Title:
METHOD FOR PRODUCING A PANE WITH A PATTERNED SURFACE, AND PANE HAVING A PATTERNED SURFACE
Kind Code:
A1


Abstract:
A method for producing a pane of a household appliance or a viewing window of an oven is provided. The method includes the steps of: providing a substrate; applying a sol-gel layer to the substrate; embossing a haptically perceptible pattern using an embossing tool in the sol-gel layer; and curing the sol-gel layer. A pane of a household appliance or piece of furniture is also provided that includes a glass or glass-ceramic substrate with a patterned sol-gel layer which has a haptically perceptible pattern.



Inventors:
Henze, Inka (Nieder-Olm, DE)
Spengler, Stefan (Budenheim, DE)
Bockmeyer, Matthias (Mainz, DE)
Rudigier-voigt, Eveline (Mainz, DE)
Schuhmacher, Joerg (Kornwestheim, DE)
Stolz, Claudia (Inglesheim, DE)
Anton, Andrea (Hueffelsheim, DE)
Settelein, Jochen (Wuerzburg, DE)
Sweeck, Tamara (Bad Muenster, DE)
Gros, Oliver (Rheinboellen, DE)
Application Number:
13/521824
Publication Date:
02/14/2013
Filing Date:
01/14/2011
Assignee:
SCHOTT AG (Mainz, DE)
Primary Class:
Other Classes:
427/162, 427/164, 427/165, 428/206, 428/210
International Classes:
C03C17/00; B05D3/02; B05D5/06; B32B5/16; B32B17/06; B32B33/00
View Patent Images:
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Primary Examiner:
POLLEY, CHRISTOPHER M
Attorney, Agent or Firm:
OHLANDT, GREELEY, RUGGIERO & PERLE, LLP (STAMFORD, CT, US)
Claims:
1. 1-23. (canceled)

24. A method for producing a pane of a household appliance or a viewing window of an oven, comprising the steps of: providing a substrate; applying a sol-gel layer to the substrate; embossing a haptically perceptible pattern using an embossing tool in the sol-gel layer; and curing the sol-gel layer.

25. The method as claimed in claim 24, further comprising molding the haptically perceptible pattern from a master to form the embossing tool.

26. The method as claimed in claim 24, wherein the step of applying the sol-gel layer to the substrate comprises coating only sections of the substrate with the sol-gel layer.

27. The method as claimed in claim 24, further comprising embossing the sol-gel layer with at least a second, different haptically perceptible pattern.

28. The method as claimed in claim 24, wherein the substrate has a thickness from 0.5 to 50 mm.

29. The method as claimed in claim 24, wherein curing the sol-gel layer comprises burning off organic constituents of the sol-gel layer.

30. The method as claimed in claim 24, further comprising adding coloring particles to the sol-gel.

31. The method as claimed in claim 24, wherein the haptically perceptible pattern is embossed regularly, at least in sections, and has a pitch from 0.1 μm to 10 mm.

32. The method as claimed in claim 24, wherein the step of providing the substrate comprises providing a transparent substrate.

33. The method as claimed in claim 24, wherein the step of providing the substrate comprises providing a glass or glass ceramic substrate.

34. The method as claimed in claim 24, wherein the step of applying the sol-gel layer comprises screen printing or inkjet printing the sol-gel layer.

35. A pane of a household appliance or piece of furniture, comprising a glass or glass-ceramic substrate with a patterned sol-gel layer which has a haptically perceptible pattern.

36. The pane as claimed in claim 35, wherein organic constituents of the sol-gel layer have been burned off.

37. The pane as claimed in claim 35, wherein the pane is a control panel.

38. The pane as claimed in claim 35, wherein the sol-gel layer is dyed.

39. The pane as claimed in claim 35, wherein the haptically perceptible pattern has a pattern depth that ranges from 50 nm to 1 mm.

40. The pane as claimed in claim 35, further comprising at least one further layer disposed on the sol-gel layer.

41. The pane as claimed in claim 40, wherein the at least one further layer comprises a lacquer layer or a metal layer disposed on the sol-gel layer.

