Wood impregnation method

Abstract

The present invention relates to a wood impregnation method and to impregnated wooden sleepers.

Description

[0001] WOOD IMPREGNATION METHOD

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application is related to and has right of priority to EP Application No. EP23176506.6, filed on May 31 , 2023, which is incorporated in its entirety for all purposes.

[0004] TECHNICAL FIELD

[0005] The present invention relates to a wood impregnation method and to impregnated wooden sleepers.

[0006] BACKGROUND

[0007] Impregnation of wooden objects in order to increase their duration is of great interest in several technical fields. Wooden sleepers, for example, continue to play an important role, especially in track construction for railways. At line speeds of below 160 km / h, they have excellent properties with regard to vibrations, noise pollution, are easily machinable, robust and not very susceptible to breakage due to their elasticity. Their elasticity also results in very smooth running and in being extremely gentle on the wheel tires and bearings of the rolling stock compared with concrete sleepers. In addition, they can be laid easily due to their relatively low weight and have a good eco-balance.

[0008] However, commonly used impregnating agents of wooden sleepers often comprise environmentally critical substances such as coal tar oils (Creosote). Thus, there is still a need for an effective and environmentally more friendly method of impregnating wooden sleepers.

[0009] Against this background it is an object of the present invention to provide a wood impregnation method of wooden sleepers that is in line with the most recent regulatory requirements, such as for example the European Biocidal Products Regulation (BPR, Regulation (EU) 528 / 2012). It is a further object of the present invention to provide a wood impregnation method improving consistency of penetration. It is a further object of the present invention to provide an environmentally preferred impregnation method compared to Creosote-based impregnation. It is a further object of the present invention to provide environmentally preferred impregnated wooden sleepers when compared to Creosote-impregnated wooden sleepers. It is a further object of the present invention to provide impregnated wooden sleepers with improved consistency of penetration.

[0010] SUMMARY

[0011] In one aspect, the present invention provides an impregnating method for wooden sleepers (10), wherein the wooden sleeper (10) is subjected to a first mechanical treatment, wherein a displacement of wood fibres is effected, wherein the wooden sleeper (10) is subjected to a second mechanical treatment, substantially severing wood fibres and wherein as impregnating agent a composition (S) is used, wherein the composition (S) comprises

[0012] A) a copper (II) salt;

[0013] B) penflufen; and

[0014] C) a cationic surfactant selected from the group consisting of tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and mixtures thereof.

[0015] In a second aspect, the present invention provides an impregnated wooden sleeper (10), wherein the impregnated wooden sleeper (10) has first regions, in which wood fibres are displaced, wherein the impregnated wooden sleeper (10) has second regions, in which parts of wood fibres are severed, and wherein the impregnated wooden sleeper (10) is impregnated with a composition (S) comprising

[0016] A) a copper (II) salt;

[0017] B) penflufen; and

[0018] C) a cationic surfactant selected from the group consisting of tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and mixtures thereof.

[0019] FIGURES Figure 1a (Fig. 1a): discloses a scheme of a wooden sleeper, which was treated with the first mechanical treatment.

[0020] Figure 1 b (Fig. 1 b): discloses the top view of a part of a first surface (11 ) of the wooden sleeper of Figure 1a.

[0021] Figure 1c (Fig. 1c): discloses the top view of a part of a second surface (12) of the wooden sleeper of Figure 1 a.

[0022] Figure 1d (Fig. 1d): discloses a detailed scheme of the first mechanical treatment (slots).

[0023] Figure 2a (Fig. 2a): discloses a scheme of a bottom side of a wooden sleeper, which was treated with the second mechanical treatment.

[0024] Figure 2b (Fig. 2b): discloses a cross section oriented in longitudinal direction of the wooden sleeper of Figure 2a.

[0025] Figure 1a in particular discloses the first mechanical treatment, a slotted perforation of at least the four largest surfaces (11 , 12) of the wooden sleeper (10). In Figure 1a, merely two surfaces (11 , 12) can be seen. The top view thereof demonstrates that the slots (13) are substantially parallel to the running direction of the wood fibres (wherein the running direction of the wood fibres is not depicted in the Figure). Further, it can be seen that the slots (13) are arranged on each of the surfaces (11 , 12) in rows and columns, respectively, such that in the rows located at the top and bottom of a given row and in the columns located at the right and left of a given column are not directly adjacent to each other.

