KR20240025002A - Sol-gel coated flat glass with nano-inclusions - Google Patents

Abstract

This invention
- Transparent substrate (1),
- relates to a coated pane comprising a sol-gel coating (2) on the surface of the substrate (1),
The sol-gel coating (2) contains a sol-gel matrix (3) based on a metal oxide or semi-metal oxide and provided with nano-inclusions (4),
The nano-inclusions 4 include a core 4a and a shell 4b arranged around the core 4a,
Shell 4b is produced by atomic layer deposition (ALD).

Description

Sol-gel coated flat glass with nano-inclusions

The present invention relates to coated flat glass, its production method, and its use.

Sol-gel coatings are well known. Here, a solution containing a precursor (sol) is applied to the surface of a sheet glass, and the precursor condenses to form a gel that remains on the surface of the sheet glass even after the solvent is discharged. The advantages of sol-gel coatings include low cost and simple wet chemical handling.

Another advantage of sol-gel coatings is that their properties can be established relatively easily, especially through the selection of precursors and/or inclusions that can be easily added to the sol solution. For example, WO2008059170A2 discloses a sol-gel coating of silicon oxide with nano-inclusions in the form of pores (created by thermally decomposed PMMA inclusions), hollow silicon oxide balls, or oil droplets. As a result of these inclusions, the refractive index of the sol-gel layer can be adjusted (reduced) so that the sol-gel coating can be used as an anti-reflective coating for glass plates. The subsequently published WO2021209201A1 discloses an optically high refractive index sol-gel coating, which in one embodiment is formed by a sol-gel matrix of silicon oxide with inclusions that increase the refractive index, in particular titanium oxide inclusions. .

However, there are limits to the ability to set the properties of a sol-gel coating by its inclusions. Therefore, the maximum achievable inclusion ratio (degree of doping) is limited.

There is a need for improved sol-gel coatings whose properties can be set over a wider range or where multifunctional coatings can be realized. Additionally, it is advantageous to improve the mechanical stability and aging behavior of sol-gel coatings.

So-called core-shell nanoparticles are known, consisting of a core and a shell of different materials. The refractive index of these nanoparticles is essentially based on the so-called quantum confinement effect and can therefore be tuned over a wide range, especially by choosing the size of the nanoparticles. Additionally, it is known that the shell of core-shell nanoparticles can be produced through atomic layer deposition (ALD). Atomic layer deposition makes it possible to produce high quality shells and precisely defined layer thicknesses. Therefore, it has been proven in the literature that the chemical resistance of nanoparticles can be improved by this ALD shell (A. W. Weimer, Particle Atomic Layer Deposition. Journal of Nanoparticle Research 21, 2019). It has also been demonstrated that the mechanical stability of nanoparticles can be improved in that the hardness and elastic modulus of the nanoparticles can be changed and the refractive index can be adjusted according to the selection of the layer thickness and the extent of the core of the shell (L. Zhang et al. Mechanical properties of atomic layer deposition-enhanced nanoparticle thin films (Nanoscale, September 2012).

WO2015075229A1 discloses a porous anti-reflective coating using wet chemically prepared organic/inorganic hybrid core-shell nanoparticles. WO2011157820A1 and WO2013174754A2 also disclose sol-gel coating using wet chemically produced core-shell nanoparticles as inclusions.

The object of the present invention is to provide pane glass with an improved sol-gel coating. It should be possible to set the properties of the sol-gel coating, especially the refractive index, accurately and reproducibly over a wide range. The coating must also be mechanically stable, resistant to aging and suitable as a multifunctional coating.

The object of the present invention is achieved by the coated glass plate of the present invention and also the method for producing it according to the independent claim. Preferred embodiments become apparent from the dependent claims.

A coated glass pane according to the invention comprises at least one transparent substrate and a sol-gel coating on the surface of the transparent substrate. Sol-gel coatings either contain a sol-gel matrix or consist of a matrix with nano-inclusions (sol-gel matrix) formed according to the sol-gel principle. Nano inclusions are also called doping of the sol-gel matrix. According to the invention, the sol-gel matrix is formed on the basis of metal oxides or semimetal oxides or consists of metal oxides or semimetal oxides. Semimetal oxides are also called semiconductor oxides. In addition to metal oxides or metalloid oxides, sol-gel matrices may also contain process-related residues or additives, such as stabilizers or UV blockers. The inclusions are introduced into the sol-gel matrix in particular by adding them to the sol (preferably as a solution), so that they are surrounded by the sol-gel matrix during condensation and drying of the sol-gel coating.

To say that an element is formed based on a material means that the element is composed primarily of that material, and especially essentially of that material, excluding impurities or doping. The proportion of the materials is greater than 50% by weight, preferably greater than 70% by weight and very particularly preferably greater than 90% by weight. With regard to metal oxides or semi-metal oxides as the material of the nano-inclusions (shell or core), the proportion is in particular greater than 99% by weight.

According to the present invention, the nano-inclusions include a core and a shell arranged around the core and surrounding it. The core and shell are made of different materials. Therefore, the nano inclusions can be considered core-shell nanoparticles. According to the invention, the shell is created by atomic layer deposition (ALD) on the core.

