Thermally Expandable Sheet with Elastic Buffer and Cover Layers

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Solution Overview

Problem

Thermally expandable sheets face issues with cracks in the thermal expansion layer when bent, leading to poor image formation and detachment from the base material, affecting the appearance and integrity of shaped objects.

Innovation Solution

A thermally expandable sheet is designed with a stress buffer layer and a cover layer, both with elastic properties, to reduce stress differences and prevent cracking, while the thermal expansion layer contains a first thermally expandable material and binder, with the cover layer concealing any cracks that may occur.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the thermal expansion layer is made thin for better flexibility, then ease of operation improves, but reliability deteriorates due to increased crack susceptibility

Engineering Contradiction:

ImproveflexibilityVSAvoidcrack resistance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent uses a composite structure consisting of a base material sheet, a thermal expansion layer, and a cover layer. This composite construction allows the thermal expansion layer to remain thin for flexibility while the cover layer provides mechanical protection against cracks, resolving the contradiction between flexibility and crack resistance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The cover layer is applied in advance to protect the thermal expansion layer from mechanical stress and cracks before the sheet is used. This beforehand cushioning prevents cracks from forming in the thin thermal expansion layer, maintaining both flexibility and reliability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If the thermal expansion layer is made thick for better expansion effect, then productivity improves, but device complexity increases due to adhesion issues

Engineering Contradiction:

Improveexpansion effectVSAvoidadhesion structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The composite structure with base material sheet and cover layer allows the thermal expansion layer to be thicker for better expansion effect while the surrounding layers provide structural support and adhesion, preventing detachment issues that would otherwise require complex adhesion mechanisms.

Inventive Principle:

Principle #40Composite materials

3Strength

If the thermal expansion layer is made rigid for better structural stability, then strength improves, but adaptability deteriorates due to crack formation when bent

Engineering Contradiction:

Improvestructural stabilityVSAvoidbending flexibility

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent segments the structure into a base material sheet, thermal expansion layer, and cover layer. This segmentation allows each layer to have optimized properties - the base material provides structural stability, the thermal expansion layer provides expansion function, and the cover layer provides bending flexibility, resolving the contradiction between strength and adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cover layer acts as a flexible shell that protects the thermal expansion layer while allowing bending. This flexible covering enables the overall structure to be adaptable to bending operations without compromising the structural stability provided by the base material and thermal expansion layer.

Inventive Principle:

Principle #30Flexible shells and thin films

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 solution effectively suppresses cracking and adhesion issues, maintaining the aesthetic quality and structural integrity of shaped objects by reducing stress differences and preventing detachment of the thermal expansion layer from the base material.

Implementation Method 1

a stress buffer layer provided on one surface of a base material and having an elastic property, a thermal expansion layer provided on the stress buffer layer and containing a first thermally expandable material that expands according to heat and a first binder, and a cover layer provided on the thermal expansion layer and having an elastic property

Methodology Applied

Scientific EffectElastic property: Elasticity

Implementation Method 2

a thermal expansion layer provided on the stress buffer layer and containing a first thermally expandable material that expands according to heat

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

A photothermal conversion layer for converting light into heat is formed on the thermally expandable sheet and the photothermal conversion layer is irradiated with light so that the thermal expansion layer can be partially or totally expanded

Methodology Applied

Scientific EffectPhotothermal conversion: Photoacoustic Effect

Data Source

PatentUS11648714B2Thermally expandable sheet and method of manufacturing thermally expandable sheet

Publication Date: 2023.05.16 CASIO COMPUTER CO LTD

AI summary

A thermally expandable sheet according to the present invention includes a stress buffer layer provided on one surface of a base material and having an elastic property, a thermal expansion layer provided on the stress buffer layer and containing a first thermally expandable material that expands according to heat and a first binder, and a cover layer provided on the thermal expansion layer and having an elastic property.