 Phosphorous acid = 4.8:1 MSA = 1.75:1 Sulphuric acid — 2.0: 1 15 Phosphoric acid =6.75:1 Sulphamic acid = 2.7:1 Each of the above solutions, diluted to a concentration of lg/L oxine coppcr was tested by die above cast iron filings corrosion test. The C,0 corrosivities (Fe solubilised after 10 minutes 20 reaction) and pH of the solutions were measured.

As shown in Table 1, similar corrosivities were observed for sulphuric, sulphamic, phosphorous and phosphoric acids. The DDBSA formulation had a significantly lower corrosivity and MSA appeared to have intermediate corrosivity, It was considered possible that differences in corrosivity may be related to the hydrogen ion contents of the solutions. Therefore 25 comparative pH measurements were made on die six formulations, also shown in Tabic 1.

Tablel. Comparison of Corrosivity and pH for Acid Solubilised Oxine Copper Products.

Sample Cu-8 (g/L) Acid Acid (g/L) pH Cio(Femg/L) 500 1.0 Phosphorous 4.8 1.67 165 504 1.0 DDBSA .7 1.94 58 650 1.0 MSA 1.75 1.81 136 523 1.0 Sulphuric 2.0 1.80 175 525 1.0 Sulphamic 2.7 1.81 178 527 1.0 Phosphoric 6.7 1.89 175 12 Although the DDBSA formulation had rhe lowest corrosivity and the highest pH, there was no obvious relationship between pH and corrosivity for the samples.

Example 2. Comparison of Acid Corrosivities in the Absence of Oxine Copper Aqueous formulations of the sbc acids were prepared to give the same acid concentrations used in the test solutions of Example 1. and tested for corrosivity by the same procedure as in Example 1.

Comparisons of the C10 corrosivities of die acid only and the acid + oxine copper products are shown in Table 2.

Table 2. C10 Corrosivities of Various Acids with and without Oxine Copper.

C10 (mg/L Fe) Acid only Acid + Oxine Copper Phosphorous Acid 55 165 DDBSA 29 58 Sulphuric Acid 46 175 Sulphamic Acid 52 178 Phosphoric Acid 66 175 Methane Sulphonic Acid 43 136 The results showed that die presence of oxine copper greatly enhanced the degree of corrosion. Thus the major cathodic reaction occurring was die reduction of cupric ions, rather than reduction of hydrogen ions which accounted for about one-third of the total corrosion.

This data confirms that the corrosivities of antisapstain solutions of this invention are due mainly to the reduction of cupric ions. Therefore in the search for suitable corrosion inhibitors for these products, no reliance can be made on corrosion inhibitors designed for systems which do not contain copper ions.

Example 3. Evaluation of Carbendazim and Oxinate Anion as Corrosion Inhibitors The search for corrosion inhibitors for oxine copper formulations was prompted by our previous discovery (Frazer, 2004) that methane sulphonic acid (MSA) afforded a cost effective 13 means of formulating such products. Although the corrosivity of MSA formulations was less than equivalent products formulated with phosphorous acid they were higher than products formulated with DDBSA, such as Hylite Extra. Therefore the objective was no locate an additive to the MSA formulations that would exhibit similarly tow corrosion characteristics to 5 formulations based on DDBSA. Ea rly studies related to determining if any of the components of oxine copper formulations such as carbendazim or the oxinate anion provided any corrosion inhibition. Therefore oxine copper formulations (based on MSA) with and without carbendazim were compared. The differences between the corrosivities of a solution without carbendazim (C|0 = 136) and with lg/L carbendazim (C10 =115) were minor and almost within experimental error.

Also small differences were observed between MSA formulations containing oxine copper (C10 — 136) and copper hydroxide (Ct0 - 161) indicating that the presence of die oxinate ion may have a weakly inhibitive effect on corrosion.

Example 4. Evaluation of DDAC as a Corrosion Inhibitor Background Preliminary visual assessments of mild steel coupons immersed in an oxine copper solution (MSA based) indicated that the quaternary ammonium salts (QAS), may have corrosion inhibitor)' properties.

As reported above, quaternary ammonium salts are known corrosion inhibitors in acid systems. However, DDAC does not have been specifically studied in this regard. In addition, the ability of quaternary ammonium salts to inhibit corrosion in acid systems containing copper ions has not previously been reported.

