Switchable Automotive Glazing UV Protection
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Solution Overview
Problem
Switchable glazings in automotive applications degrade due to UV light, high temperatures, and chemical reactions, leading to reduced serviceability and optical distortion issues.
Innovation Solution
Incorporating a UV absorptive interlayer with high absorption in the UV spectrum and an IR reflective coating to protect the switchable film, along with an impermeable edging material to prevent chemical degradation, while maintaining low autoclaving temperatures to ensure effective lamination and prevent curvature and voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a border of glass and interlayers is extended beyond the perimeter of the SPD switchable film to protect edges, then protection from chemical attack is improved, but optical distortion occurs due to thickness difference in the laminate
Solution Approach 1:
The patent applies a UV absorptive interlayer specifically at the edges and perimeter regions of the glazing assembly, where chemical exposure is most severe, rather than uniformly throughout. This localized application provides enhanced protection where needed while maintaining optical quality in the central viewing areas, resolving the contradiction between edge protection and optical distortion.
2Ease of manufacture
If standard PVB interlayer is used requiring lamination temperature at or above 120°C, then effective lamination is achieved, but degradation of SPD film occurs due to high temperature
Solution Approach 1:
The patent changes the temperature parameter of the lamination process by using a UV absorptive interlayer that can be effectively laminated at temperatures below 120°C. This temperature reduction prevents thermal degradation of the SPD film while still achieving effective lamination through the modified interlayer material properties that enable bonding at lower temperatures.
Solution Approach 2:
The UV absorptive interlayer serves as an intermediary material between the glass layers and SPD film, enabling the lamination process to occur at reduced temperatures. This intermediary layer facilitates bonding while acting as a thermal buffer that protects the temperature-sensitive SPD film from excessive heat exposure during manufacturing.
3Stability of the object's composition
If the glazing assembly is exposed to high temperatures, then resilience of plies flexes to unstressed condition, but interlayer draws in creating a scant in the glazing
Solution Approach 1:
The UV absorptive interlayer provides beforehand cushioning by maintaining its dimensional stability and adhesive properties at elevated temperatures. This prevents the interlayer from drawing in and creating scants when the glazing assembly is exposed to high temperatures, as the interlayer remains pliable and bonded throughout the temperature cycle.
Data Source
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AI summary
A window glazing (10) suitable for use in automotive applications wherein a switchable film (18) is protected from UV exposure and over-temperature exposure by a coating (14) that reflects IR and UV light in combination with an interlayer (16) that absorbs UV light.