Sol-gel coatings are inexpensive to produce. Sol-gel coatings are easy to apply to a substrate wet chemically over the entire surface of the substrate or only to selected areas. Sol-gel coatings can be used in a variety of ways and their properties are easy to control, for example by selection of materials for the sol-gel matrix and/or inclusions. This is exploited in the present invention by nano-inclusions according to the invention with a shell produced by atomic layer deposition. Nano-inclusions may, for example, affect the optical properties of the coating and/or improve its chemical or mechanical stability. Using a shell allows for better inclusion or better connection to the matrix. The use of nano-inclusions allows a very flexible setting of the refractive index, especially over a wide range, since the refractive index of nano-inclusions is based on quantum effects (quantum confinement). These quantum effects occur due to electronic interactions between the shell and the core and are affected by the materials and sizes of the core and shell. Atomic layer deposition allows the production of shells with very precisely defined layer thicknesses, allowing properties to be established accurately and reproducibly. In addition, atomic layer deposition creates very dense layers, which on the one hand ensures high chemical and mechanical stability and on the other hand makes it possible to obtain the desired properties even if the layer thickness is relatively low. By almost completely controlling the thickness, chemical composition, and density of the shell, optical effects based on quantum confinement effects that are not possible with less precise deposition processes can be achieved. Additionally, atomic layer deposition can be used for many materials, and has been particularly well studied for many oxides and nitrides, making the present invention flexible for many applications. This is a great advantage of the present invention.

It can be seen with high-resolution transmission electron microscopy (HRTEM) that the shell is created from the nano-inclusions by atomic layer deposition. Atomic layer deposition creates an ideally uniform shell even at the atomic level, resulting in an almost perfectly consistent shell layer thickness that cannot be achieved with other coating methods. The shell follows the contour of the core surface almost perfectly and, for example, in the case of a spherical core, is ideally concentric with the core.

The thickness of the sol-gel coating is preferably between 30 nm and 500 nm, particularly preferably between 50 nm and 150 nm.

In one advantageous embodiment, the sol-gel matrix is based on silicon oxide (SiO ₂ ) or consists of SiO ₂ . SiO ₂ sol-gel coatings have been well studied and can be produced with high quality. Moreover, SiO ₂ has a refractive index similar to that of common substrates (especially soda-lime glass sheets or plastic panes made of PMMA or polycarbonate). Therefore, SiO ₂ sol-gel coatings are optically compatible with these substrates. Anti-reflective properties can be created using these coatings, especially through specially designed porosity or other inclusions that lower the refractive index. However, other sol-gel matrices, for example TiO ₂ based matrices, can also be used to create an optically high refractive index layer.

Nanoinclusions are core-shell nanoparticles, where the shell is created by atomic layer deposition on the core. Nanoinclusions may alternatively be hollow particles formed by a shell and surrounding a cavity (pore) forming a core. To this end, the polymer nanoparticles are provided with a shell by atomic layer deposition, the coated nanoparticles are embedded in the coating, and the polymer core can be removed thermally or by solvent. Nano inclusions or nanoparticles are understood to mean particles with a size in the nanometer range, i.e. from 1 nm to less than 1,000 nm (1 μm). The nano-inclusions or nanoparticles are preferably spherical and therefore have a substantially circular cross-section. Alternatively, the nano-inclusions or nanoparticles may have other cross-sections, such as elliptical, oval or elongated cross-sections (ellipsoidal or oval nanoparticles).

The volume fraction of nanoparticles in the sol-gel coating (the combined volume of all nano inclusions divided by the total volume of the sol-gel coating) is preferably between 10% and 90%, particularly preferably less than 80%, and very particularly Preferably it is less than 70% or less than 60%.

Nanoinclusions can be designed in a variety of ways depending on the intended application. This applies not only to the materials of the core and shell, but also to their combinations. Both the core and shell are preferably formed of dielectric material. Dielectric materials in the sense of the present invention in particular have an electrical conductivity (reciprocal of resistivity) of less than 10 ^-4 S/m.

In one preferred embodiment, the core is designed as a pore, i.e. as a kind of empty space (in particular gas, air or vacuum filled) in the sol-gel matrix. The refractive index of the sol-gel coating can be adjusted through pores and, in particular, can be reduced compared to the refractive index of the sol-gel matrix. As a result, the coating can be provided with anti-reflective (non-reflective) properties.

In the context of the present invention, the refractive index is specified in all cases with respect to a wavelength of 550 nm. The refractive index can be determined, for example, by ellipsometry. Ellipsometers are commercially available, for example from the company Sentech.

In a further preferred embodiment, the core is formed of or based on a polymer or consists of a polymer. Using such cores, the refractive index of the coating can also be adjusted by inclusions. Additionally, in some cases, the robustness and mechanical properties of the coating may be improved. Polymethyl methacrylate (PMMA) is particularly preferred due to its moderate refractive index, good solubility, and ease of care. However, alternatively, for example polycarbonates, polyesters, polystyrene, copolymers of methyl (meth)acrylate and (meth)acrylic acid can also be used.

