EP1325096A1

EP1325096A1 - Composition for producing surfaces which are difficult to wet

Info

Publication number: EP1325096A1
Application number: EP01978411A
Authority: EP
Inventors: Harald Keller; Ekkehard Jahns; Christian Lach; Stephan Hüffer; Thilo Krebs; Yi Thomann; Thomas Frechen
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2000-10-13
Filing date: 2001-10-12
Publication date: 2003-07-09
Also published as: US20040014865A1; DE10050788A1; WO2002031080A1; JP2004511618A; KR20030042015A

Abstract

The invention relates to a composition comprising at least one hydrophilic, inorganic powder (P) having an average particle size of between 15 and 500 μm, and at least one hydrophobic, thermoplastic substance (T) which is characterised by a surface tension of between 20 and 50 mN/m. The weight ratio of the hydrophilic, inorganic powder to the hydrophobic, thermoplastic substance P:T is between 50:1 and 1:2.

Description

Composition for the production of poorly wettable surfaces

The present invention relates to compositions which comprise at least one hydrophilic, inorganic powder P with a particle size in the range from 15 to 500 μm and at least one hydrophobic, thermoplastic substance T and the use of these compositions for producing surfaces which are difficult to wet.

Conventional surfaces are usually wetted by liquids. The degree of wetting is an interplay between the cohesive forces in the liquid and the adhesive forces between the liquid and the surface.

In many cases, wetting a surface with a liquid is undesirable. For example, the wetting of surfaces with water leads to water drops remaining on the surface and evaporating, the solids dissolved or suspended in water remaining as ugly residues on the surface. This problem exists especially on surfaces that are exposed to rainwater.

Wetting a surface with water often triggers its corrosion or infestation with microorganisms as well as fouling with algae, lichens, mosses, mussels, etc.

In the case of packaging and storage containers for liquid filling goods, low wettability of the inner surfaces is desirable so that only small amounts of liquid remain in the packaging or in the storage container when emptied.

Also in apparatus and plant engineering, low wettability of plant parts that come into contact with liquids is desirable. If the system parts are highly wettable, there is a risk of increased build-up of deposits and deposits. In addition, increased wettability usually results in increased flow resistance of liquids in pipelines. It is known to reduce the wettability of a surface for hydrophilic liquids by means of a hydrophobic coating on the surface. Polysiloxanes, (per) fluorinated polymers, in particular extremely hydrophobic polytetrafluoroethylene (Teflon) and organofluorine waxes are suitable as coating materials. Fluorinated or perfluorinated polymers and fluoroorganic waxes usually have a surface tension of <20 mN / m. The coating reduces the adhesive forces between the liquid and the wetted surface.

It has also proven to be beneficial to structure hydrophobic surfaces. Such surface structures generally have regular or irregular elevations or depressions in the range from 0.1 to 1000 μm. The structuring on the one hand further reduces the adhesion of the surface for polar liquids such as water. In addition, the structuring leads to a reduced adhesion of solid deposits such as dirt particles on the surface. In addition, it has been shown that with a suitable structuring, the dirt particles are rinsed off the surface by moving water. This effect is also referred to as the self-cleaning effect or the lotus effect (see Barthlott et al., Biology in Our Time, 28, No. 5, 314-322).

For example, WO 96/04123 describes self-cleaning surfaces of objects which have an artificial surface structure which has elevations and depressions, the structure being characterized in particular by the distance between the elevations and the height of the elevations. The surfaces are produced, for example, by applying Teflon powder to a surface treated with adhesive or by embossing a structure on a thermoplastic deformable hydrophobic material.

Similar surfaces are known from US Pat. No. 3,354,022. Here too, the surface is produced either by embossing a structure or by applying hydrophobic particles, for example wax particles, to a hydrophobic surface. In addition, a surface is described that consists of wax-coated glass powder with a grain size of 3 to 12 μm.

EP 933 388 discloses a process for producing structured surfaces with hydrophobic properties, in which a negative mold is first produced by photolithography, shapes a plastic film with this shape and then hydrophobicizes the plastic film with fluoroalkylsilanes.

EP-A 909 747 describes a method for producing a self-cleaning property on ceramic bodies such as roof tiles, in which a dispersion of clay particles in an organic silicone resin solution is applied to the ceramic body and the coating is cured.

A coating method is known from JP 7328532-A, in which finely divided particles with a hydrophobic surface are applied to a moist lacquer and cured. Here, water-repellent surfaces are obtained.

The methods described in the prior art for producing surfaces that are difficult to wet are either very complex or do not lead to satisfactory results. The production of a structured surface by means of embossing processes is complex and can only be used economically on flat surfaces. Surfaces on which structuring is achieved by subsequent application of hydrophobic particles are often difficult to reproduce or have only low mechanical stability. In addition, this process is also very complex. In addition, organofluorine compounds or fluorine-containing polymers are often required, which are not only very expensive but also environmentally harmful.

The present invention is therefore based on the object of providing compositions which are suitable for producing surfaces with low wettability and which overcome the disadvantages of the prior art. This object is achieved by a composition which has at least one hydrophobic thermoplastic substance T, which is characterized by a surface tension in the range from 20 to 50 mN / m, and at least one hydrophilic, finely divided powder P with a particle size in the range from 15 contains up to 500 μm and in which the weight ratio of hydrophilic, inorganic powder to hydrophobic thermoplastic substance P: T is in the range from 1: 2 to 50: 1.

The invention thus relates to these compositions and to their use for producing surfaces which are difficult to wet.

To produce surfaces that are difficult to wet, the coating compositions can be applied as coatings to surfaces in a simple manner. They almost completely reduce the wettability of the surface and create on these surfaces a self-cleaning effect. Accordingly, the present invention also relates to a method for producing surfaces which are difficult to wet, in which a coating composition according to the invention is applied to a surface to be coated, and to the use of the coating compositions for producing surfaces with self-cleaning effects. In addition, the compositions according to the invention can be used to reduce the flow resistance in pipes by coating the inner walls of the pipes with the compositions according to the invention.

