Foaming Adhesive Sheet Composition for Bend-Resistant Bonding
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Solution Overview
Problem
Foaming adhesive sheets experience issues with adhesive layer peeling off from the substrate due to bending or burrs, and the adhesiveness is compromised by the inclusion of a foaming agent, leading to decreased handling and workability.
Innovation Solution
A foaming adhesive sheet with a curable adhesive layer and a foaming agent, where the peeling force measured by SAICAS is 2.0 N or more, ensuring excellent adhesiveness to the substrate, even under strict cross-shaped bending tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a foaming agent is included in the adhesive layer, then the foaming adhesive sheet can expand and cure to bond members, but the adhesiveness of the adhesive layer decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive layer by incorporating specific curable adhesives (epoxy resins, polyester resins, polyurethane resins) in controlled amounts alongside the foaming agent. This parameter adjustment allows the adhesive layer to maintain both foaming capability and sufficient adhesiveness before curing.
Solution Approach 2:
The adhesive layer is formulated as a composite material containing multiple components: curable adhesive (epoxy/polyester/polyurethane resin), foaming agent, and optional fillers. This composite structure enables the layer to exhibit both bonding strength and foaming expansion properties simultaneously.
2Ease of operation
If the adhesive layer is made non-pressure-sensitive for better handling, then workability improves, but close adhesiveness decreases
Solution Approach 1:
The adhesive layer exhibits dynamic properties: before curing it remains non-pressure-sensitive for easy handling and positioning, but upon heating it transforms into a cured state with high close adhesiveness. This dynamic transition resolves the contradiction between handling ease and bonding strength.
Solution Approach 2:
The adhesive layer undergoes a phase transition from uncured (non-pressure-sensitive, easy to handle) to cured (highly adhesive) state through thermal activation. This phase change allows the material to satisfy both handling requirements and bonding requirements at different stages of the process.
3Temperature
If heat resistant substrate is used for high temperature curing, then curing temperature can be increased, but close adhesiveness of the substrate decreases
Solution Approach 1:
The patent selects curable adhesives with appropriate glass transition temperatures and curing characteristics that match the high-temperature curing process. By adjusting the adhesive composition parameters (resin type, molecular weight, curing agent ratio), the system achieves good adhesion to heat-resistant substrates even at elevated curing temperatures.
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 adhesive sheet maintains strong adhesiveness to the substrate, preventing peeling during bending and when encountering burrs, while maintaining non-pressure-sensitive properties for improved handling and workability.
Implementation Method 1
an adhesive layer which is placed on at least one surface side of the substrate and includes a curable adhesive and a foaming agent
Implementation Method 2
the adhesive layer includes a curable adhesive
Data Source
AI summary
A foaming adhesive sheet comprising a substrate and an adhesive layer placed on at least one surface side of the substrate; wherein the adhesive layer includes a curable adhesive, and a foaming agent; and a peeling force of a surface side where the adhesive layer is placed, measured by SAICAS (Surface And Interfacial Cutting Analysis System) method is 2.0 N or more.