The polymer core may also function as a precursor for pores when the core is incorporated into a sol-gel matrix and then pyrolyzed as part of a heat treatment or dissolved by a solvent. For this purpose, in addition to PMMA, for example polycarbonate, polyester, polystyrene or a copolymer of methyl (meth)acrylate and (meth)acrylic acid are also suitable.

In a further preferred embodiment, the core is formed of a metal oxide or a semimetal oxide, is based on a metal oxide or a semimetal oxide, or consists of a metal oxide or a semimetal oxide. Particularly preferred is silicon oxide (SiO ₂ ). For example, in this way the refractive index of the coating can be set. Here, if the sol-gel matrix is also composed of SiO ₂ , the effect is mainly based on the shell and excellent optical compatibility with the matrix is ensured by the SiO ₂ core. Additionally, titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and hafnium oxide (HfO ₂ ) are particularly preferred. This also makes it possible to adjust and especially increase the refractive index of the coating if the sol-gel matrix consists of SiO ₂ . Additionally, the coating can provide photocatalytic, self-cleaning properties by TiO ₂ .

In a further preferred embodiment, the core is a hollow particle, i.e. formed as a shell around an empty space (in particular filled with air). The hollow particles are formed from metal oxides or semimetal oxides or based on metal oxides or semimetal oxides, for example from SiO ₂ or TiO ₂ . In particular, SiO ₂ hollow particles are commercially available and can be easily purchased. The pores of the sol-gel matrix are formed by empty spaces and their refractive index can be set accordingly, where the SiO ₂ encapsulation ensures good optical compatibility with the sol-gel matrix (at least when the sol-gel matrix is converted to SiO ₂ if created). However, hollow particle cores can also be used for other purposes, for example to create a scattering surface on a substrate that serves to outcouple light.

It is particularly preferred that the core is formed from pores of a metal oxide or semimetal oxide (in particular SiO ₂ and TiO ₂ ) or from hollow particles of a metal oxide or semimetal oxide (in particular SiO ₂ and TiO ₂ ). Very particularly preferred materials for the core are SiO ₂ pores and SiO ₂ hollow particles because of their wide application range.

The size of the core is preferably between 10 nm and 500 nm, particularly preferably between 10 nm and 150 nm and very particularly preferably between 50 nm and 100 nm. This gives good results, especially with regard to nanoparticle inclusions in the sol-gel matrix and tuning their refractive index. Here, size is understood to mean the maximum extension of the core in space, that is, the diameter in the case of spherical nanoparticles. The size of at least 80% of all cores is preferably within the specified range, particularly preferably all cores are within the specified range.

The shell of the nano-inclusions preferably has a refractive index greater than 1.5, particularly preferably greater than 1.7 and especially greater than 1.9. This is particularly advantageous when trying to achieve an increase in the refractive index of the sol-gel matrix through nano-inclusions. However, even if this is not the case, a slight increase in the refractive index due to the material of the shell may be acceptable if, for example, a significant improvement in the mechanical properties can be achieved thereby.

In a preferred embodiment, the shell is formed of or based on a metal oxide or semimetal oxide or consists of a metal oxide or semimetal oxide. Suitable metal oxides or semimetal oxides are for example silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ) or transition metal oxides, especially titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ) or hafnium oxide (HfO). ₂ ). When the sol-gel matrix is made of SiO ₂ , the SiO ₂ shell can provide a good connection between the nano-inclusions and the matrix. The other metal oxides mentioned can increase the refractive index, for example to provide reflective properties to the coating. A TiO ₂ shell can also be used to impart photocatalytic, self-cleaning properties to the coating. Shells made of SiO ₂ or TiO ₂ are particularly preferred.

Depending on the intended use, the shell may alternatively be formed of nitride or may be based on nitride. Examples include silicon nitride (Si ₃ N ₄ ) or aluminum nitride (AlN). This may be advantageous in certain application ways, for example with regard to the surface properties of the nano-inclusions and/or the connection of the shell and core. Of course, the material of the shell is selected under the condition that it must be different from the material of the core.

Although stoichiometric summation formulas are provided for better understanding, the oxides and nitrides used in the context of the present invention are not necessarily formed stoichiometrically, but may alternatively be formed low-stoichiometrically or super-stoichiometrically. It may be possible. This applies equally to the core and shell of nano-inclusions and to the sol-gel matrix. However, the shell of the nano-inclusions is preferably formed stoichiometrically, which is possible in an accurate and reproducible manner due to the deposition of a complete monolayer during atomic layer deposition.

The shell preferably has a layer thickness of 1 nm to 100 nm, particularly preferably 2 nm to 20 nm, especially 5 nm to 15 nm. These thin shells are easy to produce by atomic layer deposition, and the high density achieved with atomic layer deposition is sufficient to produce the desired properties. In the context of the present invention, unless otherwise indicated, layer thickness means the geometric thickness of the layer and not the optical thickness, which is for example the product of the geometric thickness and the refractive index.

