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EP-4737407-A1 - LOW MELTING CRYSTALLIZING ENAMEL FOR LOW EMISSIVITY COATED GLASS SUBSTRATE

EP4737407A1EP 4737407 A1EP4737407 A1EP 4737407A1EP-4737407-A1

Abstract

Described is a composition tailored in particular for automotive and flat glass applications as a glaze and/or enamel composition. Moreover, the present invention relates to a method of applying the composition on a Low-e coated side of a glass surface, in particular in the field of laminated automotive windshields, sunroofs, backlights produced via press bending process as well as architectural glass. Notably, composition according to the present invention facilitates Low-e coating dissolution and direct fusion to the glass substrate while preserving essential optical properties, and adhesion-meeting industry standards.

Inventors

  • PAULUS, HILDEGARD
  • Eschmann, Kathrin
  • SCHELLING, VOLKER
  • Kohlenbeck, Christina
  • SABERI, ALI

Assignees

  • Vibrantz GmbH

Dates

Publication Date
20260506
Application Date
20241104

Claims (15)

  1. A composition, comprising, based on the total weight of the composition, bismuth ions in an amount of 30 to 90 wt.%, calculated as Bi 2 O 3 , zinc ions in an amount of 3 to 30 wt.%, calculated as ZnO, boron ions in an amount of 0,1 to 20 wt.%, calculated as B 2 O 3 , characterized in that the weight ratio between bismuth ions and zinc ions, calculated as Bi 2 O 3 and ZnO, is 3 to 12.
  2. The composition according to claim 1, characterized in that the composition comprises bismuth ions in an amount of 40 to 85 wt%, more preferably 60 to 80 wt%, based on the total weight of the composition, calculated as Bi 2 O 3 .
  3. The composition according to claim 1 or 2, characterized in that the composition comprises boron ions in an amount of 0,1 to 18 wt%, more preferably 0,1 to 15 wt%, based on the total weight of the composition, calculated as B 2 O 3 .
  4. The composition according to claim 1 or 3, characterized in that the composition comprises 3 to 20 wt%, more preferably 5 to 18 wt%, zinc ions, based on the total weight of the composition, calculated as ZnO.
  5. The composition according to anyone of claims 1 to 4, characterized in that the composition further comprises less than 10 wt.%, preferably less than 8 wt.%, more preferably less than 7 wt.%, %, based on the total weight of the composition, sodium ions, potassium ions and lithium ions, calculated as Na 2 O, K 2 O, and Li 2 O.
  6. The composition according to anyone of claims 1 to 5, characterized in that the composition further comprises silicon ions in an amount of 0 to 5 wt.%, preferably 0 to 3 wt.%, more preferably 0 to 2 wt.%, based on the total weight of the composition, calculated as SiO 2 .
  7. The composition according to anyone of claims 1 to 6, characterized in that the composition further comprises 0,1 to 7 wt.%, preferably 0,1 to 5 wt.%, more preferably 0,1 to 3 wt.% iron ions, based on the total weight of the composition, calculated as Fe 2 O 3 .
  8. The composition according to anyone of claims 1 to 7, characterized in that the composition further comprises 0,1 to 7 wt.%, preferably 0,1 to 5 wt.%, more preferably 0 to 3 wt.% manganese ions, based on the total weight of the composition, calculated as MnO.
  9. The composition according to anyone of claim 1 to 8, characterized in that the composition is free of Al 2 O 3 .
  10. The composition according to anyone of claims 1 to 9, characterized in that the composition is in the form of a molten glass.
  11. The composition according to anyone of claims 1 to 6, characterized in that the composition further comprises an iron containing pigment in an amount of 0,1 to 30 wt.%, preferably 0,1 to 25 wt.%, more preferably 0,1 to 22 wt.%, based on the total weight of the composition.
  12. The composition according to anyone of claims 1 to 6 and 11, characterized in that the composition further comprises 0,1 to 10 wt.%, preferably 0,1 to 6 wt.%, more preferably 0,1 to 4 wt.%, based on the total weight of the composition, of a manganese containing pigment.
  13. Enamel, prepared by fusing the composition according to anyone of claims 1 to 12.
  14. A method of applying the composition according to anyone of claims 1 to 12, characterized in that the application is carried out using screen printing, inkjet printing, roller coating and spray coating on a low-e coated side of a glass surface.
  15. The method according to claim 14, characterized in that the glass surface is a surface of a soda-lime glass, borosilicate, aluminosilicate glasses and/or lion glass.