The static contact angle of a drop of liquid on a surface can be used to characterize surfaces with regard to their wettability. The static contact angle is defined as the angle enclosed by said surface and a tangent along the surface of the liquid drop in the region of the contact point of the liquid drop with the surface, the contact angle being measured by the liquid drop. A contact angle of 0 ° therefore means complete wettability and no drop formation, while a contact angle of 180 ° means complete non-wettability. The determination of the contact angle can be determined by known methods, for example with the aid of a microscope equipped with a goniometer (see also CD Bain et al., Angew. Chem. 101 (1989) 522-528 and A. Born et al., Farbe & Lack 105 (1999) pp. 96-104).

The surfaces treated with the coating compositions according to the invention generally have, for a wide variety of liquids, in particular water, static contact angles> 120 ° and in particular> 140 ° and in particular> 160 ° (determined at room temperature). Contact angles of> 160 ° are often reached, especially in water. Contact angles above 160 ° cannot usually be determined with sufficient accuracy. However, a contact angle above 160 ° usually corresponds to a complete non-wettability of the surface.

Another measure of the wettability of a surface is the "repellent power" F _R , which is defined as the reciprocal of the weight force F _H , which is required to allow a drop of liquid to run off an inclined surface. The "Repellent Power" is calculated using the following formula:

Here m stands for the mass of the liquid drop, g for the gravitational acceleration and α for the smallest possible angle of inclination of the surface to be tested against the horizontal, which is sufficient to let the liquid drop run off this surface.

The hydrophobic thermoplastic substances T contained in the compositions according to the invention, in conjunction with the hydrophilic powder, result in surfaces which are essentially composed of such a composition showing low wettability and a self-cleaning effect. At the same time, they act as binders and thus serve to fix the powder particles on the surface.

their surface tension is used to characterize the hydrophobicity of the thermoplastic substance T. It can be determined, for example, by measuring the static contact angle of water on a smooth surface coated with the substance T. The substances T contained in the compositions according to the invention are characterized by static contact angles for water of at least 90 °. The hydrophobicity can also be determined by the "hanging drop" method (pendant drop: see S. Wu, "Polymer Interface and Adhesion", Marcel Decker Inc., New York 1982, pp. 266-268). The values given for the surface tension of the binders here and below relate to the values determined according to the "hanging droplet method". Hydrophobic binders in the sense of the invention have a surface tension in the range from 20 to 50 mN / m. The surface tension of commercially available, hydrophobic substances T are given in part in the literature; see e.g. B. Wu et al. loc. P. 88 ff. And S. Ellefson et al. J. Am. Ceram. Soc. 21, 193, (1938); S. Wu, J. Colloid Interface Sci. 31, 153, (1969), J. Phys. Chem. 74, 632 (1970), J. Polym. Sei, C34, 19, (1971); R.J. Roe et al., J. Phys. Chem. 72, 2013 (1968), J. Phys. Chem. 71, 4190 (1967), J. Colloid Interface Sci. 31, 228, (1969); J.F. Padday in "Surface and Colloid Science (Ed. E. Matijevic), Wiley, New York 1969, pp. 101-149.

Preferred binders according to the invention are those which have a surface energy of <42 mN / m and in particular <37 mN / m.

As a rule, the substances T are thermoplastic or film-forming polymers which are soluble in organic solvents. Organic prepolymers which are characterized by a thermal, oxidative or photochemical curing process and thus form a solid coating with the powder.

The type of substance T often depends on the desired application and is of minor importance for the success according to the invention, provided that its hydrophobicity is in the range according to the invention. Such substances generally have a plurality of hydrocarbon radicals with at least 4 carbon atoms, for example linear or branched alkyl or alkenyl or cycloalkyl with at least 4, preferably 5 to 30 and in particular 8 to 24 C atoms and or longer hydrocarbon segments with generally at least 4 preferably at least 6 bonded, saturated carbon atoms. Examples of such hydrocarbon segments are linear or branched C -C _n -alkylene, preferably C ₆ -C _n -alkylene and Cs-Cio-cycloalkylene groups, where n is an integer> 4 or> 6. The proportion of hydrocarbon chains or hydrocarbon segments generally makes up at least 50% by weight and in particular at least 60% by weight of substance T.

Substances T include, for example, fatty acids with more than 8 carbon atoms, in particular ethylenically unsaturated fatty acids, and their esters with polyfunctional alcohols such as glycerol, ethylene glycol, propanediol, sorbitol, glucose, sucrose or trimethylolpropane, the fatty acids and their esters being oxidative harden and therefore belong to the class of prepolymers. Natural substances such as beeswax, cananauba wax, wool wax, candelilla wax and artificial waxes such as montanic acid waxes, montan ester waxes, amide waxes, for example, also come as substances T. Distearoylethylenediamine, Fischer-Tropseh waxes and wax-like polymers of ethylene and propylene (polyethylene wax, polypropylene wax).

The substances T are preferably oligomers or polymers with a number average molecular weight above 1000 daltons, in particular above 1500 daltons and in particular above 2000 daltons, the upper molecular weight limit being 10 million g / mol. The molecular weight is preferably in the range from 2500 to 5 million g / mol (determined by viscometry).