The sol-gel coating according to the present invention can be used for various purposes and perform various functions. Sol-gel coatings can be, for example:

- Anti-reflective coating: This is a coating that has a particularly lower refractive index than the substrate. This can in particular be formed by a SiO ₂ matrix whose refractive index is reduced by pores (pores that are cores of nanoparticles or hollow particles, especially SiO ₂ hollow particles that are cores of nano inclusions). The refractive index depends on pore size and pore density. The proportion of pore volume in the total volume is preferably between 10% and 90%, particularly preferably less than 80% and very particularly preferably less than 60%. SiO ₂ is particularly preferred as the shell to optimize the binding of the pores or hollow particles to the SiO ₂ matrix. However, all other materials mentioned can also be considered for the shell. This is especially true if the coating has additional properties.

- Reflection-increasing coating: This is a coating that has a particularly higher refractive index than the substrate. This can be achieved, for example, by using a sol-gel matrix with a high refractive index (especially TiO ₂ , ZrO ₂ or HfO ₂ ) or by using nano-inclusions that increase the refractive index (in particular TiO ₂ , ZrO ₂ or HfO ₂ ) as the shell or core of the nano-inclusions. This can be achieved using a SiO ₂ matrix containing.

- Hydrophilic or hydrophobic coatings, i.e. coatings that influence the utilization behavior of the substrate surface.

- Sunblock coatings, i.e. coatings that reflect or absorb electromagnetic radiation in the infrared and/or ultraviolet range.

- Photocatalytic coatings: These coatings are suitable for breaking down organic deposits and therefore have self-cleaning properties. Photocatalytic properties are achieved in particular by using TiO ₂ as a material for the shell or core of the sol-gel matrix or nano-inclusions.

- Light scattering coating: High light scattering properties are provided to the coated area of the substrate surface. This can be used, for example, to couple out the substrate light that is coupled into the substrate via the side edges and propagating therein by total reflection, the outcoupling being for lighting purposes or for display creation.

- Decorative coatings, especially colored coatings. For example, the reflection color can be set depending on the refractive index and light interference effects of the sol-gel coating.

Due to the high flexibility of the coating design (the shell and core materials of the sol-gel matrix material and the nano-inclusions can be selected independently of each other), it is possible to create multifunctional coatings, especially coatings that perform several of the functions mentioned above. An example of this is:

- Anti-reflective coating with photocatalytic properties

- Hydrophobic anti-reflective coating

- Hydrophobic photocatalytic coating

- Anti-reflective coating that blocks sunlight

- Colored anti-reflective coating.

The preferred materials for the core and shell of the nano-inclusions described above can be combined with each other essentially as desired. Particularly preferred combinations are for example:

- Core: pores, shell: SiO2: These nano-inclusions can be used to lower the refractive index of sol-gel coatings. These coatings can also increase mechanical and chemical resistance and reduce the visibility of fingerprints. In the case of SiO ₂ matrices, the SiO ₂ shell improves binding of nano-inclusions to the matrix. Such nano-inclusions can in particular be produced by nanoparticles having a polymer core (preferably a PMMA core) and a SiO ₂ shell, where the core pyrolyzes or dissolves after coating.

- Core: pores, shell: TiO ₂ : These nano-inclusions can also be used to reduce the refractive index of sol-gel coatings, where the shell additionally imparts photocatalytic properties to the coating. Therefore, a sunblock coating can also be created. This coating can in particular be produced by nanoparticles with a polymer core (preferably a PMMA core) and a TiO ₂ shell, where the core pyrolyzes or dissolves after coating.

- Core: SiO ₂ , Shell: TiO ₂ : These nano-inclusions can be used, for example, in reflection-increasing coatings, especially in the case of SiO ₂ matrices whose refractive index is increased by the TiO ₂ shell.

- Core: TiO ₂ , Shell: SiO ₂ : These nano-inclusions can be used, for example, in reflection-increasing coatings. In the case of SiO ₂ matrices, the SiO ₂ shell improves bonding to the matrix.

- Core: SiO ₂ hollow particles, shell: TiO ₂ : These nano-inclusions can be used, for example, in light scattering coatings.

The sol-gel coating can be arranged across the entire substrate surface. However, it is also possible for the sol-gel coating to be arranged only on one or more areas of the surface, leaving other areas uncoated. For example, the coating may be applied to the entire surface except for the uncoated peripheral edge areas so that the central transparent area of the substrate is completely covered with the coating. In particular, more than 80% of the substrate surface is coated. This is particularly advantageous when the coating is intended to provide as uniform properties as possible across the substrate, such as anti-reflective coatings, hydrophilic or hydrophobic coatings, sunblock coatings and/or self-cleaning coatings. However, it is also possible for the coating to be provided only in locally limited areas (e.g. camera or sensor areas with specific properties) or for the coating to be applied to the substrate in the form of a pattern. Through the wet chemical sol-gel process, it is possible to simply coat the entire area as well as coat some areas.

