DE2823574A1 - PROCESS FOR WOOD TREATMENT - Google Patents

Description

DR. BERC DIPL. ING. STAFF

DIPL.-ING. SCHWABE DR. DR. SANDMAIR 2823574

PATENT LAWYERS

P.O. Box 860245,8000 Munich

May 30, 1978

FOREST PRODUCTS UTILIZATION LABORATORY State College, Missisippi 39762 / USA

Wood treatment method

Lawyer file 29 1γ7

809851/0730

»(089) 988272 Mauerkiicherstc 45 - 8000 Munich 80 Banks: 988273 Telegrams: Bayerische Veretnsbank Munich 453100 988274 BERGSTAPF PATENT Munich Hypo-Bank Munich 3890002624 983310 TELEX; 0524560 MOUNTAIN Post check Munich 65343-808

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description

The invention relates to pressure impregnation of wood with water-compatible wood treatment materials for improvement of wood properties. The invention particularly relates to a process for impregnating wood, using water-compatible wood treatment materials in the wood Precipitation or chemical bond can be deposited, with the effectiveness and other advantages of the whole cell method can be combined with a small amount of residual liquid in the wood, which is obtained with the empty line process.

The present invention can be counted among those processes that are generally as opposed to blank line processes to whole-cell procedures. The main difference between these two methods is that In the full-cell process, the liquid introduced into the wood remains in the wood after impregnation. In contrast this is where most of the treatment fluid is used in the empty line process pressed out of the wood after impregnation. The terms "full" and "empty" are from the fact derived that the wood cells in the full cell process are essentially filled with the impregnating agents, while the impregnation agents only coat the wood cells in the case of the empty cell process.

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282357A

The full-cell process uses vacuum-pressure impregnation cycles, whereby the wood is first treated with a vacuum and then the treatment container with the ingress of air Treatment liquid is filled. After the wood is fully covered with the liquid, the pressure on one The area increases by about 10 atmospheres and so the liquid is pressed into the wood. Having treated the wood for so long has been that no more liquid is absorbed, or until a predetermined absorption of the treatment liquid is reached, the pressure is released and the Treatment liquid withdrawn from the container, usually a short treatment in a vacuum is applied to remove excess fluid from the surface of the wood.

The key feature of the empty line procedure is that that at the end of the process the pressure is reduced to or below the pressure in the wood before the impregnation, so that a withdrawal of the treatment liquid from the wood is achieved. This is usually achieved by using the Subjecting wood to a certain pressure before it is brought into contact with the treatment liquid. The initial pressure will be maintained during the time in which the treatment tank is filled with the treatment liquid, and then the pressure is increased to a second higher pressure level to allow the treatment liquid into the wood against the air pressure to press inside the wood. This achieves

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that when the pressure is reduced, the air compressed in the wood expands and most of the liquid that is in the wood was pushed in, pushes it out again. The same results can be achieved by using the Impregnation of the wood begins at or just below atmospheric pressure and then a vacuum treatment at the end of the process connects. In any case, it is customary to generate a vacuum in the treatment tank after the impregnation pressure has been released in order to recover the treatment liquid to increase and to shorten the treatment time in which the liquid from the surface of the Wood drips. The fluid that comes out of the wood due to the difference between the internal and external pressure is squeezed out is referred to as "exit liquid".

The empty cell method is particularly superior to the full cell method when it comes to treatment with water-compatible Materials, as the wood is immediately transported, processed or processed economically after treatment Can be used immediately, as the wood does not remove the potentially toxic treatment liquid from the interior the wood needs to be dried.

