Polymer Interlayer Refractive Index Matching for Optical Clarity
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Solution Overview
Problem
The presence of mottle, a visual defect caused by refractive index differences between layers, leads to optical distortion in multilayer laminate glass panels, which is problematic for applications requiring high optical quality.
Innovation Solution
A multiple layer polymer interlayer comprising a first layer with poly(vinyl butyral) resin and a high refractive index plasticizer, a second layer with poly(vinyl butyral) resin and another high refractive index plasticizer, and a third layer with poly(vinyl butyral) resin, where at least one of the plasticizers has a refractive index of at least 1.460, minimizing the refractive index difference between soft and stiff layers to reduce mottle and haze.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple layer interlayers with different plasticizers are used to achieve soft and stiff layers, then mechanical and acoustic characteristics are improved, but refractive index differences cause mottle and optical distortion
Solution Approach 1:
The patent changes the refractive index parameter of the plasticizers used in the interlayer. By selecting plasticizers with high refractive indices (≥1.460), the optical properties of the soft and stiff layers are adjusted to minimize refractive index differences, thereby reducing mottle and optical distortion while maintaining the desired mechanical and acoustic characteristics through different plasticizer compositions.
Solution Approach 2:
The patent uses composite material strategies by combining poly(vinyl butyral) resin with different high refractive index plasticizers in specific layers. The first layer uses a first high refractive index plasticizer, the second layer uses a second high refractive index plasticizer, and the third layer uses poly(vinyl butyral) resin, creating a composite structure that achieves both mechanical performance and optical quality.
2Ease of manufacture
If conventional plasticizers are used in multilayer interlayers, then manufacturing is easier and cost is lower, but optical quality deteriorates due to mottle and haze
Solution Approach 1:
The patent modifies the optical parameter (refractive index) of the plasticizers from conventional low refractive index materials to high refractive index materials (≥1.460). This parameter change improves optical quality by reducing mottle and haze while maintaining the multilayer structure and manufacturing processes, thus achieving better optical precision without significantly complicating manufacturing.
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 solution significantly decreases mottle and haze, resulting in improved optical quality and clarity of multilayer glass panels without compromising mechanical or acoustic characteristics.
Implementation Method 1
at least one of the first, second and third plasticizers is a high refractive index plasticizer having a refractive index of at least about 1.460; wherein at least one layer is a soft layer and at least one layer is a stiff layer, and wherein the difference between the refractive index of the soft layer and the stiff layer (Delta RI) is less than about 0.010
Data Source
AI summary
An interlayer comprised of a thermoplastic resin, at least one high refractive index plasticizer and, optionally, a conventional plasticizer. The use of a thermoplastic resin, a high refractive index plasticizer, and, optionally, a conventional plasticizer reduces or minimizes the optical defects caused by different refractive indices without sacrificing other characteristics of the interlayer.