Polymer Coating Tie Layers for HOE Lamination Quality
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Solution Overview
Problem
Existing methods for incorporating holographic optical elements (HOE) into laminates, such as windshields, result in significant reduction of reflection intensity and quality due to LRIC migration and material changes during lamination, leading to issues like wrinkling and bubble formation.
Innovation Solution
The use of specially formulated tie layers and coatings containing LRICs that maintain the optical properties of HOE films by minimizing LRIC migration and enhancing the bond with HOE films, using materials like EVA, TPU, and ionomer resins to form multilayer interlayers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lamination methods are used to incorporate HOE into laminates, then the lamination process can be completed, but the reflection intensity and quality of HOE are significantly reduced due to LRIC migration and material changes
Solution Approach 1:
A tie layer comprising a polymer resin and LRIC is introduced as an intermediary between the HOE and the interlayer. This tie layer prevents LRIC migration from the HOE to the interlayer, thereby maintaining the reflection intensity and quality of the HOE while enabling the lamination process to proceed.
Solution Approach 2:
The refractive index of the tie layer is specifically matched to that of the HOE (within ±0.05, preferably ±0.02) to minimize optical disturbances and maintain high reflection quality. The LRIC concentration in the tie layer is also optimized (0.1-20 wt%, preferably 0.5-5 wt%) to prevent migration while maintaining optical properties.
2Ease of manufacture
If conventional interlayers are used in lamination, then the lamination can be formed, but wrinkling and bubble formation occur due to material incompatibility
Solution Approach 1:
The tie layer acts as a buffer between the HOE and the interlayer, absorbing dimensional mismatches and preventing wrinkling and bubble formation. This intermediary layer enables the lamination process to proceed smoothly while maintaining high manufacturing precision.
Solution Approach 2:
The tie layer is formulated as a composite material comprising a polymer resin (such as EVA, poly(vinyl acetal), or polyurethane) and LRIC. This composite structure provides both the mechanical flexibility needed for lamination and the optical properties needed to match the HOE, preventing defects while enabling easy manufacture.
3Ease of manufacture
If the refractive index of the tie layer does not match the HOE, then the lamination can be formed, but optical disturbances reduce reflection quality
Solution Approach 1:
The refractive index of the tie layer is precisely controlled to match that of the HOE (within ±0.05, preferably ±0.02). This parameter matching eliminates optical disturbances at the interface, ensuring high reflection quality and intensity while allowing the laminate to be formed successfully.
Solution Approach 2:
The tie layer is specifically formulated with local optical properties (refractive index) matched to the adjacent HOE, creating a seamless optical transition. This localized quality matching prevents optical disturbances while maintaining ease of laminate formation.
Data Source
AI summary
Tie layers and structures that exhibit superior properties and that provide desirable optical properties when incorporated into laminates, such as windshields, windows or other glazings containing a holographic optical element (HOE) are disclosed. The tie layers, when used in a laminate in conjunction with the HOE film, optionally with additional polymer layers, maintain and do not detract from the HOE film properties.