42. The pane as claimed in claim 35, wherein the sol-gel layer comprises particles for matting the layer.

43. The pane as claimed in claim 35, wherein the sol-gel layer has a texture of an etched surface.

44. The pane as claimed in claim 35, wherein the pane is a thermally tempered pane.

45. The pane as claimed in claim 35, further comprising at least one transparent section and at least one opaque section.

46. The pane as claimed in claim 35, wherein the sol-gel layer is colored or opaque.

Description:

FIELD OF THE INVENTION

The invention relates to a method for producing a pane, in particular a pane for a household appliance or a viewing window for an oven or an architectural glass. Furthermore, the invention relates to such a pane.

BACKGROUND OF THE INVENTION

Methods for patterning glass surfaces are known. Usually, glass surfaces are patterned by an etching process using hydrofluoric acid. This process is complex, dangerous, and the variety of shapes is limited due to the etching process.

Furthermore, it is known to emboss films which are for example glued onto glass. Such a method is shown in DE 199 365 04 A1, for example. However, often such laminated films are prone to delamination.

Another possibility is mechanical patterning, for example by sand blasting. Here again the variety of shapes is limited, and though matt textures may be produced, it is not possible by a mechanical process to produce arbitrarily shaped haptically perceptible patterns, such as for grip surfaces.

As another alternative, document EP 0 493 202 B1 shows manufacturing of a patterned glass using a roller which embosses the pattern into the still viscous glass. However, such a process usually only allows to obtain a pattern covering the entire surface. Furthermore, the method is not suitable to produce exact pattern depths in a range below 500 μm, since due to the viscosity of the glass a rounding of the embossed shapes occurs.

OBJECT OF THE INVENTION

An object of the invention, therefore, is to provide a method which permits to produce a pane, in particular a pane of a household appliance or the viewing window of an oven or an architectural glass with a haptically perceptible pattern in an simple manner.

Moreover, the pattern should exhibit good durability.

SUMMARY OF THE INVENTION

The object of the invention is already achieved by a method for producing a pane, and by a pane of a household appliance or piece of furniture according to any of the independent claims.

Preferred embodiments and refinements of the invention are set forth in the respective dependent claims.

The invention, on the one hand, relates to a method for producing a pane which especially is a part of a household appliance or a viewing window of an oven. In particular, the pane is intended for use as a viewing window or control panel for so-called “white goods” such as cooker extraction hoods, ovens, steam cookers, microwave ovens, kitchen fronts, splash guards in kitchens, and small electrical appliances such as toasters, or for cooktops. But the pane may likewise be provided as a fireplace viewing window or for architectural glazing applications and picture framing. It may also be used in elevators, as a door, or in furniture. Moreover, the pane is intended for building glazing applications in the interior and outside. In particular it is intended for use as flooring or wall or ceiling surface or partition wall, for example in wet areas. Use thereof in the automotive, shipbuilding or aviation sector, for example as an instrument panel, or in the field of consumer electronics such as for mobile phones, computers, monitors, or television sets is also being considered.

According to the invention, first a substrate is provided. Preferably the substrate is transparent.

For example a glass or glass-ceramic substrate may be used which is particularly suitable for use at higher temperatures.

Basically, however, the invention may also be used for plastic substrates, in particular transparent plastic substrates such as polycarbonates, polyacrylates, polyolefins, in particular cyclo-olefin copolymers.

A sol-gel layer is applied onto the substrate.

In particular it is intended to apply the sol-gel layer using a printing technique.

Particularly suitable are in particular screen printing or ink jet printing techniques.

In this way even large surfaces may be coated with a sol-gel layer in a simple manner.

However, pad printing, dip coating, roll coating, flow coating, spraying, slot casting and other liquid coating techniques are likewise possible.

It is furthermore envisaged to apply the coating only in sections of the substrate. For example transparent areas may be excluded from being coated.

The invention here benefits from the fact that such a partial coating which for example may comprise graphic elements, such as letters, borders, etc. may be applied in a very simple manner using a printing process, in particular by screen printing.

Then, a haptically perceptible pattern is embossed into the sol-gel layer using an embossing tool.

The embossing tool can be formed as a stamp or as a roller, for example.