Five oxine copper formulations were prepared containing lg/L oxine copper, 2.5g/L MSA and levels of DDAC ranging from zero to 21.4g/L (note - all DDAC contents are expressed as 100% active) Corrosive properties of the formulations were tested by the cast iron filings method. Oxine copper samples based on DDBSA (I0.7g/L) and Hylite Extra were included in the comparison shown in Table 3.

The corrosion rates for ail the samples containing DDAC were similar, and significantly less than the sample containing no DDAC. The results clearly showed that DDAC is a corrosion inhibitor for this system. The corrosion rates of the DDAC containing samples were similar to the oxine copper product formulated with DDBSA (sample 504), but higher than the commercial product, Hylite Extra (sample 506). 14 Table 3. Compositions and Corrosivities of Samples Containing DDAC.

COMPOSITION C10 (9"-) mg/L Sample Cu-8 MSA DDAC 533 1.0 2.5 nil 180 538 1.0 2.5 0.6 53 537 1.0 2.5 2.3 53 536 1.0 2.5 .4 51 535 1.0 2.5 21.4 56 504 1.0 DDBSA 10.7g/L 58 506 1.0 Hylite Extra 21 Example 5. Evaluation of Benzotriazole as a Corrosion Inhibitor.

DDAC has corrosion inhibitory properties in ox.inc copper formulations. However, none of the DDAC containing formulations matched the desired low corrosion rates obtained for Hylite Extra. A further chemical that showed promise in a visual pre-sctcening trial was 25 benzotriazole.

An oxine copper/ Carbendazim/ MSA test solution was prepared. The corrosive properties of this base solution were compared to three equal solutions, which contained either DDAC or benzotriazole. The compositions of these solutions are shown in Table 4.

Table 4. Composition of Samples to Determine Corrosion Inhibitory Effects of Benzotriazole.

Oxine Sample c°PPer g/L Hylite Extra 1.0 Carbendazim MSA g/L g/L 1.0 DDAC Benzotriazole g/L g/L Proprietary (DDBSA based) Cio Corrosivity Fe (ppm) 661 1.0 1.0 3.5 - - 107 662 1.0 1.0 3.5 6.4 - 40 663 1.0 1.0 3.5 - 0.4 23 664 1.0 1.0 3.5 - 0.8 23 21 The results showed that additions of benzotriazole at 0.4 and 0.8g/L produced corrosion inhibitor^' effects significantly greater than addition of 6.4g/L DDAC. No greater benefit is achieved at 0.8g/L compared to 0.4g/L benzotriazole. Corrosion rates For the benzotriazole containing samples were similar (possibly slightly higher) to the sample of Hylite Extra.

Example 6. Evaluation of Tolyltriazole as a Corrosion Inhibitor.

A sample containing 75g/L oxine copper, 280g/L MSA (100% equivalent) and 200g/L DDAC (100% equivalent) and 30g/L tolyltriazole was prepared (sample 724), which was stable at ambient temperature . A further sample without the tolyltriazole was also prepared for comparison (sample 726). Solutions for the cast iron filings corrosion test were prepared by 15 dilution of the concentrates to oxine copper concentrations of lg/L.

Comparison of the corrosion rates of the oxine copper/MSA samples with DDAC only and DDAC plus tolyltriazole (fig.'l) showed that tolyltriazole was an effective corrosion inhibitor for this system. The corrosion rate of the tolyltriazole containing sample was comparable to Hylite Extra. 16 Example 7. Evaluation ofTebuconazole and Propiconazolc as Corrosion Inhibitors.

The triazole compounds, tebuconazolc and propiconazole have known fungicidal properties and have use as wood preservatives, although the generally high costs of these 5 compounds have precluded use in antisapstain products. However these compounds may be used at low levels to mitigate corrosion of oxine copper formulations as shown in this example.

Formulations 726, 729, and 730, containing DDAC and tebuconazolc or propiconazole were prepared as shown in Table 5.

Table 5. Compositions of Solutions Containing DDAC, and Triazoles.

Sample Oxine Cu fl'L MSA g/L DDAC (as 100%) g/L Other (g/L) 726 1.0 2.8 2.0 729 1.0 2.8 2.0 Tebuconazole (0.4) 730 1.0 2.8 2.0 Propiconazole (0.4) Hylite Extra 1.0 Carbendazim (1.0) Results from the cast iron filings corrosion test are shown in Figure 2. The two triazole compounds (propiconazole and tebuconazolc) showed good corrosion inhibition and the formulations were comparable to Hylite Extra in this regard. • 15 Example 8. Evaluation of Benzalkonium Chloride as a Corrosion Inhibitor.

