DE102005020168A1 - Coating glass or ceramic substrate with anti-reflective layer using sol-gel process, employs e.g. silicon-aluminum mixed oxide with adsorbed hydrophobe present in sol-gel binder - Google Patents

Abstract

The porous anti-reflective layer comprises a metal, metal oxide, zinc oxide, tin oxide, aluminum oxide and/or their mixtures. It is especially a silicon-aluminum mixed oxide. A hydrophobic substance is deposited on the anti-reflective layer, at least locally. It is introduced into pores of the layer, forming a coating and/or total-area internal coating. The hydrophobe, especially being a silica sol, is present as a component of the sol-gel binder. The anti-reflective layer includes porous nanoparticles. Their grain size is preferably about 8 nm. The porosity of the nanoparticles amounts to 10%-60% of the total volume of the layer. Coating onto the substrate is by a spraying, immersion, wiping, painting or spreading process. The layer is fired, preferably at a temperature between 430[deg]C and 560[deg]C for about 60 minutes. The surface is thermally-prestressed following heating, by further heating, preferably to about 670[deg]C for about 4 minutes. The hydrophobe is applied or introduced into the heated layer including porous nanoparticles. Before applying the sol-gel layer, the surface of the substrate is activated by corona discharge, flaming, ultraviolet treatment, plasma activation, sand blasting, and/or chemical treatment such as etching. Bonding agents are applied first, from the gas or liquid phase. The hydrophobe is applied by immersion, capillary techniques, centrifugation, spraying, painting, rolling and/or flooding. The hydrophobe is heated preferably for 1 hour, to e.g. 150[deg]C. Its coated thickness lies between that of a molecular monolayer and about 130 nm. The profile and duration of process parameters are adjusted for application of the sol-gel layer together with the hydrophobe, preferably by spraying or immersion.

Description

The This invention relates generally to antireflection coatings, and preferably porous Antireflection coatings and methods for the preparation of with such layers provided objects.

At the Passage of light through the interface of two media with different Refractive indices, a part of the light is reflected. When vertical Incidence of a light beam on a glass sheet with refractive index n = 1.52 the reflected portion of the light is about 4%. However, if the light falls obliquely to the interface, so will usually be a higher one Share reflected. Reflection losses in glasses, which of the cover solar energy systems such as photovoltaic cells or Solar panels serve to reduce the efficiency of these systems noticeably.

for Anti-reflection of glasses Interference optical layer systems are known in which alternately two or more layers of high or low refractive materials superimposed become. In a defined wavelength range and for one defined range of angles of incidence are in such layer systems the at the interface reflected light waves by destructive interference at least partially extinguished and thus the proportion of the reflected light is reduced. Around the design of a layer system better suited to the spectrum of a broadband light source, such as the light of the sun, or to a larger angle of incidence to be able to adapt is an elevated one Number of layers needed, which, however, for commercial reasons often not feasible or he wishes is. Consequently, such multilayer systems compromise between economic feasibility and the best possible antireflective effect represents.

alternative are simple layers usable, which has a good anti-reflection effect show if their refractive index is about the root of the refractive index value of the underlying substrate corresponds.

The since then described methods for applying single-type anti-reflection layers essentially divided into three groups. The first one describes the etching glass, the second a porous one Coating and the third a combination of the former two.

Porous layers produced by the etching of glass, however, can only be produced with glasses that undergo phase separation, such as borosilicate glass of the composition 55-82% SiO ₂ , 12-30% B ₂ O ₃ , 2- 12%, alkali metal oxides and 0-7% Al ₂ O ₃ . Also disadvantageous are the expensive etching processes and the use of difficult-to-handle acids, such as, for example, NH ₄ F-HF.

DE 102 09 949 A1 discloses the preparation of porous silica layers containing additives of phosphorus compounds for the purpose of adhesion to borosilicate glasses. However, these porous anti-reflection coatings have insufficient mechanical and chemical stability on soft glass.

US 4,271,210 describes a porous Einschichtentspiegelung on pure alumina-based, the effectiveness of which is not sufficient for the applications described above, since the minimum achievable reflection value for two interfaces at a still unsatisfactory value of about 2.5%.

adversely is however with porous Antireflective coatings that these when stored in air in particular by absorbing moisture, store water and part of it can lose the anti-reflection effect. So in such a case the minimum reflectivity for two-sided coatings down to values above approx. 4% increase. The cheap optical properties when used in photovoltaics or in thermal solar collectors are severely affected.

The DE 100 18 671 A1 discloses an article, in particular made of glass or a ceramic material, with a thin sublayer of a metal compound with preferably 4-valent metals such as Si, Ti, Zr, which are burned out at very high temperatures with decomposition of the organic fractions. After cooling, a hydrophobic organic layer is applied to this underlayer and dried.

US 6066401 describes a process for the double coating of glass, in which a covering layer consisting of a metal fluoride, preferably MgF ₂ and a porous metal oxide, for example of silicon dioxide, is applied to a substrate. As a result, however, neither a mechanically resistant nor a satisfactorily water-repellent antireflection coating is obtained.

DE 199 18 81 A1 discloses the production of a tempered safety glass provided with a smear-resistant, porous SiO ₂ antireflective layer, which is also described in the publication by M. Kursawe et. al., "Antireflective Coating on Float Glass for Solar Collectors" in Glass Processing Days, June 2001, pp. 771-774. The on this Safety glass applied and consisting of silicon dioxide anti-reflection layer, however, according to relevant experience also has insufficient permanent mechanical and chemical stability.