In one preferred embodiment, the substrate takes the form of a glass pane or a plastic pane. Here, plate glass refers to a plate-shaped or layer-shaped object that is generally rigid and can be bent elastically at best. In the case of glass panes, the substrate is preferably made of soda-lime glass, which is customary for window panes. However, other types of glass are also conceivable (e.g. borosilicate glass, quartz glass, or aluminosilicate glass). In the case of plastic panes, the substrate is preferably formed of or based on PMMA or polycarbonate (PC). The thickness of the substrate can be freely selected depending on the application. The typical thickness of window glass in architectural or automotive fields is for example 0.5 mm to 5 mm, preferably 1.0 mm to 2.5 mm.

According to the invention, the substrate is transparent. This is understood to mean a substrate that can be seen through, i.e. that can be used in particular as a window pane. The substrate may be tinted or tinted, as is particularly common in many vehicle windows. The light transmittance of the substrate in the visible spectrum range from 400 nm to 800 nm is preferably at least 10%, particularly preferably at least 30%, very especially at least 50% and especially at least 70%. This value relates to the total fraction of transmitted radiation out of the total radiation striking the substrate at an angle of incidence of 0° to the surface normal in the specified spectral range.

The coated flat glass is preferably intended as window glass, especially as window glass for buildings, interiors or vehicles.

The present invention further comprises a method of producing a coated pane according to the present invention, wherein the method includes at least:

(a) nanoparticles are provided,

(b) a shell is provided to the nanoparticles through atomic layer deposition;

(c) a sol containing a metal oxide or semimetal oxide precursor is provided,

(d) adding nanoparticles to the sol together with the shell;

(e) Applying the sol to the surface of the substrate along with nanoparticles having a shell,

(f) the sol condenses to form a sol-gel coating, wherein a sol-gel matrix is created from a metal oxide or semi-metal oxide precursor, the matrix comprising a core formed of nanoparticles and a shell arranged around this core. A nano-inclusion is provided.

Unless technically necessary, the method steps do not necessarily have to be performed in the order indicated above. Before the nanoparticles are added to the sol (method step (d)), it is necessary to provide the nanoparticles with a shell (method step (b)). Likewise, it is necessary for nanoparticles provided with a shell to be added to the sol (method step (d)) before the sol is applied to the substrate surface (method step (e)). Likewise, it is necessary to apply the sol to the substrate surface (method step (e)) before the sol condenses to form a sol-gel coating (method step (f)). However, it does not matter whether the nanoparticles are first provided with a shell (method step (b)) and then the sol with the precursor is prepared (method step (c)) or vice versa.

Since nanoparticles with shells are generally stable over a long period of time and can therefore be stored, coating the nanoparticles (method step (b)) does not necessarily have to be done immediately before the sol is prepared (method step (c)). For example, larger quantities of coated nanoparticles can be produced and stored in inventory to be used for sol-gel coating as needed.

According to the present invention, nanoparticles are provided with a shell by atomic layer deposition. Atomic layer deposition (ALD) is an efficient process for depositing thin layers down to an atomic monolayer. The components (atoms) of the material to be deposited are bound in chemical form to a carrier gas (so-called precursor or reactant). The components are alternately delivered to a reaction chamber where they each react with the object to be coated. As a result, the precursor in question becomes chemically bonded to the surface to be coated. The reaction chamber is then emptied and filled with the next precursor. Alternating layers of coating components are thus applied one after another. Suitable reactants for producing ALD coatings made of metal oxides are, for example, the corresponding methyl-metal compounds or the corresponding metal chlorides on the one hand and water vapor on the other. Methyl-metal compounds (or metal chlorides) serve as the metal source, and water vapor serves as the oxygen source. In the reaction of methyl-metal compounds, some methyl groups are separated and the metal is chemically bonded to the substrate along with the remaining methyl groups. It is bonded to the substrate via free OH groups, for example on the surface of the object to be coated or in the base layer deposited from water vapor. The reaction chamber is then filled with water vapor. In the subsequent reaction, the OH groups replace the methyl groups of the base metal layer. The next metal layer is then deposited, and the methane is removed and bonded to the OH groups from the previous deposition step. Therefore, an oxygen layer is created between the two metal layers. Alternating processes are performed until the desired layer thickness is reached. Between individual deposition steps the reaction chamber may be purged with an inert gas (e.g. argon). A characteristic feature of ALD is the self-limiting nature of the partial reaction; That is, the reactant does not react with itself or its ligand, which limits the layer growth of the partial reaction to at most one monolayer for any length of time and amount of gas. Thus, very dense layers with a precisely set layer thickness can be created. Because the gas is uniformly distributed in the reaction chamber, the object is completely coated regardless of its geometry except for the contact surfaces. ALD coatings made of semimetallic oxides can also be produced, where the metals are replaced by semimetals in the above description.

Atomic layer deposition of the shell onto the core is generally done in partial (batch processing) rather than continuous processes. A certain amount of nanoparticles are added to the reaction vessel, coated at the same time as the shell, and then removed. These reactions are usually carried out in so-called batch reactors.

