Asymmetrical Glass Laminates with TPU Interlayer
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Solution Overview
Problem
Laminates with differing glass compositions and coefficients of thermal expansion (CTE) undergo significant bowing, making it impractical or impossible to mount them in planar window frames and insulating glass units beyond a certain size.
Innovation Solution
The use of a low-modulus thermoplastic polyurethane (TPU) interlayer in glass-glass laminates helps reduce bow by mitigating thermal expansion mismatch between glass sheets, allowing for larger laminate sizes with minimal bow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If glass sheets with differing CTE are used in laminates, then design flexibility and thickness variation are improved, but bowing increases making mounting impractical
Solution Approach 1:
A TPU interlayer is introduced between glass sheets with differing coefficients of thermal expansion. This intermediary layer acts as a buffer that accommodates the differential thermal expansion between the glass sheets, preventing bowing while allowing thickness variation. The TPU interlayer absorbs the dimensional changes that occur during temperature fluctuations, maintaining the laminate's planarity.
Solution Approach 2:
The patent utilizes materials with specific thermal and mechanical parameters - the TPU interlayer has a coefficient of thermal expansion and elasticity modulus specifically suited to bridge the gap between glass sheets of different CTE values. By selecting materials with appropriate parameter ranges, the laminate can accommodate thickness variations without developing excessive bowing.
2Area of stationary object
If large-dimensioned laminates are manufactured, then architectural application versatility is improved, but bowing control becomes more difficult
Solution Approach 1:
The TPU interlayer serves as a flexible intermediary that becomes increasingly important in large-dimensioned laminates. Its elastic properties allow it to distribute thermal stresses across the entire laminate area, preventing localized bowing that would otherwise propagate across large surfaces. The interlayer's compliance enables large panes to maintain flatness despite temperature variations.
Solution Approach 2:
The laminate is constructed as a composite structure combining rigid glass sheets with a flexible TPU interlayer. This composite design leverages the complementary properties of the materials - the glass provides structural integrity while the TPU provides flexibility and thermal accommodation - enabling the manufacture of large-area laminates with controlled bowing.
3Ease of manufacture
If asymmetrical laminate construction is used, then manufacturing flexibility is improved, but internal stress and bowing increase
Solution Approach 1:
The TPU interlayer acts as a stress-absorbing intermediary between asymmetrical glass sheets. When glass sheets of different thicknesses and CTE values are combined, the TPU layer accommodates the mismatch and prevents excessive internal stress buildup. Its elastic properties allow it to deform slightly, absorbing the differential expansion and contraction forces.
Solution Approach 2:
The patent employs materials with specific mechanical parameters - the TPU interlayer has an elasticity modulus and thickness specifically selected to balance the asymmetrical construction. By adjusting the interlayer's parameters, the design achieves manufacturing flexibility while keeping internal stresses within acceptable limits.
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 TPU interlayer effectively reduces bow in large-dimensioned laminates, improving long-term reliability, manufacturability, and performance, while enabling wider thickness variations between glass sheets of differing CTE.
Implementation Method 1
Laminates having different glass compositions with differing coefficients of thermal expansion can undergo significant bowing
Data Source
AI summary
Various embodiments for a laminate glass article and related methods are provided. The laminated glass article includes a first glass layer and a second glass layer with a TPU interlayer positioned therebetween.