WO2004024407A1

WO2004024407A1 - Method for applying a hydrophobic coating to the surface of a porous substrate, maintaining its porosity

Info

Publication number: WO2004024407A1
Application number: PCT/IB2003/003680
Authority: WO
Inventors: Walter Koch
Original assignee: Nanosys Gmbh
Priority date: 2002-08-27
Filing date: 2003-08-15
Publication date: 2004-03-25
Also published as: EP1530510A1; AU2003253192A1

Abstract

According to the invention, at least one reagent containing Si-H groups is brought into contact with the surface of the substrate that is to receive the hydrophobic coating in the presence of an activator, which contains at least one organometallic compound of a metal of the subgroup IV or II of the periodic table. The organometallic compound is preferably selected from organotitanium, organozirconium and organozinc compounds and can be a titanic acid ester selected in particular from tetrabutyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetraisooctyl titanate and tetrakis(2-ethylhexyl)titanate, a zirconic acid ester selected in particular from tetrabutyl zirconate, tetraoctyl zirconate and tetrakis(2,4 pentane dionato)zirconate or a zinc acid ester such as dioctyl zincate. Preferably, the organometallic compound can be easily hydrolyzed.

Description

Process for hydrophobicizing the surface of a porous substrate while maintaining its porosity

TECHNICAL FIELD The present invention relates to a method for hydrophobizing the surface of a porous substrate while maintaining its porosity.

State of the art

It is known to cover a porous substrate with a hydrophobic layer in order to protect the substrate from water. A hydrophobic barrier layer is formed on the surface of the porous substrate, which shields the substrate from the outside, but this not only reduces or prevents water absorption and / or water permeability, but also an impairment of the gas absorption capacity and / or gas permeability coated substrate.

Coatings of this known type take place, for example, on raw or coated surfaces of wood or wood-based materials by staining, dyeing, painting, varnishing, etc. using solvent-based and / or water-dilutable paints. For this purpose, film-forming paints are used which, when dried, leave a more or less compact film with an average thickness of 10 to 100 μm on the coated surface. Depending on the thickness and nature, the cover layer formed in this way has a moderate to good barrier effect against liquid water, while its permeability to water vapor decreases with its thickness.

The coating of the surface of a substrate with a hydrophobic thin layer is known, for example, from WO-98/53921: the surface to be treated is treated with reagents containing Si-H residues in the presence of an activator based on a platinum metal; in this way the surface of a non-porous substrate such as metal or glass or a porous substrate such as sandstone, concrete, wood or textile. Whether the porosity of the substrate and in particular its gas absorption capacity and / or gas permeability is maintained after the treatment is not addressed in WO-98/53921, but is more or less to be expected with the specified layer thicknesses in the range of a few nanometers. A platinum metal compound is used in this process, which is correspondingly expensive.

SUMMARY OF THE INVENTION Accordingly, it is the object of the invention to propose a method for hydrophobizing the surface of a porous substrate while maintaining its porosity, which method is less expensive than in the aforementioned prior art.

To achieve this object, a method of the type mentioned at the outset is characterized by the combination of measures defined in claim 1. Advantageous embodiments of the method are defined in the dependent claims.

Ways of Carrying Out the Invention

The method according to the invention forms a hydrophobic thin layer on the surface of the treated substrate as a result of the treatment of the surface with at least one reagent which contains Si-H radicals in the presence of an activator which comprises at least one metal-organic compound of a transition metal. this transition metal is preferably a metal of subgroup IV or II of the periodic table, such as titanium, zirconium or zinc, and this metal-organic compound is preferably easily hydrolyzable.

The method according to the invention makes it possible to largely prevent the wetting of the surface of a porous substrate by water and the resultant water absorption and / or water permeability (ie to reduce it to such an extent that the surface can be regarded as non-wetted), while maintaining the Porosi- tat of the substrate, in particular its gas absorption capacity and / or gas permeability are maintained. The permeability of the thin film formed to water vapor and the maintenance of the porosity of the treated substrate can essentially be explained by the thinness of the layer, while it can be assumed that the good adhesion achieved by the thin film to covalent bonds, ie to a reaction between the surface to be treated and the reagent in the presence of the activator.

It has been shown that the hydrophobic thin layer formed on the surface of the substrate by the method according to the invention remains invisible and does not noticeably or insignificantly impair the gas absorption capacity and / or gas permeability of the substrate, while nevertheless successfully hydrophobizing the surface of the substrate.