Nanoparticles are preferably selected with surface groups or chemically functionalized in a manner that makes them soluble in solvents. The solvent may preferably be water, alcohol, or a water-alcohol mixture. For the batch processing, the nanoparticles are provided dissolved in a solvent. The solvent is then evaporated. The nanoparticles are then provided with a shell by atomic layer deposition and then re-dissolved in a solvent, which may be the same solvent in which the nanoparticles were provided. Of course, the shell must be selected or chemically functionalized by atomic layer deposition in a way that ensures the solubility of the coated nanoparticles. The solution containing the nanoparticles can then be added to the sol (method step (d)).

A sol is a solution containing the precursor of the sol-gel matrix dissolved in a solvent. According to the invention it is a metal oxide precursor or semimetal oxide precursor from which a metal oxide or semimetal oxide matrix can be formed. Metal oxide precursors may exist, for example, as organometallic compounds, metal alkoxides or metal carboxylates. Similar compounds can be used as semimetal oxide precursors, in which case the metal is replaced by the metalloid. In a preferred embodiment, the metal or metalloid (e.g. of a metal alkoxide or carboxylate) is stabilized by a ligand in the form of a chemical complex so that its reactivity can be reduced and the resistance of the sol to atmospheric humidity is improved. It can be. A suitable ligand is for example 2,4-diketone. The solvent is preferably water, alcohol (especially ethanol), or water-alcohol mixture.

In addition to the precursor and solvent, the sols may contain thickening agents, such as cellulose derivatives (e.g. methyl cellulose or ethyl cellulose) or polyacrylic acid to adjust the viscosity of the sol. It is possible for the solvent or thickener to also function as a complexing agent for the metal oxide or metalloid oxide precursor if appropriately selected. In this case, there is no need to add a separate ligand. The sols may also contain typical additives that are common in the field of sol-gel technology and known to those skilled in the art.

If the matrix is produced from or based on SiO ₂ , the sol will contain a silicon oxide precursor in the solvent. The precursor is preferably a silane, especially tetraethoxy silane or methyltriethoxysilane (MTEOS). However, alternatively, it is also possible to use silicates as precursors, in particular sodium silicate, lithium silicate or potassium silicate, for example tetramethyl orthosilicate, tetraethyl orthosilicate (TEOS), tetraisopropyl orthosilicate or the general form R Organosilanes of ² nSi(OR ¹ ) _4-N can also be used. Preferably, R ¹ is an alkyl group, R ² is an alkyl, epoxy, acrylate, methacrylate, amine, phenyl or vinyl group, and n is an integer from 0 to 2. It is also possible to use silicon halides or alkoxides.

The precursor may optionally already be matured in solution. Maturation may involve hydrolysis of the precursors and/or formation of (partial) aggregates by (partial) reactions between precursors (in particular polycondensation).

The precursor concentration in the sol is preferably 0.1% by weight to 20% by weight, and particularly preferably 2% by weight to 10% by weight.

Coated nanoparticles are added to the sol. This should be understood to mean that nanoparticles and sol-gel precursors are mixed in a solvent. Typically, the coated nanoparticle solution is mixed with a sol. However, in principle, it is also possible to add the precursor directly to the nanoparticle solution. In other words, sol is produced directly from it. In this case, the supply of sol and addition of nanoparticles are performed in one step.

The sols are applied to the surface of the substrate together with the coated nanoparticles dissolved therein, i.e. provided with a shell, especially by wet chemical methods, for example by dip coating, spin coating, flow coating, using a roller or brush, It is applied by spray coating, or by printing methods such as pad printing or screen printing. Drying can then occur, in which case the solvent evaporates. This drying can be carried out at ambient temperature or through separate heating (e.g. at temperatures of up to 120°C). Before the coating is applied to the substrate, the surface is generally cleaned by methods known per se.

The sol is then condensed to form the sol-gel coating according to the invention. This is preferably carried out by heat treatment at a minimum of 400°C. This can be done as a separate heat treatment. If the substrate is a curved glass plate, as is common in the automotive field, heat treatment can be performed through a glass bending process, typically at a temperature of 600°C to 700°C. If the precursor has UV-crosslinkable functional groups (e.g., methacrylate, vinyl or acrylate groups), condensation may include UV treatment instead of or in addition to heat treatment. Alternatively, condensation with a suitable precursor (e.g., silicate) may include IR treatment.

Prior to actual condensation, optional upstream drying may occur, in which case the solvent evaporates and consequently the precursor condenses. This drying can be carried out at ambient temperature or through separate heating (e.g. at temperatures of up to 120°C).

During condensation, a sol-gel matrix is formed from metal oxides or semimetal precursors. In this case, the cross-linking process typically occurs between precursors, where the precursors first combine to form aggregates (typically by hydrolysis of the precursors and agglomeration by polycondensation reactions between them) and then cross-link to form a gel. (gelation). Coagulation may partially occur in the solution (maturation) before it is applied to the pane surface. The sol-gel matrix is provided with nano-inclusions comprising a core formed from nanoparticles and a shell arranged around the core.

In method step (f), the core of the nano-inclusion according to the invention is formed from nanoparticles. This does not necessarily mean a chemical or mechanical transformation; such transformation is optional, as is evident from the two preferred embodiments described below.