Examples of such substances T are homo- or copolymers of ethylenically unsaturated monomers M, which comprise at least 50% by weight of ethylenically unsaturated monomers A with Cs-C ₃ o-alkyl groups or C ₅ -C -o-cycloalkyl groups and optionally suitable comonomers B are built up. Examples of such monomers A are:

monothylenically unsaturated ethers and esters of C ₅ -C ₃ o-alkanols or C ₅ -C 10 -cycloalkanols, for example their vinyl, allyl and methallyl ethers, such as vinyl hexyl ether, vinyl n-octyl ether, vinyl lauryl ether, vinyl stearyl ether (vinyl octadecyl ether) , Vinyl cyclopentyl ether and vinyl cyclohexyl ether;

Esters and half-esters of ethylenically unsaturated C ₃ -Cs-mono- or dicarboxylic acids with C ₅ -C ₃₀ -alkanols or Cs-Cio-cycloalkanols, for example the esters and half-esters of acrylic acid, methacrylic acid, maleic acid or fumaric acid such as n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-propylheptyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate and Stearyl (meth) acrylate, bis (n-hexyl) maleate or fumarate, bis-2-ethylhexyl maleate or fumarate, bis (2-propylheptyl) maleate or fumarate, bis-n-decyl maleate or - fumarate, bislauryl maleate or fumarate and bis-stearyl maleate or fumarate;

Amides of ethylenically unsaturated monocarboxylic acids with Cs-C ₃ o-alkylamines or Cs-Cio-cycloalkylamines, N- (n-hexyl) acrylamide and -methaerylamide, N- (n-octyl) acrylamide and -methaerylamide, N- (n-dodecyl) acrylamide and methaerylamide and N- (stearyl) acrylamide and methaerylamide;

Vinyl allyl and methallyl esters of aliphatic carboxylic acids with 6 to 30 carbon atoms, such as vinyl hexanoate, vinyl octanoate, vinyl laurate, vinyl stearate, vinyl cyclohexanoate; such as

C ₇ -C ₃ -01efins such as n-heptene, n-octene, isooctene, n-decene, dodecene, isotridecene, and also oligoolefin mixtures with a terminal double bond and 10 to 32 C atoms and the like.

The type of comonomers B is of comparatively little importance. In principle, all ethylenically unsaturated monomers which can be copolymerized with the monomers A come into consideration. These include monoethylenically unsaturated mono- and dicarboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, cotonic acid, itaconic acid, their amides, such as acrylamide, methaerylamide, maleimide, their esters with Cχ-Cs-alkanols such as methyl acrylate, methyl methacrylate, ethyl acrylate, Ethyl methacrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-butyl methacrylate, iso-butyl methacrylic, tert-butyl methacrylate, conjugated diolefins such as butadiene and isoprene, vinyl and allyl esters of aliphatic carboxylic acids with 2 to 5 carbon atoms Vinyl acetate, vinyl propionate, vinyl butyrate and vinyl pivalate, vinyl aromatic monomers such as sty- rol, tert. -Butylstyrene and vinyltoluene, ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile, as well as halogen olefins such as vinyl chloride, vinylidene chloride, chlorodifluoroethene, vinylidene fluoride and tetrafluoroethane.

Specific examples of homo- and copolymers of the monomers A are the poly-C ₅ -C ₃ o-alkyl vinyl ethers, for example polyoctadecyl vinyl ethers, which preferably have a molecular weight in the range from 2000 to 20,000, in particular in the range from 2500 to 10,000, daltons (viscosimetric determined), copolymers of the aforementioned ethylenically unsaturated mono- and dicarboxylic acids with C ₇ -C ₃₂ -01efins, for example the copolymers of maleic acid with C ₇ -C ₃₂ -01efins as well as reaction products of these copolymers with fatty alcohols of chain length Cg-C ₃₂ or with fatty amines Chain length C ₈ -C ₃₂ , the homo- and copolymers of esters of acrylic acid and / or methaeryl acid with optionally C ₅ -C ₃ o-alkanols with C ₁ -C 4 -alkyl (meth) acrylates, vinyl aromatics and / or vinyl C ₂ -Cs alkanoates and optionally further comonomers B.

Preferred substances T are also oligo- and poly-C ₇ -C ₇ -olefins such as polyethylene, polypropylene, polyisobutene, for example with molecular weights in the range from 10,000 to 10,000,000 (determined by viscometry).

Suitable substances T are also polymers which are composed almost exclusively, that is to say at least 99% by weight, of C ₃ -C ₂ -alkyl esters of acrylic acid and or of methaerylic acid, and also copolymers in which up to 50% by weight of these monomers are derived therefrom different monomers A or replaced by monomers B with a water solubility <10 g / 1. Examples of such polymers are in particular poly-n-butyl acrylate and methacrylate and poly-tert. -butyl acrylate and methacrylate.

Suitable substances T are also poly-C 1 -C 8 -alkylene oxides, such as polyoxymethylene, polypropylene oxide and polybutylene oxide, polytetrahydrofuran, furthermore polycaprolactone, polycarbonates, polyvinyl butyral, polyvinyl formal, and linear or branched polydialkyl siloxanes such as polydimethylsiloxane (silicones) ,

Polymers with siloxane side chains of the formula I are also suitable

-X + (CH _{2 a} O _b - (Si (CH ₃ ) ₂ 0) _c R] _n (I) wherein X is oxygen when n = 1, or nitrogen when n = 2, a is an integer from 1 to 2000 and R is hydrogen, trimethylsilyl or Ci-Ce-alkyl.

Such polymers can be obtained by homo- and copolymerization of ethylenically unsaturated monomers B of the formula II, optionally together with the aforementioned monomers A and / or C.

CH ₂ = C (R ') - YX-HCH ₂ -r _a O _b - (Si (CH ₃ ) ₂ 0) _c R] _n (II) where R' is hydrogen or methyl and Y is C (O), CH or a chemical bond and X, a, b, c, R and n have the meanings mentioned above.