Despite the considerable advantage of the Leerzell method in obtaining "dry" wood, this process is for a number of different reasons no practical application in the impregnation of wood

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-,he

. When treating wood with water-soluble preservatives (e.g. chromium, Köpfer, arsenic salts, which are referred to as CCÄ salts), the leakage liquid, which is obtained in the Leerzell process, cannot, for example, be used economically "because the Austrittsflussigkeit water-soluble reducing substances that have been taken out of the timber, as Mestizellalose, τχηα contains these ince the CCA-salts to precipitate a thick sludge react, again the.. dirty the treatment device makes it impossible to Äustrittsflüssigkeit again without periodically separating them from the insolubles. In addition, the leakage liquid cannot be discarded as waste liquid because it is toxic and there is a risk of environmental pollution. For these and other reasons, e.g. the preferred amount in which the CCA salts are extracted from the solution, it has become common practice to circumvent the disadvantages, ie e result from the recovery or other use of the used CCA solutions by using the full-cell process and leaving the treatment liquid retained in the wood in this and allowing the wood to dry out, which can take several months if air-dried.

In addition, it is difficult next to CCA salts and others effective and commonly used wood preservatives in the Leerzell process to treat chlorinated phenols

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apply ,, especially the tetra- and pentachlorophenols (im generally referred to as "PCP"). PCP is not soluble in neutral or acidic solutions. It is therefore necessary that the PCP in high-boiling petrochemicals, Stoddard's solvents, To dissolve kerosene and similar agents in order to bring it into an impregnable solution - the empty cell impregnation process is sometimes used to coat the cell walls with a preservation solution, as the hydrocarbon solvent must be recovered to make the process economical and to avoid bleeding of the oily Prevent solution, which would prevent the use of common wood finishes. Although the Most of the treatment solution is recovered from the wood in the Leerzell process, represents the amount of used Solvents make up most of the cost of the materials used to impregnate the wood with PCP.

In order to reduce the cost of the oleaginous solvents, the empty cell method has been replaced by other methods, in where a low-boiling liquid is used as a solvent, which is recovered and reused can. In this process, the low-boiling aliphatic hydrocarbon solvents for PCP are used after impregnation usually evaporated, the water-insoluble residue of the PCP remaining in the wood. However, these procedures point also have disadvantages, since expensive devices are used here, the evaporated solvents for reasons of

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Economic efficiency and pollution must be recovered, and in addition, from the literature

, lanae
knows that the wood is less / protected when volatile solvents are used. Another disadvantage of the use of low-boiling hydrocarbon solvents is that the protection that can be achieved for the wood on the outer surface is inadequate. It is believed that the reason for this is that some of the PCP near the surface of the wood is evaporated during the evaporation process and thus the amount of PCP remaining in this area is no longer sufficient to protect the wood.

The application also relates to an improved process for the pressure impregnation of wood, in particular To provide an improved and modified empty line process that is economical for preservation of wood can be used with common wood preservatives e.g. CCA salts and PCP.

It is also the subject of the application, an improved method for the pressure impregnation of wood with water-compatible To provide preservatives in which the treatment materials are retained in the wood as much as possible and the liquids are minimally retained in the wood.

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It is also the subject of the application to improve the surface protection of wood during impregnation with PCP To be made available in the event that low-boiling hydrocarbons are used as solvents.

These and other purposes of the present invention are accomplished by pressure impregnation of the wood achieved with water-compatible treatment materials, with the impregnated wood as long is kept under pressure until the water-compatible treatment materials have precipitated or bound in the wood and by reducing the pressure to at least or preferably below the pressure in the wood immediately before the impregnation, so that a corresponding amount of leakage liquid is obtained. In this way it is achieved that a maximum of the treatment materials in the wood is retained, and the liquid retained in the wood is reduced to a minimum.