In one embodiment of the method, the nanoparticles within the sol-gel coating remain as a core of nano inclusions after nanoparticle creation. That is, without any kind of conversion, the nanoparticles of the sol form the core of the inclusions in the sol-gel coating.

The nanoparticles may preferably be formed from or based on polymers (e.g. polycarbonate, polyester or polystyrene, or copolymers of methyl (meth)acrylate and (meth)acrylic acid, preferably PMMA) , or may be formed from or based on a metal oxide or semi-metal oxide (preferably SiO ₂ or TiO ₂ ), or may be formed from or based on a metal oxide or semi-metal oxide (preferably SiO ₂ ). Can be formed into particles. The above description of the core of the nano-inclusions applies correspondingly to the same nanoparticles in this example.

In an alternative embodiment of the method, the nanoparticles of the sol are precursors of the nano-inclusion core. This is especially true when the core of the nano-inclusions is pores. In this case, the nanoparticles function as pore formers and are preferably formed from or based on polymers (e.g. PMMA, polycarbonate, polyester or polystyrene, or methyl (meth)acrylate and (meth) (formed from or based on copolymers of acrylic acid), PMMA is particularly preferred. After the sol-gel coating is deposited, the nanoparticles decompose to create pores, which are the core of the nano-inclusions. The shell of the nanoparticle remains as a shell around the pore. The nanoparticles are preferably thermally decomposed by heat treatment at a temperature of at least 400° C., preferably at a temperature of at least 500° C. Polymeric nanoparticles are particularly carbonized. A separate heat treatment step may be provided for this, which is downstream of the sol-gel matrix condensation. However, alternatively and preferably, the condensation of the sol-gel matrix and the thermal decomposition of the nanoparticles can be carried out in the same heat treatment, which heat treatment is preferably carried out at a minimum of 500°C. This heat treatment can also be done as part of the glass bending process.

Instead of thermally decomposing the polymer nanoparticles, it is also possible to dissolve them in the coating using a solvent. For this to happen, the polymer must be dissolved in a solvent. For example, in the case of PMMA nanoparticles, tetrahydrofuran (THF) can be used.

The substrate with the sol-gel coating according to the invention can be supplied to the final destination as such. However, it is necessary to apply thermal stress or apply a bending process in advance to the coated plate glass. The coated pane can be laminated (flat or curved) with additional panes through a thermoplastic interlayer such as PVB film to form a composite pane. It is also possible to combine the coated panes with one or more additional panes via spacers to form an insulating glass unit.

The invention also includes the use of the coated flat glass according to the invention in buildings or in land, air or water transport vehicles. In this case, preferably plate glass

- From the exterior of a building to window panes, glass doors or facade members;

- Inside a building, through a windowpane, glass door or partition window in a room, or

- Through vehicle windows (e.g. through roof panels, side windows, rear windows or windshields of vehicles, especially automobiles);

or as a component thereof - for example as a component of composite panes or insulating glass units.

In the following, the invention is explained in more detail with the aid of drawings and examples. The drawings are schematic representations and are not to scale. The drawings do not limit the invention in any way.
1 is a cross-sectional view of one embodiment of a coated pane according to the present invention;
FIG. 2 is a cross-sectional view of nano-inclusions in the pane of FIG. 1.

Figure 1 shows a cross-section of one embodiment of a coated pane according to the invention. It comprises a substrate (1) with a sol-gel coating (2). The substrate 1 is a 2.1 mm thick pane made, for example, of soda-lime glass, which is provided as a glazing pane for vehicles (for example, as a component of a laminated windshield). The substrate 1 forms the inner pane of, for example, a windshield and can be connected via a PVB film on the opposite surface of the sol-gel coating 2 to the outer pane, which is likewise made of soda-lime glass with a thickness of 2.1 mm. It is plate glass.

The sol-gel coating (2) comprises a sol-gel matrix (3) made, for example, of SiO ₂ . The sol-gel matrix (3) was prepared by a sol-gel process. The sol-gel matrix (3) contains nano-inclusions (4), through which the properties of the sol-gel coating (2) can be set as desired.

Figure 2 schematically shows a cross section of the nano-inclusions 4. The nano-inclusions include a spherical core (4a) surrounded by a shell (4b). The shell 4b is produced by atomic layer deposition. For example, core 4a has a diameter of approximately 70 nm and shell 4b has a layer thickness of approximately 10 nm.

The core (4a) and shell (4b) are selected according to the intended use in order to have the necessary properties for the sol-gel coating (2). Therefore, the core may be made of SiO ₂ and the shell may be made of TiO ₂ , for example. Due to the SiO ₂ core, the nano-inclusions 4 are optically well compatible with the SiO ₂ matrix. Due to the TiO ₂ shell, the refractive index of the sol-gel coating (2) increases on the one hand and has photocatalytic properties on the other.