A haptically perceptible pattern, in the present context, is to be understood as a pattern, which due to the spacing of the individual pattern elements and due to the depth of the pattern can be felt by a person who touches it and thus clearly differs from a smooth layer. In particular, anti-slip grip surfaces are contemplated, or textures of wood, natural stone, and/or regular geometric shapes such as regular three-dimensional bodies, especially diamonds, prisms, or cylinders.

Then the sol-gel layer is cured and forms the surface or at least the pattern-defining layer within a layer system on the surface of the substrate.

Curing of the sol may be accomplished for example by simple drying, the sol, as the case may be, curing by chemical reactions.

It is contemplated to use a pure inorganic precursor, however, according to another embodiment of the invention hybrid polymeric materials of colloidal dispersions are likewise envisaged.

In one embodiment of the invention, the sol-gel layer may be fired by a thermal treatment, in particular to produce temperature-resistant haptic layers. In this case organic constituents of the sol-gel layer, if present, may be burned out, at least partially.

Sol-gel layers may be provided with such a temperature resistance that they resist a tempering process, for example. As such, firing of the layer may be accomplished during a tempering process, for example, so that no further process step is required.

One preferred embodiment of the invention contemplates to produce the pattern of the embossing tool by molding the pattern from a master. This especially permits to transfer textures of other materials to a glass or glass ceramic substrate.

In particular, it is envisaged to transfer etched textures such as for example those of etched metal or glass to the substrate.

In combination with a metallic-looking coating of the sol-gel layer, or in combination with a colorization of the layer, or with an addition of in particular metallic particles a surprising impression of an etched metal pattern may thus be created on a glass or glass-ceramic substrate, wherein in case an only partial coating the metallic appearance seamlessly merges into a transparent pane.

In a refinement of the invention it is contemplated to provide a sol-gel layer on a pane which has two different patterns. So, two areas with a different appearance may be produced in a very simple way.

To this end, it is in particular suggested to use two different stamps. However, it is also possible to provide a plurality of patterns on one stamp.

The substrate preferably has a thickness from 0.5 and 10 mm.

In one embodiment of the invention, coloring and/or opaque particles, in particular metal particles, are added to the sol-gel layer, or the sol-gel layer is coated with a further layer, especially a metallic-looking lacquer or a metal layer.

In this way, almost any surface appearance in terms of color and opacity may be provided on a transparent substrate.

In one preferred embodiment of the invention, a haptically perceptible pattern which is embossed regularly, at least in sections, has a pitch from 0.1 μm to 10 mm, preferably from 1 μm to 2 mm. Pitch herein means the space between the center of a structural element and that of another, similar structural element.

In contrast to most etching techniques or to a mechanical treatment by blasting, the invention permits to provide patterns in which the individual pattern elements are relatively large and considerably spaced from one another. So, for example, it is conceivable to create textures which resemble the surface of carbon fiber reinforced plastics.

The composite material producible and in particular produced according to invention is particularly suitable as a pane of a household appliance, a piece of furniture, a picture glazing, or an architectural glass.

The invention furthermore relates to a pane of a household appliance or piece of furniture.

It may for example be formed as a viewing window or a control panel and comprises a glass or glass-ceramic substrate with a patterned sol-gel layer which has a haptically perceptible pattern.

In particular, the pane has been produced by the method described above.

In one embodiment of the invention, organic constituents of the sol-gel layer have been burned out, so as to achieve better temperature resistance.

That is, a sol-gel layer in the context of the invention is also understood as a layer in which the organic constituents of a sol, for example a hybrid sol, have been removed.

The sol-gel layer may be dyed, for example by means of a dye or by means of coloring particles such as metal or carbon black particles.

The pattern depth of the sol-gel layer preferably ranges from 100 nm to 1 mm in order to produce clearly perceptible haptic properties of the layer.

In another embodiment, in addition or as an alternative thereto a further layer, especially a lacquer layer or metal layer, is disposed on the sol-gel layer.

This layer follows the pattern of the sol-gel layer and provides for the desired opacity, the desired gloss, and/or the desired color.

