Polyvinyl Acetal Interlayer Haze Reduction via Resin Blending
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Solution Overview
Problem
Polymer interlayers used in multiple layer panels often suffer from optical defects like mottle and high haze due to the combination of polymers with different refractive indices, which affects their clarity and mechanical performance, necessitating the development of polymer resin compositions that balance optical and mechanical properties.
Innovation Solution
A resin interlayer comprising a blend of two poly(vinyl acetal) resins with different residual hydroxyl content and a blending agent, such as polyethylene glycol alkylphenol ether, to enhance compatibility and reduce haze, while maintaining mechanical and acoustic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multilayered polymer interlayers with different glass transition temperatures are used to achieve both acoustic performance and impact resistance, then mechanical and acoustic properties are improved, but optical defects such as mottle and high haze occur due to different refractive indices between layers
Solution Approach 1:
The patent changes the chemical composition parameters of the poly(vinyl acetal) resins, specifically controlling the acetalization degree and residual hydroxyl content within defined ranges. This parameter optimization ensures that resins with different glass transition temperatures have compatible refractive indices, reducing optical defects while maintaining mechanical performance
Solution Approach 2:
The patent creates composite resin systems by blending poly(vinyl acetal) resins with different acetalization degrees (60-85 mol %) and residual hydroxyl contents (8-30 mol %). This composite approach allows the interlayer to exhibit both the acoustic performance of softer regions and the impact resistance of stiffer regions, while the controlled composition ensures optical compatibility
2Strength
If different types of optically incompatible polymers and plasticizers are blended to achieve desired mechanical properties, then mechanical performance is improved, but clarity deteriorates due to light scattering at polymer interfaces
Solution Approach 1:
The patent optimizes the chemical parameters of the poly(vinyl acetal) resins by controlling acetalization degree (60-85 mol %) and residual hydroxyl content (8-30 mol %). These parameter adjustments ensure that blended resins maintain compatible refractive indices and molecular structures, reducing light scattering while achieving desired mechanical properties
Solution Approach 2:
The patent promotes homogeneity in the resin blend by selecting poly(vinyl acetal) resins with controlled compositional parameters. The resins are chemically similar enough to blend uniformly without phase separation, yet different enough to provide varied mechanical properties. This homogeneous blending minimizes optical defects while maintaining mechanical performance
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 results in interlayers with improved optical clarity and reduced haze, suitable for various applications including automotive and architectural uses, while maintaining mechanical and acoustic properties.
Implementation Method 1
a blending agent, such as polyethylene glycol alkylphenol ether, to enhance compatibility and reduce haze
Implementation Method 2
Mottle is caused by small-scale surface variations at the interfaces between the soft and stiff layers wherein the individual layers have different refractive indices
Data Source
AI summary
Resin compositions, layers, and interlayers comprising two or more polyvinyl acetal) resins and at least one blending agent or haze reducing agent are provided. Such compositions, layers, and interlayers exhibit enhanced optical properties while retaining other properties, such as impact resistance and acoustic performance.