High-Strain Seal Material for Clean Peeling After Heat Exposure

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Solution Overview

Problem

Existing sealing members fail to maintain high sealing performance and ease of peeling after exposure to high-temperature environments for extended periods, leading to potential breakage and residue issues during peeling, which complicates recycling.

Innovation Solution

A sealing member with a surface portion having a breaking strain of 500% or more and a tensile force greater than the adhesive force, designed to withstand 100°C for 7 days, allowing easy peeling without breaking and minimizing residue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sealing member is designed to adhere strongly to the adherend to maintain high sealing performance, then the sealing performance is improved, but the ease of peeling deteriorates

Engineering Contradiction:
Improvesealing performanceVSAvoidease of peeling
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention changes the physical-chemical parameters of the adhesive layer by controlling the glass transition temperature (Tg) to be -50°C or lower and the hydroxyl value to be 10 mg KOH/g or higher. These parameter changes enable the adhesive to maintain strong adhesion at service temperatures while allowing easy peeling when heated to 80°C or higher, thus resolving the contradiction between sealing performance and ease of peeling.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention utilizes the phase transition of the adhesive layer at elevated temperatures. When the sealing member is heated to 80°C or higher, the adhesive layer undergoes a phase transition that reduces its adhesion strength, enabling easy peeling. This phase transition mechanism allows the sealing member to maintain strong adhesion during normal use while facilitating easy removal when heated, resolving the contradiction between strong adhesion and easy peeling.

Inventive Principle:
Principle #36Phase transitions

2Stability of the object's composition

If the sealing member is exposed to high-temperature environment for a long period to achieve stable sealing, then the sealing stability is improved, but the material strength deteriorates causing breakage during peeling

Engineering Contradiction:
Improvesealing stabilityVSAvoidmaterial strength
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The invention changes the chemical composition parameters of the adhesive layer by controlling the glass transition temperature (Tg) to be -50°C or lower and the hydroxyl value to be 10 mg KOH/g or higher. These parameter changes enable the adhesive to maintain its elastic properties and strength even after long-term exposure to high temperatures, preventing breakage during peeling while maintaining sealing stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite adhesive layer made from polyol and polyisocyanate that creates a unique molecular structure with specific Tg and hydroxyl value characteristics. This composite material structure provides both long-term thermal stability for maintaining sealing performance and sufficient strength to prevent breakage during peeling operations.

Inventive Principle:
Principle #40Composite materials

3Reliability

If the adhesive force is increased to ensure strong adhesion, then the sealing performance is improved, but the residue during peeling increases

Engineering Contradiction:
Improvesealing performanceVSAvoidadhesive residue
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The invention changes the chemical parameters of the adhesive layer by controlling the glass transition temperature (Tg) to be -50°C or lower and the hydroxyl value to be 10 mg KOH/g or higher. These parameter changes enable the adhesive to maintain strong bonding at service temperatures while allowing clean peeling with minimal residue when heated to 80°C or higher, thus resolving the contradiction between strong adhesion and minimal residue.

Inventive Principle:
Principle #35Parameter changes

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 sealing member maintains watertight performance and facilitates easy peeling even after exposure to high temperatures, reducing breakage and residue, thus enhancing recyclability.

Implementation Method 1

the surface portion has a breaking strain of 500% or more

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4644508A1Seal material
Publication Date: 2025.11.05 NITTO DENKO CORP
  • EP4644508A1 patent drawingFigure 1~2
  • EP4644508A1 patent drawingFigure 3A~3B
  • EP4644508A1 patent drawingFigure 4A

AI summary

A sealing member 1a has a thickness t of 1 to 40 mm. The sealing member 1a has surface portions 10e. The surface portion 10e each includes a surface 11 in a thickness direction of the sealing member 1a, and the surface portion 10e has a thickness of 300 µm. The surface portion 10e has a breaking strain of 500%. In addition, the surface portion 10e satisfies a requirement: tensile force FA [N/20 mm] > adhesive force FB [N/20 mm]. The tensile force FA is expressed as F1·tA·20/S1. The adhesive force FB is a 90° peel adhesion [N/20 mm], which is measurable by maintaining an environmental temperature of a test piece at 100°C for 7 days while the test piece prepared from the sealing member being adhered to a test plate, and by conducting a measurement by peeling the test piece from the test plate in accordance with Japanese Industrial Standards (JIS) Z 0237:2022.