In another embodiment of the invention, the sol-gel layer comprises particles for matting the layer. By adding larger particles, in particular particles having a size of more than 100 nm, a matte surface may be obtained in addition to the pattern, since the surface due to the particles has a roughness which reduces light reflections.

In one embodiment of the invention, the pane is designed to be transparent in sections thereof and simultaneously opaque in other sections.

It will be appreciated that these terms should not be understood literally, but that for example in the coated area the layer rather may still exhibit a slight transparency, and that for example the glass substrate rather may be slightly dyed, as might be the case with a viewing window of an oven.

In particular it is contemplated to provide the sol-gel layer in a colored and/or opaque form.

The invention permits to obtain embossed patterns on rigid or brittle material, such as glass or glass ceramic, in a simple manner and with a variety of appearances and haptics.

However, plastics of all kinds, polymers, metals, etc. may likewise be coated. Moreover, the invention provides for temperature resistant, corrosion resistant, non-yellowing, weather and scratch resistant coatings.

With reference to the general description above, the invention will now be described in more detail.

For manufacturing the stamp a master is used which has the desired pattern, as mentioned above. For a roughened surface this may be an appropriately etched surface, and when regular geometric shapes are desired, this may be a metal structure on which regular geometric patterns had been provided using an etching process or mechanical processes, in particular machining, grinding, or sand blasting.

The master template is preferably cleaned so as to be free of grease and lint. A polymer mass is poured onto the clean master template, in particular a two-component silicone molding compound, and cured. Curing may be accomplished, for example, by heating. Especially complex patterns may include bubbles which may be removed by applying a vacuum. The cured polymer stamps are released from the master template and are then ready to be used for embossing purposes.

After the embossing process the stamps may be cleaned, for example using an alcohol or alkaline cleaning agents, and may be reused.

In another embodiment of the invention, the embossing tool may be provided in particular in form of a transparent foil on which a lacquer had been applied which was embossed using a roller with the corresponding pattern.

The sol-gel layer may be applied on glass, glass ceramic or on another substrate using an inexpensive liquid coating process.

The sol-gel layer may comprise amorphous and/or crystalline particles as well as organic/inorganic sol-gel hybrid polymer particles, as is known in the art.

By choosing of the composition of the particles, the refractive index of the sol-gel layer may be adapted to that of the substrate and/or to that of a layer optionally arranged above. For example, high or low refractive index particles may be added to the sol.

Preferably, the refractive index of the particles ranges from 1.3 to 2.9, exemplary refractive indices are: for MgF2=1.34-1.36, for SiO2=1.45-1.5, for Al2O3=1.72-1.76, for ZrO2=2.0-2.2, for TiO2=2.4-2.9.

An advantageous method for applying the sol is screen printing, in particular for larger substrates. A screen printing process in particular allows to apply the sol only in sections of the substrate.

Thereby, areas which are not to be patterned may be excluded from being coated, and in free areas which for example serve as a viewing window or as a display or control panel, an inspection for layer roughnesses, inhomogeneities, and contaminations may be dispensed with.

Optionally, the sol-gel coating may be precured, in particular in case of hybrid polymers which for example can be precured using electromagnetic waves such as UV radiation, or by heat.

Preferably, the sol-gel layer is embossed using a polymer stamp, in continuous or static manner. This embossing stamp may likewise be provided with a sol-gel layer.

In one embodiment of the invention, the layer is cured under a defined pressure of the embossing stamp, thermally and/or photochemically. In particular photochemical curing is envisaged in which the sol-gel layer is cured through a UV radiation transparent stamp while still being in contact with the stamp.

In an alternative embodiment no pressure is required, since the sol is automatically drawn into the pattern of the stamp. This may be caused by capillary forces and/or the own weight of the stamp and may also be a result of the selected viscosity and the high plasticity of the lacquer. The lacquers preferably exhibit a low thixotropy which promotes the process of ‘automatically being drawn into the pattern’. Furthermore, the lacquers exhibit a rather Newtonian behavior which means that the shear stress is proportionally related to the shear rate.

Typical viscosities of the employed lacquers range from 50 mPas to 2500 mPas, preferably from 75 mPas to 500 mPas, more preferably from 100 mPas to 300 mPas. All values were determined at a shear stress of 85 N/m2.