[0026] In Figures 1 b and 1c, slots (13) that are made into the wooden sleeper (10) from the side below the surface (11 or 12, respectively) are shown in dashed lines. In Figure 1c, such a slot (13) is exposed for illustration purposes in the hatched area (in which the hatching serves to mark and is not intended to represent the running direction of the wood fibres) and enlarged in Figure 1 d.

[0027] To illustrate the second mechanical treatment, Figures 2a and 2b show a wooden sleeper (10) comprises two areas (14, 15), in which each a group of 14 blind holes (16) are introduced, each with a diameter of about 3 to about 4 mm to a depth of about 4 / 5 of the wooden sleeper’s depth. Reference signs

[0028] 10 wooden sleeper

[0029] 11 , 12 surface

[0030] 13 slot

[0031] 14, 15 area

[0032] 16 blind hole

[0033] D detail

[0034] DETAILED DESCRIPTION

[0035] In the following, the invention will be explained in more detail.

[0036] The terms “about” in the context of the present invention denotes an interval of accuracy that a person skilled in the art will understand to still ensure the technical effect of the feature in question. The term typically indicates a deviation from the indicated numerical value of ±10%, preferably ±5%, more preferably ±2%, and in particular ±1 %.

[0037] The term “alkyl” as used herein denotes a straight-chained or branched saturated hydrocarbon group having generally 1 to 16 carbon atoms, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, or 16 carbon atoms. The term includes methyl, ethyl, propyl, 1 -methylethyl, butyl, 1 -methylpropyl, 2-methylpropyl, 1 ,1 - dimethylethyl, pentyl, 1 -methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2- dimethylpropyl, 1 -ethylpropyl, 1 ,1 -dimethylpropyl, 1 ,2-dimethylpropyl, hexyl, 1 - methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1 ,1 -dimethylbutyl, 1 ,2-dimethylbutyl, 1 ,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3 dimethylbutyl, 1 -ethylbutyl, 2 -ethylbutyl, 1 ,1 ,2-trimethyl propyl, 1 ,2,2- trimethylpropyl, 1 -ethyl-1 -methylpropyl, 1 -ethyl-2-methylpropyl, octyl (e.g. caprly), nonyl, decyl (e.g caprin), dodecyl (e.g. lauryl), tetradecyl (e.g. myristyl), and hexadecyl (e.g. cetyl), preferably methyl and decyl.

[0038] It needs to be understood that the term “comprising” is not limiting. For the purposes of the present invention, the term “consisting of” is considered to be a preferred embodiment of the term “comprising of”. If hereinafter a group is defined to comprise at least a certain number of embodiments, this is also meant to encompass a group which preferably consists of these embodiments only. As outlined above, subject of the present invention is an impregnating method for wooden sleepers (10), wherein the wooden sleeper (10) is subjected to a first mechanical treatment, wherein a displacement of wood fibres is effected, wherein the wooden sleeper (10) is subjected to a second mechanical treatment, substantially severing wood fibres and wherein as impregnating agent a composition (S) is used, wherein the composition (S) comprises

[0039] A) a copper (II) salt;

[0040] B) penflufen; and

[0041] C) a cationic surfactant selected from the group consisting of tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and mixtures thereof.

[0042] The inventive method provides an efficient impregnation method for wooden sleepers, wherein critical substances such as coal tar oils (Creosote) can be avoided. In addition, the method provides a more homogenous impregnation of the wooden sleepers. The mechanical treatments provide for an improved penetration of the impregnating agent. In addition, the mechanical treatments provide a more homogenous drying with reduced susceptibility to cracking and stressing.

[0043] In one embodiment, the first mechanical treatment is a slotted perforation.

[0044] In one embodiment, the first mechanical treatment is a slotted perforation of at least the four largest surfaces (11 , 12) of the wooden sleeper (10), in which slots (13) are aligned substantially parallel to the running direction of the wood fibres, so that a displacement of wood fibres is effected.