As examples of suitable metal-organic compounds of a metal of subgroup IV of the periodic table, organic titanium compounds can be mentioned, inter alia titanium acid esters, including preferably tetrabutyl titanate (ie titanium (IV) butoxide), but also tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetraisooctyl titanate, tetrakis (2-ethylhexyl) titanate and the like, and also zirconium organic compounds, including tetrabutyl zirconate, tetra octyl zirconate, tetrakis (2,4-pentandionato) zirconate and the like. Zinc-organic compounds, including dioctyl zincate, can be mentioned as examples of suitable metal-organic compounds of a metal of subgroup II of the periodic table.

Substrates whose surface has hydroxyl, carboxyl, ammonium, amino and / or imino residues can be treated with the desired success, in particular substrates made of high molecular weight organic compounds containing the residues mentioned. Examples of such suitable substrates are substrates made from cellulose or cellulose derivatives or from proteins, for example wood, wood-based materials (such as chipboard, medium-density fibreboard, multilayer board, wood fiber board, cements), paper, silk, cardboard, wool, linen, flax, hemp and the like, as well as objects made from them. Suitable substrates with surfaces having the abovementioned residues can also result from a surface treatment of polymers: Examples of these are substrates made of polyamide, polyethylene terephthalate and polypropylene with a pretreated, namely by corona, plasma or flame treatment and the like, or by means of strong oxidizing agents such as chromium sulfuric acid , Hydrogen peroxide and the like modified surface. Substrates that can be treated with the desired success can also occur in mixed form: for example, wood fibers, glue, papers and / or plastics can be present on the surface of wood-based materials at the same time. In addition, it is to be expected that substrates whose surface has mercapto residues can also be treated with the desired success.

With the desired success, the method according to the invention can be applied to substrates with a naturally weathered surface, and the surface of the substrate can be both planar and non-planar.

In general, the use of the method according to the invention is not restricted by the size and / or nature of the surface to be treated. That is why plates, continuous foils, whole objects, inside and outside surfaces and appropriately pretreated surfaces, for example of plastics and artificial stones, can be treated with the desired success.

When the process according to the invention is applied to polymers (in the broadest sense), if appropriate after their surface pretreatment, a wide range of properties of the treated surface can be achieved because the treated polymers in addition to the required hydroxyl, carboxyl, ammonium, amino and / or imino residues can have further functional residues and / or the pretreated polymer surfaces can be modified further, for example through oxidation, which opens up a variety of possible applications.

Silanes, polysilanes, siloxanes, polysilazanes, polyhydrosiloxanes, polycarbosilanes, polysiloxanes and polysilsesquioxanes can be mentioned as examples of suitable reagents containing Si-H radicals. Such reagents are solids or liquids which, as such or in a medium, are in liquid, pasty or solid form and can be used, for example, as a solution, emulsion, suspension, foam or spray.

The activator can be used, for example, in the form of a solid, solution, emulsion, suspension, foam, spray or other systems containing liquid and / or solid phases.

The activator and reagent can first be mixed together and the resulting mixture is then applied to the surface to be treated. Activator and / or reagent can also first be mixed with other substances and only then applied to the surface to be treated. Optionally, the activator can first be applied to the surface to be treated, which is only then treated with the reagent. The reverse procedure, i.e. The treatment of the surface first with the reagent and then with the activator is also possible and can lead to a very deep treatment if the reagent is left over for a long time.

Depending on the choice of the suitable reagent containing Si-H residues, hydrophobic thin layers with different properties can be produced on the surface of the treated substrate, which in turn opens up a variety of possible uses, for example as a protective, impregnating, covering, coloring agent. , Decorative, reflection, adhesion promoter, biocompatibility, adhesive, adhesive, sliding, anti-blocking, anti-flame, non-stick, anti-graffiti, anti-fog, separating and / or demolding layers. In particular, by using appropriate reagents, the interface The energy of the hydrophobic thin layers formed can be varied so that, for example, differently wettable hydrophilic, oleophilic, hydrophobic or oleophobic thin layers can be produced with different contact angles.

In connection with lacquers and paints, the method according to the invention enables their surface modification with corresponding applications in the protection or renovation of buildings, monuments and / or works of art, as well as in various areas of the construction, automotive and machine industries.

