Substrates with a self-cleaning surface, a process for their production and their use

Substrates with a self-cleaning surface, a process for their production and their use

Description

The invention relates to a substrate with at least one self-cleaning surface, the substrates being in particular a substrate of glass, ceramic, plastic or metal or a glazed or enamelled substrate. The self-cleaning surface located on the substrate is based on a coating with structure- forming particles which is located on the substrate, resulting in a surface structure of elevations and depressions; the surface is at least partly hydrophobic. The invention also relates to a composition for the production of a substrate according to the invention with at least one self-cleaning surface. The invention also relates to a process for the production of the substrate with at least one self-cleaning surface, which comprises coating the substrate with the abovementioned composition. Finally, the invention also relates to the use of the substrates according to the invention with a self-cleaning surface .

It is known that to achieve a good self-cleaning effect on a surface, in addition to a good hydrophobicity this must also have a micro-rough surface structure. Both features are realized in nature, for example in the lotus leaf; the surface form from a hydrophobic material has pyramid-shaped elevations a few μm from one another. Drops of water come into contact substantially only with these peaks, so that the contact area is minuscule, resulting in a very low adhesion. These relationships and the main applicability of the "lotus effect" to technical surfaces are the doctrine of A.A. Abramzon, Khimia i Zhizu (1982), no. 11, 38-40. Without reference to the lotus effect, US 3, 354,022 discloses water-repellent surfaces, the surface having a micro-rough structure with elevations and depressions and being formed from a hydrophobic material, in particular a fluorine-containing polymer. According to one embodiment, a surface with a self-cleaning effect can be applied to ceramic brick or to glass by coating the substrate with a suspension which comprises glass beads with a diameter in the range from 3 to 12 μm and a fluorocarbon wax based on a fluoroalkyl ethoxymethacrylate polymer. Their low abrasion resistance and moderate self-cleaning effect are a disadvantage of such coatings.

The doctrine of EP 0 909 747 Al is a process for producing a self-cleaning property of surfaces, in particular roof tiles. The surface has hydrophobic elevations with a height of 5 to 200 μm. Such a surface is produced by application of a dispersion of powder particles of an inert material in a siloxane solution and subsequent curing. As in the process acknowledged above, the structure-forming particles are not fixed on the surface of the substrate in an abrasion-stable manner.

The doctrine of EP Patent 0 772 514 is self-cleaning surfaces of objects with a synthetic surface structure of elevations and depressions, the distance between the elevations being in the range from 5 to 200 μm and the height of the elevations being in the range from 5 to 100 μm and the structure comprising hydrophobic polymers or materials which have been hydrophobized in a stable manner. Etching and embossing processes, and furthermore coating processes are suitable for formation of the structures. If necessary, the formation of the structure is followed by a hydrophobization, for example a so-called silanization.

Similarly structured surfaces with hydrophobic properties are the doctrine of EP 0 933 388 A2. The surface has elevations with an average height of 50 nm to 10 μm and an average separation of between 50 nm to 10 μm, and a surface energy of the non-structured material of 10 to 20 mN/m. To achieve a particularly low surface energy and thus hydrophobic and oleophobic properties, the structured surface comprises fluorine-containing polymers or has been treated using alkylfluorosilanes. Indications of also using coating processes, instead of the shaping processes disclosed here, for structuring the surface are not to be obtained from this document.

The doctrine of DE Patent Application 100 16 485.4 is glass, ceramic and metal substrates with a self-cleaning surface based on a structured and at least partly hydrophobized coating. The coating comprises a glass flux and structure-forming particles with an average particle diameter in the range from 0.1 to 50 μm. The glass flux and structure-forming particles are present in a volume ratio in the range from 0.1 to 5 and the micro-rough surface structure has a ratio of average profile height to average distance between adjacent profile peaks in the range from 0.3 to 10. The self-cleaning surface has a higher abrasion resistance than self-cleaning surfaces of roof tiles according to the EP 0 909 747 Al acknowledged above.

The object of the invention is to provide substrates, in particular substrates of glass, ceramic, plastic and metal and glazed and enamelled substrates, with at least one self-cleaning surface which not only have a low roll-off angle or high contact angle and therefore a good self- cleaning effect, but furthermore are transparent. The self- cleaning surface should have a very high contact angle with respect to water, preferably a contact angle of about/above 150°. The transparency of a transparent substrate, such as glass or plastic, should as far as possible not be reduced. A decoration under the self-cleaning surface should remain clearly detectable. According to a further object, glass, ceramic or metal substrates or glazed or enamelled <img file="WO0249980A1_D0001.tif" />

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profile peaks - apart from in agglomerates these are smaller than the particle diameter - than surfaces with structure-forming particles in the micrometre range.

The structure-forming particles can be organic or inorganic substances. Examples of the inorganic substances which may be mentioned are: metal oxides, mixed oxides, silicates, sulfates, phosphates, borates, metal sulfides, oxosulfides, selenides and sulfoselenides, metal nitrides and oxide- nitrides and metal powders . Examples of the organic structure-forming particles which may be mentioned are carbon blacks and nanoscale organic polymeric particles, and among these fluorine-containing polymers. Many structure-forming particles with the particle diameter according to the claims, such as, in particular, 5 to less than 50 nm, are commercially obtainable. They can otherwise be obtained by precipitation processes which are known per se or by pyrogenic processes, gaseous starting substances being converted into pulverulent substances. The structure- forming particles are particularly preferably metal oxides from the series consisting of silica (Si0₂) , titanium dioxide (Ti0₂) , aluminium oxide (A1₂0₃) , zirconium dioxide (Zr0₂) and tin dioxide (Sn0₂) . These oxides are particularly preferably pyrogenically prepared oxides, and among these in particular silica. Pyrogenic silicas are commercially obtainable with an average primary particle size in the range from about 7 to 40 nm.