[0045] In one embodiment, the slot depth is at least about 10 mm, preferably at least about 20 mm. The slot depth can be up to about 150 mm, preferably up to about 120 mm such as up to about 100 mm, or up to about 90 cm, or up to about 80 cm.

[0046] Slotted perforation may be performed via machines typically used in the USA for “incising” wooden sleeper.

[0047] In one embodiment, the second mechanical treatment is an at least local introduction of blind holes (16) from at least one side of the wooden sleeper (10). In a preferred embodiment, the at least local introduction of blind holes (16) is performed from only one side of the wooden sleeper (10). The respective side of the wooden sleeper (10) will then suitably be faced to the ground. This may minimize precipitation-based impacts.

[0048] In on embodiment, the blind holes (16) have a depth of about 4 / 5 to about 7 / 8 of the extension of the wooden sleeper (10) in the direction of the blind holes (16).

[0049] In one embodiment, the blind holes (16) have a diameter of about 3 mm to about 20 mm, preferably of about 3 mm to about 12 mm such as of about 3 to about 10 mm, or of about 3 mm to about 8 mm, or of about 3 mm to about 6 mm.

[0050] In one embodiment, the wooden sleeper (10) comprises two areas having a group of about 10 to about 40, preferably of about 20 to about 40 blind holes (16). Preferably, these blind holes (16) are offset to each other.

[0051] In a preferred embodiment, the invention relates to an impregnating method for wooden sleepers (10), wherein the wooden sleeper (10) is subjected to a first mechanical treatment, specifically a slotted perforation of at least the four largest surfaces (11 , 12) of the wooden sleeper (10), in which slots (13) are aligned substantially parallel to the running direction of the wood fibres, so that a displacement of wood fibres is effected, wherein the wooden sleeper (10) is subjected to a second mechanical treatment, specifically an at least local introduction of blind holes (16) from at least one side of the wooden sleeper (10), substantially severing wood fibres, and wherein as impregnating agent a composition (S) is used, wherein the composition (S) comprises

[0052] A) a copper (II) salt;

[0053] B) penflufen; and

[0054] C) a cationic surfactant selected from the group consisting of tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and mixtures thereof.

[0055] In a preferred embodiment, the copper (II) salt is copper (II) hydroxide.

[0056] Penflufen is a succinate dehydrogenase inhibitor, which is also known as 5- fluoro-1 ,3-dimethyl-N-{2-[(2RS)-4-methylpentan-2-yl]phenyl}-1 H-pyrazole-4- carboxamide or 2'-[(RS)-1 ,3-dimethylbutyl]-5-fluoro-1 ,3-dimethylpyrazole-4- carboxanilide and has the formula (1 )

[0057] The term “tetraalkylammonium” as used herein refers to an ammonium cation, wherein four alkyl moieties are bond to the nitrogen, and wherein said four alkyl moieties can be same or different. Suitable alkyl moieties include methyl, ethyl, propyl, 1 -methylethyl, octyl, nonyl, decyl, dodecyl, tetradecyl, and hexadecyl, preferably methyl and decyl.

[0058] In one embodiment, the cationic surfactant is a mixture of a tetraalkylammonium carbonate and a tetraalkylammonium bicarbonate.

[0059] In a preferred embodiment, the cationic surfactant is a mixture of 1- decanaminium, N,decyl-N,Ndimethyl-, carbonate (also known as N,N-didecyl-N,N- dimethylammonium carbonate) and 1-decanaminium, N,decylN,N-dimethyl-, bicarbonate (also known as N,N-didecyl-N,N-dimethylammonium bicarbonate). The mixture is also known as 1 -decanaminium, N-decyl-N,N-dimethyl-, carbonate (3:2) and under CAS No 894406-76-9. Alternatively, the mixture is known as the reaction mass of N,N-didecyl-N,N-dimethylammonium carbonate (CAS No 148788- 55-0) and N,N-didecyl-N,N-dimethylammonium bicarbonate (CAS No 148812-65- 1 ).

[0060] In one embodiment,

[0061] A) the copper (II) salt is copper (II) hydroxide; and / or

[0062] C) the cationic surfactant is a mixture of 1-decanaminium, N,decyl- N,Ndimethyl-, carbonate and 1-decanaminium, N,decylN,N-dimethyl-, bicarbonate.

