WO2000038845A1

WO2000038845A1 - Method for producing an ultraphobic surface by sand blasting

Info

Publication number: WO2000038845A1
Application number: PCT/EP1999/010112
Authority: WO
Inventors: Karsten Reihs; Daniel-Gordon Duff; Juan Gonzalez-Blanco; Burkhard KÖHLER
Original assignee: Sunyx Surface Nanotechnologies Gmbh
Priority date: 1998-12-24
Filing date: 1999-12-20
Publication date: 2000-07-06
Also published as: EP1144127A1; AU3040100A

Abstract

The invention relates to a method for producing an ultraphobic surface on metal, glass, ceramics, or plastic or on a composite which is comprised of metal and plastic and which is used as supporting material. The invention also relates to the surface obtained by using said method, and to the use of the surface. According to the method, the surface of the supporting material is roughened using a fluid jet containing solid blasting abrasives, is optionally coated with a bonding agent layer, and is subsequently provided with a hydrophobic coating.

Description

Process for producing an ultraphobic surface by sandblasting

The present invention relates to a method for producing an ultraphobic surface on metal, glass, ceramic or plastic or a composite of metal and plastic as a carrier material, and the surface obtained thereafter and the use thereof. In the method, the surface of the carrier material is roughened with a fluid jet containing solid blasting agents, optionally coated with an adhesion promoter layer and then provided with a hydrophobic coating.

Ultraphobic surfaces are characterized by the fact that the contact angle of a drop of a liquid, usually water, lying on the surface is significantly more than 90 ° and that the roll angle does not exceed 10 °. Ultraphobic surfaces with a contact angle> 150 ° and the above Roll-off angles have a very high technical benefit because they e.g. are not wettable with water but also with oil, dirt particles adhere very poorly to these surfaces and these surfaces are self-cleaning. Self-cleaning is understood here to mean the ability of the surface to easily release dirt or dust particles adhering to the surface to liquids that flow over the surface.

There has been no shortage of attempts to provide such ultraphobic surfaces. For example, EP 476 510 AI discloses a method for producing an ultraphobic surface, in which a metal oxide film is applied to a glass surface and then etched using an Ar plasma. However, the surfaces produced using this method have the disadvantage that the contact angle of a drop lying on the surface is less than 150 °.

US Pat. No. 5,693,236 also teaches a number of processes for producing ultraphobic surfaces, in which zinc oxide microneedles are applied to a surface with a binder and then in different ways (e.g. partially exposed by plasma treatment). The surface structured in this way is then coated with a water-repellent agent. Surfaces structured in this way, however, also only have contact angles of up to 150 °.

It is therefore the task of providing ultraphobic surfaces and a process for their production which have a contact angle> 150 °. and preferably have a roll angle of <10 °.

The roll angle here is understood to be the angle of inclination of a basically planar but structured surface with respect to the horizontal, at which a standing water drop of volume 10 μl is moved due to gravity when the surface is inclined.

The object is achieved according to the invention by the provision of a method which is the subject of the invention for producing an ultraphobic surface on metal, glass, ceramic or plastic or a composite of metal and plastic as the carrier material, characterized in that the surface of the carrier material is coated with a solid blasting medium containing fluid jet is roughened intensively over a longer period of time, the blasting medium having a grain size <200 μm, optionally coated with an adhesion promoter layer and then provided with a hydrophobic, in particular an oleophobic coating.

Any plastic, any metal, and a composite of metal and plastic can be used as the substrate in the sense of the invention. Other substrates that can be used (carrier material) are ceramic or any materials provided with a ceramic coating, stone-like surfaces and glass. The substrate can have any shape. - -> -

The fluid jet can be formed by any liquids, in particular water or any gases, in particular air.

Any granular substance with high hardness familiar to the person skilled in the art can be used as a solid blasting agent as an additive to the fluid jet. However, the blasting agent preferably has an average grain size <130 μm.

The grain size of the abrasive is preferably at least 2 μm, particularly preferably at least 5 μm, very particularly preferably at least 20 μm.

The structures produced with the sandblasting in the surface of the carrier material have unevenness on the order of 2 μm to 500 μm, in particular from 5 μm to 200 μm.