Suitable substances T are furthermore aliphatic and partially aromatic polyesters made from aliphatic or aromatic dicarboxylic acids and aliphatic and / or aromatic diols, e.g .:

- aliphatic polyesters made up of aliphatic dialcohols with 2 to 18 carbon atoms, e.g. Propanediol, butanediol, hexanediol, and aliphatic dicarboxylic acids having 3 to 18 carbon atoms, such as adipic acid and decanedicarboxylic acid;

- Partly aromatic polyester, built up from bisphenol A and the aforementioned dicarboxylic acids with 3 to 18 carbon atoms; such as

partially aromatic polyester, made up of terephthalic acid, aliphatic dialcohols with 2 to 18 C atoms and dicarboxylic acids with 3 to 18 C atoms.

The polyesters can optionally be terminated with long-chain monoalcohols with 4 to 24 carbon atoms, such as 2-ethylhexanol or octadecanol. Furthermore, the polyesters with long-chain monocarboxylic acids with 4 to 24 carbon atoms, such as e.g. Stearic acid terminated.

Typical photochemically and / or thermally crosslinkable binders are polymers or oligers with ethylenically unsaturated double bonds, as used for the production of radiation-curable lacquers, and, based on their total weight, at least 50% by weight of C ₅ -C ₃₀ -alkyl groups, C ₅ -Cι ₀ cycloalkyl groups or hydrocarbon segments having at least 4, preferably at least 6 aliphatic hydrocarbon atoms. These include, for example, flowable preparations of polyether acrylates, polyester acrylates, polyurethane acrylates, polyesters with condensed maleic anhydride units, epoxy resins, for example aromatic epoxy resins, the oligomers or polymers are dissolved in organic solvents and / or reactive thinners to improve their flowability. Reactive thinners are low molecular weight, ethylenically unsaturated liquids which form the coating with the ethylenically unsaturated polymers during crosslinking. Radiation-curable binders and preparations containing these binders are sufficiently known to the person skilled in the art, for example from PKT 01-dring (ed.) "Chemistry and Technology of UV & EB Formulation for Coatings, Inks &Paints", Vol. 2, 1991, Sita Technology Lon- don, and commercially available, for example under the trademarks Laromer® ^® P084F, Laromer® ^® LR8819, Laromer® ^® PE55F, Laromer- ^® LR8861, BASF Aktiengesellschaft, Ludwigshafen, Germany.

The powders contained in the compositions according to the invention are hydrophilic in nature, i.e. they are wetted by water. As a rule, these are oxidic materials, preferably silicates or silicic acid or quartz, aluminosilicates, clay minerals, aluminum oxides, titanium dioxide or inorganic carbonates, e.g. Alkaline earth carbonates such as magnesium carbonate, calcium carbonate (chalk) or dolomite, alkaline earth sulfates such as calcium and barium sulfate, the former e.g. in the form of plaster.

Powders P with average grain sizes (weight-average particle diameters) in the range from 20 to 300 μm are preferred, in particular with average grain sizes in the range from 20 to 200 μm, particularly preferably in the range from 20 to 150 μm and very particularly preferably in the range from 20 to 100 μm. The weight fraction of the particles with grain sizes above 500 μm is preferably less than 10%, in particular less than 5%. The proportion by weight of particles with grain sizes below 15 μm is likewise usually less than 10%, in particular less than 5%. In particular, powders are preferred in which 90% by weight of the powder particles have grain sizes in the range from 20 to 200 μm, particularly preferably in the range from 20 to 150 μm and very particularly preferably in the range from 20 to 100 μm.

Preferred powders P are essentially composed of silicates or Si0 ₂ . Examples include sand, for example with grain sizes in the range from 20 to 200 μm, in particular 30 to 100 μm, glass or quartz powder preferably with grain sizes below 250 μm, in particular below 200 μm, particularly preferably below 150 μm and particularly preferably below 100 μm. Suitable hydrophilic powders are also pyrogenic silica, which are commercially available, for example, under the AEROSIL ^® brand, for example AEROSIL ^® 380 (from Degussa-Huls AG). In order to achieve the low wettability effect desired according to the invention, it has proven advantageous if the weight ratio of powder P to substance T in the compositions according to the invention is at least 1.1: 1, in particular at least 1.5: 1, particularly preferably at least 2 : 1 and most preferably at least 3: 1. The weight ratio is preferably at most 20: 1, in particular at most 15: 1 and particularly preferably at most 10: 1.

The compositions according to the invention are used both as coating agents, i.e. Suitable for coating conventional surfaces as well as molding compounds for the production of moldings. Because of the use of thermoplastic binders, the compositions according to the invention can be processed thermoplastically by the methods customary for this.

Coatings are produced in a known manner by applying the compositions according to the invention to the conventional surface to be coated. Shaped bodies are produced from the compositions according to the invention by using the compositions according to the invention in known shaping processes, in particular by thermoplastic processes, for example by pressing, e.g. Hot pressing, hot rolling, injection molding or extruding the compositions according to the invention above the melting or sintering temperature of the thermoplastic substance T. The processing into shaped bodies can be carried out both from solvent-containing compositions and from solid compositions, e.g. powdery or granular compositions.

Depending on the application, the compositions according to the invention can be in dry form, ie. H. be formulated as a powder preparation which comprises both the finely divided powder P and the hydrophobic substance T.

In another preferred embodiment, however, the compositions according to the invention are formulated in a form which is flowable at the processing temperature. The processing of the compositions according to the invention can of course take place both at room temperature and at temperatures below or above room temperature, e.g. at temperatures in the range from 0 ° C to 300 ° C, preferably 0 to 250 ° C, in particular 10 to 200 ° C, depending on the type of composition.

In the flowable form, the compositions according to the invention generally contain, in addition to the powder P and the hydrophobic substance P, an organic diluent or solvent, if appropriate. solvent, preference being given to those solvents which dissolve or swell the substances T. As a result, a better formation of the coating is achieved.

