Polymeric Interlayer with Dispersed Resin Domains for Rigidity and Impact Balance

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Solution Overview

Problem

Conventional polymeric interlayers for safety glass panels often face a trade-off between rigidity and impact resistance, where increasing rigidity compromises impact performance, and vice versa, while also lacking optimal optical properties such as low haze and no yellowing.

Innovation Solution

A polymeric interlayer comprising a blend of poly(vinyl acetal) resins with varying residual hydroxyl contents and a plasticizer, where the resins are dispersed to form domains within a continuous phase, enhancing both rigidity and impact resistance while maintaining suitable optical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the rigidity of conventional interlayers is increased, then the structural support properties are improved, but the impact resistance of the resulting panel worsens

Engineering Contradiction:
ImproverigidityVSAvoidimpact resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent employs a composite interlayer system consisting of multiple poly(vinyl acetal) resin layers with different residual hydroxyl contents. Specifically, it combines a first resin layer with residual hydroxyl content of 18-22% and a second resin layer with residual hydroxyl content of 26-30%, where the second layer is dispersed within the first to form domains. This composite structure allows the interlayer to simultaneously achieve enhanced rigidity from the lower hydroxyl content resin and improved impact resistance from the higher hydroxyl content resin, resolving the trade-off between these two properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating distinct regions within the interlayer with different resin compositions and properties. The dispersed domains of the second poly(vinyl acetal) resin (with 26-30% residual hydroxyl content) are distributed within the continuous phase of the first poly(vinyl acetal) resin (with 18-22% residual hydroxyl content). This local differentiation allows specific regions to contribute differently to overall performance: the continuous phase provides rigidity while the dispersed domains provide impact resistance, enabling the interlayer to optimize both properties simultaneously.

Inventive Principle:
Principle #3Local quality

2Reliability

If conventional interlayers are formulated for enhanced impact strength, then the impact resistance is improved, but the necessary rigidity required in applications requiring excellent structural support properties is lacking

Engineering Contradiction:
Improveimpact resistanceVSAvoidrigidity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent uses a composite formulation combining two poly(vinyl acetal) resins with complementary properties. The first resin (18-22% residual hydroxyl content) contributes rigidity and structural support, while the second resin (26-30% residual hydroxyl content) contributes impact resistance. By blending these resins in specific proportions and creating a dispersed phase structure, the interlayer achieves both enhanced impact strength and necessary rigidity, overcoming the limitation of conventional single-resin formulations.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent utilizes parameter changes by varying the residual hydroxyl content of poly(vinyl acetal) resins to achieve different property profiles. The first resin layer uses resins with residual hydroxyl content of 18-22% for rigidity, while the second resin layer uses resins with residual hydroxyl content of 26-30% for impact resistance. This systematic variation of the hydroxyl content parameter allows optimization of both rigidity and impact resistance in the composite interlayer system.

Inventive Principle:
Principle #35Parameter changes

3Strength

If polymeric interlayers provide optimal structural properties, then rigidity and strength are improved, but optical properties such as low haze and no yellowing are compromised

Engineering Contradiction:
Improvestructural propertiesVSAvoidoptical properties
Core Design Contradiction:
StrengthVSIllumination intensity

Solution Approach 1:

The patent employs a composite interlayer system using multiple poly(vinyl acetal) resins that maintain excellent optical properties while providing enhanced structural performance. The specific resin combination (first resin with 18-22% residual hydroxyl content and second resin with 26-30% residual hydroxyl content) and the controlled dispersion structure ensure compatibility in refractive index and optical clarity, allowing the interlayer to achieve both optimal structural properties and desirable optical properties including low haze and resistance to yellowing.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating dispersed domains of the second resin within the first resin matrix, where each phase is optimized for specific functions while maintaining overall optical compatibility. The continuous phase provides structural integrity and optical clarity, while the dispersed domains contribute to impact resistance without compromising optical properties. This local differentiation allows the interlayer to simultaneously achieve enhanced structural properties and maintain excellent optical properties.

Inventive Principle:
Principle #3Local quality

Data Source

PatentUS10611906B2Polymeric interlayers and multiple layer panels made therefrom exhibiting enhanced properties and performance
Publication Date: 2020.04.07 SOLUTIA INC

AI summary

Polymeric interlayers for use in making multiple layer panels having a unique balance of properties are provided. Single and multiple layer interlayers according to various embodiments of the present invention can be used to form multiple layer panels that exhibit both enhanced rigidity and improved impact resistance, while still retaining desirable optical performance. Interlayers and multiple layer panels of the present invention may be particularly suitable for use in a wide range of applications, including, for example, in many indoor and outdoor architectural and structural applications.