[0063] In a preferred embodiment, the composition (S) further comprises

[0064] D) a fatty acid, preferably C6-C16 fatty acids, C6-C14 fatty, more preferably C10-C12 fatty, and in particular C8-C10 fatty acids.

[0065] In one embodiment, the C6-C16 fatty acids are saturated C6-C16 fatty acids, preferably saturated C6-C14 fatty, more preferably saturated C10-C12 fatty, and in particular saturated C8-C10 fatty acids. In one embodiment, the composition (S) comprises

[0066] A) about 1 to about 6 wt%, preferably about 3 to about 5 wt%, of the copper (II) salt;

[0067] B) about 0.01 to about 0.5 wt%, preferably about 0.02 to about 0.1 wt%, of penflufen;

[0068] C) about 0.1 to about 2.0 wt%, preferably about 0.3 to about 1.5 wt%, of the cationic surfactant; and

[0069] D) optionally about 5 to about 15 wt%, preferably about 7 to about 12 wt%, of a fatty acid, each based on the total amount of the composition (S).

[0070] In one embodiment, the composition (S) comprises

[0071] A) copper (II) hydroxide;

[0072] B) penflufen;

[0073] C) a mixture of 1-decanaminium, N,decyl-N,Ndimethyl-, carbonate and 1- decanaminium, N,decylN,N-dimethyl-, bicarbonate; and

[0074] D) optionally a fatty acid, preferably of saturated C6-C16 fatty acids.

[0075] In one embodiment, the composition (S) comprises

[0076] A) about 1 to about 6 wt% of copper (II) hydroxide;

[0077] B) about 0.01 to about 0.5 wt% of penflufen;

[0078] C) about 0.1 to about 2.0 wt% of a mixture of 1-decanaminium, N,decyl- N,Ndimethyl-, carbonate and 1 -decanaminium, N,decylN,N-dimethyl-, bicarbonate; and

[0079] D) optionally about 5 to about 15 wt% of a fatty acid, preferably of saturated C6-C 16 fatty acids, each based on the total amount of the composition (S).

[0080] In one preferred embodiment, the composition (S) comprises

[0081] A) about 3 to about 5 wt% of copper (II) hydroxide;

[0082] B) about 0.02 to about 0.1 wt% of penflufen;

[0083] C) about 0.3 to about 1.5 wt% of a mixture of 1-decanaminium, N,decyl- N,Ndimethyl-, carbonate and 1 -decanaminium, N,decylN,N-dimethyl-, bicarbonate; and

[0084] D) about 7 to about 12 wt% of saturated C6-C16 fatty acids, each based on the total amount of the composition (S). For component C), mixtures of 1-decanaminium, N,decyl-N,Ndimethyl-, carbonate and 1 -decanaminium, N,decylN,N-dimethyl-, bicarbonate can comprise the 1-decanaminium, N,decylN,N-dimethyl-, bicarbonate and the 1-decanaminium, N,decyl-N,Ndimethyl-, carbonate in a ratio of about 50:1 to about 1 :5, preferably of about 20: 1 to about 1 :2, more preferably of about 15:1 to about 1 :1 , still more preferably of about 10:1 to about 2:1 , and in particular of about 9: 1 or of about 4:1 .In this connection, the ratio is preferably the weight ratio.

[0085] In one embodiment, the composition (S) comprises additional ingredients such as additional biocides and / or solvents such as suitable oils, e.g. mineral oil.

[0086] In one embodiment, the composition (S) has a density (determined at 20 °C according to Ell A.3 with a Pycnometer) of about 900 to about 940 kg / m3, preferably of about 910 to about 930 kg / m3.

[0087] In one embodiment, the composition (S) has a pH (determined at 25 °C according to CIPAC MT 75.3) of about 4 to about 7, preferably of about 5 to about 6.

[0088] In one embodiment, between about 20 kg and about 133 kg, preferably between about 25 kg and about 100 kg, and in particular between about 30 kg and about 90 kg, of impregnating agent are introduced per cubic meter of wood.

[0089] In one embodiment, a 10 cm long cross section of the impregnated wooden sleeper (10) cut out 5 cm from the end gain comprises of about 0.5 to about 4.0 mg / kg of copper, preferably of about 1 .0 to about 3.0 mg / kg of copper, and in particular of about 1 .3 to about 2.1 mg / kg of copper.