In one embodiment of the invention, bubbles are eliminated either manually, using a roller, or by applying a negative pressure.

Upon removal of the embossing stamp a patterned, thin sol-gel layer is provided which preferably has a thickness from 10 nm to 1 mm, more preferably from 50 nm to 100 μm. The patterns of this layer are defined by the pattern of the embossing stamp.

Possible patterns are both periodic and random patterns, in particular lines of a brushed surface and/or brushed and/or emerized and/or polished surface, light-scattering layers, etched surfaces, punched surfaces, three-dimensional shapes such as pyramids, inverted pyramids, etc.

The pattern depth preferably varies in a range from 50 nm to 1 mm, more preferably from 50 nm to 100 μm.

In the context of the present invention, the pattern of the sol-gel layer defines the pattern of optional additional layers, in particular metal layers or metallic shining lacquers, as is the case in one embodiment of the invention.

In particular, it is also possible to use a luster color as an additional layer. Such color usually comprises dissolved metal resinates which, at higher temperatures, form a thin metal oxide layer with a colored or metallic appearance.

Moreover, it is possible to use a lacquer which includes metal or metal oxide particles.

The embossability of the layer is adjusted through the chemical composition of the sol, the degree of hydrolysis, and/or the pH-value, and/or the content of nanoparticles. Preferably, the ratio of water to hydrolyzable groups is below 0.5.

In a preferred embodiment of the invention, the solvent content of the starting lacquer ranges from 50 to 25 mass-%, more preferably from 45 to 35 mass-%, in order to ensure screen printability. Here, the solvent fraction has been determined after drying at 100° C. for 2 h using IR radiation.

The embossability of the layer is adjusted through the chemical composition of the sol and the degree of hydrolysis. Preferably, the ratio of water to hydrolyzable groups is below 0.5.

The embossability of the layer may be adjusted via the proportion of organic functional groups and/or the content of inorganic nanoparticles and/or the morphology and/or the type of material of the nanoparticles and/or the pH of the lacquer and/or the type of shielding or the chemical stabilization of the nanoparticles.

In a dried embossable film, the mass ratio of hydrolyzed UV cross-linkable component and nanoparticles preferably is between 90:10 and 40:60, more preferably between 70:30 and 50:50.

In case of reactive embossing using UV light, the mass fraction of UV cross-linking monomers should not be smaller than 10%.

Generally, however, especially if the layer is fired in a subsequent process step, the organic content should not be selected too high, in particular an organic content from 5 to 80 mass-%, preferably from 10 to 50 mass-% is envisaged.

In one embodiment, burning out of the organics and layer compaction result in a reactive bonding to the substrate and/or formation of a transition zone in which for example an ion exchange occurred. This contributes to an improved mechanical stability of the layer and improved adhesion of the layer.

This transition zone may have a thickness from 0.5 nm to 10 μm, preferably from 5 nm to 500 nm.

For this purpose, sintering or densification additives may be added to the embossing lacquer. For glassy layers, these may include for example ions, salts, alkoxides, and/or metal oxides of the alkali and/or alkaline earth elements and/or transition elements.

In a specific embodiment, such compounds may diffuse from the substrate into the applied layer and/or may be introduced from the nanoparticles and/or via a second coating or by infiltration.

In one particular embodiment, the embossed layer according to the invention includes at least two, preferably three or more different metal cations, for example Si, and/or K, and/or Na, and/or Mg, and/or Na, and/or Ca, and/or Li, and/or Ba, and/or Zn, and/or Bi, and/or B, and/or Zr, and/or Ti, and/or Al, and/or Ce.

Both gas phase and liquid phase coating techniques may be used.

Such layers and/or layer systems preferably exhibit a scratch resistance of more than 300 g, preferably more than 700 g in the BSH test. In the pencil hardness test, they preferably exhibit a hardness of more than 1H, more preferably of more than 3H.

Depending on the required temperature stability of the final product, the sol-gel layers may be cured at a temperature from 50 to 1000° C., preferably from 100 to 900° C., most preferably from 400 to 730° C. The pattern is maintained, even if the organic components are almost completely burned out.

