Decorative Mirror Coating Dissolution via Phosphate Salt

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Solution Overview

Problem

The production of partial mirrors with high mechanical resistance and varying designs is economically inefficient due to the challenges of depositing reflective coatings on large substrates and the need for high-temperature resistant coatings, especially when tempered glass cannot be cut to specific dimensions.

Innovation Solution

A method involving a soda-lime-silica glass sheet coated with a reflective layer, where a phosphate salt composition is selectively applied to areas intended to become non-reflective, and then tempered at high temperatures to dissolve the coating, creating non-reflective zones, allowing for the production of decorative mirrors with reflective and non-reflective patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the reflective coating is deposited after thermal toughening, then the mechanical strength and impact resistance of the mirror is improved, but the production cost increases and the manufacturing process becomes more complex due to the inability to cut toughened glass

Engineering Contradiction:

Improveimpact resistanceVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The reflective coating is deposited on the glass substrate before thermal toughening, allowing the glass to be cut and processed while coated. The coating is then protected from dissolution in areas where it should remain by applying a protective composition selectively, rather than requiring post-toughening coating operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of protecting the coating from heat everywhere and then removing it selectively, the invention inverts the approach by applying a protective composition only in areas where the coating should be preserved, allowing the coating to be dissolved by heat in all other areas during toughening.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If the reflective coating is deposited before thermal toughening on large substrates, then the production is more economically attractive, but the coating must resist temperatures above 500°C which requires specialized high-temperature resistant coatings

Engineering Contradiction:

Improveproduction economyVSAvoidcoating temperature resistance

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The protective composition is applied selectively only in specific zones where the reflective coating needs to be preserved, rather than coating the entire substrate. This allows the coating to be exposed to high temperatures in non-protected areas during toughening, dissolving it to create non-reflective zones, while remaining intact in protected areas.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If masks are used to deposit reflective coating only on certain areas of large substrates, then partial mirrors can be produced, but the production cost increases significantly

Engineering Contradiction:

Improvedesign customizationVSAvoidproduction cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The entire substrate is coated with the reflective coating in advance using economical large-area deposition techniques without masks. The selective pattern is then created by applying the protective composition only in desired areas before toughening, avoiding the need for expensive masked deposition or post-processing laser ablation.

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 reduces production costs and enables the creation of partial mirrors with high mechanical resistance and customizable designs by dissolving the reflective coating in non-reflective zones during tempering, resulting in mirrors with specific reflection and transmission properties suitable for various applications.

Implementation Method 1

causing the dissolution of the reflective coating in the application zones so as to form said non-reflective zones

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

the glass sheet can be thermally toughened, by heating it above its glass transition temperature and then rapidly cooling it so as to create compressive stresses on the glass surface

Methodology Applied

Scientific EffectThermal tempering: Heat Treatment

Data Source

PatentEP3826972B1Method for obtaining a decorative mirror

Publication Date: 2024.03.27 SAINT GOBAIN VITRAGE SA

AI summary

The subject of the invention is a method for obtaining a decorative mirror comprising reflective zones that form a pattern and non-reflective zones, said method comprising the following steps: - the supply of a sheet of soda-lime-silica glass coated with a reflective coating over the entirety of one of its faces, then - a step of applying a composition containing a phosphate salt to said reflective coating only in application zones, said application zones being the zones intended to become the non-reflective zones, then - a step of tempering said sheet of glass, in which said sheet of glass is subjected to a temperature of at least 550°C, causing the reflective coating to discern walls in the application zones so as to form said non-reflective zones in which the sheet of glass is not coated.