Description

The present invention relates to a composition tailored in particular for automotive and flat glass applications as a glaze and/or enamel composition. Moreover, the present invention relates to a method of applying the composition on a Low-e coated side of a glass surface, in particular in the field of laminated automotive windshields, sunroofs, backlights produced via press bending process as well as architectural glass. Notably, composition according to the present invention facilitates Low-e coating dissolution and direct fusion to the glass substrate while preserving essential optical properties, and adhesion-meeting industry standards. Low-Emissivity (Low-E) coatings are thin, transparent layers applied to glass surfaces to reduce heat transfer and improve energy efficiency. These coatings are designed to reflect infrared (IR) radiation while allowing visible light to pass through, helping to regulate temperature by minimizing heat loss in cold weather and reducing heat gain in hot weather. Despite reflecting infrared heat, Low-E coatings are designed to allow visible light to pass through, ensuring that the natural brightness of the outdoors is not compromised. This makes Low-E glass energy-efficient while still being transparent and visually clear. There are two main types of Low-E coatings, typically classified based on how they are applied and their functionality: Soft Coat (High-Performance Low-E) coatings are made by depositing multiple layers of silver or other metals onto the glass using a vacuum deposition process. Soft coats are typically applied to the inside surfaces of the glass in insulating glass units (IGUs) (i.e., double or triple glazing). These coatings are more effective at reflecting infrared radiation, thus offering better insulation, but they are more vulnerable to damage and must be protected by placing them between layers of glass. Hard Coat (Durable Low-E) coatings are made by applying a thin oxide layer to the glass during manufacturing, often as part of the glass itself. These coatings are more durable and scratch-resistant compared to soft coats but are slightly less effective in reflecting infrared radiation. Hard coats are often used in single-glazed windows or as part of laminated glass. Benefits of Low-E Coatings are the reduction of heating and cooling costs by improving the thermal performance of windows. In the winter, they minimize heat loss, and in the summer, they help keep the interior cool by reducing heat from outside. Low-E glass blocks a significant amount of ultraviolet (UV) light, which helps to prevent fading furniture, curtains, carpets, and other interior furnishings. By minimizing the transfer of heat, Low-E windows help maintain a consistent indoor temperature, improving comfort for building occupants. Finally, insulating glass units with Low-E coatings may offer some reduction in noise transmission from outside, although this is primarily achieved by increasing the number of glass layers or the thickness of the air space between them. That said, low-Emissivity (Low-E) coatings on glass play a crucial role in both automotive and architectural applications by enhancing energy efficiency and providing the various protective benefits mentioned above. The majority of Low-E coatings are stack of few micrometers thin multilayer typically composed of silver protected with oxide/non-oxide protecting multi layers such as SnO2, ZnAlOx, SiOx, Si3N4, SiOxNy, Nb2O5, TiOx, ZnOx/AlOx, NiCrOx, ZnSnOx, indium-tin oxide (ITO), creating a smooth and non-porous surface. In certain applications, such as in the automotive glass industry, it may be necessary to decorate or cover portions of a glass substrate with enamel. For example, an obscuration enamel might be applied around the edges of the substrate to protect an underlying adhesive from UV damage. However, standard commercially available enamels are not suitable for use on glass substrates coated with Low-E coatings because they cannot completely etch through multilayer coatings. This limitation can lead to issues such as discoloration, poor adhesion, delamination, and loss of coating functionality. To address this, the coating must first be removed chemically or mechanically using abrasive wheels or laser beams from the area where the enamel will be applied, allowing the enamel to fuse directly with the bare glass. This additional process is costly and can introduce quality defects, mechanical damage, create unwanted flaws, and reduce the mechanical properties of the final glass substrate. To avoid the edge deletion process, different approaches were practiced. One of these approaches is a two-step process disclosed in WO 2019/016639 A. In the first step, a provisional corrosive enamel in the form of a paste which contains inter alia P2O5-Na2O is applied to the desired area. The glass substrate is then fired at a temperature of 500 to 700 °C, where the provisional enamel digests the Low-e coating. After heating, the