In the case of wood products, the method according to the invention enables the formation of well-adhering, weather-resistant, colorless and invisible, water-impermeable but water-vapor-permeable thin layers (which can be hydrophobic or hydrophilic, or oleophobic or oleophilic) directly on the wood or on wood surfaces previously coated with organic substances, for example on raw, stained, glazed, impregnated or lacquered surfaces of wood and wood-based materials such as medium-density fibreboard, chipboard, multi-layer board, wood fiber cement, which can then be used indoors or outdoors. The method according to the invention can also be used for fungicide-free protective treatment (preservation and / or preservation) of wood.

In general, the method according to the invention can be combined with other treatments in order to achieve or intensify effects of the type mentioned above. The good adhesion of the thin layer to the treated surface of the substrate in combination with the properties of the thin layer itself that can be achieved on its free surface result in a wide variety of applications, including for the thermal application of plastics which are sprayed directly onto the treated surface or can be injected, or for non-stick finishing of wooden cement boards, for antigraffiti treatment, for fungicide treatment, for biocide treatment, for the treatment of skiing surfaces and the like. The following examples illustrate individual aspects of the invention, the method according to the invention being used under room conditions. However, the method according to the invention can also be carried out without problems under other atmospheric conditions, for example under carbon dioxide, nitrogen, etc. at temperatures other than room temperature and under pressure or vacuum.

example 1

Solid beech served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in toluene was used as the activator. The mixing ratio was 8% tetrabutyl titanate solid per 100 parts of polysiloxane. 10 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 2 Solid spruce served as substrate. A 5% solution of hydride-terminated polysiloxane 50 mPas in toluene was used as the reagent. A 1% solution of tetrabutyl titanate in xylene was used as an activator. The mixing ratio was 8 parts tetrabutyl titanate solid to 100 parts polysiloxane. 10 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 3 Solid spruce served as a substrate, radial cut. A 5% solution of hydride-terminated polysiloxane 40 mPas with an Si content of 4.2 mmol / g in ethyl acetate was used as the reagent. A 1% solution of tetrabutyl titanate in butyl acetate 98/100 was used as an activator. The mixing ratio was 10 parts tetrabutyl titanate solid to 100 parts polysiloxane. 10 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated end grain wood surface could not be wetted.

Example 4

A medium-density fibreboard with a thickness of 19 mm served as the substrate. As

Reagent was a 10% solution of trimethylsilyl-terminated polysiloxane 45 mPAs in ethyl acetate techn. A 1% solution of tetrabutyl titanate in ethyl acetate was used as the activator. The mixing ratio was 10 parts tetrabutyl titanate solid to 100 parts polysiloxane. 20 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface of the medium-density fiberboard could not be wetted either on the cut edge or on the surface.

Example 5 A pure silk tie painted with silk paints served as the substrate. A 5% solution of trimethylsilyl-terminated polysiloxane 45 mPAs with 7.8 mmol / g Si-H content in ethyl acetate was used as the reagent. A 1% solution of tetrabutyl titanate in ethyl acetate was used as the activator. The mixing ratio was 5 parts tetrabutyl titanate solid to 100 parts polysiloxane. 10 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the wetting behavior of red wine of 12.0% alcohol by dripping was examined: the treated silk tie surface did not absorb the test reagent and remained free of stains.

Example 6

A 13 mm thick chipboard was used as the substrate. A 10% solution of trimethylsilyl-terminated polysiloxane 100 mPAs with 3.8 mmol / g Si-H content in naphtha (bp approx. 130-160 ° C.) was used as the reagent. As The activator served a 1% solution of tetrabutyl titanate in white spirit freed from aromatic compounds. The mixing ratio was 7 parts tetrabutyl titanate solid to 100 parts polysiloxane. 20 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated chipboard could not be wetted either on the surface or on the cut edge.

Example 7

An impregnated, dark red-brown, solvent-containing spruce board, which was glazed with an oil / alkyd resin glaze, served as the substrate. A 5% solution of trimethylsilyl-terminated polysiloxane 500 mPAs with 1.1 mmol / g Si-H content in naphtha (bp approx. 130-160 ° C.) was used as the reagent. A 1% solution of tetrabutyl titanate in white spirit freed from aromatic compounds served as the activator. The mixing ratio was 7 parts of solid tetrabutyl titanate per 100 parts of polysiloxane. 15 g / m ^{2 of} the reaction liquid were applied by spraying. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated spruce board could not be wetted on the glazed side.