[0090] In one embodiment, the timber of the wood sleeper (10) is beech or oak.

[0091] In one embodiment, the method comprises an additional impregnating step, wherein the impregnating agent is an aqueous impregnating agent. This additional impregnating step can be performed prior to the impregnating with the composition (S) or downstream, preferably prior to the impregnating with the composition (S).

[0092] As aforementioned, the present invention further relates in a second aspect to an impregnated wooden sleeper (10), wherein the impregnated wooden sleeper (10) has first regions, in which wood fibres are displaced, wherein the impregnated wooden sleeper (10) has second regions, in which parts of wood fibres are severed, and wherein the impregnated wooden sleeper (10) is impregnated with a composition (S) comprising

[0093] A) a copper (II) salt;

[0094] B) penflufen; and

[0095] C) a cationic surfactant selected from the group consisting of tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and mixtures thereof.

[0096] Particular embodiments (e.g. regarding composition ingredients and conditions) are already above-outlined in the inventive method and shall hold for the inventive impregnated wooden sleeper, as well. In the following, particular embodiments of the impregnated wooden sleeper are described in further detail. It is to be understood that each embodiment is relevant on its own as well as in combination with other embodiments.

[0097] In one embodiment, the first regions have slots (13), which are aligned substantially parallel to the running direction of the wood fibres and are introduced in surfaces (11 , 12) of the impregnated wooden sleeper (10), so that wood fibres are displaced.

[0098] In one embodiment, the first regions is located over the whole surface of at least one of the largest surfaces, preferably over the whole surfaces of at least the four largest surfaces (11 , 12).

[0099] In one embodiment, the second regions have blind holes (16) introduced from one side of the impregnated wooden sleeper (10), so that parts of wood fibres are severed.

[0100] In one embodiment, the second regions is located at two areas of the wooden sleeper (10), wherein these areas have a group of about 10 to about 40, preferably of about 20 to about 40 blind holes (16). Preferably, these blind holes (16) are offset to each other.

[0101] In one embodiment, the invention relates to an impregnated wooden sleeper (10), wherein the impregnated wooden sleeper (10) has first regions, in which slots (13) are aligned substantially parallel to the running direction of the wood fibres and are introduced in surfaces (11 , 12) of the impregnated wooden sleeper (10), so that wood fibres are displaced, wherein the impregnated wooden sleeper (10) has second regions in which there are blind holes (16) introduced from one side of the impregnated wooden sleeper (10), so that parts of wood fibres are severed, and wherein the impregnated wooden sleeper (10) is impregnated with a composition (S) comprising

[0102] A) a copper (II) salt;

[0103] B) penflufen; and

[0104] C) a cationic surfactant selected from the group consisting of tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and mixtures thereof.

[0105] In a preferred embodiment, the copper (II) salt is copper (II) hydroxide.

[0106] In a preferred embodiment, the cationic surfactant is a mixture of 1-decanaminium, N,decyl-N,Ndimethyl-, carbonate and 1 -decanaminium, N,decylN,N-dimethyl-, bicarbonate.

[0107] In a preferred embodiment, the composition (S) further comprises

[0108] D) a fatty acid, preferably C6-C16 fatty acids, C6-C14 fatty, more preferably C10-C12 fatty, and in particular C8-C10 fatty acids.

[0109] In one embodiment, the C6-C16 fatty acids are saturated C6-C16 fatty acids, preferably saturated C6-C14 fatty, more preferably saturated C10-C12 fatty, and in particular saturated C8-C10 fatty acids.

[0110] In one embodiment, the composition (S) comprises

[0111] A) about 1 to about 6 wt% of the copper (II) salt, preferably of copper (II) hydroxide;

[0112] B) about 0.01 to about 0.5 wt% of penflufen;

[0113] C) about 0.1 to about 2.0 wt% of the cationic surfactant, preferably of a mixture of 1-decanaminium, N,decyl-N,Ndimethyl-, carbonate and 1 -decanaminium, N,decylN,N-dimethyl-, bicarbonate; and

[0114] D) optionally about 5 to about 15 wt% of a fatty acid, preferably of C6-C16 fatty acids, each based on the total amount of the composition (S).