In addition to the structure-forming particles, the self- cleaning surface of substrates according to the invention comprises a layer-forming material, which can be an inorganic or organic material. The layer-forming material either forms a homogeneous layer in which the structure- forming particles are fixed in the form of their primary particles and/or agglomerates, or the structure-forming particles are fixed on the substrate by means of the layer- forming material. Some of the primary particles and/or <img file="WO0249980A1_D0002.tif" />

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the glazing/enamel layer and optionally additionally the structure-forming particles during the firing.

According to a further alternative, coating materials with Me-O-Me* structural elements are those systems such as are formed from organometallic compounds of the elements boron, silicon, aluminium, titanium and zirconium which have at least two hydrolysable groupings during alcoholysis/hydrolysis with a subsequent condensation reaction and optionally subsequent firing.

According to a preferred embodiment of the substrate according to the invention with a self-cleaning surface, the structured coating comprises structure-forming particles with an average diameter of less than 100 nm, in particular in the range from 5 nm to less than 50 nm, and a layer-forming inorganic or organic material in a weight ratio in the range from 100 : 1 to 1 : 2, in particular 20 : 1 to 1 : 1. A ratio outside the limits mentioned is indeed possible, but if the content of layer-forming material is too low, a possibly inadequate fixing of the structure-forming particles is the consequence. In the case of too high a content of the layer-forming material, the self-cleaning effect decreases because the structure- forming particles may be sunk too low in the layer-forming material .

Preferred substrates have a coating which substantially comprises structure-forming particles and a layer-forming inorganic material, but the coating can additionally comprise adhesion promoters or those compounds such as are formed from auxiliary substances present and/or precursors of the layer-forming material during the production of the coating, including a heat treatment step which may be necessary or firing.

In order to impart to the structured surface the necessary hydrophobic properties and also the desired high contact <img file="WO0249980A1_D0003.tif" />

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3 ri PJ TJ P¹ ft 3 TJ TJ P- 3 φ Φ PJ cr 3 Oi PJ P. 3 co 3 O TJ 3 0J TJ cπ

10 P- rt Φ PJ 3 cr cr O CD &lt;; &amp; Φ ϋ CO rt O PJ P¹ TJ cr P- 3 ø⁾ CD PJ rt rt cr - o

PJ Φ Oi p. O 0 0 3 TJ Φ Oi rt rt 3 P- 3 3 n φ rt Ω 03 p. -&gt; cr P- 0

0 ri P- Φ Hi tr σ PJ CO P- cr 3 P- 3 CO O PJ P. rt PJ 03 Φ O tr ft ri - P- Φ Hi Oi P- P- £ ri rt P¹ Φ Ω Φ PJ Ω CO cr ra ^"P ?r 0 O P- P- 3 O 3 P- cr

CQ PJ 3 J Ω Ω P- Φ ^{^} J ~3 P¹ rt P, 03 3 Ω 3 03 Hi 1 3 Ω CO Ω Φ O J O * rt 3 03 rt 3 Φ CQ ( * Φ 3 Φ O Φ PJ P. P¹ Ω Φ p. ti

3 P- 0 3 ra TJ Ω cr rt 03 O CD J p. CD O 03 P" P- rt 0 p. Φ O t→ Φ

0 1 0 Hi p&gt; ri 3 P. O • 03 - O- 3 P- Ω 3 03 φ O 3 cr 3 Φ 03 Φ 3 Hi PJ

03 O Hi 0 P- Hi tr O PJ PJ Φ P- ≤ O PJ PJ 3 φ CO CO - TJ TJ *&lt; P- O

P- 1 r 3 PJ 03 TJ rt P¹ rt 3 cr 03 rt Ω PJ Ω ft cr 3 p, Ω φ 03 ≤

P¹ CO rt Φ Ω rt Φ P- 03 Hi cr φ P- Ω • Φ cr PJ 3 cr cr TJ P-¹ 0J Φ P- p.

PJ P- cr rt 1 Φ PJ ^ 3 φ Φ 3 Ω PJ Φ 3 Oi Φ ri 03 0J 3 ra 03 Φ ~ o

3 Φ cr Ω . 3 rr CO Ω rt cr TJ CO O ft P, CO Φ 0J 3 O

Φ 03 Φ 0 Ω P- Hi P^J Ω *• Φ 3 PJ 03 cr 3 ri Hi ri O P- CD 3 Hi O rr O 3 φ Φ Φ o cr P 3 PJ tr PJ P- 3 o &lt; o •. P- o rt P" ri rt rt CO Ω J J rt PJ TJ rr ft σ &lt; 03 3 -&gt; Ω p, Φ 3 3 ti cr 1 cr 3 ri J cr Hi 3 rt cr 03 J cr P- 03 φ rt CO Φ ft P. 03 P- CQ φ O

PJ Ω 3 P- PJ φ P- P- Φ ri Φ Ω rt ri Φ 3 1 3 φ Hi

&lt; rr Ω 3 &lt; rt rt PJ 3 3 tr rt ri PJ PJ TJ ^' ri X Hi

P- 3 ft P- P- cr cr 3 CO CO Φ P- Φ J rt Hi Φ Φ J

3 i 3 3 3 P- φ P- Φ Ω CO rt Φ ri PJ • 3 iO PJ ri iO CO 03 3 3 Φ ra 0 TJ Φ CO Φ 3 03 J 1 PJ 03 φ

co to t P¹

O n o en O n

TJ rt Di Hi O TJ TJ O PJ Ω Ω 3 O r-3 P» ra TJ ØJ Oi M TJ CO J Ω TJ ι-3 ri CO CT cr o cr 3 ØJ O p, ϋ 0 p, 3 cr O PJ ti cr o 3 PJ tr 0J P- O øJ 3 Ω cr O P cr Φ rt PJ ^ φ ti P CQ Φ Φ 3 rt tQ φ o tr P. 0 ^ ØJ O p. σ Ω Φ 3 o Φ 3 ri &lt;! Oi p. P- φ 3 ø 03 ^ ØJ 3 rt Φ PJ 03 rt &lt;: φ 3 ft O O TJ Pi ØJ 3 P- ri