Depending on the curing temperature and the composition of the sol-gel, the pattern depth may decrease by 0 to 60% as compared to the master pattern. If necessary, this may be compensated for by using a master pattern with a greater pattern depth.

In one preferred embodiment of the invention,

hydrolyzed and condensed epoxy- and/or methacrylate-functionalized, and/or ally- and/or vinyl-functionalized alkoxysilanes, which are filled with amorphous and/or crystalline nanoparticles and which are added as an alcoholic dispersion, are used as a sol-gel precursor. In this way, shrinking between 0 and 25% may be achieved.

In one particularly preferred embodiment of the invention, irregularly shaped fibrous particles are used, especially SiO2 particles, in particular with a diameter from 5 to 15 nm and a length from 5 to 150 nm. Other embodiments use mixtures of spherical particles of different sizes ranging from 5 to 125 nm.

Such fibrous particles are obtained, for example, by stringing together individual spherical particles.

Alternatively, fibrous or spherical particles of SiO2, SiOyNaxKz, SiOxByKz, TiO2, ZrO2, C, Si, ZnO, Al2O3, or CeO2

may be used.

Especially the mechanical strength of the patterned layer may be adjusted via the chemical composition of the inorganic constituents (molecularly disperse sol-gel components and inorganic nanoparticles).

Preferred materials are those that are sintered easily. For this purpose, both amorphous and crystalline compositions of molecularly dispersed silicon oxide in the sol-gel precursor and crystalline and/or amorphous inorganic nanoparticles may be used.

By proper choice of the sol-gel precursor, a composition may be adjusted which corresponds to a low temperature sintered multicomponent glass, such as for example used for enamel coatings.

For further modification of the haptics, in particular to achieve a velvety effect to the touch, for example amorphous, substantially spherical silicon oxide nanoparticles with a mean particle size from 300 to 600 nm or platelet-shaped inorganic particles or irregularly shaped particles with an mean size from 100 to 1000 nm may be used. These particles may be produced by flame pyrolysis, for example.

In another embodiment of the invention, the patterned sol-gel layer has an intrinsic color, for example due to absorption or due to interference effects. Absorption may be adjusted through the choice of the molecularly dispersed sol-gel precursor and/or by adding absorbent nanoparticles or pigments. In particular inorganic nanoparticles absorbing in the visible and/or infrared wavelength range may be used, such as CuO, Co2O3, C, TiC, ZrC, TiN, ZrN, Ag, Al, Fe2O3, SiN, BN.

The thickness of the sol-gel layer preferably ranges from 0.05 to 3 μm. The layer material preferably comprises amorphous or hybrid polymeric silicon oxide, optionally with fractions of amorphous or nanocrystalline oxide and/or non-oxide metal compounds such as TiO2, MgF2, MgOxFy, CaF2, CaOxFy, CaO, K2O, MgO, Li2O, Na2O, ZrO2, Yttrium-stabilized ZrO2, Ca-stabilized ZrO2, Mg-stabilized ZrO2, Ce-stabilized ZrO2, Si-stabilized ZrO2, Al2O3, CeO2, Gd2O3, Bi2O3, B2O3, ZnO, ITO, SiN, SiON, SiC, SiOC, TiN, TiC, TiON, TiOC, ZrC, ZrN, ZrON, ZrOC and/or hybrid polymeric derivatives thereof or compounds of the particles.

The coating solution may comprise amorphous or crystalline molecularly or colloidally dispersed or hybrid polymeric sol-gel precursors of silicon, titanium, boron, bismuth, sodium, lithium, potassium, calcium, zirconium, phosphorus, niobium, hafnium, yttrium, aluminum, zinc, magnesium, tin (e.g. SiORxRy, TiORxXy, ZrORxXy, AlORxXy, ZnORxXy, MgORxXy, CaORxXy, SnORxXy, NaOR, KOR, BOR3, MgOR2). The particles in the sol-gel precursor preferably have a particle size ranging from of 0.05 to 200 nm, more preferably from 1 to 100 nm.