It It is an object of the invention to provide a process for producing an antireflective coating, which preferably increased having chemical and mechanical resistance, and preferably resistant to water absorption and an article having such an antireflection coating to provide.

These Task becomes surprising simple way already with a procedure with the characteristics of the Claim 1 and by objects with the features of the claims 25 and 26 solved.

In the method for producing an article comprising at least one coating and one substrate, in which the coating comprises at least one antireflection coating, in which the antireflection coating is produced by a sol-gel method, and the antireflection coating is a porous antireflection coating,
For example, the porous antireflection coating comprises a metal or metal mixed oxide, in particular a zirconium oxide, tin oxide, aluminum oxide and / or mixed oxides of the above oxides, in particular a silicon-aluminum mixed oxide, and is thus made mechanically stable and resistant despite its porosity in an unexpectedly surprising manner.

Especially Preferably, a hydrophobic substance is at least in one area applied to the anti-reflection layer and / or in an area introduced the antireflection coating and thereby surprisingly effectively, deterioration of optical properties the anti-reflection layer, thus an increase in the reflectivity avoided.

When According to the invention, the antireflection coating is understood to mean a coating which at least in a part of the visible, ultraviolet and / or infrared spectrum of electromagnetic waves a reduction of reflectivity on the surface a substrate coated with this layer. It should As a result, in particular the transmitted portion of the electromagnetic Radiation increases become.

The Stating that "one hydrophobic substance at least to a region of the anti-reflection layer applied and / or in a region of the anti-reflection layer is introduced ", indicates that the hydrophobic substance is on an area of one already applied with an antireflection coating provided substrate, in the surface introduced by its already applied anti-reflection layer or applied to the substrate together with an anti-reflection layer can be.

These Antireflection coatings are not only mechanically and chemically very stable but in more surprising Also have self-cleaning effect.

The hydrophobic substance may additionally the Adhesion of liquids complicate, which often lead to dirt particles, and relieved about it the rinse off of impurities, in particular of water-soluble impurities, there at contaminated sites due to, for example, weather-related water entry first a release pollution and then drainage of dissolved pollution is effected when the hydrophobic substance is not only in the pores but also on the outwardly facing parts of the surface act can. As thermal solar panels, photovoltaic modules, roofs and Walls of conservatories or greenhouses as well in architectural glazing usually no horizontal Alignment is present, this self-cleaning effect in particular on the otherwise slightly polluting exterior surfaces of great advantage.

Furthermore is the use of the inventive article in the domestic water heating, process heat generation and in the parabolic trough power plant technology advantage.

Further can by a spectrally offset at least partially ver and anti-reflective effect and color effect on the layer become.

In Advantageously, the anti-reflection layer comprises a porous anti-reflection layer or consists of a single-layer anti-reflection layer of the porous anti-reflection layer, in their pores, the hydrophobic substance, in particular as a coating and preferably as a full-surface Inner coating is applied. This will be surprising Effectively the storage of moisture, water or the adhesion of liquids reduced in the area of the pores. As a result, changes will be made the refractive index of such porous layers, even in the wet room area or greatly mitigated in the outdoor area.

It is advantageous if the antireflection coating comprises porous nanoparticles having a particle size of about 2 nm to about 20 nm, preferably about 5 nm to about 10 nm, particularly preferably about 8 nm, contains.

Especially good antireflection properties are in particular in the case of single-layer antireflection coatings obtained when the volume fraction of the pores 10% to 60% of the total volume the anti-reflection layer is.

It is a great advantage of the invention that if the substrate Glass or glass covers, this also after the coating thermally toughened and thus can be thermally cured without As a result, the coating takes noticeable damage.

Preferably is thermally cured by at least the one to be hardened Area of the glass during a period of about 2 minutes to 6 minutes, preferably 4 minutes a temperature of about 600 ° C up to about 750 ° C, preferably brought to a temperature of about 670 ° C.

If an activation of the surface the substrate may be made prior to the application of the sol-gel layer thereby the adhesion the applied layer can be improved.

Advantageous can activate by corona discharge, flaming, UV treatment, Plasma activation and / or mechanical processes, such as roughening, Sandblasting, and / or chemical processes, such as etching, take place.

In front the application of the sol-gel layer and / or the hydrophobic substance can Furthermore, one or more adhesive layers of the gas or the liquid phase be applied in addition for activation or alternatively the adhesion of the applied layer to increase.

Advantageous Further, if the hydrophobic substance is for a period of about 2 min to about 2 h, preferably for about 1 h, to about 50 ° C up to about 950 ° C, most preferably about 150 ° C is heated, since this leaves remaining residues of the order of the hydrophobic Substance can be driven off and thus the desired reflectivity the layer is obtained.

By Control of temperature and exposure time should be ensured be that the hydrophobic layer preferably no temperatures above of 300 ° C assuming temperatures in these processes are particularly preferred from below 200 ° C respected.

Advantageous becomes the hydrophobic substance with a layer thickness of about one at least partial coverage of a molecular monolayer to about 200 nm, preferably from about this molecular monolayer to about 130 nm and includes, a substance which belongs to the group is selected, the silanes, preferably fluoroalkylsilanes, chloroalkylsilanes, hydrocarbon compounds with at least one nonpolar radical, nonpolar hydrocarbon compounds, Contains silicones and their mixtures or consists of these.