The method of the invention is particularly useful for treatment of wood with CCA salts, since the exit liquid contains essentially no metal ions and thus the problems that arise when recovering or discarding the used solution are eliminated. Another advantage is that the treated wood removed from the treatment tank is essentially substantial is "dry". It can therefore be used immediately, transported or subjected to further treatment, e.g. impregnation with creosote for the use of the wood in shipping,

are fed. 809851/0730

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Since the treatment materials can react in situ during pressure impregnation, it is possible. Wood with PCP too protect without using hydrocarbon solvents. According to the process of the invention, sodium penta {or Tetra) chlorophenolate dissolved in an alkaline solution, the wood is impregnated with this solution and the solution im Wood held in place without the liquid leaking out of the wood until the natural acidity of the wood causes a precipitate of the water-insoluble PCP in the wood. In the event that the acidity of the wood is not responsible for the precipitation of the PCP is sufficient in an appropriate amount, the wood can first be filled with a Acid, e.g. acetic acid, before it is impregnated with the sodium pentachlorophenolate solution. It will believed that the acid treatment of the pentachlorophenolate to form insoluble PCP precipitates in situ in the Wood the retention of the PCP and the achieved protection of the wood is longer lasting than that when using either vaporizable or non-vaporizable petroleum based solvents is achieved.

As expected, the response between the treatment materials will be and the wood is accelerated significantly when the wood is heated during the time that the impregnation solution is in place located in the wood. The corresponding treatment times and temperatures depend on the Type of wood being treated and the type of treatment

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liquid. However, these data can be determined quickly by simple experiments.

Typical data were obtained, for example, from the treatment of conifers (Southern pine) with CCA salts. It was found, that, for example, a temperature in the range of about 65.5 to 121 C is suitable. At temperatures below those given above the reaction rate is disproportionately slow and at higher temperatures there is a risk of damage of the wood. The preferred area for treatment of coniferous woods with CCA salts is around 82 to 115 ° C, in particular 93 to 100 ° C.

Treatment times vary considerably and are dependent on the temperature of the treatment cycle. There were obtained satisfactory results with treatment times of about 1 to 7 hours. There can of course be longer treatment times be applied. However, these are not necessary in the interests of the productivity of the process. There is also an extension of the treatment time over the There is no longer any need for a time in which the desired reactions have almost or completely ended.

EXAMPLE 1

30 dried (moisture content 15%) sticks for tomato cultivation (0.035 cbm) and 15 sticks for viticulture (0.046 cm) from softwood (Southern pine) were modified as follows

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ns

Blank cell treatment with 2.0% solution of CCA (based on the oxide): a

A vacuum of 0.70 kg / cm is set and the vacuum is maintained for 5 minutes. After that, the container filled with the CCA solution without changing the initial pressure. Thereafter, the pressure after a period of

2
5 minutes increased by 0.70 kg / cm until the pressure after 45 minutes

had reached a value of 7 kg / cm. The excess preservative was removed while the pressure in the

Cylinder was maintained at 7 kg / cm.

The total absorption of CCA solution in the printing period is

3
carried 0.575 g / cm. After that, the treated sticks were used for

Treated with steam for 1 1/2 hours at a pressure of 7 kg / cm,

a maximum temperature of approx. 115 C was reached after 1 hour. This temperature was then for a 1/2 Maintain hour. At the end of the steaming phase, a sample of the exit solution was taken. This sample had a pH of 3.1.

The sticks were then subjected to a vacuum of 66 cm (26 ") Hg for 1 hour before they were removed from the treatment container were removed and weighed to determine the retained solution. The one withheld during treatment Solution (net amount) was 0.164 g / cm.

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The treatment solution used and the one after the treatment The exit solution resulting in sticks was analyzed. The following results were obtained:

sample

Treatment solution

Exit solution

Reduction in% pH CuO CrO ₃ As ₃ O ₅ j CuO CrO ₃ ^As ₂ ° 5

1.5 0.345 0.958 0.718

3 _f l 0.021 0.016 0.019

93.9 98.3 97.4

EXAMPLE 2

Precipitation of copper and chromium from the acidic copper chromate solution in the hardened (moisture content 20%) softwood by steam treatment before the outlet solution is drawn off:

A kilned piece of softwood with a diameter of 165 mm and a length of 45.7 cm was impregnated as follows:

A) Preservation solution:

It was a 2.38% solution (based on the oxide) of acid Copper chromate produced by using a commercially available preservation concentrate, Contains 3.84% copper sulfate (anhydride), 5.01% sodium dichromate (anhydride) and 0.20% chromic acid (anhydride) was diluted with water. The pH of the freshly prepared solution was 3.4.