[0115] In one embodiment, the slot depth is at least about 10 mm, preferably at least about 20 mm. The slot depth can be up to about 150 mm, preferably up to about 120 mm such as up to about 100 mm, or up to about 90 cm, or up to about 80 cm. In one embodiment, the blind holes (16) have a depth of about 4 / 5 to about 7 / 8 of the extension of the impregnated wooden sleeper (10) in the direction of the blind holes (16).

[0116] In one embodiment, the blind holes (16) have a diameter of about 3 mm to about 8 mm.

[0117] In one embodiment, the wooden sleeper (10) comprises two areas having a group of about 10 to about 40, preferably of about 20 to about 40 blind holes (16).

[0118] Preferably, these blind holes (16) are offset to each other.

[0119] In one embodiment, the timber of the wood sleeper (10) is beech or oak.

[0120] EXAMPLES

[0121] Methods

[0122] Copper can be detected according to EN ISO 11885 via ICP / OES. Prior to this, an aliquot of the ground sample can be solubilized by microwave pressure digestion using nitric acid and hydrogen peroxide.

[0123] Penflufen can be detected according to AA-A036 (quantitative detection via HPLC / DAD). Therefore, an aliquot of the ground sample can be homogenized in methanol for two hours in an ultra-sonic bath. After filtration through a 0.45 pm PTFE filter, the probe was analysed via HPLC / DAD. Materials

[0124] Suitable timber for wooden sleepers include beech and oak such as European oak and American oak.

[0125] Tanasote® S40 can be purchased from Arxada AG and comprises the following ingredients (TC - technical material):

[0126] Wolmanit® CX-8 WB can be purchased from Wolman Wood and Fire Protection GmbH, Germany (previously BASF Wolman GmbH) and comprises the following ingredients:

[0127] In general, beech is treated in a two-step impregnation, whereas oak is treated in a one-step impregnation.

[0128] Prior to impregnation, the respective wood can be mechanically treated according to the inventive process in order to increase the impregnating agent uptake.

[0129] Two-step impregnation (beech) The inventive method comprises a first impregnation i) using (aqueous)

[0130] Wolmanit® CX-8 WB and a second impregnation ii) using (lipophilic) Tanasote® S40.

[0131] While impregnating, the vessel may be under pressure (e.g. -0.8 to 10 bar). Impregnating may take 20 to 360 min. After each impregnating step, the impregnating agent is pumped off and a pressure may be applied (e.g. -0.8 to 3 bar) for a suitable time range (e.g. 30 min to 240 min).

[0132] One-step impregnation (oak) The inventive method comprises a one-stage impregnation method using (lipophilic) Tanasote® S40.

[0133] While impregnating, the vessel may be under pressure (e.g. 1 to 12 bar).

[0134] Impregnating may take 20 to 360 min. After impregnating, the impregnating agent is pumped off and a pressure may be applied (e.g. 0 to 4 bar) for a suitable time range (e.g. 30 min to 240 min).

[0135] The inventive method provides an uptake of the impregnating agent of at least 20 kg / m3.

Claims

WHAT IS CLAIMED:1 . An impregnating method for wooden sleepers (10), wherein the wooden sleeper (10) is subjected to a first mechanical treatment, wherein a displacement of wood fibres is effected, wherein the wooden sleeper (10) is subjected to a second mechanical treatment, substantially severing wood fibres and wherein as impregnating agent a composition (S) is used, wherein the composition (S) comprisesA) a copper (II) salt;B) penflufen; andC) a cationic surfactant selected from the group consisting of tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and mixtures thereof.

2. The impregnating method according to claim 1 , wherein the first mechanical treatment is a slotted perforation of at least the four largest surfaces (11 , 12) of the wooden sleeper (10), in which slots (13) are aligned substantially parallel to the running direction of the wood fibres, so that a displacement of wood fibres is effected, and / or wherein the second mechanical treatment is an at least local introduction of blind holes (16) from at least one side of the wooden sleeper (10).

3. The impregnating method according to claim 1 or 2, whereinA) the copper (II) salt is copper (II) hydroxide; and / orC) the cationic surfactant is a mixture of 1-decanaminium, N,decyl- N,Ndimethyl-, carbonate and 1 -decanaminium, N,decylN,N-dimethyl-, bicarbonate.