Suitable solvents are volatile organic solvents which, after application of the composition according to the invention, e.g. after application of a composition formulated as a coating agent, if necessary by heating, evaporate and thus allow the formation of a uniform film of the substance T. Examples of suitable solvents are ketones, such as acetone, ethyl methyl ketone, volatile esters of acetic acid, such as ethyl acetate, n-butyl acetate, cyclic ethers, such as tetrahydrofuran, and aliphatic and aromatic hydrocarbons, such as turpentine oil, petroleum, petrol, toluene and xylene. Preferred organic solvents are the aforementioned aliphatic and aromatic hydrocarbons.

In the liquid formulations, the solids content (total amount of powder P and substance T, based on the total weight of the formulation) is in the range from 0.5 to 90% by weight. With conventional paints, the solids content is often in the range from 20 to 90% by weight. In the case of sprayable paints, it can also be below it, e.g. in the range of 0.5 to 20% by weight.

The compositions according to the invention can also be formulated as aerosols. In addition to the powder P and the substance T, they then contain at least one blowing agent and, if appropriate, also one of the solvents mentioned in the liquid formulations. Suitable propellants are the substances customary for this, such as propane, butane, dimethyl ether, CO ₂ , N ₂ 0 and mixtures thereof. The solids content of sprays is generally in the ranges customary for this, for example in the range from 0.1 to 10% by weight, where the solids can also comprise solid additives in addition to components P and T. The remaining proportions of the coating agents formulated as aerosols relate to propellant gases and optionally solvents.

In principle, all conventional surfaces can be coated with the compositions according to the invention. Examples of conventional surfaces are the surfaces of wood, metal, for example steel or stainless steel, glass and plastic. Of course, the coating compositions of the invention can also be used to coat rough or porous surfaces such as concrete, plaster, paper, fabric, for example textile fabrics for clothing, umbrellas, tents, awnings and for comparable applications, leather and hair. The composition is applied to the surface to be coated (hereinafter also referred to as the substrate) depending on the configuration of the composition, hereinafter referred to as the coating agent, and the type of substrate by the application methods customary in coating technology. In the case of solvent-containing, flowable coating compositions, the application is generally carried out by brushing, knife coating, spraying, for example by means of airbrushing, dipping or rolling and then drying the coating, the solvent evaporating.

If a thermally, oxidatively or photochemically crosslinkable prepolymer is used as substance T, then the coating compositions are often free-flowing even without the addition of solvents and, if appropriate after dilution with a reactive diluent, can be applied by the process mentioned above The actual coating is then carried out by thermal, oxidative or photochemical curing (crosslinking) of the prepolymers.

In the case of powdery coating compositions, the powder coating processes customary in powder coating technology are used. In these processes, the powdered coating agent is applied in the desired amount to the substrate to be coated and then heated, the thermoplastic polymer binder flowing away and forming a polymeric film which fixes the powder particles according to the invention on the surface.

To achieve the desired effect, the coating agent is preferably used in an amount of at least 0.01 g / m ² , in particular at least 0.1 g / m ² and especially at least 0.5 g / m ² and preferably not more than 1000 Apply g / m ² , based on the solid components in the coating agent, to the surface to be coated. Solid components are essentially components i) and ii). This corresponds to a basis weight of the coating of at least 0.01 g / m ² , in particular at least 0.1 g / m ² and especially at least 0.5 g / m ^2, remaining after the evaporation of volatile constituents. The coatings are often applied in amounts of up to 300 g / m ² to the surface to be coated (based on solid constituents), but larger amounts of coating agent will also be applied in other forms of application, for example in the form of facade paints, plastering and jointing materials or in the coating of concrete roof tiles, roof tiles, exposed concrete, washed concrete, masonry or composite materials containing concrete. It has also proven useful to roughen the surfaces provided with the binders according to the invention, for example by means of a grinding process, for example by treatment with a fine-grained abrasive with a grain size of 80 to 400, or by sand blasting, shot peening or brushing. This further improves the water-repellent property of the surface according to the invention.

The substrates coated with the coating compositions according to the invention are distinguished by very low adhesion forces to liquids and solids. Liquids, especially hydrophilic liquids, such as water, aqueous solutions, dispersions and suspensions, polar organic liquids, especially those that are water-soluble, e.g. -C-alkanols, glycols, glycerol and their mixtures, but also melting of polar organic compounds, e.g. of carbohydrates and comparable compounds, pearl off these coatings without residue.

In addition, the surfaces coated with the coating compositions of the invention are notable for a self-cleaning effect. Solids, particularly particulate solids, can be removed from the surface by rinsing with liquids such as water without detergent. Surprisingly, the particulate solids can also be removed very easily using compressed air.

The moldings according to the invention also have these properties. Furthermore, the molded articles surprisingly do not lose these properties if their surface is damaged, for example by scratches, notches, cracks or comparable damage as a result of mechanical action. Such damage can also be repaired, e.g. by grinding without loss of properties.

Furthermore, the flow resistance of liquids, in particular water and aqueous solutions, is reduced when flowing through tubes, capillaries or nozzles which are coated with the coatings according to the invention.

Because of their properties, the coating compositions of the invention can be used in a variety of ways.

Materials susceptible to corrosion, such as concrete, reinforced concrete, wood or metal, can be effectively protected against corrosion by coating with the coating compositions according to the invention. The coating compositions according to the invention are furthermore suitable for the surface finishing of paper, cardboard or plastic films.

Electrical devices that are exposed to the weather and contaminate under weather conditions, such as high-voltage overhead lines, voltage conversion devices, insulators, parabolic antennas, etc., and which suffer in performance losses when they are dirty or moist, can be treated with the coating compositions according to the invention. This reduces soiling and avoids a loss in performance.