Preferred silanes have the general formula (CF _x H _y ) - (CF _a H _b ) - (CF _{a '} H _b' ) _m -Si (OR) ₃ on, in which
x and y independently of one another have the value 0, 1, 2 or 3 and x + y = 3,
a, a 'and b, b' independently of one another have the value 0, 1 or 2 and
a + b = 2 and a '+ b' = 2 gives and
n and m are independently an integer from 0 to 20 and together yield a maximum of 30 and
R is a straight-chain, branched, saturated or unsaturated, optionally heteroatom-containing, C ₁ - to C ₈ -alkyl radical.

Especially preferred alkyl radicals include methyl, ethyl and / or propyl radicals and / or their amino derivatives.

Articles produced according to the method have at least one antireflection coating, preferably a single-layer antireflection coating, with a coating comprising a porous ceramic nanoparticle whose pores are at least partially coated, in particular lined, with a hydrophobic layer in which the porous ceramic nanoparticles SiO ₂ and Al ₂ O ₃ include.

When the molar ratio of aluminum to silicon in the mixed oxide of the ceramic nanoparticles is from about 1: 4.0 to about 1:20, more preferably about 1: 6.6, thus, if the silicon-aluminum composite oxide is a composition (SiO ₂ ) _{1 -x} (Al ₂ O ₃ ) _{x / 2} with x = 0.05 to 0.25, preferably 0.15, the coating has a particularly high mechanical and chemical resistance.

With ceramic nanoparticles having a particle size of about 2 nm to about 20 nm, preferably about 5 nm to about 10 nm, more preferably about 8 nm, it is advantageously achieved that the transmission and reflective properties of the layer or layer system are only slightly degraded by scattering.

When the hydrophobic substance forms a layer having a layer thickness in the range of about ei A molecular monolayer up to about 20 nm, the influence on the optical design of the layer or the layer system remains relatively low, so that layer designs essentially do not need to be changed.

If the hydrophobic substance forms a layer with a layer thickness in the range of about preferably from about 20 nm to about 150 nm, more preferably up to about 130 nm, the optical design of the layer or the layer system can usually only with a change in the layer thickness of the hydrophobic substance layer provided. Here can in first order the change this layer thickness be made so that by the hydrophobic substance modified optical path length in the layer is compensated by the layer thickness change. Preferably will this compensation for one central spectral range and vertically incident light made.

Prefers the substrate comprises a glass substrate comprising a soda-lime glass, for example Schott B270, and / or a borosilicate glass.

Very Advantageously, the surface the glasses to be coated be structured to thereby especially for oblique incidence Light a raised To support passage through the glass and thus solar Energy generation to increase the efficiency.

Advantageously, a low-iron or iron-free glass, in particular with a Fe ₂ O ₃ content of less than 0.05% by weight, preferably less than 0.03% by weight can be used, since this has reduced absorption and thus enables a higher efficiency, in particular when using solar energy ,

excellent optical properties in the ultraviolet spectral range can be achieved when the glass substrate is a quartz glass.

advantageous Applications arise when the object is part of a cover of solar thermal collectors or part of a cover of photovoltaic modules is.

The Statement "part of one" here means that the object can be the whole part itself or too only one part comprises: for example, a part of a cover, such as the sun-directed top cover or only a part can form from this or even a full-surface all-round coverage may include.

In very advantageously, the object can be part of a display and in particular part of an instrument glazing in a motor vehicle or an aircraft, since in addition to the long-term stable Antireflection also added anti-fog properties.

The same advantageous properties arise when the object Part of a motor vehicle or aircraft disc is.

Also as part of a spectacle lens these very beneficial effects are used.

Further can These positive qualities can be useful if the subject frequently changes Temperatures, such as part of a refrigerator, in particular as part of a Lens of a refrigerator or a freezer, is exposed.

Also As part of a wet cell glazing, the fog-reducing and long-term stable effect of the invention be of great advantage.

by virtue of good thermal resistance The item can also be part of an additional lens for lamps and lighting, in particular for architectural lighting or for motor vehicle headlights be. Also in these applications, the fog-reducing and improved self-cleaning effect of great advantage.

Especially in the field of architecture or interior design, this is expanding Range of uses, when the article is part of a coloring layer in which the coloring either by incorporation of pigments or by the optical design of the single layer or the layer system causes can be.

The Invention will be described below with reference to preferred embodiments and with reference to the accompanying drawings in more detail described in which

1 the reflectivity as a function of wavelength,

2 : a long-term experiment after applying a hydrophobic substance and

3 : shows a tabular representation of the mechanical and chemical stability of the anti-reflection layer.

general description the invention:

By means of the method according to the invention, it is possible to produce objects, in particular different types of glasses, with at least one mechanically and chemically stable antireflection coating to provide.

For the production engineering Use have sol-gel process for application, in particular for large-scale application; the porous anti-reflection layer or a porous antireflective coating system proven, in which by a metal or metal mixed oxide in the sol-gel layer, in particular by an aluminum oxide or a silicon-aluminum mixed oxide, their mechanical resistance and also their chemical resistance clearly increased is.

By the application of a hydrophobic substance becomes the anti-reflection layer almost completely resistant to water absorption and keep her Great optical properties permanently.

There are a variety of hydrophobic, organic preparations that can be applied either during manufacture or even later by the end user such as the known under the brand "Clear Shield ^® " products. The document WO 00/37 374 shows an example of this approach. However, the layers disclosed in this document do not have the desired mechanical resistance and resistance.