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B) impregnation stage:

After a pressure in the treatment tank for 5 minutes

of 2.8 kg / cm was maintained, the container became filled with the preservation solution at this pressure

2 and then the pressure was increased to 9.84 kg / cm. This pressure was maintained for 2 hours. The excess preservation solution was withdrawn from the treatment tank,

while a pressure of 9.8 kg / cm was maintained in the container. At the end of the pressure treatment period and before Beginning the treatment with steam, a sample of the exit solution was taken, while the pressure was applied for a brief moment little has been reduced. The pH of the sample of the exit solution was 3.85. The adsorbed during the printing period

The amount of the preservation solution was 0.469 g / cm.

Thereafter, the sample was kept at a temperature of 100 C for 3

Steamed for hours while maintaining a pressure of 9.8 kg / cm in the container. At the end of the steam treatment phase a sample of the exit solution was drawn. This solution had a pH of 5.45.

The treated wood sample was then subjected to a vacuum treatment of 66 cm Hg for 1 hour and then the sample became removed from the container and weighed to determine the amount of solvent retained (net amount). The pH the solution obtained during the final vacuum treatment was 5.50. The back during the treatment

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net amount of solution held was 0.146 g / cm. The overall

3 absorption was thus reduced to over 0.321 g / cm.

A disc was cut from the center of the sample from the treated wood and placed in an oven to dry laid to determine the average moisture content. The moisture content of the oven dried sample was 40.3% -

The copper and chrome amounts of the treated samples were analyzed. The results are summarized in the following table. In the following table, sample 1 relates to the initial treatment solution; sample 2 is the exit solution after the impregnation but before the steam treatment, the sample 3 is the exit solution after the impregnation and steam treatment and sample 4, the solution stripped from the wood during the final vacuum treatment.

Reduction of reduction of

sample pH % CuO CuO in % % CrO CrO ₃ 8th in % 1 3.40 0.717 - 1.661 98 - 2 3.85 0.628 12, 41 1.527 99 , 07 3 5.45 0.014 98 06 0.027 , 37 4th 5.50 0.025 96, 58 0.009 , 46

The disc cut from this example after the treatment and steaming was entirely of the preservative soaked.

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EXAMPLE 3

The wood sample was subjected to a blank-cell treatment with an 0.5% Ba (OH) "solution before the treatment with the CCA solution to precipitate the sugars contained in the wood so that they do not contaminate the exit solution.

The analysis of the exit solution after the CCA impregnation phase showed a reduction in the CuO content of 100% and the CrO and As_0 content of 99.56% in the treatment solution.

Sufficient CCA concentrate was added to a portion of the exit solution until the concentration of CCA was up to 2.0% based on the oxide. No precipitation was found in this sample after storage for 2 weeks in the laboratory. This shows that a considerable amount of the wood sugars was precipitated in the wood ^{and that} contamination of the exit solution could thus be prevented.

EXAMPLES 4-6

In Examples 4 to 6 samples of coniferous wood (Southern pine) with CCA salts were changed by changing the process conditions, as indicated in the following table. In this table, the "initial pressure" stands for the Print before impregnation. In the column "impregnation pressure" is the pressure in the treatment tank after the Filling of the container with the treatment liquid

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give. The term "steam treatment temperature (° C)" indicates the maximum temperature reached after a period of 1 hour after the impregnation pressure has been set had been. The term "treatment time" refers to the time in which the impregnation pressure and the steam treatment temperature was maintained.