The coating compositions according to the invention are also suitable for protecting against contamination, in particular from surfaces which are exposed to the weather, for example roofs, facades, windows, garden and balcony furniture, motor vehicles, traffic signs, billboards, solar systems, etc. It is also conceivable to use the inventive systems Coating agents in the sanitary area, for example as a coating for fittings, wet rooms, bathtubs, swimming pools, wall and floor tiles, etc. The use of the coating agents not only prevents deposits of dirt from the water, but also the infestation and growth of undesirable organisms, such as Microorganisms, algae, lichen and moss.

Furthermore, the coating compositions according to the invention can be used to coat system parts which come into contact with liquids. Pipes, boilers, tanks, reactors, heat exchangers, evaporators, condensers, pumps, nozzles, atomizers, spray dryers, crystallizers, filling systems, etc. are to be mentioned here in particular. Equipping these parts of the plant with the coating compositions according to the invention prevents the separation of solid components or decomposition products from the liquids. This reduces the formation of deposits, deposits, blockages and dirt on the surfaces of the parts of the system which come into contact with the liquids. In addition, the coatings in the system parts, e.g. in pipes, the flow resistance of liquids. In this way, you reduce the amount of energy required to transport particularly high-viscosity liquids through the system components.

By equipping the cooling surfaces of cooling units with the coating agents according to the invention, the frequently occurring icing can be reduced. The use of the coating compositions according to the invention for the coating of

Ship hulls reduce the sliding resistance through the water and thus reduce the fuel requirement. With airplanes you can go through Coating the outer surfaces with the coating compositions according to the invention reduce the risk of icing.

Packagings for liquid filling goods, which are equipped with the coating agents according to the invention, can be emptied almost without residues and, on the one hand, enable better use of the filling goods and facilitate recycling of the packaging materials, since they are not contaminated by residues of the filling goods.

Storage containers, the inner surfaces of which are equipped with the coating compositions according to the invention, can be emptied more easily and, because of the self-cleaning effect, can be cleaned in a simple manner by rinsing with water without the use of surfactants.

Fabrics, in particular textile fabrics, which are equipped with the coating compositions according to the invention are notable for high water impermeability and low water absorption and are dirt-repellent. Treatment with the agents according to the invention makes the fabric virtually water-repellent. Dirt particles can easily be rinsed off with water without significant water absorption. The coating compositions according to the invention are therefore suitable as water and dirt-repellent finishing for fabrics, for example for the production of clothing, tents, awnings, tarpaulins, umbrellas, for lining rooms, e.g. Automotive interiors can be used to cover seats, for example in the automotive sector.

Leather that has been treated with the coating compositions according to the invention is suitable for the production of leather clothing and shoes with water and dirt-repellent properties.

In the field of cosmetics, the coating compositions according to the invention can be used as hair treatment compositions, e.g. in the form of hair sprays, provided that they contain cosmetically compatible substances T as binders, e.g. contain the polymers usually used for this.

As already mentioned, the compositions according to the invention can also be used as molding compositions for the production of moldings. Accordingly, the present invention also relates to moldings comprising at least one hydrophilic, inorganic powder P with a particle size in the range from 15 to 500 μm and at least one hydrophobic, thermoplastic substance T, which is characterized by a surface tension in the range from 20 to 50 mN / m is characterized in which the weight ratio of hydrophilic, inorganic powder to hydrophobic thermoplastic substance P: T is in the range from 1: 2 to 50: 1.

With regard to the advantageous properties, the moldings according to the invention are comparable with objects which have a coating according to the invention, i.e. its surface is extremely difficult to wet, especially for the hydrophilic liquids mentioned above. Their surfaces have a self-cleaning effect. Shaped bodies according to the invention are also distinguished by a lower flow resistance compared to shaped bodies made from conventional materials. These properties also apply if the surface is damaged, e.g. not lost through scratching. Surprisingly, the advantageous properties of the shaped bodies can be further improved by treatment with fine-grained abrasive materials.

The present examples are intended to illustrate the invention without, however, restricting it.

I. analytics

1.1 General regulation for determining the repellent power

The coated object to be examined is mounted on a measuring table, the inclination of which can be adjusted from 1 ° to 90 °. Then drops of liquid are dropped onto the sample with the aid of a cannula, the distance between the cannula and the sample surface being 10 mm. The drops have a defined mass, which is determined by prior weighing. By gradually lowering the angle of inclination α, the minimum angle of inclination at which the drops just barely roll off is determined. The repellent power F _{R is} calculated from the minimum angle of inclination α, the drop mass m and the acceleration due to gravity g according to the above formula. The repellent power is given in (millinewton) ^-1 and is a quantitative measure of the ability of a surface to drop liquid droplets without residue.

1.2 Determination of the contact angle:

The contact angle was determined using a Gl type device from Krüss GmbH. For this purpose, a drop of distilled water was placed on the surface to be examined using a stainless steel cannula with an inner diameter of 0.5 mm. Then, using a goniometer, the contact angle between water drops and surface optically determined. In the case of very hydrophobic surfaces, as are the subject of the present invention, the water drop practically no longer adheres to the surface. When exiting the stainless steel cannula, the water drop then adheres to the cannula until it drips due to its weight. With such surfaces, the contact angle can no longer be determined exactly, but can be estimated at> 160 °.

Preparation Examples:

Example 1: Coating agent Bl

1.5 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) were dissolved in 6 g of petroleum spirit (boiling range 60 to 140 ° C.). 28.5 g of quartz powder with a grain size below 250 μm (Mikrosil SP3 from Westdeutsche Quarzwerke GmbH) were added to this solution and the whole was mixed on a roller board.

Example 2: Coating agent B2

3 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) were dissolved in 6 g of petroleum spirit (boiling range 60 to 140 ° C.). 27 g of quartz powder with a grain size below 250 μm (Mikrosil SP3 from Westdeutsche Quarzwerke GmbH) were added to this solution and the whole was mixed on a roller board.