For the production of hydrophobic surfaces also inorganic-organic hybrid polymers are used, which are known for example under the brand ORMOCER ^® the Fraunhofer Institute for Silicate Research. In this case, however, it should be prevented that the respective pores are completely filled by the layer formers in the hydrophobic substances.

Even though the invention is not porous Einschichtentspiegelungssysteme is limited, can with these already a broadband anti-reflection can be achieved, which also has a wide angle of incidence range shows high anti-reflection effect. So even with a single porous anti-reflection coating, For example, on soda lime glass or borosilicate glass a significant reduction the reflections in the visible wavelength range of light, 380 up to 780 nm or even for the spectrum of solar radiation in the range of 300 to about 2500 nm can be achieved.

The preferred water-repellent porous monolayer anti-reflection layer is applied to a substrate containing a soda lime glass, for example the Schott AG glass B270, a borosilicate glass, a quartz glass, a iron-free flat glass or a similar transparent article, which may be a thermally resistant plastic, for example, applied.

Further This antireflection coating may be due to its temperature resistance also applied to glass ceramics, such as thermal protection glasses be.

The Substrate can be of different shape. So is both the Use of flat as well as tubular or rod-shaped substrates possible.

According to one preferred embodiment includes the porous Layer porous Nanoparticles with a grain size from about 2 nm to about 20 nm, preferably from about 5 nm to about 10 nm, more preferably about 8 nm.

A preferred embodiment The invention comprises a layer of porous nanoparticles in which the volume fraction of the pores 10% to 60% of the total volume of the layer is. In this area of porosity will usually provide optimal results in reflection reduction reached.

The porous Nanoparticles of the antireflection coating are used in the sol-gel process, which as a spraying process, Dipping method, wiping method a coating or rolling process and / or Räkelverfahren feasible is applied to the substrate.

at The preferred sol-gel process is a reaction of organometallic Starting materials in the dissolved Condition for exploited the formation of the layers. Through a controlled hydrolysis and condensation reaction of the organometallic starting materials a metal oxide network structure builds up, i. a structure, in which the metal atoms are linked together by oxygen atoms are, along with the elimination of reaction products such as Alcohol and water. By adding catalysts can thereby Hydrolysis reaction can be accelerated.

In a preferred embodiment, in the sol-gel coating, the substrate or article is withdrawn from the solution at a pulling rate of about 200 mm / min to about 450 mm / min, preferably about 300 mm / min, the moisture content of the atmosphere between about 4 g / m ³ and about 12 g / m ³ , more preferably about 8 g / m ³ .

If the sol-gel coating solution is to be used or stored for an extended period of time, it is advantageous to stabilize the solution by adding one or more complexing agents. These complexing agents must be soluble in the dipping solution and should ver advantageously with the solvent of the dipping solution turns be. Preference is given to organic solvents which simultaneously have complex-forming properties, such as methyl acetate, ethyl acetate, acetylacetone, acetoacetic ester, ethyl methyl ketone, acetone and similar compounds. These stabilizers are added to the solution in amounts of 1 to 1.5 ml / l.

The solution for preparing the porous layer contains from about 0.210 mole to about 0.266 mole, preferably from about 0.238 mole silicon, about 0.014 mole to about 0.070, preferably about 0.042 mol aluminum, about 0.253 mmol to about 0.853 mmol, preferably about 0.553 mmol HNO ₃ , about 5.2 mmol to about 9.2 mmol, preferably about 7.2 mmol acetylacetone and at least one lower-chain alcohol. The acetylacetone surrounds the triply charged aluminum ions and creates a protective cover.

Next nitric acid are also other acids suitable, such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, boric acid, formic acid or Oxalic acid.

With this solution, chemically and mechanically resistant porous aluminum-silicon mixed oxide layers are obtained, wherein the ratio between silicon and aluminum in the ceramic nanoparticles is about 1: 4.0, preferably about 1:20, more preferably about 1: 6.6, and the silicon-aluminum Mixed oxide of the composition ( SiO ₂ ) _1-x (Al ₂ O ₃ ) _{x / 2} with x = 0.05 to 0.25, preferably 0.15.

These porous Mixed oxide layers, are not only chemically resistant and mechanically extremely resistant but to lead to a drastic increase the transmission of the layer or the layer system on the substrate.

A particularly preferred embodiment comprises a solution for producing the porous aluminum-silicon mixed oxide layer, in which the lower-chain alcohol has the general formula C _n H _{2n + 1} OH with n = 1, 3, 4 or 5, preferably n = 2. With this solution, porous layers are obtained, which are very resistant to abrasion.

According to the invention the applied to a soda-lime glass sol-gel layer, in particular with the porous one Nanoparticles, at a temperature between about 400 ° C and about 700 ° C, preferably between 430 ° C and 560 ° C during one Period of about 30 minutes to 120 minutes, preferably 60 minutes, baked. For thermally stable glasses, as. For example, borosilicate let yourself raise the temperature and thus shorten the heating time. Borosilicate glasses can be added a shortened one Duration at temperatures up to 900 ° C and quartz or quartz glasses at Temperatures are heated to above 1100C °.

