FI83603B - MEDEL FOER IMPREGNERING AV MASSIVT TRAE. - Google Patents

Abstract

1. A concentrate for impregnating solid wood in order to preserve the latter, based on a copper salt and monoethanolamine and, if required, a salt with a fungicidal anion, wherein the concentrate contains from 5 to 50% by weight of monoethanolamine and, if required, further alkali such that a pH of not less than 8 is established.

Description

1 83603

The present invention relates to the preparation of substances for pressure impregnation of (solid) wood based on aqueous copper salt, monoethanolamine and possibly other ingredients, in particular fungicidally active salts based on anion, such as boric acid salts. preparations.

To date, chromium-containing, adhesive wood preservatives have been used to protect wood that is exposed to the open air or moisture or in contact with the ground. These wood preservatives are used as aqueous solutions with a concentration of, for example, 2-6%, depending on the severity of the subsequent conditions of use of the wood to be impregnated, and impregnation 15 is carried out by means of industrial impregnation equipment (pressure impregnation).

Due to the required anti-decay effect, only substances containing not only chromate but also copper are used in connection with ground contact. Preparations 20 are divided into CK-type (copper-chromium-based), CKB-type (copper-chromium-boron-based), CKF-type (copper-chromium-fluorine-based) and CKA-type (copper-chromium-copper-based) products.

These wood preservatives adhere through the chromate component 25: after impregnation, the chromates react with the wood components and are reduced to trivalent chromium compounds, raising the pH of the wood so that the copper and chromium compounds in the wood precipitate as water-insoluble compounds.

30 However, chromates, ie compounds of hexavalent chromium, pose a significant environmental risk when leaching occurs due to weather conditions during leakage or attachment, so that surface, ground and drinking water are contaminated; the maximum concentration considered to be tolerable in water is, for example, 0.05 ppm. Even when chromium is present in wood in the 2 8360ό insoluble trivalent form, it can be converted back to hexavalent chromium compounds through oxidation during combustion, which can then be extracted from the ash; this causes waste concept-5 lyong problems.

Hitherto, chromium-free, copper-containing water-soluble wood preservatives have been proposed for industrial impregnation, in which, for example, copper arsenates and borates have been converted into a water-soluble basic form by complexation with ammonia; through the evaporation of ammonia and the lowering of the pH caused by the constituents of the wood (the specific pH of the wood is about 5), these substances attach to the wood. In addition to the odor load they cause, these impregnation solutions or concentrates can also lose their stability due to the evaporation of ammonia, so that the solutions are no longer usable for impregnation. In addition, the absorption of the preservative into the wood is prevented when the ammonia content is insufficient.

Amines, for example ethylenediamine, which have good complexing properties, which have good complexing properties, have also been recommended for copper- and fluorine-containing wood preservatives used to protect wood materials (e.g. particle board); these substances are mixed in very concentrated form with glue and sprayed with it on the chips. They are not suitable for the protection of whole wood, as ethylenediamine complexes are also stable at the specific pH values of the wood (5-6) and thus do not adhere; they are washed out of the wood with water.

Copper attachment is only successful when organic, water-insoluble copper salts can be formed. Thus, wood preservatives containing copper salts of N-nitrosocyclohexylhydroxylamine have been described (renamed copper salt of N-cyclohexyldioxiniacenium oxide, Cu-HDO). Cu-HDO is converted by means of polyamines, for example ethylenediamine or diethylenetriamine, into wood preservative concentrates which are dissolved in water for impregnation. They adhere to the wood as the pH decreases to about 7.5 due to the effect of the wood components. However, this attachment occurs so rapidly that, in the case of pressure-5 impregnation, the absorption of Cu-HDO into the wood is prevented. For example, in the case of pine, which is inherently easy to absorb, Cu-HDO only reaches the outermost layer, about 10-15 mm thick; the amount of preservative decreases rapidly as it moves deeper than the surface.

If other amines are used to form the complex, for example alkanolamines, in particular monoethanolamine, Cu-HDO is completely soluble only in very concentrated solutions, and when the mixture is diluted with water to the working concentration, it precipitates again.

15 It has now been found that the disadvantages described above can be avoided by using water-dilutable substances obtained from (inorganic) copper compounds (water-soluble or insoluble, such as copper sulphate, copper fluoroborate, copper hydroxide, copper borate, copper borate, or copper oxychloride) by complexing with monoethanolamines in aqueous solution, the pH of the ready-to-use dilution should be at least 8.

25 Water-dilutable substances generally contain, in their concentrated form, 1 to 15% by weight of copper, calculated as the element.

Suitable concentrates contain, for example (in weight percent), 5 to 50% copper salt, 5 to 50% monoethanolamine, up to 50% fungicidally active anion salt and up to 5% free base, the sum being in each case 100 (% by weight), 4 83603 and optionally very small amounts of other constituents, such as amines, ammonia, corrosion inhibitors and, if necessary, water, the proportion of which, however, can generally be considered small and which is intended primarily to improve handability. However, the invention likewise also relates to impregnation solutions which can be prepared by diluting with water, in which the concentration is correspondingly lower.