Example 3: Coating agent B3

1.5 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) were dissolved in 8 g of petroleum spirit (boiling range 60 to 140 ° C.). 28.5 g of quartz powder with a grain size below 100 μm (Mikrosil SP10 from Westdeutsche Quarzwerke GmbH) were added to this solution and the whole was mixed on a roller board.

Example 4: Coating agent B4

3 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) were dissolved in 6 g of petroleum spirit (boiling range 60 to 140 ° C.). 27 g of quartz powder with a grain size below 100 μm (Mikrosil SP10 from Westdeutsche Quarzwerke GmbH) were added to this solution and the whole was mixed on a roller board. Example 5: Coating agent B5

1.5 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) were dissolved in 7 g of petroleum spirit (boiling range 60 to 140 ° C.). To this

The solution was given 28.5 g of quartz powder with a grain size below 48 μm (Mikrosil LM300 from Westdeutsche Quarzwerke GmbH) and the whole was mixed on a roller board.

Example 6: Coating agent B6

3 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) were dissolved in 6 g of petroleum spirit (boiling range 60 to 140 ° C.). 27 g of quartz powder with a grain size below 48 μm (Mikrosil LM300 from Westdeutsche Quarzwerke GmbH) were added to this solution and the whole was mixed on a roller board.

The polyoctadecyl vinyl ether used in the examples has a surface tension of 27.7 mN / m, determined on a melt by the hanging drop method.

Example 7: Coating agent B7

40 g of pyrogenic silica (Aerosil® 380 from Degussa-Hüls AG) with a BET surface area of 380 m ² / g (determined in accordance with DIN 66131) were suspended in 1000 g of gasoline (boiling range 60 to 80 ° C.). 60.8 g of a copolymer of maleic acid and a 1-olefin mixture (chain length C ₂ nC ₂ ) were added in a molar ratio of 1: 1 (number-average molecular weight approx.

4000 g / mol) and stirred at 60 ° C until the polymer had dissolved. The solvent was then removed in vacuo and the residue was dried at 50 ° C. in a vacuum drying cabinet. The residue was then ground to a powder in a hammer mill. 2 g of the powder were dispersed in 98 g of gasoline (boiling range 60 to 140 ° C).

Example 8: Coating agent B8

150 g of the hydrophobic polymer A of the sieve fraction 0-36 μm described below and 350 g of quartz powder (Mikrosil LM 300 from Euroquarz with a particle size distribution of 6-32 μm) were placed in a glass bottle. The powder mixture was homogenized for several hours by rolling on a laboratory roller board. Preparation of the hydrophobic polymer A as a powder

360.8 g of copolymer composed of maleic anhydride and 1-01efin (mixture of chain lengths Co- ₂₄ ) in a molar ratio of 1: 1 and 480 g of 1-octa-decanol were added to a closed stirring apparatus. The mixture was stirred at 140 ° C. for 7 h with constant flushing with nitrogen. After cooling, 832.3 g of colorless polymer with a melting point of 58 ° C. were obtained. The product was ground for further use in an IKA A10 analytical mill, and the ground material was separated using a sieve set on an Analyzer vibrating sieve from Fritsch. The sieve fractions from 0 to 36 μm were used.

Example 9: Molding compound Fl

55 g of sea sand (sieve fraction 36-63 μm) were added at 70 ° C. to 45 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) and the mixture was homogenized by stirring.

Example 10: Molding compound F2

120 g of sea sand (sieve fraction 36-63 μm) were added at 70 ° C. to 30 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) and the mixture was homogenized by adding 10 g of gasoline (boiling range 60 to 80 °) C) with stirring.

Example 11: Molding compound F3

32 g of gypsum (building gypsum from Rigips GmbH) were added at 70 ° C. to 8 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) and the mixture was homogenized by adding 7 g of gasoline (boiling range 60 to 80 ° C) with stirring.

Example 12: Molding compound F4

45 g of gypsum (building gypsum from Rigips GmbH) were added at 70 ° C. to 5 g of polyoctadecyl vinyl ether with a molecular weight of approx. 3000 g / mol (determined by viscometry) and the mixture was homogenized by adding 16 g of gasoline (boiling range 60 to 80 ° C) with stirring.

Example 13: Molding compound F5 Molding compound F2 was poured onto an aluminum foil at 70 ° C. After cooling, the solid was ground to a powder in an impact measuring mill.

Example 14: M6 molding compound

30 g of polymer from Example A were homogenized with 70 g of quartz powder (Mikrosil LM 300 from Euroquarz with a particle size distribution of 6-32 μm) on a laboratory roller board for several hours and then poured into aluminum. The mixture was heated to 70 ° C. for 3 hours. After cooling, the plates were obtained with a thickness of 5 mm.

III applications:

III-1 coatings

The coating agent B1 to B6 was applied with a doctor blade at a doctor blade gap of 400 μ onto steel sheets (Bonder type 26 S 60 OC from Chemmetall) and dried at room temperature. Coating agent B8 was applied in an analogous manner, except that the steel sheet was preheated to 100 ° C. before application. After application and drying, the coatings were sanded with sandpaper (320 grit) and the sanding dust was removed by rinsing with water.

Coating agent B7 was uniformly sprayed onto a wooden board using an airbrush (type HY-MAX HP-101) and dried at room temperature.

The surfaces coated with the coating agents B1 to B7 are extremely hydrophobic. When water is dripped on, the drops roll off the surface without wetting it. The static contact angle with water was more than 160 ° in all cases.

The repellent power of the surfaces coated with the coating agents B1 to B7 is given in Table 1. The determination was made with drops from deionized water. The drop mass was 4.3 mg.