In Particularly advantageously, the porous aluminum-silicon mixed oxide layer forms no crystals but a network that is amorphous up to the smallest dimensions is. Due to the stability of the porous network Is it possible, the one with the porous one Aluminum-silicon mixed oxide Thermally bias provided substrates or glass substrates a mechanical hardening or to achieve stabilization of the antireflective article.

at a particular embodiment The invention relates to the substrate with the porous layer thereon at a temperature of about 600 ° C up to about 750 ° C, preferably at about 670 ° C over a Period of about 2 minutes to 6 minutes, preferably 4 minutes thermally hardened or thermally toughened the glass. This will add an extra Stabilization of the glass substrate and the applied porous anti-reflection layer achieved. The process parameters of the thermal curing are based on the respective Adjust substrate material and optimize.

at a further embodiment The invention is the surface of the article is activated prior to coating with the sol-gel layer.

such Activation methods include oxidation, corona discharge, Flaming, UV treatment, plasma activation and / or mechanical Procedures, such as roughening, sandblasting, and plasma treatments or also treatment of the substrate surface to be activated with Acid and / or Alkalis.

As well Is it possible, one or more prior to coating the article of the invention Adhesive layers from the gas or liquid phase to apply. bonding agent include silanes and silanols having reactive groups. In individual cases it is appropriate the substrate surface previously roughen, for example mechanically by sandblasting or chemically, for example by etching.

at a preferred embodiment gets on with the porous Antireflective coating coated substrate an initially liquid or in a solvent dissolved hydrophobic substance by processes such as drainage, Capillary technique, spinning, spraying or diving applied. Furthermore, the hydrophobic substance may be in a wiping process, a coating or rolling process and / or with a Squeegee methods are applied to the substrate.

The porous Anti-reflection layer should be hydrophobic before coating Substance be solidified so far that it no longer leads to flow disturbances, such as zone-wise contraction of the coating, comes. By applying the hydrophobic solution to the porous anti-reflection layer can be an intensive penetration, occupancy and crosslinking of the hydrophobic Substance with the porous Anti-reflection layer done.

According to one Further development of the invention, the hydrophobic substance at about 50 ° C to about 450 ° C, preferred at about 150 ° C for about 2 min to about 2 h, preferably for baked out about 1 h. In an advantageous manner, this results within the trained porous Layer a hydrophobic surface coverage, the so thin is that they are based on the optical design of the anti-reflective coating almost no influence.

It can according to the invention even a monomolecular coating of the surface of the anti-reflection layer take place with the hydrophobic substance, without thereby affecting the advantageous Effects noticeably impaired become.

The preferred hydrophobic components or components of the hydrophobic Substance include at least one member of the group which silanes, preferably fluoroalkylsilanes, chloroalkylsilanes, hydrocarbon compounds with at least one nonpolar radical, nonpolar hydrocarbon compounds, Contains silicones and their mixtures or consists of these.

In the inventive method preferred silanes have the general formula (CF _x H _y ) - (CF _a H _b ) - (CF _{a '} H _b' ) _m -Si (OR) ₃ in which
x and y independently of one another have the value 0, 1, 2 or 3 and x + y = 3,
a, a 'and b, b' independently of one another have the value 0, 1 or 2 and
a + b and a '+ b' = 2 gives and
n and m are independently an integer from 0 to 20 and together yield a maximum of 30 and
R is a straight-chain, branched, saturated or unsaturated (optionally heteroatom-containing) C ₁ - to C ₈ -alkyl radical.

preferred Alkyl radicals are methyl, ethyl and propyl radicals, and their amino derivatives.

Silanes are preferred which contain halogen atoms or halogen-comprising groups, such as, for example, end or medium CF ₂ and CF ₃ groups, which increase or mediate the hydrophobic properties of the silane.

The invention Antireflective coating is something after heating on the surface weaker hydrophobic. By making the hydrophobic substance with its hydrophobic substance Groups, however, to the surface the pores are bound, this preferably even as a full-surface inner coating prove is surprising effectively yet the inner surface of the pores sustainable against Water intake protected.

at showed all the conventional porous anti-reflection products investigated by the inventors that, when stored in air, it stores water in the pores and, as a result, their antireflective effect will largely be achieved over time get lost. The minimum reflection thereby increases on both sides coated layers to values above about 4%, which in the inventive antireflection coatings is greatly reduced or even substantially no longer takes place.

According to one particularly preferred embodiment The invention relates to the process parameters of the sol-gel process, in particular by setting the spray parameters and the course and drying time of the porous anti-reflection layer so adjusted to apply both layers in a spray pass with two spray heads can be.

One followed by the sol-gel process energy-intensive heating the hydrophobic substance is omitted, because the warming the layer or the layer system in the context of the sol-gel process also for the heating of the hydrophobic substance, this means expelling the solvent, in which the hydrophobic substance is dissolved, sufficiently effective is.

The invention water repellent porous Single-layer antireflection coating is over a long time compared to one, as studies of the inventors showed Water absorption and storage largely resistant.

The inert outer layer of the single-layer antireflection coating consists in Contrary to the mentioned in the prior art documents are not enough Crystals but from a network down to the smallest dimensions porous Particle.

The according to the process obtained layers show a double-sided coating Low-iron glasses cause only slight turbidity due to scattering and increase the solar AM 1.5 transmission (Air Mass Transmission) to values> 96%.

The weighted D65 weighted visual reflection of the inventive article is in other than solar applications with a preferably blue one Reflection color in the case of double-sided coating even less than 1.5%.

by virtue of of the flat transmission band allows the present invention the production of anti-reflection coatings for installation in solar systems with a wider usable angle of incidence, what with previously available, repeatedly coated glass is not possible.

Around the coating in its quality and usability were distinguished by the Inventors performed several different tests.