Surprisingly, the effect of the ultraphobic properties of the treated surfaces is partly due to the partial incorporation of the blasting agent into the surface of the carrier material.

The blasting agent is likewise preferably a metal oxide powder, in particular corundum, very particularly preferably a raw, i.e. unused corundum with sharp-edged particles.

The substrate is preferably roughened uniformly by means of a blasting device which generates a fluid jet and in which the fluid and blasting agent are mixed by raster-shaped guiding of a jet nozzle over the substrate surface.

The jet pressure is preferably 3 to 7 bar and the distance of the jet nozzle from the substrate surface is 1 to 3 cm with a nozzle diameter of, for example, 1 to 2 mm. The treatment time is in particular about 0J to 10 min for an area of 1 cm ² . After sandblasting, the surfaces thus obtained are provided with a hydrophobic or in particular oleophobic coating.

A hydrophobic material in the sense of the invention is a material which shows a contact angle with respect to water of greater than 90 ° on a flat, non-structured surface.

An oleophobic material in the sense of the invention is a material which, on a flat, unstructured surface, has a contact angle with respect to long-chain n-alkanes, such as n-decane, of greater than 90 °.

The ultraphobic surface preferably has a coating with a hydrophobic phobicization aid, in particular an anionic, cationic, amphoteric or nonionic, surface-active compound. Suitable are monomeric or polymeric compounds with a functional group which creates an adhesion to the substrate and has a hydrophobic residue. Suitable hydrophobic residues are alkyl residues, fluorinated alkyl residues or siloxane groups.

Surfactant compounds with any molecular weight are to be regarded as phobicization aids. These compounds are preferably cationic, anionic, amophotere or non-ionic surface-active compounds, such as those e.g. in the directory "Surfactants Europa, A Dictionary of Surface Active Agents available in Europe, Edited by Gordon L. Hollis, Royal Socity of Chemistry, Cambridge, 1995.

The following may be mentioned as anionic phobicization aids: alkyl sulfates, ether sulfates, ether carboxylates, phosphate esters, sulfosucinates. Sulfosuccinatamides, paraffin sulfonates, olefin sulfonates, sarcosinates, isothionates, taurates and Linginian compounds. Quaternary alkylammonium compounds and imidazoles may be mentioned as cationic phobicization aids

Amphoteric phobicization aids are, for example, betaines, glycinates. Propionates and imidazoles.

Nonionic phobicization aids are, for example: alkoxylates, alkyloamides. Esters, amine oxides and alkypolyglycosides. Also suitable are: reaction products of alkylene oxides with alkylatable compounds, such as. B. fatty alcohols, fatty amines, fatty acids, phenols, alkylphenols, arylalkylphenols, such as styrene-phenol condensates, carboxamides and resin acids.

In the case of the monomolecular phobing aids, preference is given to those in which 1 to 100%, particularly preferably 60 to 95%, of the hydrogen atoms are substituted by fluorine atoms. Examples include perfluorinated alkyl sulfate, perfluorinated alkyl sulfonates, perfluorinated alkyl phosphonates, perfluorinated alkyl phosphinates and perfluorinated carboxylic acids.

Compounds with a molecular weight M _w > 500 to 1,000,000, preferably 1,000 to 500,000 and particularly preferably 1,500 to 20,000 are preferably used as polymeric phobicization aids for hydrophobic coating or as polymeric hydrophobic material for the surface. These polymeric phobicization aids can be nonionic, anionic, cationic or amphoteric compounds. The polymeric phobicization aids can contain groups which promote adhesion to the substrate and / or contain groups which are self-crosslinking or can be crosslinked with an external hardener. Furthermore, these polymeric phobicization aids can be homopolymers and copolymers, graft and graft copolymers and random copolymers. The polymeric phobicization aids preferably contain alkyl groups.

R R perfluorinated alkyl groups or siloxane groups. (e.g. - Si - O - Si units

RR with R * = C, -C ₄ alkyl, preferably methyl).

Particularly preferred polymerizing auxiliaries are those of the type AB, BAB and ABC block polymers. In the AB or BAB block polymers, the A segment is a hydrophilic homopolymer or copolymer and the B block is a hydrophobic homopolymer or copolymer or a salt thereof.