ØJ 3 3 p. 3 φ 3 3 O P- Φ ri 3 3 rt P- Φ ti Φ 3 P- rt P. Ω O 3 P- P- Ω 3 O o. 0 CO O P- 3 φ O- Hi Ω X P- P- ØJ 3 PJ Ω - r 3 Ω PJ Oi O 03 Ω 3 3 rt CQ TJ

Oi TJ P- Hi Ω rr ri PJ ft PJ Ω "&lt; 3 Hi Φ 3 P- 3 P- rt &lt;! 03 3 cr

P- PJ 03 P- O Hi φ rt Φ rt 0 i Φ Ω 3 TJ rt P- Φ ti 0⁾ 0 rt PJ 0J O P- Ω 3 P- O = O P&gt; 0 P- 03 cr ri P- ra Φ CO 0 P- 0 3 Φ σ

P- 03 CO 0⁾ 3 p, 3 X p. Hi P. 1 P. Pi Φ 3 P- 3 03 O 3 rt CD Oi r P-

0 rt 3 Ω 3 rt P- 0 P- Hi PJ P- 3 €, 3 r P- 3 P- P- ^ N

3 P- tr cr O 0J rt ØJ cr 3 3 0J 03 P- 0 3 TJ 3 TJ P- P- O r 03 O O Ω 03 P-

Ω 03 P- P Λ CT rt φ CQ rt TJ 3 φ "&lt; Oi CO rt ØJ rt X P- Hi 3 ¹ — ' 3 P. 3

0 Φ φ CO 3 Φ Φ Φ TJ 3 O 3 03 cr cr rr rt O 03 tr O CQ

P. TJ μQ &lt;! ø Φ ri 03 rt « 3 P. P- 03 O rt rt TJ Φ rt 3 cr 3 3 03 Hi TJ 03 TJ

PJ 3 φ 3 O Ω P- 3 cr P- Oi CQ 3 Hi cr P- ØJ P- 0J ri Φ CO Ω 3 3 Φ rt cr øJ

TJ P. Φ Oi P- 3 O ØJ tr Φ P- Ω Φ PJ CO rt Φ Ω P. ri Ω 3 Φ cr tr ti p. ϋ o Ω

0 ft 3 Ω CD 3 03 ra P⁾ p. 3 cr PJ rt 3 03 P- Hi 03 r 3 PJ σ rt

P" P- rt tr TJ rt 03 rt 03 P- TJ PJ Oi Φ P- 3 øJ 3 0 PJ rt cr PJ rt P- P-

^•&lt;: Ω ^ O 03 O O ti r Ω P- rt Ω 0J 3 P- Ω CQ 0J &lt; &lt; ti 03 ri Φ 3 Φ N O

Ω P&lt; cr P. o CD p. PJ ri O O PJ Oi 3 φ P. Φ cr φ P Φ P- 3

0 φ Φ Φ P¹ P- rt 3 TJ 3 O 3 rt n ft 3 P- P¹ ti P- 3 rt 0J rt 3 3 PJ 3 *•

3 03 PJ &lt; 0J &lt; rt TJ Φ Ω ø⁾ Oi PJ P- o cr Φ PJ ØJ Hi TJ ØJ Ω rt cr p. Φ O rr 3 CO rt 0J Λ Φ P- p. • ft tr rt ft Ω Φ rt 3 rt ti PJ CQ cr P- φ φ 03 P¹ Oi PJ

Φ 0 J 3 3 O φ 3 O PJ Φ 3 3 Φ φ Φ O p, Φ O Φ ^ 0J CD

3 P, rt 0 Φ rr 3 Ω M ri Φ O i 3 TJ H rt 3 rt Ω 3 TJ 3 ØJ rt Ω

CO ri p. O 3 Hi Φ rt P- 0J PJ Φ O P- TJ 0 ri C0 Ω ri cr rt PJ J tr Φ ØJ 3 O P- P. o cr 3 ØJ rt ri O p. ti en Ω 0J 3 ≤ O Φ Ω Φ Φ P- rt ^&lt; ø rt 03 ti 3 03 rt Hi Hi Φ φ r-¹ Φ rt Hi P¹ ti TJ P- Ω- O O p.

P- rt P- 0 cr O PJ • P- P- 3 Φ rr p. rt 3 ti ØJ 03 3 φ

0 PJ 3 O CO CD rt ti φ ri Hi 03 3 O Ω øJ CQ P- 3 ra P- P- cr Ω P- i rt Φ 03

3 Φ 3 3 O cr CO 3 O 3 P- ι-3 ri P¹ rt Ω 03 rt 3 P- Φ p^J P- 3

• Ω 3 CQ φ 3 P- H tr 3 cr Φ ft ^■g rt . Φ PJ P- 3 D Hi 03

0 rt O TJ &lt; O PJ 3 3 CO CO Φ CD cr P- O P- Φ 0 rt CO rt

3 Hi φ Φ Hi Hi rt CQ P- rt P- -. Φ PJ Oi rt 03 03 3 cr rt Ω Hi a tr 3 3 0 φ 3 ri PJ rt Λ PJ rt cr rt Φ Φ r 0 P- O

Φ ^ rt ra rt P 01 ti TJ CO PJ Φ 3 P- 03 3 Φ P- ti P¹ 0 O Φ X Hi

3 cr P- 3 P- PJ r 3 ti P- co rt 0 PJ CD PJ ø 3 Hi Hi TJ rt PJ Φ

CD Hi φ O 3 TJ PJ p. 0J Φ PJ 3 Oi Hi rt 03 3 3 Ω 1 P rt cr 3 ≤

PJ 3 3 P- 0 0 P¹ rt rt TJ o φ φ rt Ω PJ O cr φ P- cr ft 03 ω • X Hi P- cr tr φ = 3 P. o rt M rt 0J rt 3 P- Φ 3 Hi P-

