Laminated Curved Glazing with Refractory Enamel Separation
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Solution Overview
Problem
In laminated curved glazings for motor vehicles, unwanted interactions between the enamel layer and the stack of thin layers during bending can lead to degradation of the enamel's adhesion and optical appearance, particularly when the stack contains nitride layers and the enamel contains bismuth, resulting in bubble formation and reduced chemical resistance.
Innovation Solution
A method involving a glass sheet coated with a stack of thin layers, where refractory particles based on oxides, carbides, or metals with dimensions greater than or equal to 30 μm are deposited on the enamel layer, followed by pre-firing to partially or completely dissolve the stack, preventing bonding between glass sheets during bending and maintaining the enamel's adhesion and aesthetic appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the enamel layer and stack of thin layers are arranged on the same glass sheet to protect coatings inside the laminated glazing, then the coatings are protected, but unwanted interactions occur during bending leading to degradation of enamel adhesion and optical appearance
Solution Approach 1:
A separation layer comprising at least one oxide layer and at least one nitride layer is introduced between the enamel layer and the stack of thin layers. This intermediary layer prevents direct contact and unwanted interactions between the enamel and the conductive stack during bending, while still allowing the coatings to be protected inside the laminated glazing. The oxide layer (such as silicon oxide, aluminum oxide, or zinc oxide) and nitride layer (such as silicon nitride or aluminum nitride) create a protective barrier that eliminates bubble formation and maintains enamel adhesion.
2Strength
If bismuth-containing enamel is used to prevent bonding between glass sheets during bending, then non-stick properties are achieved, but interactions with nitride layers cause bubble formation and reduced chemical resistance
Solution Approach 1:
The separation layer with oxide and nitride layers acts as a mediator that allows the bismuth-containing enamel to maintain its non-stick properties during bending while preventing direct harmful interactions with the underlying nitride layers of the conductive stack. This intermediary structure preserves the chemical resistance and adhesion of the enamel by eliminating direct contact between reactive components.
Solution Approach 2:
The invention uses a composite structure consisting of multiple layers: the bismuth-containing enamel layer, the separation layer comprising oxide and nitride layers, and the stack of thin layers. This composite material structure combines the non-stick properties of bismuth enamel with the protective barrier properties of the oxide-nitride separation layer, achieving both bending resistance and chemical stability.
3Strength
If the stack contains nitride layers and the enamel contains bismuth, then non-stick properties are achieved, but bubbles form within the enamel close to the interface, causing significant lowering of adhesion
Solution Approach 1:
The separation layer comprising oxide and nitride layers is positioned between the bismuth-containing enamel and the nitride layers of the conductive stack. This intermediary structure prevents the formation of bubbles at the enamel interface by eliminating direct contact between bismuth and nitride layers, thereby maintaining enamel adhesion while preserving the non-stick properties during bending.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively prevents interactions between the enamel and the stack, ensuring the enamel's adhesion and optical appearance are maintained, while avoiding bonding between the glass sheets, thus enhancing the chemical resistance and aesthetic quality of the laminated glazing.
Implementation Method 1
a step of pre-firing the enamel layer during which the stack of thin layers under the enamel layer is at least partially dissolved by said enamel layer
Implementation Method 2
refractory particles based on oxides, carbides or metals with dimensions greater than or equal to 30 μm are deposited on the enamel layer
Implementation Method 3
A glass frit is composed of fine particles of glass with a low melting point which, under the effect of a firing heat treatment, softens and adheres to the glass sheet
Implementation Method 4
which, under the effect of a firing heat treatment, softens and adheres to the glass sheet
Implementation Method 5
enamel layers, generally black and opaque... protect from ultraviolet radiation, the polymer seals
Implementation Method 6
when current supplies are provided, electrically conductive layers can dissipate heat by the Joule effect
Implementation Method 7
due to their reflection of infrared radiation, these layers have solar control or low-emissivity properties
Data Source
AI summary
A method for obtaining a laminated curved glazing, particularly for a motor vehicle windscreen or roof. The method includes the deposition (b) of an enamel layer on a stack of thin layers deposited on a first glass sheet as well as the deposition (c), at least on the enamel layer, of refractory particles based on oxides, of metals or carbides, at least one dimension of which is larger than 30 μm. The stack of thin layers is completely dissolved by the enamel layer at the end of a bending procedure (d) carried out before laminating (e) the first glass sheet with an additional glass sheet by a lamination interlayer.