Anionic, polymeric phobicization aids are also particularly preferred, in particular condensation products of aromatic sulfonic acids with formaldehyde and alkylnaphthalenesulfonic acids or from formaldehyde, naphthalenesulfonic acids and / or benzenesulfonic acids, condensation products from optionally substituted phenol with formaldehyde and sodium bisulfite.

Also preferred are condensation products which can be obtained by reacting naphthols with alkanols, additions of alkylene oxide and at least partial conversion of the terminal hydroxyl groups into sulfo groups or half esters of maleic acid and phthalic acid or succinic acid.

In another preferred embodiment, the phobicization aid is from the group of the sulfosuccinic acid esters and alkylbenzenesulfonates. Sulfated, alkoxylated fatty acids or their salts are also preferred. Alkoxylated fatty acid alcohols are understood in particular to be those with 5 to 120, with 6 to 60, very particularly preferably with 7 to 30, ethylene oxide units, C ₆ -C ₂₂ fatty acid alcohols which are saturated or unsaturated, in particular stearyl alcohol. The sulfated alkoxylated fatty acid alcohols are preferably present as a salt, in particular as an alkali or amine salt, preferably as a diethylamine salt. Hydrophobic monomers. which are used to prepare the polymeric phobicization aids are compounds of the formula

where x is a natural number from 6 to 12 and

R 'is hydrogen or methyl, stearyl methacrylate or behenyl methacrylate.

Monomers that are used to introduce the coupling agent group to the substrate are e.g. Vinylphosphonic acid, mono (hydroxyethyl methacrylate) phosphate, vinylphenylphosphonic acid, trimethoxyvinylsilane, trimethoxysilylpropylmethacrylate, vinylsilatran, diethylaminoethyl methacrylate, acrylic acid, methacrylic acid, itaconic anhydride or maleic anhydride.

Monomers which serve to introduce a self-crosslinking group are e.g. Trimethoxysilylpropyl methacrylate or trimethoxyvinylsilane (silane functional).

Special functional monomers are used to enable crosslinking of the polymer layer.

The acetoacetic acid ester group can be crosslinked with di- or polyamines, di- or polyisocyanates or di- or polyacrylates (Michael addition). They are introduced by the monomer aceracetic acid methacryloyloxyethyl ester.

The epoxy group is cross-linkable with amines or anhydrides. They are introduced using the monomer glycidyl methacrylate.

The isocyanate group can be crosslinked with di- or polyacetoacetic esters, di- or polyols, di- or polyamines or compounds with at least two azomethine groups. They can be introduced using α.α-dimethyl-3-isopropenyl-benzyl isocyanate or isocyanatoethyl methacrylate.

The hydroxy group can be crosslinked with di- or polyisocyanates, melamine resins or urea resins. You can by hydroxypropyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate. Hydroxyethyl methacrylate or hydroxyethyl acrylate are introduced.

The anhydride group can be crosslinked with di- or polyols or di- or polyamines. They can be introduced with itaconic or maleic anhydride.

Crosslinking can also be carried out in a mixture or in a two-layer application, using two polymeric phobicization auxiliaries which have groups which react with one another.

The isocyanate, epoxy or anhydride functional polymers can also be reacted with hydroxyethyl acrylate or methacrylate. The resulting (meth) acrylate-functional resins can be crosslinked radically (photochemically, by electron beams or radical initiators).

0 - 50% by weight of monomers which are neither adhesion-promoting, hydrophobic or crosslinking can be added to the polymeric phobicization auxiliaries during the preparation. Examples include styrene, methyl methacrylate, butyl acrylate, butyl methacrylate, ethylhexyl methacrylate, methyl acrylate or ethyl acrylate.

The polymeric phobicization auxiliaries are preferably prepared by radical polymerization in the presence of an initiator (peroxy or azo compound) in a solvent. Ketones, such as butanone, methyl isobutyl ketone or cyclohexanone, are preferred for polymeric phobicization auxiliaries containing perfluoroalkyl groups. In order to improve the adhesion of the hydrophobic or oleophobic coating on the sandblasted substrate, it may be advantageous to first coat the surface of the sandblasted substrate with an adhesion promoter layer. An adhesive layer may therefore be applied between the surface and the hydrophobic or oleophobic coating. In principle, any substance which is familiar to the person skilled in the art and which increases the bond between the surface and the respective hydrophobic or oleophobic coating is suitable as an adhesion promoter. Preferred adhesion promoters, for example for thiols as a hydrophobic coating, are noble metal layers, for example made of Au. Pt or Ag or those made of GaAs, especially gold. The layer thickness of the adhesion promoter layer is preferably from 10 to 100 nm.