Example 8 An impregnated and dark red-brown, solvent-containing spruce board of unknown origin, which had been impregnated and glazed with an oil / alkyd resin glaze, was used as the substrate and was exposed to the weather for 5 years. A 5% solution of trimethylsilyl-terminated polysiloxane 500 mPAs with 2.1 mmol / g Si-H content in naphtha (bp. Approx. 130-160 ° C.) was used as the reagent. A 1% solution of tetrabutyl titanate in white spirit freed from aromatic compounds served as the activator. The mixing ratio was 7 parts tetrabutyl titanate solid to 100 parts polysiloxane. 50 g / m ^{2 of} the reaction liquid were applied by spraying. After drying overnight at room temperature, the water Wetting behavior was examined by dripping on distilled water for two hours: the treated spruce board could not be wetted on the glazed, weathered side.

Example 9

Exposed sandstone of the "rorschacher sandstone" type served as the substrate. A 10% solution of dimethylsiloxane-methylhydrogensiloxane copolymer 45 mPas in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in toluene was used as the activator. The mixing ratio was 7% solid tetrabutyl titanate per 100 parts of polysiloxane. 30 g / m ^{2 of} the reaction liquid were applied by spraying. After drying overnight, the water wetting behavior was examined by spraying with tap water: the treated surface could not be wetted.

Example 10

Concrete served as the substrate. A 10% solution of Si-H-terminated polydimethylsiloxane 3 mPas in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in white spirit was used as the activator. The mixing ratio was 10% solid tetrabutyl titanate per 100 parts of polysiloxane. 50 g / m ^{2 of} the reaction liquid were applied by spraying. After drying overnight, the water wetting behavior was examined by spraying with tap water: the treated surface could not be wetted.

Example 11

A fiber cement facade painted with a solvent-based facade paint based on acrylate served as the substrate. A 5% solution of Si-H-terminated polydimethylsiloxane 500 mPas in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in white spirit with 18% by weight of aromatic compounds served as the activator. The mixing ratio was 10% solid to 100 parts of polysiloxane. 50 g / m ^{2 of} the reaction liquid were applied by spraying. After drying overnight, the water Wetting behavior examined by spraying with tap water: The treated surface could not be wetted.

Example 12 A weathered shutter, painted with a silicone alkyd resin paint, served as the substrate. A 5% solution of Si-H-terminated polydimethylsiloxane 3 cSt in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in white spirit with 18% by weight of aromatic compounds served as the activator. The mixing ratio was 7% solid tetrabutyl titanate per 100 parts of polysiloxane. 50 g / m ^{2 of} the reaction liquid were applied by spraying. After drying overnight, the water wetting behavior was examined by spraying with tap water: the treated surface could not be wetted.

Example 13

A tennis ball of an unknown brand served as the substrate. A 5% solution of Si-H-terminated polydimethylsiloxane 100 cSt in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in white spirit with 18% by weight of aromatic compounds served as the activator. The mixing ratio was 7% solid tetrabutyl titanate per 100 parts of polysiloxane. 10 g of the reaction liquid were applied uniformly over the surface by spraying. After drying overnight, the water wetting behavior was examined by submerging it several times in tap water: the treated tennis ball did not get wet.

Example 14

An interior plaster served as the substrate. A 5% solution of Si-H-terminated polydimethylsiloxane 500 cSt in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in white spirit with 18% by weight of aromatic compounds served as the activator. The mixing ratio was 7% solid tetrabutyl titanate per 100 parts of polysiloxane. There were 30 g / m ^{2 of} the reaction liquid evenly over the Surface applied by spraying. After drying overnight, the water wetting behavior was examined by spraying with tap water: the treated surface could not be wetted.

Example 15

Oak parquet pieces served as the substrate. A 5% solution of Si-H-terminated polydimethylsiloxane 1000 cSt in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in toluene was used as the activator. The mixing ratio was 8% tetrabutyl titanate solid per 100 parts of polysiloxane. 20 g / m ^{2 of} the reaction liquid were applied to the cut edges by spraying. After drying overnight at room temperature, the water wetting behavior of the cut edges was examined by dripping on distilled water for 30 minutes: the treated surface could not be wetted.