The other columns of the table contain the amounts of the active ingredients as a percentage of the initial treatment solution, the exit solution and the amount of active ingredients in percent that are retained in the wood became. In Examples 4 and 5, the temperature in the treatment tank was not above ambient temperature and therefore no complete deposition of the CCA salts was observed within the observation time of 6 hours. In contrast, Example 6 shows that with a steam treatment at a temperature of 98.9 C, more than 95% of the CCA salts in the wood after a treatment time of only 2 hours

are deposited.

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Temp. D.

example At first
print ₉
(kg / an) Impregnation
pressure
(kg / arT) Steam
plot
( ° C) Treatment
Time
(Hours.) ' TREATMENT SOLUTION
% CuO% CrO ₃ As , 382 1 , 010 0, 2 ° 5 EXIT SOLUTION
% CuO% CrO ₃ 0.425 % AS ₂ O ₅ 4th 0.7 7th no 3 0 , 331 0 , 962 0, 718 0.139 0.338 0 , 070 5 0.7 7th no 6th 0 , 314 0 , 904 0, 692 0.096 0.006 0 , 170 6th 0.7 7th 98.9 ° C 2 0 819 0.011 0 , 017

below

LO example RETAINED % CrO SALT 2 ° 5 O % CuO 57.9 % As 3 4th 63.6 64.8 90 5 5 71.1 99.3 75 9 6th 96.5 97

K)

cn

EXAMPLE 7

A kilned softwood piece with a gauge of 14.6 cm and a length of 45.7 cm _WUR de impregnated as follows:

A) Preservation solution:

1.50% technical sodium pentachlorophenolate solution in water, Starting pH 10.3.

B) Impregnation process:

The wood was placed in a pressure vessel and then the

Pressure adjusted to 2.1 kg / cm air pressure - Then the container was without changing the pressure with the preservation

solution filled and the air pressure increased to 10.54 kg / cm and

maintained for 2 hours.

Then the preservation solution was removed from the wood,

while maintaining the pressure in the cylinder at 10.54 kg / cm.

The total absorption of the preservative during the pressure treatment was 0.523 g / cm.

The wood was then steamed for 3 hours at 100 C

acts while maintaining a pressure of 10.54 kg / cm in the cylinder became. By reducing the pressure briefly at the end of the steam treatment phase, a The exit solution was sampled. This solution had a pH of 5.0. The wood was then one for 1 hour Vacuum of 66 cm Hg and then out of the treatment vessel taken out and weighed. The retained solution

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during treatment (net weight) was 0.122 g / cm, which means that the amount of exit solution was 76.6%, based on the total absorption. During the final vacuum treatment, a sample of the peeled off Solution taken and the pH determined. The pH was 5.15.

C) Analysis of drilling chips to determine the PCP:

Three interior sections were taken from the centerline of the sample at 48.9 intervals around the circumference. The interior sections were divided into 12.7 mm segments and tested for PCP content using the lime ignition method examined. The analysis results are summarized in the following table:

Depth, measured from the surface content (mm) (g / cm)

0.0-12.7 0.0063

12.7-25.4 0.0025

25.4-38.1 0.0031

38.1-50.8 0.0025

D) Analysis of the PCP content of the starting treatment solution and of the exit solution after the steam treatment: The samples of the initial treatment solution and the exit solution were tested for PCP content by means of the lime glow method examined and the results are summarized as follows:

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PCP content (%) starting treatment solution 1.143

Exit solution after the

Steam treatment 0.026

The reduction in the PCP content, that is, that retained in the wood The PCP content was accordingly 97.7%.