P- P- o cr 1 P- Ω o ^• ; ti PJ φ CT P- cr &lt;! Φ ri Φ O 3 TJ CO P- Ω

0 3 3 ØJ 03 3 P- PJ rt Hi &lt;A° Φ ØJ ØJ Φ ti Φ PJ 3 Ω P- ri ri cr

3 CQ &lt;; cr ri φ Φ O PJ PJ ^ Φ φ •• P" 3 P. 1 3 tr rt 3 0 TJ 3

Φ Φ Φ 03 P I ra CO φ ti P TJ • ØJ O Hi P- CO P- &lt; Ω p. P&gt; rt

0 rr 3 o 3 Φ TJ p. P- J TJ ti en CQ Hi 0 3 rt O φ φ O *&lt; cr p. 0 rt cr O P- 3 cr 1 PJ σ p. P- &gt; o φ ri CO ri 3 3 CO TJ Φ

CQ o p. 3 rt 0 3 Φ ^ cr Hi H¹ Φ 3 ra 3 PJ r 03 Φ rt

Φ 3 rr cr p, O CD P- o ^•^ Hi 3 TJ Φ P- 03 rt rr P- p. o Ω rr 3 O P- P- P- CQ rt 3 P- Ω P Ω Φ P 3 3 ØJ 03 3 3 φ o Hi rr O cr CO 3 O 03 PJ 3^* CD Ω cr 3 PJ ^J ti ^&lt; Φ ri 03 CO P. Φ 3 O P- rt

Φ φ 3 3 Φ PJ P- 3 Φ PJ 3 rt Hi ri Φ cr 3 TJ ri O 3 rr P- P- 3 03 tr rt ØJ P- rt P⁾ φ 0J CD Φ 0 ri Φ cr P- 03 Ω P¹ PJ P- CO tr 03 P¹ P- 3 Ω Cr Ω O 3 rt 3

O Φ 3 ØJ o 3 Φ ^&lt; O a 01 Φ Hi a cr rt Φ

3 ^ φ ri rt 3 Φ 3 • φ cr 3 ra Φ ti rr CT Φ ø⁾ rt 3 rt 3 ti cr 3 O Φ 3

According to preferred embodiments of the composition, this comprises inorganic layer-forming materials or at least precursors thereof. Particularly suitable layer-forming organic materials are glass frits and oxidic raw materials (= precursors) which are capable of glass formation with other substances, such as, in particular, boric acid (B₂0₃) , bismuth oxide (Bi₂0₃) , alkali metal and alkaline earth metal oxides, zinc oxide and lead oxide as well as alkali metal silicates, and phosphates and borates. Most glass-forming substances are contained in the composition in particulate form. Alkali metal oxides and alkali metal silicates are expediently contained in the composition in the form of aqueous alkali solution or in the form of water-glass (sodium silicate solution) .

According to a further alternative, the compositions according to the invention comprise an organometallic compound of one or more of the elements boron, silicon, aluminium, titanium and zirconium as the layer-forming material. The organometallic compounds are preferably those which contain alkoxy groups, acetyl groups or acetylacetonate groupings, so that Me-0-Me^% structural elements are formed by a condensation reaction, wherein Me and Me can be identical or different and represent the elements mentioned.

The structure-forming particles and the layer-forming material are usually contained in the .composition according to the invention in a weight ratio of 100 : 1 to 1 : 2; the weight ratio is preferably in the range from 20 : 1 to 1 : 1.

Pulverulent compositions according to the invention can be applied to the substrate by dusting or by electrostatic coating.

A preferred embodiment of the composition according to the invention also comprises, in addition to the layer-forming ω t to P¹ P&gt; en o cπ o en o cπ

PJ H Ω CQ Hi 3; 03 O tr a 3 TJ Hi Φ 03 3 3 CD tr Hi Ω CQ rt TJ Ω Φ O Ω Φ CD 3 3

Λ cr o O ^&gt; rt X ØJ 0 ra ØJ cr P- rt 3 PJ 3 Φ ti 0 P¹ cr PJ O X Hi O CD TJ P- φ øJ

3 Φ PJ O 3 O P- ^ P- rt 0 H Φ ti Oi rt σ P- P- 3 ØJ Φ P. 3 PJ 3 rt ti rt

Φ rt &amp; O p. 3 Oi φ P- 3 Φ ra P- 3 3 Φ TJ Φ CD 3 rt TJ 03 rt TJ 3 3 TJ PJ PJ Φ P- Φ

0 φ P o Ω Φ p. Ω CO p. TJ 3 φ Ω p&gt; P ri rt CO CO ti C0 Hi P- 0 TJ CO O tr ^ 3 p.

