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EP-4739635-A1 - COATED SUBSTRATE, PASTE, AND METHOD FOR PRODUCING SAID PASTE

EP4739635A1EP 4739635 A1EP4739635 A1EP 4739635A1EP-4739635-A1

Abstract

The invention relates to a coated substrate made of glass or a glass ceramic, wherein the coating has pigment particles embedded in a glass matrix, wherein the coating has an average layer thickness of 2 to 5 µm, wherein the coating has a transmittance (formula (I)) of at most 2%, wherein the pigment particles have an average particle size d 50 of less than 1.0 µm, wherein the polydispersity index PI of the particle size distribution of the pigment particles is at most 2.0.

Inventors

  • Menke-Berg, Yvonne
  • Schuhmacher, Jörg
  • Treis, Philipp
  • GABRIEL, Annelie
  • SCHIWIETZ, Christine
  • TORRES ALMAGRO, Maximilian
  • STETTNER, Stefan
  • SCHELLENBERG, KATHRIN

Assignees

  • SCHOTT AG

Dates

Publication Date
20260513
Application Date
20240703

Claims (16)

  1. 1. Coated substrate made of glass or a glass ceramic, wherein the coating has pigment particles embedded in a glass matrix, wherein the coating has an average layer thickness of 2 to 5 pm, wherein the coating has a transmittance Tvis of at most 2%, wherein the pigment particles have an average particle size dso of less than 1.0 pm, wherein the polydispersity index PI of the particle size distribution of the pigment particles is at most 2.0.
  2. 2. Coated substrate according to claim 1, characterized in that the pigment particles have a sphericity M-J of at least 0.6.
  3. 3. Coated substrate according to claim 1 or 2, characterized in that the coating has a waviness Wt of less than 0.3 pm.
  4. 4. Coated substrate according to one of the preceding claims, characterized in that the coating contains 7.5 to 50 vol.% pigment particles.
  5. 5. Coated substrate according to one of the preceding claims, characterized in that the coating does not contain pigment agglomerates which have a maximum diameter of more than 1.0 pm.
  6. 6. Coated substrate according to one of the preceding claims, characterized in that further coatings different from the coating are arranged on the substrate.
  7. 7. Paste for producing a coated substrate according to one of the preceding claims, comprising a glass-based binder, a pigment and a carrier medium, wherein the pigment particles have a particle size d50 of less than 1.0 pm.
  8. 8. Paste according to claim 7, characterized in that the paste contains the following proportions in % by weight: Solids (consisting of binder and pigment) 35 - 60 (preferably 37.5 - 55), Carrier medium 40 - 65 (preferably 45 - 62.5).
  9. 9. Paste according to claim 7, characterized in that the paste contains the following proportions in % by weight: Solids (consisting of binder and pigment) 60 - 80 (preferably 57 - 75), Carrier medium 20 - 40 (preferably 25 - 33).
  10. 10. Paste according to one of claims 7 to 9, characterized in that the polydispersion index PI of the particle size distribution of the pigment particles is a maximum of 2.0.
  11. 11. Paste according to one of claims 7 to 10, characterized in that the pigment particles have a sphericity M-J of at least 0.6.
  12. 12. Paste according to one of claims 7 to 11, characterized in that the paste has a viscosity of 2000 to 8000 mPas at a shear rate of 200/s.
  13. 13. A process for producing a paste according to any one of claims 7 to 12, comprising the steps of • Production of a starting powder from a precursor solution, wherein the particles contained in the starting powder have a particle size of at most 20 nm, • Calcination of the starting powder, • Drying of the calcined starting powder, • Mixing the dried powder with the binder and the carrier medium to produce the paste.
  14. 14. The method according to claim 13, wherein the precursor solution is a metal-containing nitrate, sulfate, carbonate or chloride solution, wherein the precursor solution preferably contains Mn and/or Fe and/or Co and/or Ni and/or Cu and/or Cr.
  15. 15. The method according to claim 13 or 14, wherein the particles of the dried powder have a sphericity M-J of at least 0.6.
  16. 16. The method according to one of claims 13 to 15, wherein the production of the starting powder takes place by means of a hot gas process, in particular with the aid of a pulsation reactor.