Preferred adhesion promoters for functional polymerizing auxiliaries are vinylphosphonic acid, mono (hydroxyethyl methacrylate) phosphate, allylphosphonic acid, allylamine, maleic anhydride, acrylic acid, allyl sulfide, trimethoxyvinylsilane, trimefhoxysilylpropyl methacrylate, trime hoxysilyloxy methyl methoxyl methoxyl methoxyl methoxyl methoxyl methoxyl methoxyl methoxy Aminophoshonic acids of the formulas are preferred

in which

R, and R ₄ for hydrogen, C, -C ₂₂ alkyl or for C ₆ -C ₁₀ aryl, preferably for hydrogen or phenyl,

R, for C ₂ -C ₂₂ alkylene or C ₅ -C ₂₀ cycloalkylene and R stands for hydrogen or C, -M-Alkvl.

With the method according to the invention, ultraphobic surfaces can be produced in which the contact angle of a drop lying on the surface is> 155 °. The invention therefore also relates to the ultraphobic surfaces obtained by the process according to the invention.

These ultraphobic surfaces have the advantage, among other things, that they are self-cleaning, and the self-cleaning can be carried out by exposing the surface to rain or moving water from time to time. Due to the ultraphobic surface, the water drops roll on the surface and dirt particles, which adhere very poorly to the surface, deposit on the surface of the rolling pots and are thus removed from the ultraphobic surface. This self-cleaning works not only in contact with water but also with oil.

There are a large number of possible technical uses for the surface produced using the method according to the invention. The following applications of the ultraphobic surfaces produced by the process according to the invention are therefore also claimed:

With the ultraphobic surface produced by the method according to the invention, ship hulls can be coated in order to reduce their frictional resistance.

The fact that water does not adhere to the ultraphobic surface produced by the process according to the invention makes it suitable as a rust preventive for base metals of any kind. Furthermore, sanitary facilities, in particular toilet bowls, can be provided with the ultraphobic surface produced by the process according to the invention in order to reduce their susceptibility to contamination.

Another application of the ultraphobic surface is the coating of surfaces on which no water should adhere in order to avoid icing. The surfaces of heat exchangers are an example here. in refrigerators or the surfaces of aircraft called.

The surfaces produced with the method according to the invention are also suitable for attachment to house facades, roofs, monuments in order to make them self-cleaning.

The ultraphobic surfaces produced by the process according to the invention are also particularly suitable for coating shaped articles which are translucent. In particular, it is translucent glazing of buildings, vehicles, solar panels. For this purpose, a thin layer of the ultraphobic surface according to the invention is evaporated onto the molded body.

The invention also relates to a material or building material having an ultraphobic surface according to the invention.

Another object of the invention is the use of the ultraphobic surface according to the invention for the friction-reducing lining of vehicle bodies, aircraft or ship hulls.

The invention also relates to the use of the ultraphobic surface according to the invention as a self-cleaning coating or planking of buildings, roofs, windows, ceramic building materials, for example for sanitary facilities, household appliances. The invention relates to the use of the ultraphobic surface according to the invention as a rust-protecting coating of metal objects.

The method according to the invention is explained below using examples.

Examples

example 1

An extruded polymethyl methacrylate plate with an area of 10 × 10 mm ² and a thickness of 3 mm was sandblasted with a 3-chamber blasting device (type designation: Kermo 3) from Renfert GmbH, D-78245 Hilzingen. Corundum from Renfert was used as the abrasive. Air served as the fluid for the fluid jet. It was an unused abrasive with an Al ₂ O ₃ content <99.5% by weight and an average grain size of 125 μm. A round nozzle with a diameter of 1.2 mm from Renfert was used as the jet nozzle. The polymer plate was sandblasted with 5 bar blasting pressure, the distance of the round nozzle from the polymer surface being 1.5 cm and the blasting nozzle being guided in a grid pattern over the plate. The plate was treated for 1 minute. The substrate then had irregularly distributed depressions and elevations with a size of 50 to 200 μm.