3 P- i CQ P- TJ rt P- cr CO 3 rr CO Φ P- ri P- *&gt; o Ω ar φ 03 P¹ P- p. 3 P-

CO iQ Φ 3 cr 3 PJ Hi 0J PJ 0J ØJ rt 3 O Ω PJ ØJ ω ØJ 03 ti 3 P- Φ P- P- 3 PJ PJ

3 P- P-¹ Φ 0 ti CD O Ω rr Ω 03 ti P- 3 P" rt 3 03 Φ Ω 3 P¹ rt 0 rt 03 CO 3 P¹

3 P- 3 Hi tr Φ ri P- P» 03 Φ O PJ 3 ri 03 Φ Hi « Φ PJ ø⁾ P- PJ Hi P- cr CO r-3 O φ Oi Ω P- rt 3 Oi P- ra 3 O P¹ CQ 03 Hi rr P. rt P. O O Φ O Φ cr

Oi rt Ω O N cr P- μQ 0 Oi Hi O it rt P- cr PJ PJ P- P¹ 3 03 rt 3 Oi i 03 φ ØJ

P- 3 cr P" 3 J CD Φ 3 O 3 p. PJ P- Φ Ω ti cr O Ω Φ 03 3 O ^ Ω r - 3

3 Φ P- Φ rt rt 3 iQ p. P- ti rt rt cr CD P- P- P- 3 P- P. Φ tr rt Ω

3 Oi 03 øJ PJ P- i ra Oi TJ Φ P- cr Φ φ Ω σ Φ 3 rt Ω TJ 03 Φ ^• cr P- Hi O

P- 3 P- O Hi rt 3 ØJ p, O φ 3 3 - cr Φ 3 01 cr - O p. Φ Ω ØJ TJ O 3 rt

3 P- 3 3 ØJ ti ØJ 3 rt φ TJ 3 Φ P- rt P- Φ Hi φ TJ 3 0 ØJ 3 TJ ri 03 cr

Z 3 PJ 3 P- Ω 3 rt O Ω PJ 03 3 3 Ω ft PJ Ω 3 3 Hi P. 3 P- P- Φ cr ^ CQ 3 φ Ω Φ 0J 3 ti PJ rt 0⁾ cr P. O ^ * φ PJ Φ φ TJ TJ Ω P- 3 Φ 03

P- Ω CQ P- rt p. P&gt; TJ ti rt PJ 3 CD 0 Φ ø Ω ØJ rt P Hi ri 0 0 3 CO X rt 03

Ω PJ P- TJ rt Ω 3 P- PJ 03 P- p, o 03 rt r o ^ øJ 03 ti Φ P- 03 3 ^ PJ φ rt

CT 3 03 P O CT PJ p. ø 01 03 O Ω φ 03 O tr Φ Ω Φ Φ 3 Φ rt φ H 3 P- &lt;; rr 3 3 ti

O p, 3 Φ rt ri 3 Ω Hi 0 PJ μ-&gt; TJ p, ri Oi PJ rr rt Φ cr PJ TJ Ω 3

Ω tr 0J TJ CQ ø P- Φ 03 Ω PJ 3 CO TJ O 0 O 3 tr P- P- 3 Φ P" ^ Ω

ØJ Φ tr Φ J 3 tr Hi O 1 PJ cr P rt Oi 3 PJ 3 Hi P, Ω Ω P¹ 3 O rr Ω Φ r

3 0 P 3 φ O p, 3 r-¹ rt p, 0 Φ cr P- tr tr Φ O rt O ^ CO 3 P- Ω O 0 3

PJ &lt; rt O O P φ P- cr 03 Φ 3 03 Hi rt 3 ti ØJ 3 3 O PJ 3 Hi Hi ti

Ω 3 Φ P- CD ti Hi 3 TJ rt ?r Φ ^&gt; Φ TJ CO rt Φ cr r 3 ri TJ TJ TJ σ 3 ra CD 0 Φ o Φ P- CO O P- p. PJ φ ti 3 PJ CO øJ rt Φ - P- CQ Φ o PJ p. ^ ØJ Φ P- ti ra

0 P&gt; CO PJ 3 φ 1— • Φ 03 P. 3 3 0 cr 3 P¹ O CO O o. 3 Hi

TJ p, en • PJ 3 3 CO Ω Ω O 3 rt tr P- Ω Hi Φ rt CO ØJ P- rt Ω ØJ O φ rt Ω 0

CQ o 3 O Φ 3 0 Hi P- rjd P- 03 rt Φ Φ cr N O rt Φ Φ TJ Hi Pi cr cr ri

P- PJ -3 φ CQ Oi 3 ri P- 3 • rt

• O Ω ft cr 03 CQ Ω Hi Φ 3 Φ 3 P- 03 TJ p. PJ Φ 3

CQ 3 " -* P- PJ D cr TJ ø p, i 0 0 ØJ ri O P¹ CO p. P- PJ tr PJ P-

Φ P- Φ P¹ 0 r O ^ 0 σ P- Φ 01 0 ≤ PJ 3 P CD rt Hi 3 P- - P- 3 TJ P¹ TJ 3

Ω ØJ 3 Φ ti Oi 03 Ω 03 rt 3 cr 03 TJ 3 0 Φ 0 PJ 03 ? 3 rt TJ ^ 3 Ω CO

TJ Ω φ 3 ri ti P- Φ Φ Φ p- 03 0 ØJ Hi ti ti Ω Φ rt rt P- ti 0

P. 0 O ØJ Φ CO P- rt O rt PJ 3 Ω ra rt r P- Φ ≤ . cr P- 3 P- TJ 3 TJ

0 p, 3 Oi «• PJ cr Q P- Ω 3 PJ øJ cr Hi P- P- Φ ø^j Φ cr φ 3 CO Ω o O TJ 0J

Ω rt 03 0⁾ φ Φ O PJ P- Oi 3 3 O rt O 3 3 O P- CO PJ s; 03 0 ti φ 0 PJ P- 03 ri 3 3 *&lt; i Φ Oi O 01 ti P- 3 P- - øJ Hi Ω Ω TJ rt Φ Φ 03 rt

