Wood preservative for subsequent application

Details Wood preservative for subsequent application Wood preservative for subsequent application

1999-09-01

2002-03-05

Green, Anthony (Department: 1755)

Compositions: coating or plastic

Coating or plastic compositions

Contains fireproofing or biocidal agent

C106S018300, C106S018310, C424S404000, C424S405000, C424S638000, C514S557000, C514S561000, C514S574000

Reexamination Certificate

active

06352583

ABSTRACT:

The present invention relates to the use of a wood preservative for the supplemental protection of wood, comprising a copper compound, an alkanolmonoamine and a complexing organic carboxylic acid or its ammonium or alkali metal salts and a wrap for the supplemental protection of wood which contains this wood preservative.
For the supplemental maintenance of transmission poles existing in the grid of telephone and electricity-supplying companies, or similar poles, wraps with water-soluble wood preservatives are applied in particular in the groundline region. It is known to employ, for this purpose, water-soluble salts based on inorganic fluorine compounds, e.g. alkali metal fluorides, in some cases together with alkali metal bichromate or boron compounds such as boric acid or borax. However, these salts act exclusively against wood-destroying Basidiomycetes, while not providing an activity against soft rot for applications which involve contact with the soil. Substances which have been proposed as active against soft rot are, on the one hand, dinitrophenol (Barry A. Richardson: Wood preservation—The Construction Press Ltd., Lancaster p. 181) or combinations of the abovementioned compounds with water-soluble copper salts, e.g. copper sulfate or copper acetate. Mixtures of copper sulfate, also in combination with alkali bichromate, with boric acid and copper acetate with alkali fluoroborates are part of the prior art. In the meantime, dinitrophenol has been excluded due to its toxicity.
The water-soluble abovementioned copper compounds, alone, but also in the abovementioned combinations, do not have good diffusion properties for sufficiently penetrating for example the sapwood of pine poles, also during long standing times, and to reach the heart.
Wood preservatives based on copper and amines as complexing agent have been proposed for large-scale impregnation, in particular boiler pressure impregnation.
EP-B-211 181 relates to a wood preservative based on a copper salt and monoethanolamine for the boiler pressure impregnation of wood.
EP-B 270 848 describes a wood preservative based on a copper compound, a carboxylic acid and an aliphatic polyamine for boiler pressure impregnation.
EP-A 423 674 describes a wood preservative based on a metal salt of an N-organyldiazeniumdioxy compound and a complexing polymeric amine for the boiler pressure method.
All the above-described wood preservatives feature high copper fixation potential in the wood. This limits the diffusibility of the copper, which is why these systems are not suitable for the supplemental protection of wood.
“Known, currently used systems for the supplemental protection of wood contain, for example, combinations of copper naphthanate, boron compounds and fluorine compounds. An example of this product type which is used mainly in the USA is CuRAP 20 (ISK Biotech), a paste containing 18.16% of amine-based copper naphthenate and 40% of sodium tetraborate decahydrate. Analyses on poles (wood species: Douglas-fir and pine), which have been treated with this product, showed that, after 1 to 3 years of application, most of the copper is distributed virtually only in the outer zone (0-10 mm) in the wood (depth of penetration analyzed: up to 25 mm) and these products thus only have a very limited diffusibility as regards copper (Conserving energy by environmentally acceptable practices in maintaining and procuring transmission poles. 15th annual report, September 1995, J. J. Morrell, Oregon State University, Corvallis, Oreg.).”
WO 96/23636 describes wood preservatives in paste form which comprise a fungicidal metal compound and a fungicidal boron compound. The metal compounds also embrace copper complexed with aminocarboxylic acids or polycarboxylic acids.
WO 96/23635 describes a wood preservative which comprises a metal chelate. Described are copper complexes with amino acids, iminodiacetic acid, ethylenediaminotetraacetic acid, dicarboxylic acids and polyphosphates.
The copper complexes with nitrogen-containing complexing polycarboxylic acids, e.g. imidodiacetic acid, ethylenediaminotetraacetic acid or nitrilotriacetic acid, do not become fixed in wood, but are leached completely from the wood (WO 96/23635, page 20, Table 6) and thus diffuse from wood into the environment when exposed to moisture (weathering, contact with the soil), which not only means increased pollution, but, as time goes by, the wood is not protected sufficiently against soft rot. This also applies to other complexing acids such as the hydroxycarboxylic acids, e.g. citric acid, malic acid and tartaric acid.
In contrast, copper chelates with other dicarboxylic acids, for example phthalic acid, maleic acids, lack sufficient diffusibility.
Thus, formulations based on the abovementioned substances alone are not ideally suited for the supplemental protection of wood.
German Patent Application DE-A 196 08 435 describes the use of a wood preservative for the supplemental protection of wood which comprises a copper compound, a polyamine and an inorganic fungicide.
It is an object of the present invention to provide a wood preservative for the supplemental protection of wood which features good diffusibility of the copper in the wood combined with good protection against soft rot and Basidiomycetes.
It is a further object of the present invention to provide a wrap which comprises this wood preservative for the supplemental protection of wood.
We have found that these objects are achieved by a wood preservative, for the supplemental protection of wood, based on a copper compound, an alkanolmonoamine and a complexing organic carboxylic acid or its ammonium or alkali metal salts and, if appropriate, further auxiliaries and, if appropriate, water.
For the sake of simplicity, all or some of the copper compound may also be present in the form of the salt of the complexing organic carboxylic acid (e.g. copper citrate, copper tartrate).
To improve the activity, inorganic fungicides may also be admixed to the wood preservative as a complement.
These wood preservatives are especially suitable for the supplemental protection and supplemental maintenance of wood and are used in the form of wraps and by the injection inoculation-method, the drilled hole method and the paste method. In the presence of moisture, e.g. ground contact, they penetrate the sapwood, and they have a good depth action.
Copper compounds which can be used are compounds which are soluble or insoluble in water, e.g. copper sulfate, copper acetate, copper citrate, copper tartrate, copper naphthenate, copper hydroxide, copper hydroxycarbonate, copper oxychloride, copper oxide, copper borate, copper fluoride, copper fluoroborate, bis(N-cyclohexyldiazeniumdioxy)copper, or mixtures of these.
Preferred are copper hydroxycarbonate, copper hydroxide and mixtures of these.
Copper hydroxide, specifically stabilized copper hydroxide (Norddeutsche Affinerie), is especially preferably used.
The activity of the wood preservatives can be improved by the salts of N-cyclohexyldiazenium dioxide and other diazenium dioxides, e.g. as the potassium salt, in which case, as a rule, the abovementioned bis(N-cyclohexyldiazeniumdioxy)copper is formed with copper compounds.
The mixtures comprise from 0.25 to 15% by weight of copper, calculated as the element. Some of the copper can also be replaced, for example by a corresponding zinc compound.
The following can be used as alkanolmonoamines: monoalkanolmonoamines, dialkanolmonoamines, trialkanolmonoamines having 2 to 18 C atoms, and N—C
1
-C
4
-monoalkylmonoalkanolmonoamines, N—C
1
-C
4
-dialkylmonoalkanolmonoamines, N—C
1
-C
4
-monoalkyldialkanolmonoamines and mixtures of these.
Suitable examples are: monoethanolamine, diethanolamine, triethanolamine, 3-aminopropanol, monoisopropanolamine, 4-aminobutanol, monomethylethanolamine, dimethylethanolamine, triethylethanolamine, monoethylethanolamine, N-methyldiethanolamine and mixtures of these.
The following are preferably used: monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, and mixtures of these.
Monoethanolamine i

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