Table 1:

Probe repellent power

Bl 60 mN " ¹

B2 91 mN " ¹ B3 80 mN " ¹

B4 296 mN " ¹

B5 104 mN " ¹

B6 169 mN " ¹ B7 100 mN- ¹

Wettability test:

The steel sheets coated with the coating agents B1 to B6 were attached to a measuring table arrangement for determining the repellent power. At an angle of inclination of 10 °, the following aqueous liquids were applied in a defined amount as drops:

- water (30 mg),

Coffee (30 mg),

Honey (59 mg), aqueous hydrochloric acid (32% by weight, 41 mg), aqueous sodium hydroxide solution (5% by weight, 45 mg), - 30% by weight solution of polyacrylic acid in water (47 mg) .

30% by weight solution of a copolymer of vinyl pyrrolidone and vinyl imidazole in water (35 mg).

All drops ran away from the coated steel sheets at an angle of inclination of 10 ° to the horizontal.

In a comparative experiment, the liquids listed above were applied to untreated steel sheets. The angle of inclination of the sample was also 10 ° to the horizontal. In all cases the surface was wetted; with the exception of water, all liquids left residues on the steel sheets.

Dirt removal test:

The steel sheets coated with B1 to B6 were soiled with soot powder (Printex® V, BASF Drucksysteme GmBH). Water was then dripped onto the coating. The soot powder was completely removed by the water droplets, so that the original surface was restored. The use of cleaning agents was not necessary.

In a comparative experiment, an untreated steel sheet was soiled with soot powder (Printex® V, BASF Drucksysteme GmBH). Water was then dripped onto the foils. There- the soot powder was only partially removed by the water droplets, soot spots were left on the steel sheet.

Coating sheet steel with coating agent B8

The powder mixture B8 described was sprayed with a PEM-CG2 (Corona) type powder spray gun onto Chemetall's Bonder 26S 60OC steel sheet. The conveying air volume was 4.5 m ³ / h, the metering air volume 2.0 m ^{3 /} h.

The sprayed sheets were then heated to 120 ° C. in a laboratory drying oven for 20 minutes, during which the powder layer was filmed. After cooling, the surface was roughened with sandpaper (320 grit) and the sanding dust was removed.

The surfaces coated with the coating agent B8 are extremely hydrophobic. When water is dripped on, the drops roll off the surface without wetting it. The static contact angle with water was more than 160 ° in all cases.

The repellent power of the surfaces coated with the coating agent is 177 mN ^-1 . The determination was made with drops from deionized water. The drop mass was 4.3 mg.

II1-2 molded body

The molding compounds F1 to F4 were poured into an aluminum mold at 70 ° C. After cooling and drying, plates with a thickness of about 5 mm were obtained. The molding compound F5 and the molding compound F6 were each pressed in a press with a pressure of approximately 7.4-10 ⁷ Pa to form a plate with a thickness of approximately 2 mm.

The boards were sanded with sandpaper (320 grit) and the sanding dust was removed by rinsing with water.

The plates produced from the molding compositions F1 to F6 are extremely hydrophobic. When water is dripped on, the drops roll off the surface without wetting it. The static contact angle with water was more than 160 ° in all cases. A molded body Fl scratched with needles also had these properties.

A molded body F6 scratched with needles also had these properties.

Claims

claims

1. Composition comprising at least one hydrophilic, inorganic powder P with an average grain size in the range from 15 to 500 μm and at least one hydrophobic, thermoplastic substance T, which is characterized by a surface tension in the range from 20 to 50 mN / m, in which the Weight ratio of hydrophilic, inorganic powder to hydrophobic thermoplastic substance P: T is in the range from 50: 1 to 1: 2.

2. The composition of claim 1, wherein the inorganic powder consists essentially of silicates.

3. The composition of claim 1 or 2, wherein the inorganic powder is a quartz powder.

4. A composition according to any one of the preceding claims, wherein the thermoplastic binder is an oligomer or polymer having a number average molecular weight above 1000 daltons.

5. Composition according to claim 4, characterized in that the polymer is a homo- or copolymer of ethylenically unsaturated monomers, which is selected from polymers which comprise at least 50% by weight of ethylenically unsaturated monomers A with C ₅ -C ₃ o- Alkyl groups and / or Cs-Cio-cycloalkyl groups and, where appropriate, suitable comonomers B and oligo- and poly-CC ₆ olefins.

6. Composition according to one of the preceding claims in the form of a flowable preparation, additionally comprising at least one organic diluent or solvent.

7. Composition according to one of claims 1 to 6 in the form of an aerosol, additionally comprising at least one propellant.

8. Use of compositions according to one of claims 1 to 7 for the production of difficult to wet surfaces.

9. A process for producing a surface which is difficult to wet, characterized in that a coating composition according to one of Claims 1 to 7 is applied to a conventional surface.

5

10. The method according to claim 9, characterized in that applying the composition in an amount of 0.01 to 1000 g / m ² , based on the solid components in the composition, on the surface to be coated.

10

11. The method according to claim 9 or 10, characterized in that the surface obtained is roughened after the application of the coating agent.

15 12. A process for producing a surface which is difficult to wet, characterized in that a molding is produced from a composition according to one of Claims 1 to 6 by a molding process.

13. The method as claimed in claim 12, characterized in that the surface of the shaped body produced by shaping is roughened.

14. Shaped body comprising at least one hydrophilic, inorganic powder P with a particle size in the range from 15 to

500 μm and at least one hydrophobic, thermoplastic substance T, which is characterized by a surface tension in the range from 20 to 50 mN / m, in which the weight ratio of hydrophilic, inorganic powder to hydrophobic thermoplastic substance P: T in the range from 1: 2 to 50: 1.

15. Use of compositions according to one of claims 1 to 7 for the production of surfaces with self-cleaning effect and / or for reducing the flow resistance in

35 tubes.

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