03 p. Ω rt 3 03 Φ φ p&gt; rt P, 3 0 3 3 cr 0 TJ p, P- p. P- P- ra CQ rt O PJ O TJ ≤ p. J 0 cr Φ ØJ 3 rr CO 0 Φ PJ 3 p. O O O rt Ω

P- PJ TJ ≤ Hi r cr 1 3 Ω ri Φ rt Φ 3 ØJ 03 O Ω 3 &lt; Hi P- P¹

3 3 ØJ TJ ø cr Hi 0 P- Hi O P| Ω P- Ω 3 TJ Φ CD P. P- Ω Φ P- O Φ

CO P- 3 ØJ p. P- P- ØJ CD Ω 0 3 O 0J O 0 TJ o Φ 3 Φ 03 Φ CD O 03 0J 3 03

Ω CQ P. rt Ω ri 3 TJ cr ti PJ &lt; rt ØJ TJ 3 3 φ P- 0 Oi tr rr 03 ra Hi Ω TJ -

PJ rt P- cr 3 o, cr 3 Φ ri 3 PJ TJ p. 3 P. ra 03 Φ 03 • O TJ Ω

3 0J Φ P- Ω - P¹ PJ Ω P- ? 3 3 Oi tr P. ØJ rt CO rr 3 3 rt CD PJ ØJ

X μQ Ω 3 *&lt; ØJ rt o 3 J rt Ω P- rt 3 3 ti P- Ω cr P- P- 3

P- 3 O 3 P¹ 0J Φ 3 CQ P- rt 0 Φ 03 3 O o tr J rt 3 φ rr Ω P¹

Φ Hi ØJ P t * Hi J TJ TJ P- o 3 ri Φ ri Hi P. CO r PJ o "&lt; 0J tr P-

P- 0 PJ P. rt ^ PJ H 3 ti 0 03 Φ Φ rt Φ tr O ti rt rt φ μQ

PJ 3 0J p. Φ cr ri 03 P- 3 PJ PJ ≤ Hi ft ri Hi cr P- P- 3 ri 03 ØJ ri Φ O 03 Φ P- P, O cr CQ PJ O φ φ 03 O P- P-

P- CO ^ p, CO rt φ rr rt 0⁾ Hi Φ P" r Hi ft 3 3 o.

Φ 0 P" P- Φ cr CO PJ cr ≤ 03 ØJ Φ Hi CT Ω

03 P, PJ 3 3 Φ rt φ CO O Φ PJ tr

CO cr O ti ^ Ω φ φ

<img file="WO0249980A1_D0004.tif" /> D &gt; Ω PJ cr co t TJ O Ω P» TJ Ω r-3 CD Ω tr CD 03 Ξ CO tr Ω ØJ Φ 0J Ω H TJ cr r-3 O 03

Φ rt cr Oi ^ • 0 3 ri 0 ti cr ^p- cr J 3 3 P- ri p. cr J Hi Qm 0 cr ti ^ cr tr 3

CD ri TJ Φ cr Oi H CO 3 O Φ Φ μ-i £U 03 ti tr rt O P- Φ TJ r 0J Φ Φ Pi φ Ω

03 3 PJ 3 Φ P Cr 3 &lt; ØJ TJ Ω Ω 01 0J P- Φ 03 cr 3 3 Φ Φ rt p. P- cr

Ω ti P- p, o ^ P- o Φ 3 p. o φ 3 CO 3 3 0J ft TJ CO P- P- Ω P P- cr φ 0 03 CQ rt rt rt Ω Φ TJ 3 ti ri P- P- 0J 03 P- 3 φ Ω ti PJ Φ Ω Ω r Φ 3 ^ i TJ 3 ØJ ØJ cr 3 P- PJ ra cr p, CO 3 3 Ω 03 rt 03 3 tr CD H 0 Φ PJ 3 0 • 0J ØJ φ 03 CO P- ØJ cr P. rt 03

PJ ti Ω 0 0 PJ P- P- CO 03 3 rt rt ti tr 0 O

3 Φ 3 tr TJ TJ ft Φ P" 3 3 rt 3 cr φ PJ co P- O tr PJ P ØJ

Ω P- P- cr PJ P- 3 0 iΩ CQ cr 03 ri O ØJ °. 03 PJ 3 ^ O tr P- TJ ^ P- Ω ^ co

P¹ PJ 0 p. N 0 p. 0 rt ^ P- 3 øJ P&gt; 3 &lt; X Ω 3 •^ P 0 r N Φ Φ o 0 p. 3 3 P- tr rt 3 Φ CO O Ω P. rt 0 Φ øJ O 03 t ft • ti 0 Φ Ω 3 o TJ 3 P- P- O p. rt Hi cr Φ 0J øJ Ω X P- O tr cr O O rt

3 0 *&lt; CO N Ω O ri ri 0J 03 P¹ PJ Ω ^ tr T) P- ^ Φ P- 0 Hi 3 03

3 P- Φ 3 0J Hi - Hi 3 PJ Ω Ω ? ?r 0 CD P- ti rt ti X N TJ

3 3 0J 3 rt 0J rt Φ O Ω 0 Φ øJ ^ ^ Ω ri P- Ω P- cr Φ 3 rt ØJ 0J φ P- rt O rt

* CQ rt 0 CO P- 03 0J TJ ti ft CD 3 Ω P¹ O PJ Oi φ O 3 rt &lt;: 3 cr 3 O

3 Φ O ti 3 3 3 TJ Ω Ω rt rt PJ P- PJ rt CQ Φ TJ P- φ Φ

TJ TJ ti rt 3 3 PJ Ω Φ P- ri P p. 0J O ti ti rt 3 3 P- φ 03 ri 0 rt O ^p. TJ 3 ø p. øJ φ P- cr rt 3 O 3 Φ P- 3 ri P- P- P- CO φ Ω 03 3 ri P. cr Φ 3 0J 3 rt Oi φ ri rt φ O cr Φ CQ J CO Pi PJ ø 3 tr φ 3 Φ P P- O rt 0 r Φ P Ω φ tr P- CO rt O 3 P, 03 01 o 03 rt rt Ω • 3 φ P- Hi 03 P- J 03 0J 3 O Φ 03 Φ 3 ? ? - O ri J φ rt rt 3 Hi 3 cr P- P&gt; 03 ti Ω rt rt 3 ft Oi P- tr ØJ H CO 0 0 ft 03 ti cr P- 3 tr Φ Ω O rt