Description

Coated substrate, paste and method for producing the paste Description The invention relates to a coated substrate made of glass or a glass ceramic, as well as a paste for producing such a coated substrate and a corresponding method for producing the paste. Coated substrates made of glass or glass ceramic and in particular transparent substrates made of glass or glass ceramic with a coating in the form of a decoration are known in the prior art in a variety of designs. For example, such coated substrates made of glass and glass ceramic are used as fireplace viewing panels and create a separation between the combustion chamber of the fireplace stove and the surrounding area. A coating in the form of an opaque decoration is often applied to an edge area of the substrate and serves to conceal the transition areas between the fireplace viewing panel and the stove door in which the fireplace viewing panel is mounted. The use as a fireplace viewing panel places high demands on the decoration and substrate. When the fireplace is in operation, the fireplace viewing panel is sometimes exposed to high temperatures of well over 100 °C. Heating the substrate and decoration in this way usually causes a non-negligible thermal expansion of the substrate and decoration, which can lead to the decoration detaching from the substrate if the extent of the expansion varies. Glass-ceramic substrates are often used as fireplace viewing panels, with a thermal expansion coefficient in the range of 0 to 2 x 10' 7 K' 1 in a temperature range of 20-700 °C. In another application scenario, coated glass substrates are also used in vehicle construction in the form of viewing windows, for example. Here, too, the glass substrates are only provided with a decorative coating in certain areas, with the coating usually serving to cover mounting areas of the window or wires running in the window or electronic components located behind the window. The substrates used in such applications are often made of borosilicate glass or soda-lime glass and have thermal expansion coefficients in the range of 10' 6 K -1 to 10' 5 K -1 . Coated glass substrates are also used as viewing windows for oven doors, although in this case substrates made of borosilicate glass or soda-lime glass are also often used. In the application scenarios described above for decorations to conceal certain areas, the basic requirement for the decoration is to be completely opaque, i.e. not to be seen through. In order to produce such opaque layers on transparent substrates, enamel systems with a high degree of pigmentation and a layer thickness of at least 5 pm are often used. An enamel usually consists of a melted glass frit and pigment(s), whereby a paste comprising the glass frit, the pigment and a binder is applied to the substrate and then fired to produce the enamel. During the firing process, the glass frit melts and forms a glass matrix that is bonded to the substrate and in which the pigment is embedded. At typical process temperatures for firing such a decorative layer of 600-950°C, a glass frit is required that melts well in this range. Such glass frits usually have a coefficient of thermal expansion (CTE) of at least 4 x 10' 6 K' 1 or more. Pigments that are stable in such a firing process are usually oxides, especially above all non-ferrous metal spinels. Such spinels have a CTE of around 10 x 10' 6 K' 1 . The resulting CTE of the decorative layer is then around 6 x 10' 6 K -1 and, at the above-mentioned layer thicknesses of more than 4 pm, creates a tension between the substrate and the decorative layer, which can lead to a reduction in the mechanical strength of the component. In contrast, the present invention is based on the object of specifying a coated substrate and a paste for producing such a coated substrate, which overcomes the above-mentioned disadvantages of the prior art and at the same time provides a decoration that is opaque and at the same time resistant to thermal stress. In a first aspect, the invention relates to a coated substrate made of glass or a glass ceramic, wherein the coating has pigment particles embedded in a glass matrix, wherein the coating has an average layer thickness of 2 to 5 pm, preferably 2 to 4 pm, particularly preferably 2 to 3.5 pm, wherein the coating has a transmittance Tvis of at most 2%, preferably at most 1%, particularly preferably at most 0.5%, very particularly preferably at most 0.3%, wherein the pigment particles have an average particle size dso of less than 1.0 pm, preferably less than 0.8 pm, particularly preferably less than 0.6 pm, wherein the polydispersity index PI of the particle size distribution of the pigment particles is at most 2.0, preferably at most 1.5, particularly preferably at most 1. A particle size dso of less than 1.0 pm, in particular less than 0.8 pm, and especially less than 0.6 pm of the pigment particles in conjunction with a polydispersity index of maximum 2 results in a particularly h