E) Determination of the fixation of the PCP in the wood:

a) General procedure:

A 19.0 mm disc was cut from the center piece of the treated wood section. From this A 19.0 mm wide strip was sawn out of the disc so that the central core is in the center of this strip found. The outer edge opposite the core of the strip was 76.2 mm wide in 12.7 mm portions divided and these portions then subjected to the acid test, and 25.4 mm portions were used for the pH determination. '

b) Acid determination:

Each sample was divided into 3.175 mm portions and covered with 50 ml of boiling distilled water. The mixture was shaken for 30 minutes and poured through a Whatman 541 paper filter. 3 ml of the filtrate were in a Put in test tubes and mixed with dilute hydrochloric acid in order to precipitate any PCP that may be present (the sensitivity this method is 100 ppm).

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Results of the acid test:

Sample distance from the wood surface (mm)

Precipitation
included not included

0.0 until 12.7 very little Yes 12.7 until 25.4 Yes 25.4 until 38.1 Yes 38.1 until 50.8 Yes 50.8 until 63.5 Yes 63.5 until 76.2

F) Moisture content after treatment:

A 19 mm thick disc was removed from the center of the treated Pole section sawn out and oven dried to determine the average moisture content immediately after treatment. The moisture content of this disc was 38.6%.

EXAMPLE 8

In Example 7, the acidity of the wood was only determined by reducing the pH of the treatment solution for the precipitation of the PCP in the wood. The wood was prior to the impregnation with Pentachlorphenolatlosung with acetic acid using a modified procedure Leerzeil treated to festzusiä-len, _O b, the increased acidity which makes effective method.

A sample of the softwood (Southern pine) was placed in a treatment tank and then a pressure of

0.7 kg / cm set. Without releasing the pressure, that was

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add a 0.8 molar solution of glacial acetic acid to the container

and the pressure was increased to 8.4 kg / cm and maintained for 2 hours. _D i _e acetic acid from the wood

withdrawn while maintaining a pressure of 8.4 kg / cm. The wood was then kept at 98.9 ° C for 3 hours treated with steam. The pressure was then released and the wood treated in vacuo for 1 hour.

Immediately after the above acid treatment of the wood, identical procedural measures were repeated, with a 4% strength alkaline solution of sodium pentachlorophenolate was used as the impregnation solution.

After treatment with PCP it was found that the exit solution contained less than 0.008% PCP. This shows that more than 99.8% of the PCP of the treatment solution is deposited in the wood has been. Following the procedure described in Example 1, an attempt was made to wash the PCP out of the wood. However, the result was negative. It was found that the PCP precipitated in the wood was not in noticeable amounts, that is, in amounts greater than 100 ppm, could be washed out when the wood was treated with boiling water.

Drilling chips were taken from the treated wood and the amount of PCP deposited in the wood at different depths using the lime glow method determines:

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sample (mm) PCP (g / cm) 0.0 - 12.7 0.0177 12.7 - 25.4 0.0136 25.4 - 38.1 0.0127 38.1 - 50.8 0.0123

Examples 7 and 8 above show that the chemically precipitated PCP is tightly bound and will not wash out can, and if so, only in traces. It has thus been found that this fixation of the PCP in the wood reduces the effectiveness of the Maintains wood preservation for an extended period of time.

Another advantage of fixing the PCP in the Wood yields lies in the potential environmental pollution is significantly reduced by the PCP if the PCP is firmly bound in the wood. Contrary to the results that obtained when carrying out the process according to the invention, when using conventional high-boiling petrochemical Solvent the PCP does not precipitate in the wood, but it is kept in solution by the organic solvents. As a result, the PCP can escape from the wood over a longer period of time, depending on the Soil type and other basic conditions to which the wood is exposed, e.g. temperature change, air pressure, the Humidity and other environmental conditions.

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EXAMPLE 9

Air-dried (moisture content 25%) softwood fence posts were made a size of approximately 10.2 260 cm into one

Given a pressure vessel and set an air pressure of 1.4 kg / cm. The pressure was maintained for about 5 minutes and then the container was filled with a CCA solution (see table

1) filled without releasing the initial pressure. There-

after the pressure was increased to 9.8 kg / cm over a time of about

55 minutes increased. The temperature of the CCA impregnation solution was about 32.2 ° C and the total absorption was 0.503 g / cm ³ .