Example 16

Maple parquet straps served as the substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in toluene was used as the activator. The mixing ratio was 8% tetrabutyl titanate solid per 100 parts of polysiloxane. 20 g / m ^{2 of} the reaction liquid were applied to the cut edges by spraying. After drying overnight at room temperature, the water wetting behavior of the cut edges was examined by dripping on distilled water for 30 minutes: the treated surface could not be wetted.

Example 17

Beech parquet straps served as the substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in butyl acetate 98/100 was used as the reagent. A 1% solution of tetrabutyl titanate in toluene was used as the activator. The mixing ratio was 8% tetrabutyl titanate solid per 100 parts of polysiloxane. 20 g / m ^{2 of} the reaction liquid were applied to the cut edges by spraying. After drying overnight at room temperature, the wetting behavior the cut edges were examined by brushing on a water-thinnable parquet sealing lacquer: the parquet lacquer did not adhere to the treated surface.

Example 18

Cross-sections of pine branches served as the substrate. A 10% solution of hydride-terminated polysiloxane of molecular weight 26,000 in xylene was used as the reagent. A 1% solution of tetrabutyl titanate in toluene was used as the activator. The mixing ratio was 7% solid tetrabutyl titanate to 100 parts polysiloxane. 50 g / m ^{2 of} the reaction liquid were applied to the cut edges by spraying. After drying overnight at room temperature, the wetting behavior of the cut edges was investigated by dripping tap water: the treated surface could not be wetted.

Example 19

Solid spruce served as the substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in toluene was used as the reagent. A 1% solution of tetrabutyl titanate in xylene was used as an activator. The mixing ratio was 8 parts tetrabutyl titanate solid to 100 parts polysiloxane. The spruce test specimens were immersed in the reaction liquid for 5 seconds. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 20

Solid ash served as the substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in toluene was used as the reagent. A 1% solution of tetrabutyl titanate in xylene was used as an activator. The mixing ratio was 8 parts tetrabutyl titanate solid to 100 parts polysiloxane. The ash test specimens were immersed in the reaction liquid for 10 seconds. After drying overnight at room temperature, the water wetting behavior was determined by dripping on distillation Water was examined for two hours: the treated surface could not be wetted.

Example 21 A raw blockboard was used as the substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in toluene was used as the reagent. A 1% solution of tetrabutyl titanate in xylene was used as an activator. The mixing ratio was 8 parts tetrabutyl titanate solid to 100 parts polysiloxane. The block board was once brushed with the reaction liquid. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 22

A new concrete control panel served as the substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in toluene was used as the reagent. A 1% solution of tetrabutyl titanate in xylene was used as an activator. The mixing ratio was 8 parts tetrabutyl titanate solid to 100 parts polysiloxane. The control panel was brushed once on all sides with the reaction liquid. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 23

A new precision control panel served as the substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in toluene was used as the reagent. A 1% solution of tetrabutyl titanate in xylene was used as the activator. The mixing ratio was 8 parts tetrabutyl titanate solid to 100 parts polysiloxane. The control panel was brushed once on all sides with the reaction liquid. After drying overnight at room temperature, the water wetting behavior was determined by dripping on distilled water examined for two hours: the treated surface could not be wetted.

Example 24 Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in xylene was used as the reagent. A 1% solution of tetrakis (2,4-pentandionato) zirconate ("zirconium (IV) acetylacetonate") in toluene was used as the activator. The mixing ratio was 8% tetrakis (2,4-pentanedionato) zirconate solid to 100 parts of polysiloxane. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 25

Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in xylene was used as the reagent. A 1% solution of tetrabutyl zirconate in toluene was used as the activator. The mixing ratio was 8% tetrabutyl zirconate solid per 100 parts of polysiloxane. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 26

Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in naphtha (bp. Approx. 130-160 ° C.) was used as the reagent. A 1% solution of tetrapropyl titanate (“tetrapropyl orthotitanate”) in toluene was used as the activator. The mixing ratio was 8% solid tetrapropyl titanate per 100 parts of polysiloxane. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 27

Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in naphtha (bp. Approx. 130-160 ° C.) was used as the reagent. A 1% solution of tetra-butyl titanate in toluene was used as an activator. The mixing ratio was 8% tetra-üe / t-butyl titanate solid per 100 parts of polysiloxane. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface was only slightly wettable.

