Flexible Adhesive Tape for Structural Bonding
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Solution Overview
Problem
Existing structural bonding methods using thermally curing liquid adhesives face issues such as lack of initial tack, adhesive bleeding, and limited ability to bridge gaps, especially in complex or uneven surfaces, and are not suitable for high-temperature applications.
Innovation Solution
A flexible, pressure-sensitive adhesive sheet structure with an open-cell, chemically cross-linked foam substrate and a thermally curable pressure-sensitive adhesive on both sides, which provides initial tack, prevents bleeding, and can bridge gaps up to a few mm, while maintaining dimensional stability during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermally curing liquid adhesives are used for structural bonding, then high bond strength can be achieved, but initial tack is lacking and components slip during curing
Solution Approach 1:
The adhesive is applied in a pre-tacky state before thermal curing, allowing components to be positioned and held securely before the final bond is formed. The pressure-sensitive adhesive provides immediate initial tack, while the thermally curable component develops full bond strength during subsequent heating.
2Strength
If high epoxy content is used in liquid adhesive, then bond strength increases, but tackiness is lost
Solution Approach 1:
The invention combines two adhesive systems into a single composite: a pressure-sensitive adhesive component that provides immediate tack, and a thermally curable adhesive component (with epoxy, polyurethane, or acrylic) that provides high bond strength. This composite formulation allows both tackiness and strength to coexist without the trade-off present in single-component systems.
3Area of stationary object
If liquid adhesive is used for large-area bonding or uneven surfaces, then coverage is improved, but adhesive bleeding and contamination occur
Solution Approach 1:
The adhesive composition is designed to change its flow parameters in response to temperature. At application temperature, it maintains controlled viscosity to prevent bleeding. During thermal curing, the viscosity increases as the thermally curable component sets, locking the adhesive in place and preventing contamination while maintaining coverage over large areas and uneven surfaces.
4Stability of the object's composition
If pre-crosslinking is done to prevent bleeding, then adhesive stability improves, but gap-bridging capability is reduced
Solution Approach 1:
The pressure-sensitive adhesive component provides preliminary stability and tack at room temperature without pre-crosslinking, allowing the adhesive to remain stable during application. The thermally curable component then provides controlled crosslinking during curing, maintaining gap-bridging capability throughout the process while preventing bleeding once cured.
5Stability of the object's composition
If fabric carrier is used in adhesive tape, then dimensional stability improves, but heat resistance is limited for high-temperature curing
Solution Approach 1:
The invention uses a flexible foam substrate instead of fabric carrier. The foam substrate provides dimensional stability while being thermally stable at high curing temperatures (up to 200°C or higher). The open-cell structure of the foam allows the thermally curable adhesive to penetrate and bond effectively, and the foam itself can serve as part of the bonding structure.
6Strength
If activation occurs at elevated temperatures, then bond strength is maximized, but sensitive components are damaged
Solution Approach 1:
The pressure-sensitive adhesive component provides preliminary bonding at room temperature or low temperature, securing components in place before thermal curing. This allows sensitive components to be positioned and initially bonded without exposure to high temperatures, and the thermal curing is then applied to maximize bond strength for heat-tolerant applications.
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
Ensures precise bonding with high bonding strengths and gap filling capabilities, suitable for various materials and temperatures, including high-temperature applications.
Implementation Method 1
A flexible, pressure-sensitive adhesive sheet structure with an open-cell, chemically cross-linked foam substrate and a thermally curable pressure-sensitive adhesive on both sides, which provides initial tack
Implementation Method 2
thermally curable pressure-sensitive adhesive on both sides... thermally curable adhesive comprises at least (i) a polymer, at least (ii) a reactive component, at least (iii) an activator
Implementation Method 3
the open-cell foam substrate (a) is a chemically cross-linked foam
Implementation Method 4
One way to prevent 'bleeding' due to liquefaction is to pre-crosslink the polymer component typically present in the liquid adhesive
Data Source
AI summary
The present invention relates to a flexible pressure-sensitive flat adhesive structure for improved structural adhesion, in particular for gap width compensation, of various materials such as e.g. metal, wood, glass and/or plastic.