Multi-Layer Removable Coating for Shaped Glass Articles
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Solution Overview
Problem
Forming three-dimensionally shaped glass articles is challenging due to high softening points of certain glass compositions, which require high temperatures, leading to surface deformation and potential visual defects or fractures, especially when molding causes direct contact between the mold and the glass.
Innovation Solution
A method involving a multi-layer removable coating on the glass article, where an inner 'soft' glass layer with a lower softening point is in contact with the glass, and an outer 'hard' glass layer with a higher softening point is applied over it, allowing for shaping at temperatures close to the glass's softening point without surface damage, and preventing sticking to the mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If high temperature heating is applied to shape glass articles with high softening points, then the glass can be formed into 3D shapes, but surface deformation and visual defects occur
Solution Approach 1:
A multi-layer coating system is applied to the glass article surface before molding. The coating acts as an intermediary layer between the mold and the glass surface, preventing direct contact and thus preventing surface deformation and visual defects while allowing the glass to be shaped at high temperatures.
Solution Approach 2:
The patent modifies the surface properties of the glass article by applying a coating with different thermal and mechanical properties than the bulk glass. This parameter change allows the surface to withstand high temperature molding without deforming, while the bulk glass maintains its shape-forming capability.
2Ease of manufacture
If high temperature heating is applied to reach visco-elastic state, then glass shaping becomes feasible, but glass fractures or cracking may occur
Solution Approach 1:
The multi-layer coating serves as a protective intermediary that distributes thermal stress and mechanical load during the molding process. This prevents stress concentration at the glass surface that would lead to fractures or cracking, thereby maintaining structural integrity while enabling high-temperature shaping.
3Shape
If direct contact between mold and glass surface occurs, then shaping can be achieved, but surface abnormalities and sticking to mold occur
Solution Approach 1:
The multi-layer coating is specifically designed to prevent direct contact between the mold and the glass surface. The coating layers have controlled viscosity and adhesion properties that allow the glass to conform to the mold shape while preventing sticking and surface abnormalities.
Solution Approach 2:
The patent changes the surface parameters of the glass article by applying a coating with optimized rheological properties. The coating's viscosity at processing temperature allows it to flow and conform to the mold while preventing excessive adhesion, thus achieving good shape without surface defects or sticking.
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
This method enables the precise shaping of glass articles with high softening points without surface deformation or sticking issues, maintaining the glass's integrity and facilitating the reuse of molds.
Implementation Method 1
The inner layer may comprise a first glass having a softening point of at least about 50° C. less than a softening point of the glass article
Implementation Method 2
The inner layer may comprise a first glass having a viscosity from about 104 P to about 107.5 P at the forming temperature. The outer layer may comprise a second glass having a viscosity from about 107.8 P to about 1014 P at the forming temperature
Data Source
AI summary
A method for producing a shaped glass article may include heating at least a portion of a mold-facing surface of the glass article to a forming temperature, shaping the glass article in a mold, and removing the multilayer coating from the glass article. The glass article may be coated with a multi-layer removable coating including an inner layer in contact with the glass article and an outer layer disposed over the inner layer. The mold may be in direct contact with the outer layer during shaping. The inner layer may include a first glass having a softening point of at least about 50° C. less than a softening point of the glass article. The outer layer may include a second glass having a softening point of at least about 50° C. greater than the softening point of the glass article.