After the desired total absorption has been achieved
was, steam was fed into the treatment tank and the CCA solution in the tank to 93.3 C within a time of
Heated for 30 minutes. This temperature was for 60 minutes
maintain. No precipitation of CCA salts from the treatment solution was observed during this heating phase.

At the end of the heating phase, the CCA solution was removed from the treatment tank without changing the pressure became. The pressure was then released to collect the exit solution separately from the CCA solution. The temperature the exit solution was 82.2 ° C. After releasing the pressure in the treatment tank, the wood became a final one Vacuum treatment at 63 cm Hg for a period of 60 minutes.

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The wood was removed from the container and weighed The preservation solution retained in the wood (net weight) was 0.112 g / cm.

The analysis results regarding the CCA content before Treatment, after treatment and after heating, and of a sample of the exit solution after heating summarized in Table 1 below.

solution

CCA before treatment

Table 1

Metal content (% based on oxide) pH CuO ^Cr0 3 ^As 2 ° 5 ^Sa l ^{z in} total

1.92 0.304 0.870 0.643 1.817

essentially as above exit solution 4.18 0.008 0.017 0.022 0.047

CCA after treatment and 2.03 warming

Inside sections were taken from the center line of each item for the amount of copper, chromium retained and arsenic to be determined after treatment. The inner sections were cut into 12.7 mm segments and similar segments were combined for the analyzes. The results of these analyzes are summarized in Table 2 below:

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Table 2

Distance from the retained metal content (g / cm) surface (mm) (based on oxide)

CuO CrO-As O salt in total

O , 0122 O , 0062 O , 0042

0.0 to 12.7 0.0026 0.0056 0.0040 12.7 to 25.4 0.0019 0.0039 0.0003 25.4 to 38.1 0.0012 0.0028 0.0002

The modified blank line method of the invention is above has been described as a process in which sodium salts of chlorinated phenates and for the impregnation of the wood CCA salts can be used. The inventive method however, it is also useful for treating wood with other wood treatment agents, e.g. water-compatible Materials such as wood softeners, anti-stain agents, film formers, colorants, flame retardants, antistatic agents Agents, extended stabilizers and other wood treatment agents, the method according to the invention is Also suitable for leaching materials from the wood, e.g. wood sugar, or suitable for the wood sugar to precipitate in the wood before the final preservation. The pH of the treatment liquid can be adjusted in this way be that it dissolves the sugar maximally and it can be the treatment liquid - if it is desired the sugar to fix in wood - cations, e.g. barium or copper cations are added to insoluble sugar products to build.

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The modified blank line method of the invention enables it is possible to carry out a large number of impregnation sequences without having to interpose the drying or hardening stages required in the full-cell process. According to the invention treated samples can for example immediately after being treated with CCA salts according to the invention are treated with an oily preservative. The CCA treatment can be followed by a PCP treatment. This increases the wood protection and this process can be used to advantage when out For reasons of environmental pollution, no arsenic salts may be present in the treatment liquid.

Another modification of the method according to the invention lies in having CCA salts in the surface regions of the wood is deposited while the wood is treated with a solution of PCP and liquid hydrocarbons. if the pressure in the system is released, the CCA treatment is started Liquid is pushed out of the wood by the evaporation of the hydrocarbon.