Complexation can take place in the presence of fungicidal anions such as borates or fluorides. Dissolution of the copper compounds in monoethanolamine, optionally with the addition of water, gives very concentrated water-soluble pastes or concentrates in liquid form which, when dissolved in water, can be used to impregnate wood. The pH of the saturated impregnation solution is at least 8, in particular 9-10 (depending on the concentration). When impregnation is performed by the printing method, the copper component penetrates well into the wood. The pH of the wood preservatives according to the invention decreases during impregnation under the influence of the acids contained in the wood, and copper precipitates at a pH of about 7; namely, the complexing ability of monoethanolamine is no longer sufficient when the pH drops below 7-7.5 to keep the copper in solution so that the copper adheres. The degree of attachment of copper is then of the same order of magnitude as that of chromate- and copper-containing wood preservatives to date; i.e., at least 85%, on average 90-95% of the copper components adhere. The attachment is then partly dependent on the excess monoethanolamine necessary to adjust the pH in the presence of strong acids or fungicidal anions; however, some of the pH-adjusting effect can also be achieved by adding, for example, alkali hydroxide, for example as much as is needed to change the pH by no more than one unit. 35 In general, this measure affects the proportion of fungicidal anions 5 83603, i.e. acid residues; Irrespective of complexation, the pH can also be adjusted with bases, ammonia or other water-soluble amines.

For economic reasons, monoethanolimine in particular is suitable as a complexing agent; the preparation of the wood preservatives according to the invention is also possible using other alkanolamines, for example isopropanolamine, 1,1- or 1,2-diaminoethanol, aminoethyleneethanolamine, diethanolamine, dimethylethanolamine, etc.

10 The amount of alkanolamines to be added is such that it is sufficient, firstly, to complex copper (1 gram of copper usually requires 4 molar equivalents of amine) and, secondly, to form both alkanolamine salts of fungicidal anions (fluoride, borate, fluoroborate) or acid esters, the pH of the impregnation solution is set to at least 8, preferably 9 to 10.

To test the invention in practice, the following procedure was followed: The indicated amount (4 or 3%) of the concentrate was diluted with water, and the resulting solution was absorbed into pine logs.

After drying, said logs were rinsed with distilled water for 4 weeks, at which time the water was changed to fresh daily. The amount of 25 copper extracted was then determined.

Example 1

A mixture of 33.3% by weight of CuSO 4 * 5H 2 O, 33.3% by weight of monoethanolamine and 33.4% by weight of water was in each case dissolved in 40 g of 1 Isa water (hereinafter referred to as "4% solution"). ). 7.5% is extracted from copper.

6 83603

Example 2 20.0 wt% 3Cu (OH) 2 * CuCl 2 40.5 wt% monoethanolamine and 40.0 wt% water 5 (4% aqueous solution); 10.5% of the copper is extracted.

Example 3 15.0 wt% Cu (OH) 2-CuCO 3 16.0 wt% monoethanolamine, 16.0 wt% aminoethylethanolamine, 25.0 wt% H 2 BO 3 and 38.0 wt% water (4-%: aqueous solution); extraction: Cu 10.5%; B 85.5%. Example 4 13.5 wt% Cu (OH) 2 25.0 wt% boric acid, 17.5 wt% monoethanolamine, 17.5 wt% aminopropanol and 26.5 wt% water (4% aqueous solution); extraction: Cu 7.7%; B 86.5%. Example 5 50% Cu (BF4) 2 solution (50% solution in water), 30% monoethanolamine and 20% water (3% aqueous solution; definition as above); 25 extraction: Cu 10.5%; F 70.0%; B 75.0%.

Example 6 16.5% Cu (OH) 2 * CuCO 3, 10% NH 4 HF 2, 36.0% monoethanolamine and 3.5% water (3% aqueous solution); extraction: Cu 0.5%; F 78.5%. Example 7 15.0% Cu (OH) 2 * CuCO 3 30% aminoethanolamine, 35 25.0% boric acid and 7 83603 27.0% water (4% aqueous solution); extraction: Cu 12.5%; B 88.0%. Example 8 70% copper borate paste (50% dispersion in water) and 30% monoethanolamine (4% aqueous solution); extraction: Cu 7.5%; B 85.0%. Example 9 75% copper borate paste (50% dispersion in water) and 25% monoethanolamine (4% aqueous solution); extraction: Cu 6.2%; B 66.1%. Comparative test 1 Chromium-containing salts:

15 1a) Type CKB

Cu content 8.6%

Cr content 13.6% B content 4.4%

1b) Type CKF

20 Cu content 7.7%

Cr content 25.5% F content 14.5% la) Type CKB Extraction (%)

Cu 8.0 25 Cr 2.0 B 93.5 lb) Type CKF Extraction (%)

Cu 13.5

Cr 18.5 30 F 72.5

Comparative Experiment 2 (not according to the invention) 12.0% CuO, 22.0% ethylenediamine, 12.0% KHF2 and 54.0% water

Dissolve 3% in water. Extraction: Cu 75.5%; F 92.5%.

Claims (4)

1. Solid wood impregnation agent, which is based on a water dilutable preparation containing copper salt, monoethanolamine and optionally a salt formed with a fungicidal anion, characterized in that it contains 5-50 weight percent. % monoethanolamine and possibly any other base 1 in such an amount that when the agent is diluted to a usual concentration of concentration containing 1-5% by weight of non-aqueous constituents, the pH of the aqueous solution is at least 8. 2. An agent according to claim 1, characterized in that it additionally contains a boric acid or boric acid. 3. A process for pressure impregnation of wood, characterized in that an aqueous solution prepared from the agent according to claim 1 or 2 is used, which solution contains copper salt and monoethanolamine and has a pH of at least 8. Process for preparing an impregnation solution for the process according to claim 3, characterized in that the agent according to claim 1 or 2 is diluted with water or a concentrate of copper salt and optionally monoethanolamine diluted and the pH of the solution is adjusted at least to the value 8 by adding it. monoethanolamine and optionally a base.