Example 28

Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in naphtha (bp. Approx. 130-160 ° C.) was used as the reagent. A 1% solution of tetraethyl titanate in toluene was used as the activator. The mixing ratio was 8% solid tetraethyl titanate per 100 parts of polysiloxane. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was investigated by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 29 Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in naphtha (bp. Approx. 130-160 ° C.) was used as the reagent. A 1% solution of tetraisopropyl titanate in toluene was used as the activator. The mixing ratio was 8% solid tetraisopropyl titanate per 100 parts of lysiloxan. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 30

Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in naphtha (bp. Approx. 130-160 ° C.) was used as the reagent. A 1% solution of tetrakis (2-ethylhexyl) titanate in toluene was used as the activator. The mixing ratio was 8% tetrakis (2-ethylhexyl) titanate per 100 parts of polysiloxane. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could be wetted after one hour.

Example 31 Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in naphtha (bp. Approx. 130-160 ° C.) was used as the reagent. A 1% solution of tetraisooctyl titanate in toluene was used as an activator. The mixing ratio was 8% solid tetraisooctyl titanate per 100 parts polysiloxane. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was examined by dripping on distilled water for two hours: the treated surface could not be wetted.

Example 32

Nordic spruce, radial cut, solid served as substrate. A 5% solution of hydride-terminated polysiloxane with a molecular weight of 26,000 in xylene was used as the reagent. A 1% solution was used as the activator. Solution of dioctyl zincate ("zinc octoate") with 8% metal content in toluene. The mixing ratio was 8% dioctyl zincate solid per 100 parts of polysiloxane. 40 g / m ^{2 of} the reaction liquid were applied by brushing. After drying overnight at room temperature, the water wetting behavior was investigated by dripping on distilled water for two hours: the treated surface could not be wetted.

All experiments as described in the examples given above were also carried out as a control without an activator: in all the control experiments it was found that the corresponding reagent containing Si-H does not bind to the surface, or only insignificantly, without the activator, and the desired properties cannot be achieved or can only be achieved to a small extent. Experiments with pure solvent or with a solution or suspension containing only the activator did not give the result obtained with the corresponding Si-H reagents.

In the presence of the activator, all experiments, as described in the examples given above, resulted in a coating with an invisible thin layer which could not be removed with xylene, naphtha and / or butyl acetate. The thin layers produced directly on wood fiber were dishwasher-safe over more than 10 washing cycles (M-Net detergent, from Migros). After storage in water for one month, the thin layers still showed their original behavior. Raw spruce panelers treated by the method according to the invention showed no decrease in the hydrophobicity produced by the coating on the wood fiber, even after they had been exposed to the weather for six months (45 °, oriented to the south).

The concentrations and times given in the examples given above were chosen so that practical conditions for coating a surface, for example with an impregnating were simulated with it. However, the method according to the invention can also be carried out with other concentrations, application quantities and / or exposure times.

In some of the examples, the coating was carried out by brushing, spraying, spraying or dipping. However, the coating can also be carried out in another way, for example by flooding, misting, gassing, rolling, printing or rolling.

Claims

claims

1. A method for hydrophobicizing the surface of a porous substrate while maintaining its porosity, wherein at least one reagent containing Si-H residues in the presence of at least one

Activator comprising metal-organic compound is brought into contact with the surface of the substrate to be made hydrophobic, characterized in that the metal of the organometallic compound is a transition metal.

2. The method according to claim 1, characterized in that the transition metal is a metal of subgroup IV of the periodic table.

3. The method according to claim 2, characterized in that the metal is titanium.

4. The method according to claim 3, characterized in that the metal-organic compound is a titanium acid ester.

5. The method according to claim 4, characterized in that the titanium ester is selected from tetrabutyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetraisooctyl titanate and tetrahis (2-ethylhexyl) titanate.

6. The method according to claim 2, characterized in that the metal is zirconium.

7. The method according to claim 6, characterized in that the metal-organic compound is a zirconic acid ester.

8. The method according to claim 7, characterized in that the zirconic acid ester is selected from tetrabutyl zirconate, tetraoctyl zirconate and tetrakis (2,4-pentandionato) zirconate.

, A method according to claim 1, characterized in that the transition metal is a metal of subgroup II of the periodic table.

10. The method according to claim 9, characterized in that the metal is zinc.

11. The method according to claim 10, characterized in that the metal-organic compound is a zinc acid ester.

12. The method according to claim 11, characterized in that the zinc ester is dioctyl zincate.

13. The method according to claim 1, characterized in that the metal-organic compound is easily hydrolyzable.