Laminated Glazing Interlayer with Segmented Light Diffusing Layer

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Solution Overview

Problem

Existing laminated glazing technologies for automotive and architectural applications lack optimal light performance, thermal stability, and optical properties, particularly in terms of haze, transparency, and transmissibility.

Innovation Solution

A laminated glazing structure comprising two sheets of glass bonded by a thermoplastic interlayer, which includes a polyvinyl acetal film with reduced plasticizer content, a low refractive index layer, and a light diffusing layer in direct contact with one glass sheet, enhancing light outcoupling and optical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If light diffusing particles are embedded between two PVB films, then adhesion to glass surfaces is improved, but light outcoupling is reduced

Engineering Contradiction:
ImproveadhesionVSAvoidlight outcoupling
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The interlayer is segmented into three distinct functional zones: a first PVB layer for adhesion to the first glass surface, a light diffusing layer with particles for light scattering, and a second PVB layer for adhesion to the second glass surface. This segmentation allows each layer to optimize its specific function without compromising the others.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the interlayer structure are assigned different properties: the PVB layers provide adhesion and flexibility, while the light diffusing layer provides light scattering. The light diffusing particles are localized in the central layer rather than distributed throughout the entire interlayer, creating local quality variations that optimize both adhesion and light outcoupling.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If plasticizer content in PVB film is reduced, then surface smoothness and print quality are improved, but film flexibility and adhesion are reduced

Engineering Contradiction:
Improvesurface smoothnessVSAvoidadhesion
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The interlayer is divided into plasticizer-free PVB layers for printing and plasticized PVB layers for adhesion. The first and second PVB layers have reduced or no plasticizer content to provide smooth surfaces for light diffusing layer application, while the third PVB layer contains plasticizer to ensure flexibility and adhesion to glass surfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The plasticizer content parameter is varied across different layers of the interlayer structure. The outer PVB layers have low or zero plasticizer content (0-5 wt%) for surface smoothness, while the inner PVB layer has higher plasticizer content (15-40 wt%) for maintaining flexibility and adhesion properties.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If light diffusing layer is placed in direct contact with glass surface, then light outcoupling is improved, but adhesion uniformity is reduced

Engineering Contradiction:
Improvelight outcouplingVSAvoidadhesion uniformity
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The interlayer is segmented into adhesion-optimized PVB layers and a light diffusing layer. The PVB layers serve as interface layers that ensure uniform adhesion to glass surfaces, while the light diffusing layer is positioned between the PVB layers to maximize light outcoupling without directly contacting the glass.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The PVB layers act as intermediary layers between the glass surfaces and the light diffusing layer. These intermediary PVB layers provide uniform adhesion to the glass while allowing the light diffusing layer to be positioned optimally for light outcoupling, mediating between the requirements for adhesion uniformity and light performance.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 proposed structure achieves improved light performance, thermal stability, and optical properties, including enhanced haze, transparency, and transmissibility, while allowing for decorative patterns and efficient light guiding.

Implementation Method 1

a light diffusing layer (103) in direct contact with the first glass sheet (101), wherein the light diffusing layer (103) comprises light scattering particles

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

a low refractive index layer (104) arranged between the polyvinyl acetal film A (102A) and the light diffusing layer (103), having a refractive index of

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP4556219A1Improved illuminable lamination interlayer and glazing
Publication Date: 2025.05.21 KURARAY EURO GMBH
  • EP4556219A1 patent drawingFigure 1
  • EP4556219A1 patent drawingFigure 2
  • EP4556219A1 patent drawingFigure 3

AI summary

Described is a lamination interlayer and laminate structure which enables the application of optically improved functional layers, structures or patterns, especially for transparent lighting and display applications.