4. The impregnating method according to any one of claims 1 to 3, wherein the composition (S) further comprisesD) a fatty acid, preferably C6-C16 fatty acids, more preferably C8-C10 fatty acids.

5. The impregnating method according to any one of claim 1 to 4, wherein the composition (S) comprisesA) about 1 to about 6 wt% of the copper (II) salt, preferably of copper (II) hydroxide;B) about 0.01 to about 0.5 wt% of penflufen;C) about 0.1 to about 2.0 wt% of the cationic surfactant, preferably of a mixtureof 1 -decanaminium, N,decyl-N,Ndimethyl-, carbonate and 1 -decanaminium, N,decylN,N-dimethyl-, bicarbonate; andD) optionally about 5 to about 15 wt% of a fatty acid, preferably of C6-C16 fatty acids, each based on the total amount of the composition (S).

6. The impregnating method according to any one of claim 1 to 5, wherein the composition (S) has a density (determined at 20 °C according to Ell A.3 with a Pycnometer) of about 900 to about 940 kg / m3, preferably of about 910 to about 930 kg / m3and / or wherein the composition (S) has a pH (determined at 25 °C according to CIPAC MT 75.3) of about 4 to about 7, preferably of about 5 to about 6.

7. The impregnating method according to any one of claim 2 to 6, wherein the slot depth is at least about 10 mm, preferably at least about 20 mm.

8. The impregnating method according to any one of claim 2 to 7, wherein the blind holes (16) have a depth of about 4 / 5 to about 7 / 8 of the extension of the wooden sleeper (10) in the direction of the blind holes (16) and / or wherein the blind holes (16) have a diameter of about 3 mm to about 20 mm, preferably of about 3 mm to about 12 mm.

9. The impregnating method according to any one of claims 1 to 8, wherein between about 20 kg and about 133 kg, preferably between about 25 kg and about 100 kg, and in particular between about 30 kg and about 90 kg, of impregnating agent are introduced per cubic meter of wood.

10. Impregnated wooden sleeper (10), wherein the impregnated wooden sleeper (10) has first regions, in which wood fibres are displaced, wherein the impregnated wooden sleeper (10) has second regions, in which parts of wood fibres are severed, and wherein the impregnated wooden sleeper (10) is impregnated with a composition (S) comprisingA) a copper (II) salt;B) penflufen; andC) a cationic surfactant selected from the group consisting of tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and mixtures thereof.11 . The impregnated wooden sleeper (10), wherein the first regions have slots (13), which are aligned substantially parallel to the running direction of the wood fibres and are introduced in surfaces (11 , 12) of the impregnated wooden sleeper (10), so that wood fibres are displaced, and / or wherein the second regions have blind holes (16) introduced from one side of the impregnated wooden sleeper (10), so that parts of wood fibres are severed.

12. The impregnated wooden sleeper (10) according to claim 10 or 11 , wherein the composition (S) comprisesA) about 1 to about 6 wt% of the copper (II) salt, preferably of copper (II) hydroxide;B) about 0.01 to about 0.5 wt% of penflufen;C) about 0.1 to about 2.0 wt% of the cationic surfactant, preferably of a mixture of 1-decanaminium, N,decyl-N,Ndimethyl-, carbonate and 1 -decanaminium, N,decylN,N-dimethyl-, bicarbonate; andD) optionally about 5 to about 15 wt% of a fatty acid, preferably of C6-C16 fatty acids, each based on the total amount of the composition (S).

13. The impregnated wooden sleeper (10) according to any one of claims 10 to12, wherein the slot depth is at least about 10 mm, preferably at least about 20 mm.

14. The impregnated wooden sleeper (10) according to any one of claims 10 to13, wherein the blind holes (16) have a depth of about 4 / 5 to about 7 / 8 of the extension of the impregnated wooden sleeper (10) in the direction of the blind holes (16).

15. The impregnated wooden sleeper (10) according to any one of claims 10 to14, wherein the blind holes (16) have a diameter of about 3 mm to about 20 mm, preferably of about 3 mm to about 12 mm.

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