PJ rt cr ri cr cr &lt; P" rt 3 O rt TJ X X O rt Pi Φ 3 PJ ^ O a. 0J 03 3 tr φ T P- 3 TJ φ φ Φ ^ Φ P- cr ri rt ^ ^ cr P¹ ri P&gt; rt 3 Φ ft Φ P. rt ra Φ 03 Ω øJ p. P. 3 φ 0 O C0 03 rt Φ ? P- rt Φ ti ti rt PJ 3 ØJ 0 r

*^• • rt p. CD Φ P- CQ rt Oi P- P- Φ 0 øJ - 0 O P¹ cr 3 rt P. 3 Φ

•t TJ 3 rt rt 03 PJ " ø⁾ cr 3 rt P¹ 3 P- X TJ ^ P- rt P- CO

P¹ P- ti ri P- ri ^ P- TJ φ 0 Ω cr ØJ ØJ 3 : ti cr P- Ω P- »i rt - &lt;! φ rt 0 Φ Ω 3 φ ^•g øJ Φ φ 3 3 O &lt; 03 O O O 0 ft 3 J Φ cr P-

03 cr Ω a 3 Ω P- p. p. 03 Φ φ 3 Φ P- 3 ri tr cr CO 3 Φ ra

03 Φ ft ri P- ft rt 3 0 p- 3 P¹ P- Φ Φ CD ø) Ω

03 03 ØJ 3 3 € 0- cr P- tr « P- 3 O ØJ •&lt;; rt O ft rt Φ N 03 03 ^ 3 TJ ^ o rt 3 03 3 P. ri P-¹ cr P- Ω 03 P- 3 &lt; ti 3 P- X r cr X P- Ω 3 CD ri Φ φ ra cr P Φ ^ P- rr O → rt 3 φ Pi ØJ O J φ Φ 0J 3 0 p. Ω ØJ p, P-

PJ PJ P- 0J Ω O Φ ti CO 0J 3 0 3 3 3 CQ ØJ O O 0J ? rt

3 &lt;J 03 PJ 3 rt cr Ω 03 PJ rt TJ Φ 03 ti TJ rt øJ 3 Ω D P- ^ φ Ω CD 0 TJ O rt 03 CO P- P- i Φ Z • rt φ H J P- Ω TJ Φ ra en ri rt Φ 0 3 øJ 3 ØJ Φ r P- O CO Φ P- ti ØJ Φ CQ 3 Φ p. ØJ o PJ cr ri ri rt P- CD TJ 3 Φ 3 3 O Hi rt TJ 3 Ω Φ CQ • P- P- 3 PJ P-

CQ Φ 0 CO cr X rt 0 Oi TJ TJ 3 Φ ØJ cr p&gt; Ω rt &lt;! 3 rt O 03 Pi rt 3

3 Φ ri 0J ØJ φ Φ Φ ω P- CQ £ Φ ti rt Φ rt P- P- rt Ω H O φ

3 3 3 Ω CO P- øJ rt • • Φ P- p, ØJ O ØJ 3 O PJ CO O cr 03 cr φ PJ

03 Hi O φ 03 P" r 3 cr rt 03 tr 3 Φ ti 3 3 P- P¹ ^ φ Oi p- Φ 0 ra 3 rt P- P- 3 cr 03 ri Φ øJ 0J TJ CD o 0J i φ PJ

PJ PJ ti P- ≤ tr cr O P- PJ ØJ 0 *&lt; P¹ Φ ri α O 3 p. 0 P. &lt; 03 P-

3 3 0 3 P- CQ φ Φ 3 3 3 PJ ØJ Φ Hi Φ ra 0⁾ 3 &lt;! 0 ØJ rt rr

Φ CO ØJ rr rt * O Ω 3 ØJ •- Ω CO P- 3 φ TJ rr P- r 3 r P O tr P o Φ O rt φ O 0J P- tr rr cr P, cr P- TJ O

PJ Φ 0⁾ Φ PJ r φ CO 3 P. φ cr P¹ P Ω ØJ 0 P- Φ ^ o O PJ 3 rt ti «. PJ ft ti P- PJ TJ P¹ φ 0 03 rt CQ o 3 O CO K tr 3 p. φ 3 3 3 0 tr Hi 03 3 Φ P- P- 3 P- cr rt P- CD rt ft

0 « Ω CQ P- 03 ^ φ CQ rt PJ 3 CO Φ O P- N . P" O

Φ cr PJ rt Ω P- Φ cr 3 CQ 0J P- øJ 3 Ω P- Φ • ;