To determine the mechanical resistance of the standardized Taber Abraser test, a stricter alcohol scrubbing test and an Sidolin ^® -Schrubb-test was performed on the samples.

In the Taber Abraser test, the coated disc is placed on a turntable, on which roll two friction belts, which are provided with a defined load. In this standard test, the sample is loaded twice by 500 grams. The wheels make about ten revolutions on the sample surface. The wheels cross a complete circle on the sample surface. The size of the surface tested here is 30 cm ² . The resulting wear marks a pattern in the form of crossed arches. This ensures that essentially every angle of the test area is subjected to the test.

At the Alcohol scrub test becomes a stamp with a weight of approx. 3600 g over the sample surface emotional. An alternating linear motion is performed by one on one Eccentric disc bolted shaft generates. The plastic stamp had Hereby a diameter of approx. 20 mm. The stamp was fitted at the point of support, where he is the sample surface touched, with one piece Felt to absorb the wetting agent, in this case pure alcohol.

Examines were samples of dimensions 10 cm × 10 cm. The maximum stroke was 8 cm. The stamp moved over the sample surface a hundred times.

The Sidolin scrub test differs from the alcohol scrub test only in the wetting agent used. It was used to wet the felt piece sold under the brand name Sidolin ^® Henkel detergent. This test was also carried out with one hundred strokes.

The results of these tests are in 3 shown for different process temperatures and demonstrate the excellent resistance of the inventive layers.

As a "sample" is in 3 the inventive antireflection coating and as "control" a conventional antireflection coating referred to.

3 shows a table with the results of the comparison tests between unstabilized and with aluminum oxide stabilized anti-reflection layers. The table also demonstrates the effect of the mechanical and chemical stabilization of the novel antireflection coating by doping it with aluminum oxide.

To an aluminum doping with 15 mol% aluminum content, but already before introducing the hydrophobic substances into the pores, improve the results of the Taber Abraser Tests significantly. About that In addition, in particular the wiping resistance is increased dramatically and thus a significantly improved serviceability of Achieved coating.

In the alcohol scrub test (modified Taber test with 3700 g load, 100 strokes at halved stamp area), in the same way with a commercial glass cleaner (Sidolin) performed all undoped samples showed, as shown in the table, strong attacks of surface coating. The samples according to the invention, which are stabilized with alumina, show lower attacks, or in the case of higher as 430 ° C reheated samples no longer attack.

It It was thus evident that in the layers according to the invention a detachment of the layer at all not and mechanical damage only very diminished, if at all, occurrence.

In 1 the reflectivity or the reflection characteristic of a preferred inventive porous Al ₂ O ₃ doped anti-reflection layer is shown as a function of the wavelength.

• 1. eine bei 430°C ausgeheizte Probe,
• 2. eine bei 430°C ausgeheizte und bei 670°C vorgespannte Probe,
• 3. eine bei 560°C ausgeheizte und
• 4. eine bei 560°C ausgeheizte und bei 670°C vorgespannte Probe.

Placed in 1 the properties of four samples prepared according to the invention:

• 1. a sample baked out at 430 ° C.,
• 2. a heated at 430 ° C and biased at 670 ° C sample,
• 3. a baked at 560 ° C and
• 4. one baked at 560 ° C and at 670 ° C before tense sample.

2 shows the reflection characteristic of the inventive porous Al ₂ O ₃ doped anti-reflection layer as a function of wavelength.

• 1. null Tagen;
• 2. zwei Tagen;
• 3. zehn Tagen;
• 4. siebzehn Tagen;
• 5. fünfunddreissig Tagen

Plotted are the properties of 5 samples, which after a period of:

• 1st zero days;
• 2. two days;
• 3. ten days;
• 4. seventeen days;
• 5. thirty-five days

exposition were taken in the air.

Out 2 It is surprisingly clear how long-term stable the porous antireflective coating according to the invention is compared with the storage of moist air. As can be seen from the identical graphs, almost no moisture or no water is embedded in the pores of the layer, which is very clearly evident from the substantially identical reflection properties.

preferred embodiments of the sol-gel method

preferred embodiments of the sol-gel process are exemplified by the preparation of a Sols for producing the mechanically stable antireflection coating shown.

First, a first solution based on a silica sol with a nominal particle size of 8 nm is prepared. The final solution contains silicon in a concentration of about 0.28 mol / l and low-water ethanol as a solvent. With the aid of a 1-n-HNO ₃ solution, an HNO ₃ concentration of 60 mmol / l is set.

A second solution is prepared which contains 0.28 mol / l of aluminum in the form of the hydrous chloride AlCl ₃ .6H ₂ O. The solvent used is likewise low-water ethanol, to which 485 g of acetylacetone (2,4-pentanedione) are added per 100 l of ready-to-use solution.

By Mix the two solutions in relation to 85:15 becomes a Si-Al mixed solution with a silicon content of 85% and an aluminum content of 15% receive.

so prepared dipping solutions are over a long time Time stable and can be over several Be used for months.

It be in the present embodiment 25 liters of dipping solution prepared for double-sided coating of a carefully cleaned, 4 mm thick, preferably made of low-iron float glass Glass panel used with a surface to be coated of 40 cm by 40 cm becomes.

The Glass pane is in the dipping solution Completely immersed, 10 seconds in the solution leave and then at a speed of about 300 pulled out mm / min.

To drying at 23 ° C up to 28 ° C at a humidity of 4 to 12 g / kg will be over the entire area obtained very homogeneous, essentially non-scattering layers.