The substrate treated in this way was coated with an approximately 50 nm thick gold layer by sputtering. This coating method corresponds to the method which is also customary for preparation in electron microscopy and is described by Klaus Wetzig, Dietrich Schulze, "In situ Scanning Electron Microscopy in Material Research", page 36-40, Akademie Verlag, Berlin 1995. This reference is hereby introduced as a reference and is therefore to be regarded as part of the disclosure.

Finally, the gold layer of the sample was coated with a few drops of a solution of n-perfluorooctanethiol in α, α, α-trifluorotoluene (1 g / 1) at room temperature in a closed vessel for 24 hours, then rinsed with α, α, α-trifluorotoluene and dried. For water, the surface has a static contact angle of> 160 °. With an inclination of the surface to <3 ° a W ^τ rolls assertropfen from the volume of lOμl.

Example 2

A 30 x 30 mm ² and 2 mm thick titanium plate was roughened as in Example 1 with a fluid jet containing corundum, but here an abrasive material with an average grain size of 90 μm was used. These roughened plates are cleaned in ethanol and air-dried. They are then immersed in a 0J% solution of phosphate-functional, perfluorinated binder (solvent MIBK) for 24 h and then swirled briefly in pure MIBK and then dried at 120 ° C. for 20 h.

The binder is made as follows:

I. Phosphonate functional, perfluorinated binder

70 g of perfluorinated acrylate (Zonyl TA-N ^® ), 25 g of methyl acetoacetic acid, 5 g of a 50% aqueous solution of vinylphosphonic acid, 100 g of methyl isobutyl ketone, 1 g of azobisisobutyronitrile and 5 g of one are mixed ethoxylated nonylphenol (with 20 ethylene oxide units) and let the solution run into a flask heated to 90 ° C in 2 hours. 3 ml of triethylamine are added and the mixture is stirred for 6 hours.

The surface has a statistical contact angle of> 150 ° for water. If the surface is inclined by <10 °, a water drop with a volume of 10 μl rolls off. Example 3

A 30 x 30 mm ² and 2 mm thick titanium plate was roughened as in Example 1 with a fluid jet containing corundum, but here an abrasive material with an average grain size of 90 μm was used. These roughened plates are cleaned in ethanol and air-dried. They are then immersed in a 0J% solution of perfluorinated binder (solvent MIBK) for 24 h and then swirled briefly in pure MIBK and then dried at 120 ° C. for 20 h.

The binder is made as follows:

The mixture of 70 g of perfluorinated acrylate, 30 g of trimethoxysilylpropyl methacrylate, 1 g of azobisisobutyronitrile and 100 g of methylbutyl ketone is heated to 65 ° C. for 16 h. 0J% by weight, based on the polymer mass of dodecylbenzenesulfonic acid, is added to this solution before use.

II. Silane-functional, perfluorinated binder

The perfluorinated acrylate is an acrylate with a fluorinated C ₆ -C _{] 2} radical and an average structural formula corresponding to:

^C 9 ^F 19 ^CH ₂ ^C 2 ~ ^" -CH ₂ = CH ₂

The surface has a statistical contact angle of> 150 ° for water. If the surface is inclined by <10 °, a water drop with a volume of 10 μl rolls off. Example 4

A 30 x 30 mm ² and 2 mm thick titanium plate was roughened as in Example 1 with a fluid jet containing corundum, but here an abrasive material with an initiated grain size of 90 μm was used. These roughened plates are cleaned in ethanol and air-dried. They are then immersed in a 0.1% strength solution of aminophosphonic acid in butanol for 24 h and then swirled briefly in pure MIBK and then dried at 120 ° C. for 1 h. A 0J% solution of epoxy-functional, perfluorinated binder (solvent MIBK) is applied to the adhesive layer applied in this way by homogeneous spraying with an atomizer attachment for standing cylinders with ground glass (Görres; 2 bar N ₂ pre-pressure) from a distance of approx. 20 cm. The plate is then dried at 120 ° C. for 20 h. The aminophosphonic acid is produced as follows:

III. Aminophosphonic acid dissolved in butanol

The mixture of 1 1, 6 g 1, 6-diaminohexane, 212 g benzaldehyde, 500 g butanol and 1 g phosphorous acid is boiled for 8 hours on a water separator for light solvents. 164 g of phosphorous acid are added and the mixture is heated at 120 ° C. for 2 hours.

