Mica Sandwich Panels Using Silicate Adhesives

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Solution Overview

Problem

Mica-based sandwich structures, particularly honeycomb structures, exhibit limited thermal resistance due to the use of silicone-based adhesives, which poses a security issue in fire-resistant applications.

Innovation Solution

The use of alkali metal silicates as adhesives, such as lithium, sodium, and potassium silicates, to bond mica paper layers with a folded core, forming a foam structure that enhances mechanical strength and thermal insulation by increasing the contact surface and reducing fire propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If silicone-based adhesive is used to bond mica paper layers, then ease of manufacture is improved, but thermal resistance deteriorates

Engineering Contradiction:
Improveease of manufactureVSAvoidthermal resistance
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The patent changes the chemical composition parameters of the adhesive from silicone-based to alkali metal silicate-based, fundamentally altering the material properties to achieve both ease of manufacture and superior thermal resistance. This parameter change enables the adhesive to withstand high temperatures while maintaining bonding effectiveness.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite adhesive system using alkali metal silicates (such as lithium silicate, sodium silicate, or potassium silicate) that combines the benefits of mineral-based thermal stability with adhesive bonding properties. This composite material approach resolves the contradiction by integrating multiple functional properties into a single adhesive system.

Inventive Principle:
Principle #40Composite materials

2Temperature

If alkali metal silicate adhesive is used to bond mica paper layers, then thermal resistance is improved, but device complexity increases

Engineering Contradiction:
Improvethermal resistanceVSAvoiddevice complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The alkali metal silicate adhesive exhibits self-foaming behavior when exposed to heat, automatically filling voids and crevices in the honeycomb structure without requiring additional processing steps or tools. This self-service mechanism simplifies the overall manufacturing process despite the advanced material properties, as the adhesive autonomously optimizes its distribution and bonding effectiveness.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The adhesive utilizes phase transition from liquid to foam structure when heated, automatically filling the honeycomb core voids and creating a integrated bonding system. This phase transition simplifies the manufacturing process by eliminating the need for complex application equipment or multi-step procedures, as the material self-adjusts its state to achieve optimal bonding.

Inventive Principle:
Principle #36Phase transitions

3Temperature

If foam structure is formed by alkali metal silicate, then thermal insulation is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvethermal insulationVSAvoidmanufacturing precision
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The invention deliberately creates a porous foam structure within the honeycomb core using alkali metal silicate adhesive. This porous configuration provides excellent thermal insulation by trapping air pockets and reducing heat conduction pathways. The controlled porosity is achieved through the adhesive's inherent foaming characteristics, which naturally create the desired structure without requiring precision control of each individual pore.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The adhesive autonomously forms the foam structure and fills the honeycomb voids through self-foaming when heated, eliminating the need for precise manual control of foam expansion. This self-service mechanism reduces manufacturing precision requirements by allowing the material to self-regulate its expansion and distribution, achieving uniform thermal insulation without complex process control.

Inventive Principle:
Principle #25Self-service

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 alkali metal silicate adhesive system improves the fire resistance and mechanical strength of mica-based sandwich panels by forming a foamed structure that completely embeds the core, offering superior thermal insulation and reducing fire propagation.

Implementation Method 1

the alkali metal silicate adhesive system improves the fire resistance and mechanical strength of mica-based sandwich panels by forming a foamed structure that completely embeds the core

Methodology Applied
Scientific EffectFoam formation: Foam

Implementation Method 2

coating of a liquid mineral solution comprising said alkali metal silicate(s) onto a first layer comprising mica paper, or disposing a fibre mat impregnated with said alkali metal silicate(s) onto said first layer, thereby forming a first hydrated alkali metal silicate(s) surface

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 3

heating the obtained foldcore or honeycomb sandwich structure at a temperature comprised between 250 and 350°C, preferably between 270 and 330°C for a time period comprised between 1 and 20 minutes, preferably between 5 and 15 minutes

Methodology Applied
Scientific EffectThermal curing: Heat Treatment

Implementation Method 4

a folded core or honeycomb structure comprising (or preferably consisting of) mica paper

Methodology Applied
Scientific EffectGeometric structure: Geometry

Data Source

PatentEP4054834B1Mica based sandwich structures
Publication Date: 2023.11.29 COGEBRI SA
  • EP4054834B1 patent drawingFigure 1

AI summary

The present invention is related to a composite sandwich panel (1) a comprising a first layer (2) comprising mica paper, a folded core or honeycomb structure (3) comprising mica paper and a second layer (5) comprising mica paper; characterised in that the first (2) and second (5) layers comprising mica paper are glued onto the foldcore by means of mineral adhesive comprising one or more alkali metal silicate(s).