Laminated Glazing Coloring via Anthraquinone Migration

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Solution Overview

Problem

Existing laminated glazing manufacturing processes face challenges in modifying the coloring of glass sheets with functional coatings, as the heat treatments during lamination can alter the desired tint, requiring expensive and complex solutions to maintain optical properties and achieve uniform coloration.

Innovation Solution

A process involving a transparent thermoplastic spacer and a polymeric layer with an anthraquinone coloring agent is used, allowing the coloring agent to migrate during the lamination process, ensuring uniform coloration without altering the functional coating stack, and maintaining low manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a functional coating stack is deposited on glass sheets to achieve desired optical properties, then the thermal and optical selectivity is improved, but the color uniformity deteriorates due to heat treatment alterations during lamination

Engineering Contradiction:
Improveoptical selectivityVSAvoidcolor uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent divides the coloring function into two separate components: the functional coating stack maintains its optical selectivity while a separate polymeric layer with anthraquinone coloring agent provides the desired color. This segmentation allows each component to optimize its specific function without interfering with the other, resolving the contradiction between maintaining optical selectivity and achieving color uniformity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The polymeric layer acts as an intermediary between the glass substrate and the functional coating stack. It provides the coloring function while being chemically compatible with both the glass and the functional layers, allowing heat treatment to proceed without altering the functional coating's optical properties or the desired color uniformity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If heat treatment is applied during lamination to bond glass sheets, then the bonding strength is improved, but the color of functional coatings deteriorates

Engineering Contradiction:
Improvebonding strengthVSAvoidcolor stability
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameter of the coloring system by using anthraquinone-based polymeric layers instead of traditional metallic or ceramic coatings. This parameter change allows the material to withstand the heat treatment temperatures (typically 120-180°C during lamination) without undergoing color alterations, while still providing the desired coloring effect and maintaining bonding strength.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If specific functional stacks are developed for laminated glass to prevent tint variation, then the color stability is improved, but the manufacturing complexity and cost increase

Engineering Contradiction:
Improvecolor stabilityVSAvoidstack complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses a relatively simple and inexpensive polymeric layer with anthraquinone coloring agent instead of complex multi-layer functional stacks designed specifically for lamination. This simpler, more economical approach achieves the desired color stability without requiring expensive and complex stack optimizations, making it suitable for mass production.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Reliability

If functional coatings are applied before lamination to ensure color properties, then the optical selectivity is improved, but the color uniformity deteriorates during the lamination process

Engineering Contradiction:
Improveoptical selectivityVSAvoidcolor uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies the polymeric coloring layer to the glass substrate before lamination, allowing the color to be uniformly distributed across the surface. The preliminary application ensures that the coloring agent is in place before the heat treatment of lamination begins, and the subsequent heat treatment process actually enhances color uniformity rather than degrading it, while the functional coating stack maintains its optical selectivity.

Inventive Principle:
Principle #10Preliminary action

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

This method allows for simple and cost-effective modification of the final coloring of laminated glazing, ensuring homogeneity over large surfaces and maintaining the selectivity of the functional coating, while correcting color imperfections during the assembly and heat treatment phases.

Implementation Method 1

heat treatment under pressure and/or vacuum of the laminated glass at a temperature between 100 and 200°C during which the coloring agent present in the polymer layer migrates to the thermoplastic interlayer

Methodology Applied
Scientific EffectMigration: Diffusion

Implementation Method 2

heat treatment under pressure and/or vacuum of the laminated glass at a temperature between 100 and 200°C during which the assembly of the laminated glazing is carried out

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Implementation Method 3

heat treatment under pressure and/or vacuum of the laminated glass at a temperature between 100 and 200°C during which the assembly of the laminated glazing is carried out

Methodology Applied
Scientific EffectPressure: Compression

Data Source

PatentEP3600883B1Laminated glazing comprising a stack of layers
Publication Date: 2023.08.30 SAINT GOBAIN VITRAGE SA

AI summary

The present invention relates to a method for producing coloured laminated glazing comprising at least a first glass sheet and a second glass sheet which are connected to one another by a thermoplastic interlayer. The method comprises the steps of: depositing a stack of layers comprising at least one functional layer on at least one face of the first and/or second glass sheet; depositing a polymer layer on at least one face of the first and/or second glass sheet using a wet process, said polymer layer comprising a colouring agent and polymer compounds; drying and optionally hardening the polymer layer; assembling the glass sheet that has been coated with the coloured polymer layer with a colourless transparent thermoplastic interlayer and with the second glass sheet, such that the coloured polymer layer is in direct contact with the interlayer; degassing, during which the air trapped between the glass sheets and the thermoplastic interlayer is removed; and heat-treating the laminated glass, under pressure and/or vacuum, at a temperature of between 100 and 200°C, during which the colouring agent in the polymer layer migrates towards the thermoplastic interlayer and the laminated glazing is assembled.