The coated glass pane is then exposed for a period of one Brought to a temperature of 430 ° C and then at 670 ° C during a Thermally cured for four minutes.

The disk thus obtained shows a reflection characteristic as a function of wavelength directly after cooling to room temperature, as shown in FIG 1 for those with the reference number 1 providing curve is shown.

The curves 2 . 3 and 4 show the reflectivity of the above-mentioned further samples 2 . 3 and 4 ,

The thus obtained layers show a lasting only a slight haze Scatter and increase the solar AM 1.5 transmission to approx. 97%.

Since the desired long-term stability of the optical properties is achieved only by the hydrophobic coating of the pores, the just cooled, provided on both sides with a porous SiO ₂ layer with 15 mol% Al ₂ O ₃ soft glass was in a fluoroalkylsilane-containing solution for a period of about Immersed for 10 seconds, left in this solution and then pulled out of the solution at a speed of about 5 mm / s.

By Bake out at a temperature of 150 ° C in air over a period of one Hour becomes the excess hydrophobic solution driven out of the pores. This turned out to be exactly the same wavelength-dependent reflection curve as before treatment with the fluoroalkylsilanes.

The unchanged optical properties suggest that only a monomolecular layer The fluoroalkylsilane was bound in the pores, but the most surprising achieved a sufficient hydrophobic long-term effect.

Claims (58)

