Compositions and process for the protective treatment of wood

Details Compositions and process for the protective treatment of wood Compositions and process for the protective treatment of wood

2000-10-06

2002-02-19

Green, Anthony (Department: 1755)

Compositions: coating or plastic

Coating or plastic compositions

Contains fireproofing or biocidal agent

C106S018330, C106S284000, C427S298000, C514S642000, C514S643000

Reexamination Certificate

active

06348089

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to compositions based on coal-tar oil for the protective treatment of wood. It furthermore relates to a process for the protective treatment of wood using the compositions according to the invention.
BACKGROUND OF THE INVENTION
The use of coal-tar oil for protecting wood against rot and attack by insects has been known since the middle of the 19th century and is still customarily employed for preserving masts, fences, beams etc. Even early on, attempts were made to use coal-tar oil in the form of emulsions in water or aqueous protective salt solutions (zinc salts, copper salts). However, these use forms did not give the desired results, and most tar oils were still used undiluted. In addition, attempts were made to improve the unsatisfactory stability of coal-tar oil emulsions by “homogenization” (analogously to the process used for milk) or by treatment with specifically adapted dispersing apparatus (for example ULTRA-TURRAX®) and diverse additives (AT-PS-86,925, EP-A-0 227 430). These processes involve expensive equipment and consume a lot of energy. More recently, the application of coal-tar oil emulsions in water attracted renewed interest, in particular since in this manner it is possible to partially eliminate or reduce some disadvantages of the undiluted coal-tar oil, such as, for example, the unpleasant odour, the tendency to sweat and the sticky surface of the treated woods (U.S. Pat. No. 5,098,472).
This known process has the disadvantage that the emulsions are relatively unstable and that, owing to the emulsion, the effective proportion of coal-tar is reduced by the proportion of water and the emulsifier(s), so that the amount that is applied has to be increased to ensure effective and long-lasting protection.
OBJECT OF THE INVENTION
Accordingly, it was an object of the present invention to eliminate or reduce the disadvantages of the known preparation processes and applications of tar oil emulsions.
According to the invention, this object is achieved by the compositions described below and pressure treating wood with a composition of the present invention.
SUMMARY OF THE INVENTION
Surprisingly, it has been found that, by using biocidally active quaternary ammonium compounds, if appropriate together with polar solvents, such as, for example, glycol derivatives, it is possible to prepare stable emulsions and microemulsions of coal-tar oil in water by simple stirring without any special equipment requirements. Not only does the biocidal action of the quaternary ammonium compounds compensate for the fact that the tar oil is diluted, but it has additionally been found—contrary to expectations—that the depth of penetration and the activity spectrum considerably exceeds those of the pure undiluted tar oil.
The compositions according to the invention comprise at least the following components:
a) 5-90 parts, preferably 10-90 parts, of coal-tar oil
b) 2-20 parts of a biocidally active quaternary ammonium compound
c) 10-90 parts of water.
Here and below, all amounts are stated in parts by mass.
Suitable biocidally active quaternary ammonium compounds are, for example:
N—C
8-20
-alkyl-N,N-dimethyl-N-benzylammonium chloride, bromide or iodide
*)
N,N-di-C
6-20
-alkyl-N,N-dimethylammonium chloride, bromide or iodide
*)
N—C
6-20
-alkyl salts
*)
of pyridine, quinoline, etc.
N—C
6-20
-alkyl-N,N,N-trimethylammonium chloride, bromide or iodide
*)
N,N-di-C
6-20
-alkyl-N-methyl-N-poly(ethoxy)ammonium salts
*)
*)
Instead of the halides, it is also possible for the salts of other inorganic acids or organic carboxylic acids to be present, for example acetate, propionate, sulphate, etc.
It has been found, for example, that an emulsion comprising only 30% of tar oil, about 10% of a cationic ammonium compound, about 5% of auxiliary and 55% of water was at least twice as effective against wood-destroying fungi as undiluted pure coal-tar oil.