The binder is made as follows:

IV. Epoxy functional, perfluorinated binder

The mixture of 60 g of perfluorinated acrylate, 20 g of styrene and 20 g of glycidyl methacrylate is heated. 1 g azobisisobutyronitrile and 100 g butanone at 65 ° C for 16 hours. The surface has a statistical contact angle of> 150 ° for water. If the surface is inclined by <10 °, a water drop with a volume of 10 μl rolls off.

Example 5

In this example, a 2 mm thick titanium plate was roughened with a fluid jet containing corundum, just as in Example 1.

The plate treated in this way was immersed for 5 hours at pH 7 in a 1% by weight solution of Fluowet PL80 (mixture of perfluorinated phosphonates and phosphinates) from Clariant and then rinsed with water and dried at 60.degree.

For water, the surface has a static contact angle of> 160 °. If the surface is inclined by <3 °, a water drop with a volume of 10 μl rolls off.

Example 6

In this example, a 2 mm thick steel plate made of V4A steel was roughened as in Example 1 with a fluid jet containing corundum.

The plate treated in this way was immersed for 5 hours at pH 7 in a 1% by weight solution of Fluowet PL80 from Clariant and then rinsed with water and dried at 60.degree.

For water, the surface has a static contact angle of> 160 °. If the surface is inclined by <5 °, a water drop with a volume of 10 μl rolls off. Example 7

In this example, a 2 mm thick titanium plate was roughened with a fluid jet containing corundum exactly as in Example 1.

The plate treated in this way was immersed for 5 hours at pH 7 in a 1% by weight solution of Hoe S2746 (mixture of perfluorinated phosphonates and phosphinates) from Clariant and then rinsed with water and dried at 60.degree.

For water, the surface has a static contact angle of> 160 °. If the surface is inclined by <5 °, a water drop with a volume of 10 μl rolls off.

Example 8

In this example, a 2 mm thick titanium plate was treated exactly as in Example 1. In this example, too, the surface for water has a static contact angle of> 160 °. If the surface is inclined by <3 °, a drop of water with a volume of 1 Oμl rolls off.

Claims

claims

1. Method for producing an ultraphobic surface on metal. Glass, ceramic or plastic or a composite of metal and plastic as the carrier material, characterized in that the surface of the carrier material is roughened intensively over a longer period of time with a fluid jet containing solid blasting agents, the blasting agent having a grain size <200 μm, optionally with a Coating layer and then coated with a hydrophobic, especially an oleophobic coating.

2. The method according to claim 1, characterized in that the blasting agent has a grain size <130 microns.

3. The method according to any one of claims 1 or 2, characterized in that the blasting agent is a metal oxide, preferably corundum, particularly preferably raw corundum with sharp-edged particles.

4. The method according to any one of claims 1 to 3, characterized in that the carrier material is roughened with a fluid jet at a jet pressure of 3 to 7 bar and at a distance from the nozzle head to the surface of 1 to 3 cm.

5. The method according to claim 4, characterized in that the treatment time of the roughening is approximately from 0.1 to 10 min / cm ² .

6. The method according to any one of claims 1 to 5, characterized in that the surface is coated after roughening with a thin layer of noble metal as an adhesion promoter layer, preferably a gold layer, in particular by depositing a 10 to 100 nm thick layer.

7. Ultraphobic surface obtained by a method according to any one of claims 1 to 6.

8. Material or building material having an ultraphobic surface according to claim 7.

9. Use of the ultraphobic surface according to claim 7 for the friction-reducing lining of vehicle bodies, aircraft or ship hulls.

10. Use of the ultraphobic surface according to claim 7 as a self-cleaning coating or planking of buildings. Roofs, windows, ceramic building material, e.g. for sanitary facilities, household appliances.

11. Use of the ultraphobic surface according to claim 7 as a rust-protecting coating of metal objects.

12. Use of the ultraphobic surface according to claim 7 as a top layer of transparent panes, in particular glass or plastic panes, in particular for solar cells, vehicles or greenhouses.