Previous examples show die corrosion inhibition properties of DDAC in acid oxine copper, systems. The ability of other quaternary ammonium salts, such as alkyl (CI 2-'16) dimethyl benzyl ammonium chloride, commonly referred to as benzalkonium chloride (BAC), is 20 demonstrated in this example.

Aqueous solutions prepared by dissolving coppcr oxide in MSA at 70°C and adding quantities of BAC and/or tolyltriazole to the cooled solutions. The working solution concentrations and the CIO corrosivities of the tested solutions are shown in Tabic 6. 17 Table 6■ Compositions and Corrosivities of Formulations Containing BAC and Tolyltriazole.

Cu2+ MSA BAC as 100% Tolyltriazole C10 corrosivity Sample (g/L) (g/L) (g/L) (g/L) (g/L) 720 0.18 2.2 - - 186 721 0.18 2.2 - 0.57 24 722 0.18 3.2 1.75 0.53 19 723 0.18 3.0 1.75 - 40 Comparison of the corrosivities of samples 720 and 723, shows that the quaternary ammonium salt, BAC, is also effective corrosion inhibitor. This indicates that the inhibition is related to the functional moiety of the quaternary ammonium ion rather than the hydrocarbon groups, and that all quaternary ammonium compounds will therefore exhibit corrosion inhibitive properties. The sample containing tolyltriazole (721) showed a greater inhibitory effect compared 10 to the sample containing BAC. However as shown in Examples 6 and 7, the quaternary ammonium salt may be advantageously combined with a triazole to produce lower corrosivity' than either inhibitor alone.

Example 9. Corrosion Inhibitive Properties of QAS in Other Acid Systems.

Alternative acid systems used to commercially to solublise oxine copper include DDBSA and phosphorous acid. The sulphonic acid, DDBSA, has anionic surfactancy properties whereas quaternary ammonium salts are cationic surfactants. Although it is possible to combine anionic and surfactant surfactants in formulations there is a net cancelling of the activities of the individual compounds and upon dilution with water in working solutions highly insoluble compounds are formed. We have therefore not applied this corrosion inhibition technology to oxine compound formulations based on DDBSA.

However this technology may be usefully applied to inhibit corrosion in oxine coppcr formulations based on strong acids, such as phosphorous acid as shown in this example, as follows: Sample (A) -10g of oxine copper were dissolved in 48 g Phosphorous acid + 65.5 g Water. 18 Sample (B) - To 6.17g of Sample (A) , 4i 17 g of 80% DDAC was added to produce a clear solution.

Both products (A) and (B) were diluted with water to equivalent 1g/L as oxine copper and tested for corrosivity by the cast iron filings test method. The compositions and corrosivities 5 of the test solutions are shown in Table 7.

Table 7. QAS as Corrosion Inhibitor for Oxine Copper in Phosphorous Acid.

Oxine Copper Phosphorous Acid DDAC Corrosivity Sample g/L g/L g/L (ppm Fe) 500 1.0 4.8 - 164 531 1.0 4.8 5.5 56 The results indicate that the levels of inhibition provided by DDAC in phosphorous acid 10 systems are similar to that provided in the MSA system described in Example 4.

Example 10. Efficacy of two Oxine Copper Products Containing QAS.

Two oxine copper products containing DDAC were prepared as concentrates as per Table 8.

Table 8. Compositions of Concentrates containing Oxine Copper and DDAC.

Sample 395 Sample 431 (%w/w) ' (%w/w) Oxine Copper 4.3 4.5 MSA (as 100%) 8.7 11.6 DDAC (as 80%) .9 23.6 Ethylene glycol 70.6 - Water - 60.3 Tribromophenol 5.4 19 Both these products were trialled at 2% v/v. The reference sample of Hylite Extra was mailed at a dilution of 1.2% v/v.

Timber lengths of 100 x 25mm were taken from a sawmill green chain (prior to antisapstain treatment) and pieces were selected containing high sapwood contents. The timber 5 was cut to 400 mm lengths and pieces containing significant wane or defects were rejected. The pieces were stacked in piles to allow some degree of randomness of wood selection for the individual wood treatments.

Individual pieces were dipped for 10 seconds in a plastic tub containing the various treatment solutions. After dipping, the boards were rested in a near vertical position until drip 10 free. The boards were then transferred to a warm room ar 24°C and 50% RH, individually placed on their sides on shelves to partially air dry for three days before placing in plastic bags and sealed for storage. Each treatment comprised 30 boards arranged in a packet 10 high by three wide.