A preferred embodiment of the invention comprises UV light curable hybrid polymers, in particular in form of a hydrolyzed and condensed alkoxysilane precursor, such as glycidyloxypropyltriethoxysilane, glycidyloxypropyltrimethoxysilane, methacryloxytrimethoxysilane, methacryloxytriethoxysilane, allylsilane, vinylsilane.

This precursor constitutes the binder for silicon oxide nanoparticles which are added to the sol. Preferably, silicon oxide nanoparticles are used which are fixed with a sol whose degree of condensation is greater than 60%. Preferably, the volume fraction of the silicon oxide nanoparticles is greater than 20%, more preferably greater than 40%.

When thermally treated at temperatures above 200° C., such a layer exhibits a micro- or mesoporosity. The porosity may range from 1 to 50% (open porosity). A temperature treatment at 500° C. results in pores with a pore diameter from 0.4 to 15 nm. These pores preferably have a bottleneck-shaped geometry and are distinguished by a pore diameter that is larger than the pore outlet or the connection of the pores. In a preferred embodiment of the invention, the pore diameter ranges from 3 to 10 nm, and the size of the pore outlet ranges from 1 to 6 nm.

In one embodiment of the invention, a methacrylic acid complexed sol-gel precursor may be used as the UV-crosslinking component, in particular titanium alkoxide and/or zirconium alkoxide, reacted with methacrylic acid.

For producing a screen-printable lacquer system, sol-gel precursors with a low solvent content are preferably used. Preferred solvents exhibit a vapor pressure of less than 2 bars, an evaporation number of more than 35, and/or a boiling point above 120° C.

For example, when producing the sol-gel precursor a solvent exchange of highly volatile alcohols may be accomplished for ethylene glycol monoethyl ether and/or ethylene glycol monoisopropyl ether and/or 4-hydroxy-4-methyl-2-pentanone and/or terpineol and/or diethylene glycol monoethyl ether and/or tripropylene glycol monomethyl ether.

In another embodiment of the invention, the embossing lacquer comprises a high proportion of polysiloxane. In particular branched or linear methyl and/or phenylpolysiloxanes may be used.

These polysiloxanes may be provided with UV-crosslinking organic functional groups. Polysiloxanes having a high inorganic solids content are preferably used.

In another embodiment of the invention, curing during the embossing process is exclusively accomplished by UV light. In another embodiment, a final thermal curing is performed in a temperature range from 100 to 1000° C., in particular between 450 and 740° C.

The duration of thermal curing may range from 2 min to 180 min, preferably from 3 min to 60 min.

The contact pressure of the stamp during embossing is preferably adjustable between 0.01 and 5 bars.

In a refinement of the invention, compounds having a dewetting or wetting effect may be added to the lacquer system comprising the sol. These may be for example fluoro-organosilane compounds. Prior to coating, the substrate may be treated with a primer, or the surface may be preconditioned before applying the embossing lacquer, for example by a plasma treatment.

In another embodiment of the invention, the master pattern and/or the embossing stamp are coated with solutions which form a monolayer that has a wetting or dewetting effect.

To ensure a long shelf life of the lacquer system,

to adjust the pot life on the screen and for high reproducibility of the embossing result, a multi-component lacquer system, in particular a two- or three-component lacquer system may be used.

In one particular embodiment, a two-component system is used. One component thereof is the hydrolyzed organically functionalized silane, for example a solvent-reduced hydrolyzate of tetraalkoxysilane and glycidylpropyltrialkoxysilane. Another, second component comprises the metal oxide and/or semi-metal oxide nanoparticles with a photoinitiator in a high-boiling solvent.

Before use, the two components are mixed in an appropriate ratio and can then be used for more than 24 h.

DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail with reference to the drawings of FIGS. 1 to 6:

FIG. 1 schematically illustrates a master pattern 1 which in this embodiment is a metal plate that has an etched periodic pattern with diamonds as pattern elements 2. The spacing of these pattern elements 2 is referred to as pitch t.

As shown in FIG. 2, a curable polymer mass is applied thereto to produce a stamp 3.

After thermal curing of the polymer mass, as shown in FIG. 3, a stamp 3 has been created which comprises impressions of the pattern elements 2. So the pitch t is identical.