PJ P- 3 3 rt 0J ri P- P- 3 cr 3 t O Ω &amp; ri O P- Ω 3 O r α r

P- • cr rt cr Φ O ?r CO Φ 03 Φ 3 ri

CO CO to to P» P¹ cπ O en o en o en

<img file="WO0249980A1_D0005.tif" />

CO co to to P" cπ o cπ o en o cπ

Ω ≥ 03 3 &gt; P- 3 cr ≤ rt Pⁱ , TJ rt Ω t-3 rt P- Hi ØJ

0 TJ rt P- p^J 3 φ Φ P- PJ O Φ P- 0J cr J cr t 3 0

TJ ti Ω ft &lt; 3 P- rt p. 03 rt P P- 3 Φ φ ri CQ

TJ P¹ 3 ri Φ Φ rt CO cr CQ H 03 cr rt Ω TJ 3

0 P- Ω O ri 3 P- cr Φ o P- ? cr 3 ri PJ ØJ ØJ

03 Ω ft 3 rt 0 rt PJ o rt ØJ Ω 3 PJ ø⁾ Φ P. rt 03

P- ØJ 3 ti PJ P- 3 o cr 3 Φ &lt;; 3 μQ rt P- 03 rt rt ti O rt O Φ O CO PJ Φ CO Φ O 3 P- 0

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structure-forming particles substantially only particles with a particle diameter of less than 100 nm, preferably less than 50 nm, to be baked and then to be hydrophobized.

After the formation of the structured surface, the hydrophobiza ion stage follows:

The hydrophobization can be carried out by application of a hydrophobic lacquer or by polymerization of monomers on the micro-rough surface. Suitable polymeric lacquers are solutions or dispersions of e.g. polyvinylidene fluoride. A hydrophobization can also be carried out by plasma polymerization of completely or partly fluorinated vinyl compounds .

The hydrophobization is particularly expediently carried out using reactive alkyl- or, preferably, fluoroalkylsilanes and oligomeric alkyl- or fluoroalkylsiloxanes. The silanes or siloxanes preferably contain one or more alkoxy or acetyl groups, such as ethoxy groups, as the reactive group. Crosslinking of the hydrophobizing agent and also chemical bonding thereof to a silicatic surface containing silanol groups is possible by means of these functional groups. Silanizing agents which are particularly preferably to be used are tridecafluorooctyltriethoxysilane and oligomers thereof. Such products can be applied to the surface to be hydrophobized in the form of dilute organic, in particular alcoholic, aqueous-organic and aqueous solutions, for example by dipping, spraying or brushing.

After application of a solution comprising a fluorine- containing silane or siloxane to the substrate, the substrate is dried and cured, preferably at a temperature of up to 500 °C, for example for 30-60 min at about 150 °C, 10-15 min at 250 to 300 °C or 1 min at about 500 °C. The optimum of the after-treatment with heat in respect of highest abrasion resistance is at a temperature in the range from 200 to 300 °C.

Using dilute solutions of the silanes or siloxanes mentioned, layers a few nm thick which have a very high chemical and mechanical resistance and are 2- and 3- dimensional siloxane networks are obtained.

The hydrophobic layers accessible using reactive fluoroalkylsilanes or -siloxanes are distinguished by a similarly good hydrophobicity and oleophobicity, so that substrates according to the invention contaminated with hydrophobic dirt particles can also easily be cleaned with water.

The invention also relates to the use of a substrate according to the invention with a self-cleaning surface. Examples are glass panes for vehicles and windows, construction glass, ceramic tiles, roof tiles, covers on photovoltaic solar cells, metal profiles and lacquered substrates, such as car lacquers.

The substrates according to the invention with a self- cleaning surface are distinguished by a very high efficiency of the self-cleaning property. The contact angle of preferred substrates according to the invention with respect to water is in general about and often above 150°.

A particularly outstanding feature of substrates according to the invention is the transparency of the nanostructured coating. Transparent substrates of plastic and glass and glazed or enamelled substrates are accordingly particularly suitable for being provided with a transparent coating according to the invention and therefore for obtaining high-quality self-cleaning surfaces which are themselves transparent and therefore also clearly reveal underlying decorations . Essential advantages of compositions according to the invention are their easy accessibility and range of variation in respect of composition. The compositions can therefore be used for coating the most diverse substrates and producing good self-cleaning properties.

The stages of the process according to the invention are based closely on those process stages such as are used, for example, for decoration purposes in the glass and ceramics industry, but are also conventional in the lacquering of metallic substrates with stoving lacquers. The devices and technologies known to the expert can therefore be used.

Examples

Production of float glass or high-grade steel with a transparent self-cleaning surface

1. 4 mm float glass was coated with a composition according to the invention by means of screen printing. The composition comprised 0.5 wt . % boric acid (B₂0₃) and 4 wt . % pyrogenic silica in a screen printing medium (no. 80858 from dmc² AG) . The pyrogenic silica had an average diameter of the primary particles of 12 nm. The printing medium was a water-friendly medium. The screen printing was carried out using a 100 T screen. After drying, the coating was shock-fired at 660°C in the course of 4 min. The hydrophobization of the structured stoved surface was carried out using a fluoroalkylsilane formulation, that is to say an ethanolic solution of tridecafluorooctyltriethoxysilane. The solution was introduced over the surface, and curing was then carried out at elevated temperature .

The float glass coated in this way was transparent and had a contact angle of above 150°. 2. Example 1 was repeated with the only difference that the composition comprised 0.5 wt . % diammonium hydrogen phosphate ((NH)₂HP0₄) [sic] instead of boric acid as the layer-forming material. After the hydrophobization, the glass coating showed outstanding self-cleaning properties .

It is assumed that during firing vitreous structures with the structural element Si-O-B or Si-O-P or metal-O- P form between the boric acid or the phosphate and reactive centres of the glass or metal and the structure-forming silica particles.

3. Substrate was degreased V4A high-grade steel . A composition with 4 wt.% pyrogenic silica (d = 12 nm) and diammonium hydrogen phosphate in an amount of (a) 0.25 wt.%, (b) 0.5 wt.% and (c) 1.0 wt . % in screen printing medium 80858 was used for the coating. After coating by means of screen printing, firing was carried out for 6 minutes at 660 °C. A scratch-resistant self- cleaning surface was obtained in all three cases.