Inspection of the treated timber was made after nine weeks storage of average infection (two faces) per board. A fass / fail criterion was used whereby a failed surface is defined as 15 having greater than 5% fungal coverage of the board surface area.

The trial results expressed as % failed surfaces were as follows: Sample 395 (Oxine Cu + DDAC + Tribromophenol) = 11% Sample 431 (Oxine Cu + DDAC) = 2% Hylite Extra = 65% Sample 431, containing oxine copper and the higher level of DDAC, performed significantly better than Hylite Extra, which contained similar levels of oxine copper in the trial treatments. Sample 395, containing the co-active tribromophenol performed better than Hylite Extra, but not as well as sample 431, which had a higher DDAC content.

Example 11. Use of Oxine Coppcr/QAS Formulations with Other Fungicides (Two-Pot Mixtures).

Composition 784 was prepared with the following components (%w/v); Oxine copper (7.5); DDAC (20); Tolyltriazole (1.5); MSA (28); Non-ionic surfactant (4.5); Ethylene glycol (7.5), Water (46.5).

Composition 784 was diluted to 2% (v/v) for efficacy evaluation by the same procedure outlined in Example 10. A second 2% dilution of composition 784 was prepared and 0.8% (v/v) of a 50% suspension of chlorothalonil was added directly to the working solution while stirring to ensure a uniform suspension. A third preparation of 2% (v/v) of Hylite Extra was used as a reference control to assess the comparative efficacies of the compositions. The trial results expressed as % failed surfaces after 13 weeks were as follows; 2% Composition 784 (Oxine copper + DDAC) = 17% fails Above composition + 0.4% chlorothalonil = 3% fails 5 2% Hylite Extra = 45% fails The results show potentially high fungicidal efficacy is achievable from such two pot: mixtures, Example 12. Incorporation of a Third Active in Oxine Copper/QAS formulations.

In some cases it may be advantageous to incorporate additional fungicides into formulations of oxine copper and QAS. For instance, to improve resistance to mould fungi, the fungicide ortho-plicnyl phenol (OPP) may be employed as per the Composition 785 as follows; Composition 785 (%w/v); Oxine copper (7.5); DDAC (36.8); OPP (7.5); MSA (28); tolyltriazole (1.5); Nonionic 15 surfactant (6); Water (31).

Composition 785 was diluted to 2% (v/v) for efficacy evaluation by the same procedure outlined in Example 10. Comparative evaluations with a similar composition without OPP and Hylite Extra were made after 13 weeks storage as follows; 2% Composition 785 (oxine copper + DDAC + OPP) ~ 5% fails 20 2% Composition 784 (oxine copper + DDAC) = 17% fails 2% Hylite Extra — 45% fails The result showed that the incorporation of OPP into the formulation improved fungicidal efficacy of the oxine copper/DDAC combination.

Example 13. Further Example of the Efficacy Contribution of DDAC.

Composition 785 in Example 12, which contained oxine copper, DDAC and OPP was compared to two similar formulations with adjusted DDAC levels to determine the contribution of DDAC in the formulation.

The concentrations of the working solutions, in which the test pieces of wood were dipped are shown in Table 9. The test method used was similar to that described in Example 10. However the wood showed some signs of pre-infection which was reflected in the relatively high infection levels of all treatments in the trial. 21 Table 9. Efficacy of Oxine Copper Compositions with Varying DDAC levels Oxine DDAC OPP Tolyltriazole % Fails Sample copper (g/L) (g/L) (g/L) (g/L) (9 weeks) 797 1.5 0 1.5 0.3 36 796 1.5 4.0 1.5 0.3 19 785 1.5 7.36 1.5 0.3 Hylite Extra 1.5 1.5 g/L Carbendazim 83 The results confirmed the importance of the quaternary ammonium salt in the 5 formulations with increased efficacy related to higher levels of DDAC. 22 REFERENCES Abdel Hamid, Z., Soto, T. Y., El Dahan, H. A. and Omar, A. M. A.(1998) JVeiv Cationic Surfactant as Corrosion Inhibitor for Mild steel in Hydrochloric Acid Solutions. 5 Anticorrosion Methods and Materials 45, 306-311.