FIG. 4 shows how a glass substrate 4 is coated with a sol-gel layer 5. Coating is accomplished by a screen printing process during which only a section of the glass substrate 4, here the edge region, is printed.

Then, as shown in FIG. 5, stamp 3 is pressed onto sol-gel layer 5. Stamp 3 may also be pressed onto areas of the glass substrate 4 which are not coated. The dimension of the patterned layer is defined by the screen printing process.

FIG. 6 schematically shows the final product, namely a household appliance 6 which comprises a pane 9 produced according to the invention, as a front pane.

Pane 9 has the patterned sol-gel layer 5 in its upper surface area. In this case it is provided as a haptic pattern, i.e. to achieve a specific tactile effect when touched. Furthermore, the household appliance 6 has a handle 8 for opening and a display field 7 in which patterned sol-gel layer 5 is omitted.

In detail, a patterned layer may be produced as follows, for example:

In a vessel, 22.3 g (0.08 mol) of GPTES (glycidyloxypropyltriethoxysilane) is provided with 4.1 g (0.02 mol) of TEOS (tetraethoxysilane), and is hydrolyzed with 2.3 g of water in which 0.344 g of PTSA (p-toluenesulfonic acid) had been dissolved. After having been stirred for 2 min, 110 g of a 15 mass-% alcoholic dispersion of irregularly shaped SiO2 nanoparticles in isopropanol is added to this hydrolyzate.

The nanoparticles have a fibrous shape, for example, with a diameter from 5 to 15 nm and a length from 30 to 150 nm. 15 g of tripropylene glycol monomethyl ether is added to this solution, and the highly volatile solvent is removed in a rotary evaporator at 100 mbar and 50° C. bath temperature. Then, 0.6 g of the cationic photoinitiator Irgacure® 250 in 1 g of ethylene glycol isopropyl ether is added to the embossing sol.

This lacquer system allows to apply layers to one side of a soda lime glass by screen printing using a 180 mesh. After the solvent has been dried off between room temperature and 80° C., with or without air circulation, a patterned silicone stamp (PDMS) is applied, and then curing is accomplished through the stamp using a UV lamp. When the stamp is removed the pattern of the stamp had been transferred into the nanoparticle-functionalized lacquer. The layers are now thermally cured at temperatures of 670° C. for 4 min. The final thickness of the layer ranges from 2.5 to 3 μm.

Subsequently, a stainless steel layer is applied by a sputtering process in a thickness of at least 100 nm.

Alternatively, a layer may be applied as follows:

In a vessel, 16.7 g (0.06 mol) of GPTES (glycidyloxypropyltriethoxysilane) is provided with 4.1 g (0.02 mol) of TEOS (tetraethoxysilane) and 3.56 g (0.02 mol) of MTEOS (methyltriethoxysilane), and is hydrolyzed with 2.3 g of water in which 0.344 g of PTSA (p-toluenesulfonic acid) had been dissolved. After having been stirred for 2 min, a mixture of 44 g of a 30 mass-% alcoholic dispersion of spherically shaped SiO2 nanoparticles with a diameter from 40 to 50 nm in isopropanol and 11 g of an alcoholic dispersion of spherical SiO2 nanoparticles with a diameter from 10 to 15 nm is added to this hydrolyzate.

16 g of ethylene glycol monoethyl ether is added to this solution, and the highly volatile solvent is removed in a rotary evaporator at 100 mbar and 50° C. bath temperature. Then, 0.6 g of the cationic photoinitiator Irgacure® 250 in 1 g of ethylene glycol monoethyl ether is added to the embossing sol.

This lacquer system allows to apply layers to one side of a soda lime glass by screen printing using a 180 mesh. After the solvent had been dried off between room temperature and 50° C., with or without air circulation, a patterned silicone stamp (PDMS) is applied, and then the layer is cured through the stamp using a UV lamp. When the stamp is removed the pattern of the stamp had been transferred into the nanoparticle-functionalized coating. The layers are now thermally cured at temperatures from 300 to 500° C. A preferred heating rate is 3 K/min, with a holding time of 1 h at 500° C. The final thickness of the layer is 2.5 μm.

The invention permits to provide specific haptics and appearances on almost any substrates in a very economical way.