In the above examples, the treatment solution was separated from the wood while maintaining the impregnation pressure prior to the time the wood was heating became. This is not absolutely necessary and if desired, the temperature of the wood can be increased by heating the Impregnation solution can be increased (e.g. by steam-heated

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Coils) before the time before the impregnation solution is withdrawn from the treatment tank. In a another embodiment of the method according to the invention In some cases, the treatment solution can be heated prior to addition to the treatment vessel. The treatment liquid but can also be withdrawn from the container while maintaining sufficient pressure to prevent the exit to prevent the liquid from coming out of the wood, and a steam treatment or treatment with a second liquid can be used to heat the wood. in the in the latter case, the liquid is added to the treatment tank while maintaining sufficient pressure to prevent the liquid from leaking out of the wood. In the event that a hot water bath is used for the final treatment, it can be advantageous to use water-compatible wood treatment materials, e.g. the above-mentioned wood softeners, anti-stain agents, film formers, colorants, flame retardants, antistatic agents, appropriate stabilizers and other wood treatment agents to the treatment liquid to add. Even if the first treatment with PCP was carried out, it can be advantageous to use diluted solutions add CCA salts to the water to provide additional protection for the wood surface. There the CCA salts are firmly bound to the wood, this additional protection is beneficial to the surface regions

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of the wood against possible loss and leaching of the PCP. This final procedural stage is therefore not only intended to bring about the precipitation or fixation of the preservative in the wood, but also to at least improve the surface properties of the wood.

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Claims (17)

Claims 1. Method of treating wood, thereby characterized in that the wood is placed in a pressure treatment vessel at an initial pressure, a introduces aqueous treatment liquid into the container, the pressure in the container to impregnate the wood with the Treatment liquid increased above the initial pressure, the pressure in the container is maintained in order to leave the treatment liquid in the wood until that in the treatment liquid If treatment materials are bonded or deposited in the wood, then apply pressure in the container to the or reduced below the initial pressure so that the used treatment liquid can escape from the wood and collects the used treatment liquid. 2. The method according to claim 1, characterized in that the aqueous treatment fluid contains a wood preservative. 3. The method according to claim 2, characterized in that the wood preservative is copper, chromium or arsenic salts contains. r (CS9) 988272 988273 988274 983310 809851/0730 Mauerkircherstr. 45 - 8000 Munich 80 telegrams: BERGSTAPF PATENT Munich TELEX: 0524560 BERG d Banks: Bayerische Vereinsbank Munich 453100 Hypo-Bank Munich 3890002624 Post check Munich 65343-808 INSPECTED 4. The method according to claim 2, characterized in that the wood preservative is a sodium chlorophenolate. 5. The method according to claim 4, characterized in that the aqueous treatment fluid is an alkaline solution of the
Is sodium pentachlorophenolate. 6. The method according to claim 1, characterized in that the wood in the time in which the treatment fluid is in
Wood is located, is heated. 7. The method according to claim 6, characterized in that the wood is heated from about 65 C to about 120 C. 8. The method according to claim 6, characterized in that the wood is heated by the treatment fluid warmed up. 9. The method according to claim 6, characterized in that the wood is heated by means of steam. 10. The method according to claim 6, characterized in that the wood is heated by means of a second treatment liquid will. 11. The method according to claims 9 and / or 10, characterized in, that the second treatment liquid wood treatment 809851/0730 Contains agents selected from the group consisting of colorants, wood softeners, anti-splintering agents, film formers, Anti-flame agents, anti-static agents, polymerizable mixtures and additional wood preservatives. 12. The method according to claim 4, characterized in that the wood is pretreated with an acid. 13. The method according to claim 12, characterized in that the pretreatment is carried out with acetic acid. 14. The method according to any one of the preceding claims, characterized in that the wood is pretreated that the wood according to the method according to claim 1, however treated with hot water or steam instead of the aqueous treatment liquid. 15. The method according to any one of the preceding claims, characterized in that the wood is pretreated with metal ions is used to precipitate the sugars in the wood. 16. The method according to claim 1, characterized in that the wood with a solution of pentachlorophenol and a low-boiling hydrocarbon or a chlorinated solvent is pretreated for the pentachlorophenol, before the aqueous treatment liquid is added to the container and wherein the treatment fluid contains CCA salts. 809851/0730 _ ₄ _ 17. The method according to claim 1, characterized in that the treated wood continues to be impregnated with creosote. 809851/0730