Al-Fatkh, Y., Alhajjar, F.H., Hamoud, H.S. and Al-Shamali, F.S (1980). Further Experiments on the Control of Corrosion of Mild Steel in Crude OH Distillation.

Corrosion Science 20,1195-1200.

Athat, M. and Qutaishi, M.A. (2002). Corrosion Inhibition of Carbon Steel in Hydrochloric Acid by Organic Compounds. British Corrosion Journal 37, 155-158.

Bentiss, F., Lagrence, M., Traisnel, M. and Hornez, J. C. (1999). The Corrosion 15 Inhibition of Mild Steel in Acidic Media by a new Triazole Derivative. Corrosion Scicnce 41789-803.

Bentiss, F., Traisnel, M., Vesin, H. and Lagrenee, M. (2003) Linear resistance model of the inhibition mechanism of steel in HCl by triazole and oxadiazole derivatives: structure 20 activity relationships. Corrosion Science 45 371-380.

Bereket, G. and Yurt, A (2002). Inhibition of die Corrosion of Low Carbon Steel in Acidic Solution by Sclccted Quaternary Ammonium Compounds. Anti Corrosion Methods and Materials 49, 210-220.

Chebabc, D., Ait Chikh, Z., Hajjaji, N., Srhihi, A. and Zucchi,F. (2003). Corrosion Inhibition of Armco Iron in 1M HCL Solution by Alkyltriazoles. Corrosion Science 45, 309-320.

Chemicca Ltd (1989). Improvements in or Relating- to Fungicides. NZ Patent 225428.

El Dahan, H. A., Mohamed, T. Y. S. and Abo El-Enin, S. A. (1999). Efficient Quaternary Ammonium Salt as Corrosion Inhibitor for Steel Pickling in Sulphuric Acid Media. Anti-Corrosion Methods and Materials 46, 358-363. 23 Gomaa, G. K. (1998). Influence of Copper Cation on Inhibition of Corrosion for Steel in Presence of Benzotriazole in Sulfuric Acid. Materials Chemistry and Physics 55(2), 131-138.

Gomaa, G. K. (2000). Effect of Copper Cation on Corrosion of Steel by Tolyltriazole in Acidic Medium. Indian Journal of Chemical Technology 7, 300-306.

Green, B. P. (1998) A Biocidal Corrosion Inhibiting- Compound. Int. Patent W098/22554.

Hatsutori, A., Nakamura, K., Noda, T. and Washama, T. (1995). Corrosion Prevention with Copper Ions for Stainless Steel in Handling of Organic Sulfonic Acids. Jpn. Kokai Tokkyo Koho. Application: JP 94-68530.

Kravitz, J.I. (2003). Antimicrobial Lubricant Coating and Method for Using. U.S Pat. 15 6,525,005.

Maynard, N. P. (1999). A Biocidal Composition Containing Phosphite Ions. International Patent, WO 9953760.

Muralidharan, S., Quraishi, M.A. and Iyer,S.V.K. (1995). The Effect of Molccular Structure on Hydrogen Permeation and die Corrosion Inhibition of Mild Steel in Acidic Solutions. Corrosion Science 37 1739-1750.

Neufeld, P. (Ed.) 1989. A working Party Report on Practical Corrosion Principles. 25 European Federation of Corrosion Publications No 2, Institute of Metals, London.

Scheets, P. V. (1992). The Effects of Flow Velocity and pH on the Corrosion Rate of Mild Steel in a Synthetic Minewater. Journal of the South African Institute of Mining & Metallurgy. 92(10), 275-81.

Singh, I. and Singh, M. (1987). Effect of Metallic Cations on the Corrosion and the Hydrogen Absorption by Cold-rolled Mild Steel in Inhibited Sulfuric Acid. Corrosion 43(7),425-9. 24 Subrahmanyam,D. V. and Hoey, G. R. (1975). Effect of Water Quality on the Corrosion and Electrochemical Behavior of Mild SteeJ in Synthetic Acid Mine Waters. Corrosion 31(6), 202-7.

Tadros, A. B. (1988). Inhibition of die Acid Corrosion of Steel by 4-amino-3-hydrazino-thio-lj2,4-triazoIes. J. Electroanal. Chem. 246 433-439.

Wahdan, M. H., Gomma, G. K. (1997). Effect of Copper Cation on Electrochemical Behavior of Steel in Presence of Imidazole in Acid Medium. Materials Chemistry and Physics 47(2-3), 176-183.