Alternatively, for example, the core 4a may be formed as a cavity (pore), and the shell 4b may be formed as SiO ₂ . The refractive index of SiO ₂ decreases due to pores, so the sol-gel coating (2) can be used as an anti-reflection coating. The pores are preferably created by adding PMMA nanoparticles with a shell (4b) produced by atomic layer deposition to the sol in the case of sol-gel coating and thermally decomposing the PMMA nanoparticles after coating, with the result that the pores are formed in the core ( 4a) is produced. A shell made of TiO ₂ provides an anti-reflective coating with additional photocatalytic properties.

(1) Substrate
(2) Sol-gel coating
(3) Sol-gel matrix of sol-gel coating (2)
(4) Nano-inclusions in the sol-gel coating (2)
(4a) Core of nano-inclusions (4)
(4b) Shell of nano-inclusions (4)

Claims (15)

- Transparent substrate (1),
- in a coated pane comprising a sol-gel coating (2) on the surface of the substrate (1),
The sol-gel coating (2) contains a sol-gel matrix (3) based on a metal oxide or semi-metal oxide and provided with nano-inclusions (4),
The nano-inclusions 4 include a core 4a and a shell 4b arranged around the core 4a,
The shell 4b is a coated plate glass produced by atomic layer deposition.
Coated glass pane according to claim 1, wherein the sol-gel matrix (3) is based on silicon oxide (SiO ₂ ).
3. Coated pane according to claim 1 or 2, wherein the shell (4b) has a refractive index greater than 1.5, preferably greater than 1.7 and particularly preferably greater than 1.9.
4. The shell (4b) according to any one of claims 1 to 3, wherein the shell (4b) is based on a metal oxide or semi-metal oxide, preferably silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ) or a transition metal. Coated flat glass formed on the basis of oxides, in particular titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), or hafnium oxide (HfO ₂ ).
Coated glass pane according to any one of claims 1 to 4, wherein the layer thickness of the shell (4b) is 1 nm to 100 nm, preferably 2 nm to 20 nm, particularly preferably 5 nm to 15 nm. .
The method according to any one of claims 1 to 5, wherein the core (4a)
- With Qigong,
- based on polymer, preferably polymethyl methacrylate (PMMA),
- based on metal oxides or semi-metal oxides, preferably silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ) or hafnium oxide (HfO ₂ ). , or
- Coated flat glass formed from hollow particles based on metal oxides or semi-metal oxides, preferably silicon oxide (SiO ₂ ).
Coated glass pane according to any one of claims 1 to 6, wherein the core (4a) has a size of 10 nm to 500 nm, preferably 10 nm to 150 nm.
8. Coated glass pane according to any one of claims 1 to 7, wherein the substrate (1) is formed from a glass pane or a plastic pane.
Coated glass pane according to any one of claims 1 to 8, wherein the volume fraction of nano-inclusions (4) in the sol-gel coating (2) is from 10% to 90%.
A method of manufacturing coated plate glass, the manufacturing method comprising:
(a) nanoparticles are provided,
(b) the nanoparticles are provided with a shell 4b by atomic layer deposition,
(c) a sol containing a metal oxide or semimetal oxide precursor is provided,
(d) Adding the nanoparticles (4a') to the sol together with the shell (4b),
(e) Applying the sol together with the nanoparticles (4b) having a shell to the surface of the transparent substrate (1),
(f) the sol is condensed to form a sol-gel coating (2), wherein the sol-gel matrix (3) is created from a metal oxide or semi-metal oxide precursor, and a core formed of nanoparticles in the sol-gel matrix ( 4a) and a nano-inclusion (4) comprising a shell (4b) arranged around the core (4a).
11. A method according to claim 10, wherein the sol is condensed by heat treatment at a minimum of 400° C. to form a sol-gel coating (2).
The method of claim 10 or 11, wherein the nanoparticles
- based on polymer, preferably polymethyl methacrylate (PMMA),
- based on metal oxides or semimetal oxides, preferably silicon oxide (SiO ₂ ) or titanium oxide (TiO ₂ ), or
- formed of hollow particles based on metal oxides or semi-metal oxides, preferably silicon oxide (SiO ₂ ),
Manufacturing method in which the core (4a) of the nano-inclusions (4) remains in the sol-gel coating (2).
The method of claim 11, wherein the nanoparticles are formed based on a polymer, preferably polymethyl methacrylate (PMMA), and are decomposed during heat treatment to create pores in the core (4a) of the nano-inclusions (4). Manufacturing method.
According to any one of claims 10 to 13,
- Nanoparticles (4a') are provided dissolved in a solvent,
- evaporate the solvent,
- A shell 4b is provided to the nanoparticles 4a' by atomic layer deposition (ALD),
- The nanoparticles (4a') are dissolved in the solvent together with the shell (4b),
- A manufacturing method in which the solution thus obtained is added to the sol.
Use of the coated plate glass according to any one of claims 1 to 9 in buildings or land, air or water transportation, wherein the sol-gel coating (2) is an anti-reflection coating, a reflection-increasing coating, a hydrophilic or hydrophobic coating. Applications that are coatings, sunscreen coatings, photocatalytic coatings, light scattering coatings and/or decorative coatings.