Method for producing an article comprising at least one coating and one substrate, wherein the coating comprises at least one antireflection coating in which the antireflection coating is produced by a sol-gel process, characterized in that the antireflection coating is porous, the antireflection coating Metal or metal mixed oxide, in particular a zirconium oxide, tin oxide, aluminum oxide and / or mixed oxides of the above oxides, in particular a silicon-aluminum mixed oxide. Method for producing an at least one coating and a substrate comprising article preferably according to claim 1, in which the coating has at least one antireflection coating includes, a hydrophobic substance at least to one area applied to the anti-reflection layer and / or in an area the anti-reflection layer is introduced. Method according to claim 1 or 2, characterized that the hydrophobic substance in the pores of the porous anti-reflection layer, in particular as a coating and preferably as a full-surface inner coating, is applied. Method according to Claims 1 to 3, characterized the antireflection coating contains porous nanoparticles. Method according to Claims 1 to 4, characterized that the porous ones Nanoparticles one grain size from about 2 nm to about 20 nm, preferably from about 5 nm to about 10 nm, more preferably about 8 nm. Method according to one of the preceding claims, characterized characterized in that the porosity of Nanoparticles 10% to 60% of the total volume of the anti-reflection layer is. Method according to one of the preceding claims, characterized characterized in that the porous nanoparticles as part of the sol-gel layer with a spray process, a dipping process, a wiping process, a coating or rolling process and / or be applied to the substrate by a doctor blade method. Method according to one of the preceding claims, characterized in that the antireflection coating, in particular with the porous one Nanoparticles while a period of about 30 minutes to 120 minutes, preferably during about 60 min, on an increased Temperature between about 400 ° C and about 700 ° C, preferably between 430 ° C and heated to 560 ° C and is heated by this. Method according to claim 8, characterized in that that at least a portion of the surface of the article after the Heat is thermally biased. Method according to claim 8 or 9, characterized that is thermally biased by the fact that the at least one Area during a period of about 2 minutes to 6 minutes, preferably 4 minutes a temperature of about 600 ° C up to about 750 ° C, preferably brought to a temperature of about 670 ° C. Method according to one of claims 1 to 9, characterized that the hydrophobic substance on the heated, porous nanoparticles comprehensive Layer is applied and / or introduced into this. Method according to one of claims 1 to 11, characterized that activation of the surface of the substrate before the application of the sol-gel layer takes place. Method according to claim 12, characterized in that that activation by corona discharge, flaming, UV treatment, plasma activation and / or mechanical processes, such as roughening, sandblasting, and / or chemical processes, such as etching he follows. Method according to one of claims 1 to 13, characterized that before applying the sol-gel layer and / or the hydrophobic substance one or more adhesion promoter layers from the gas or the liquid phase be applied. Method according to claim 10, characterized in that that the hydrophobic substance by dipping, capillary techniques, spin, Spraying, painting, Rolling and / or draining (flooding) up and / or introduced becomes. Method according to one of claims 1 to 15, characterized that the hydrophobic substance for a period of about 2 minutes to about 2 hours, preferably about 1 hour h, to about 50 ° C up to about 450 ° C, most preferably about 150 ° C heated becomes. Method according to one of claims 1 to 16, characterized in that the hydrophobic substance having a layer thickness of about at least a partial molecular monolayer to about 200 nm, preferably from about an at least partial molecular monolayer to about 130 nm is applied. Method according to one of claims 1 to 17, characterized in that the hydrophobic substance comprises at least one substance which selected from the group is the silanes, preferably fluoroalkylsilanes, chloroalkylsilanes, Hydrocarbon compounds having at least one nonpolar radical, nonpolar hydrocarbon compounds, silicones and mixtures thereof contains or consists of these. A method according to claim 18, characterized in that the silanes the general formula (CF _x H _y ) - (CF _a H _b ) - (CF _{a '} H _b' ) _m -Si (OR) ₃ in which x and y independently of one another have the value 0, 1, 2 or 3 and x + y = 3, a, a 'and b, b' independently of one another have the value 0, 1 or 2 and a + b = 2 and a '+ b' = 2 and n and m are independently an integer from 0 to 20 and together give a maximum of 30 and R is a straight-chain, branched, saturated or unsaturated, optionally containing heteroatoms, C ₁ - to C ₈ alkyl. Method according to claim 19, characterized the alkyl radicals are methyl, ethyl and / or propyl radicals and / or their amino derivatives include. Method according to one of claims 1 to 20, characterized that the porous anti-reflection layer on a soda lime glass, borosilicate glass, quartz glass, plastic or on a crystalline or partially crystalline material or ceramic or partially ceramic material, in particular a Glass ceramic, is applied. Method according to one of claims 1 to 21, characterized in that the porous anti-reflection layer is applied to a low-iron glass, which preferably has a Fe ₂ O ₃ content of less than 0.05% by weight, preferably less than 0.03% by weight. Method according to one of claims 1 to 22, characterized that the porous anti-reflection layer on a flat or tubular substrate is applied. Method according to one of claims 1 to 23, characterized that the process parameters of the course and drying time of the porous anti-reflection layer be adjusted so that the sol-gel layer together with the hydrophobic substance, preferably applied in a spray or dipping passage. Object produced by a method according to one of the preceding claims. Article, in particular produced according to one Process according to one of the claims from 1 to 25, with at least one antireflection coating, preferably a single-layer antireflective coating, where the coating a porous one Coating is and the coating comprises porous ceramic nanoparticles. Article, in particular produced according to one Process according to one of the claims from 1 to 25, with at least one antireflection coating, preferably a porous one Single-layer antireflection coating whose pores are at least partially coated with a hydrophobic layer, in particular lined are. Article according to claim 26 or 27, characterized the antireflection coating is a metal or metal mixed oxide, in particular a zirconia, tin oxide, alumina and / or mixed oxides of above oxides, in particular a silicon-aluminum mixed oxide comprises. An article according to claims 26 to 28, characterized in that the porous ceramic nanoparticles comprise SiO ₂ and Al ₂ O ₃ . Article according to claim 28 or 29, in particular manufactured according to a method according to one of the claims of 1 to 17, characterized in that the volume fraction of the pores 10% to 60% of the total volume of the anti-reflection layer. An article according to claims 28 to 30, characterized that the molar ratio from aluminum to silicon of the composite oxide of ceramic nanoparticles from about 1: 4.0 to about 1:20, more preferably about 1: 6.6. An article according to any one of claims 28 to 31, characterized in that the silicon-aluminum mixed oxide has a composition (SiO ₂ ) _1-x (Al ₂ O ₃ ) _{X / 2} where x = 0.05 to 0.25 0.15. An article according to any one of claims 28 to 32, characterized in that the ceramic nanoparticles have a particle size of about 2 nm to about 20 nm, preferably about 5 nm to about 10 nm, most preferably about 8 nm. An article according to any one of claims 28 to 33, characterized characterized in that the hydrophobic substance forms a layer with a layer thickness in the range of about 10 to about 200 nm, preferred from about 45 nm to about 150 nm, more preferably about 70 up to about 130 nm. An article according to any one of claims 28 to 34, characterized characterized in that the substrate is a glass substrate which a soda lime glass and / or borosilicate glass. An article according to any one of claims 28 to 35, characterized in that the glass substrate comprises a quartz glass or consists of a quartz glass. An article according to any one of claims 28 to 36, characterized characterized in that the glass substrate is a flat, rod-like or tubular shape having. An article according to any one of claims 28 to 35, characterized characterized in that the article is part of a cover of thermal Solar collectors is. An article according to any one of claims 28 to 35, characterized characterized in that the article is part of a picture glazing. An article according to any one of claims 28 to 35, characterized in that the article is part of a cover of photovoltaic modules is. An article according to any one of claims 28 to 35, characterized characterized in that the article is part of a cover of solar cells is. An article according to any one of claims 28 to 35, characterized characterized in that the object is part of a display. An article according to any one of claims 28 to 35, characterized in that the article is part of an instrument glazing in a motor vehicle or an aircraft. An article according to any one of claims 28 to 35, characterized characterized in that the object is part of a dashboard glass. An article according to any one of claims 28 to 35, characterized in that the article is part of a vehicle window is. An article according to any one of claims 28 to 35, characterized characterized in that the article is part of an auxiliary lens for lamps and lighting, in particular for architectural lighting or for motor vehicle headlights is. An article according to any one of claims 28 to 35, characterized characterized in that the article is part of an attachment disc of a TV, video or audio device is. An article according to any one of claims 28 to 35, characterized characterized in that the article is part of a watch glass. An article according to any one of claims 28 to 35, characterized characterized in that the object is part of an optical device. An article according to any one of claims 28 to 35, characterized characterized in that the object is part of a spectacle lens. An article according to any one of claims 28 to 35, characterized in that the article is part of a telescope or microscope is. An article according to any one of claims 28 to 35, characterized characterized in that the article is part of an architectural glass is. An article according to any one of claims 28 to 35, characterized characterized in that the object is part of a showcase. An article according to any one of claims 28 to 35, characterized characterized in that the object is part of a cooling device, in particular part of a Lens of a refrigerator or a freezer is. An article according to any one of claims 28 to 35, characterized in that the article is part of a plastic glazing is. An article according to any one of claims 28 to 35, characterized in that the article is part of a wet cell glazing is. An article according to any one of claims 28 to 35, characterized characterized in that the object is part of a computing or telecommunications device. An article according to any one of claims 28 to 35, characterized in that the article is part of a coloring layer with hydrophobic properties.