Claims (35)

CLAIMS:

1. A biocidal composition (whether to be further diluted or not) consisting of at least: I oxine copper, an acid or acids that at least in part solubilises the oxine copper, and 5 at least one quaternary ammonium salt; wherein said at least one quaternary ammonium salt sufficient by itself, or said at least one quaternary ammonium salt is sufficient together with optional additives, to ensure the C10 corrosiveness (mg/L Fe) is less than 165.

2. A composition of claim 1 which is an antisapstain composition. 10

3. A composition of claim 1 or 2 wherein the quaternary ammonium salt presence is a corrosion inhibiting presence of said at least one quaternary ammonium salt.

4. A composition of any one of claims 1 to 3 wherein said acid or acids is a strong acid or are strong acids.

5. A composition of claim 4 wherein said acid is MSA (methane sulphonic acid), 15 phosphorous acid, or both.

6. A composition of claim 4 wherein the acid is MSA.

7. A composition of any one of claims 1 to 6 wherein said at least one quaternary ammonium salt is selected from the group consisting of didecyl dimethyl ammonium chloride (DDAC) and benzalkonium chloride (BAC). 20

8. A composition of any one of claims 1 to 7 wherein said at least one quaternary ammonium salt itself is a biocide.

9. A composition of any one of claims 1 to 8 wherein a coactive is present or is added prior to use.

10. A composition of claim 9 wherein said coactive is at least one of the group comprising 25 benzimidazoles and OPP (ortho-phenyl phenol).

11. A composition of claim 10 wherein OPP is present.

12. A composition of any one of claims 1 to 11 having, in addition, at least one triazole.

13. A composition of claim 12 wherein said triazole is a corrosion inhibiting triazole.

14. A composition of claim 12 or 13 wherein said triazole is selected from a group typified by 30 benzotriazole, tolyltriazole, tebuconazole and propiconazole.

15. A composition of claim 14 wherein at least one of tebuconazole and propiconazole is present.

16. A composition of any one of claims 1 to 15 wherein there is present (a) DDAC, BAC, or both, and (b) a triazole. 35 17. A composition of any one of claims 1 to 16 diluted or to be diluted by a carrier lio(^r

A v I 1 4 JAN 2009 26

18. A composition of claim 17 wherein said carrier liquid is or includes water.

19. A composition of claim 17 or 18 wherein said carrier liquid is, or includes, a glycol.

20. A composition of any one of claims 17 to 19 wherein it has been diluted and water comprises over 95% v/v of the diluted composition. 5

21. A biocidal composition of any one of the preceding claims wherein the C10 is less than 136.

22. A biocidal composition of claim 21 wherein the C10is less than 100.

23. A biocidal composition of claim 22 wherein the C10is less than 80.

24. A biocidal composition of claim 23 wherein the C10 is less than 60. 10

25. A biocidal composition of claim 24 wherein said C10.is less than 50

26. A biocidal composition of claim 25 wherein said C10.is less than 40,

27. A biocidal composition of claim 26 wherein said C10 is less than 30.

28. A composition of claim 1 having at least a sufficient presence of a suitable triazole or suitable triazoles in conjunction with said at least one quaternary ammonium salt so as to inhibit 15 corrosion to a C10 corrosivity below than that would otherwise be the case with the triazole or quaternary ammonium salt alone.

29. A composition of claim 28 wherein said acid or acids is a system includes or consists solely of one or both of MSA and phosphorous acid.

30. A "two pot" antisapstain composition (whether to be further diluted or not, and 20 irrespective of whether dilution is post or premixing) comprising or including, (I) as the first "pot": a composition of any one of the preceding claims, and (II) as the second "pot": a fungicidal composition.

31. A composition of claim 1 comprising or including 25 1 to 25% oxine copper, 1 to 70% of oxine copper solubilising acid(s), 1 to 70% of quaternary ammonium salt(s), 0 to 10%) of at least one triazole, 0 to 80% organic carrier(s), 30 0 to 80% surfactant(s), and 0 to 80% water, and, optionally, other content

32. A composition of claim 31 wherein at least one coactive selected from the benzimidazoles or OPP is/are present. % 1 k JAN ZOffl '' ^ > 27

33. A method of treating a substrate which involves coating and/or impregnating with a composition of any one of claims 1 to 32.

34. A substrate treated by a composition in accordance with any one of claims 1 to 32.

35. A substrate of claim 34 which is a wood or limber. DATED THIS fj-f'^ DAY OF-'.^a AUENTS BOR THI APPLICANT