With the aid of these compositions, it is possible to utilize the excellent activity of coal-tar oil, supported by long-term experience, and at the same time to reduce considerably the disadvantages of odour, of sweating at high ambient temperatures, of elutability and of the oily sticky surface of the wood.
Simultaneously, better, i.e. more uniform and deeper, distribution of the protective composition in the wood is achieved and—this appears to be particularly advantageous—the wood can have a higher moisture content than would be possible if pure tar oil was used. Thus, the time and energy for drying the raw wood, for example beams and masts, can be reduced considerably.
DETAILED DESCRIPTION OF THE INVENTION
A further advantage of the compositions according to the invention consists in the fact that they can be processed at normal ambient temperatures, in contrast to pure tar oil. That is to say that pure tar oil, owing to its viscosity and flow behaviour, can only be processed at temperatures of about 100° C., which is associated with a high energy input. Moreover, this property of tar oil stands in the way of deep penetration and optimum distribution in the wood.
The intense odour of coal-tar oil is caused, in particular, by bi- and tricyclic aromatic compounds, for example naphthalene and alkylnaphthalenes. Only some of these can be removed by distillation since, if they are removed completely, a tar oil is formed which has a viscosity which is too high and not even manageable at 100-120° C. Because of the way in which they are prepared, the compositions according to the invention permit the use even of tar oils of relatively high viscosity which, accordingly, are highly deodorized, which facilitates the use of coal-tar oil even in sensitive areas, for example beams for underground rails, or makes this use possible in the first place.
Preferably, the compositions according to the invention additionally comprise up to 20 parts of a polyglycol compound to improve (storage) stability. These include, for example, polyethylene glycols and polypropylene glycols, and their alkyl and aryl ethers and esters.
Particular preference is given to polyethylene glycol compounds such as, for example, polyethylene glycol, to ethoxylated phenols and to diethylene glycol monobutyl ethers.
In addition to the formulation components already mentioned, the compositions according to the invention may comprise, for example, the following substances:
resins, binders, polymers
waxes
dyes
pigments
antioxidants
odour-masking substances
markers (tracers)
They preferably comprise one or more components from the group of the resins, binders, waxes, dyes and pigments.
Particularly preferred binders are alkyd resins and similar resins based on natural oils, such as linseed oil or soya oil, in particular those which are water-soluble or water-dilutable owing to reaction with ethylene oxide or propylene oxide.
To widen the activity spectrum, the compositions according to the invention preferably additionally comprise an effective amount of one or more insecticides, fungicides, algicides or bacteriocides.
They may comprise, for example, one or more of the following active compounds:
Amphoteric surfactants having biocidal action
Methyl benzimidazol-2-ylcarbamate
1,2-Benzisothiazol-3-one
Biguanides having biocidal action
Organic and inorganic boron compounds
&agr;-tert-Butyl-&agr;-(p-chlorophenethyl)-1H-1,2,4-triazol-1-ethanol
2-sec-Butylphenyl N-methylcarbamate
(±)-cis-4-[3-(tert-Butylphenyl)-2-methylpropyl]-2,6-dimethylmorpholine
5-Chloro-2-methyl-4-isothiazolin-3-one
2-(4-Chlorophenyl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol
1-(6-Chloro-3-pyridinyl)methyl-4,5-dihydro-N-nitro-1H-imidazol-2-amine
Chlorohexidine and its salts
Chlorinated phenols, for example tetra- and penta-chlorophenol
Chloronitrobenzene derivatives
1-[4-(2-Chloro-&agr;,&agr;,&agr;-trifluoro-p-tolyloxy)-2-fluorophenyl]-3-(2,6-difluorobenzoyl)urea
1-(4-Chlorophenyl)-3-(2,6-difluorobenzoyl)urea
&agr;-[2-(4-Chlorophenyl)ethyl]-&agr;-(1,1-dimethylethyl)-1H-1,2,4-triazol-1-ethanol
Cyano(4-fluoro-3-phenoxyphenyl)methyl 3-

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