Laminated Glazing Moisture Control for SPD Stability
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Solution Overview
Problem
Suspended particle devices (SPDs) in laminated glazings degrade rapidly due to high temperatures and moisture, especially when moisture levels are not controlled within the interlayer materials, leading to reduced switching characteristics over time.
Innovation Solution
Incorporating an interlayer material with a predetermined low moisture content, such as polyvinyl butyral (PVB) or ethylene vinyl acetate (EVA), dried to specific levels (e.g., 0.24 weight % or lower) to reduce moisture content, which enhances the stability and switching performance of SPDs by preventing moisture-induced degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If interlayer material with normal moisture content is used, then ease of manufacture is improved, but reliability of SPD device deteriorates due to rapid degradation from moisture and heat
Solution Approach 1:
The interlayer material is pre-dried to a predetermined low moisture content (e.g., 0.1-1.0% by weight, preferably 0.24% or lower) before lamination. This preliminary drying action prevents moisture from being present during the critical early stages of SPD operation, thereby preventing degradation while maintaining ease of manufacture through a simple pre-treatment step
Solution Approach 2:
The moisture content parameter of the interlayer material is changed from normal levels to a predetermined low level. This parameter change fundamentally alters the chemical environment around the SPD device, preventing moisture-induced degradation and extending switching characteristics lifetime without complicating the manufacturing process
2Reliability
If interlayer material is dried to low moisture content, then reliability of SPD device is improved, but manufacturing complexity increases due to additional drying process
Solution Approach 1:
The drying process is performed as a preliminary step before lamination, allowing the interlayer material to be pre-conditioned to the correct moisture level. This separates the drying operation from the lamination process itself, making the additional step more manageable and less complex than it initially appears
Solution Approach 2:
The dried interlayer material acts as an intermediary barrier between the external environment (moisture and heat) and the SPD device. By positioning this pre-dried layer adjacent to the SPD before lamination, it creates a protective interface that simplifies the overall system design while maintaining high reliability
3Ease of manufacture
If interlayer material with high moisture content is used, then ease of manufacture is improved, but duration of SPD switching characteristics deteriorates due to moisture-induced degradation
Solution Approach 1:
The moisture content parameter of the interlayer material is fundamentally changed from normal levels to a predetermined low level (0.1-1.0% by weight). This parameter change directly extends the duration of SPD switching characteristics by preventing moisture-induced degradation, while the drying process remains a simple pre-treatment that does not significantly impact manufacturing efficiency
4Duration of action of stationary object
If interlayer material is dried to low moisture content, then durability of SPD device is improved, but manufacturing cost increases due to additional drying process
Solution Approach 1:
The interlayer material is pre-dried to a predetermined low moisture content before lamination. This preliminary action ensures durability from the outset by preventing moisture accumulation, while the drying process itself is a relatively simple and cost-effective pre-treatment step that can be integrated into existing manufacturing workflows
Solution Approach 2:
The drying process provides beforehand cushioning by removing moisture that would otherwise cause future degradation. This preventive measure protects the SPD device from moisture-induced damage before it occurs, extending durability while avoiding the need for more expensive corrective measures later in the product lifecycle
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 low moisture content in interlayer materials significantly reduces high-temperature degradation and maintains the switching characteristics of SPDs for a longer period, ensuring the SPDs remain functional between low and high light transmission states.
Implementation Method 1
the interlayer material has been dried to a predetermined moisture content to increase the time over which the suspended particle device is switchable
Data Source
AI summary
A laminated glazing comprising an SPD ply comprising a suspended particle device having a low light transmission off-state and a high light transmission on-state, at least one interlayer ply comprising an interlayer material, and at least one glazing ply is disclosed. The interlayer material has been dried to a predetermined moisture content to increase the time over which the suspended particle device is switchable between the low light transmission off-state and the high light transmission on-state. Use of a dried interlayer to increase the time over which an SPD film is switchable between a low light transmission off-state and a high light transmission on-state is also disclosed. Additionally a process for producing the aforementioned laminated glazing is disclosed. It has been found that the moisture content of the interlayer material is a factor in determining the switching characteristics over time of an SPD film incorporated into a laminated glazing.