Inductively Heatable Adhesive Tape with Differential Detachment
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Solution Overview
Problem
Existing methods for bonding plastic substrates using heat-activated adhesives face challenges in efficiently heating the adhesive without damaging sensitive components and are economically unfavorable, especially when using high-frequency induction heating, which can lead to contamination and recycling issues.
Innovation Solution
A heat-activated bondable surface element with an electrically conductive structure and two layers of different heat-activatable adhesives, where one adhesive loses its bonding effect at a specific temperature, allowing controlled bonding and separation, thereby avoiding the drawbacks of prior art methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-frequency induction heating is used to heat the adhesive, then heating speed is improved, but electronic components are damaged and contamination occurs
Solution Approach 1:
The adhesive layer is segmented into two distinct adhesive layers with different thermal behaviors. The first adhesive layer has a lower decomposition temperature and decomposes at a controlled rate when heated, while the second adhesive layer has a higher decomposition temperature and maintains structural integrity. This segmentation allows the heating process to be controlled such that the first layer decomposes and releases gas to create porosity without damaging electronic components, while the second layer provides the necessary bonding strength.
Solution Approach 2:
The invention changes the thermal parameters of the adhesive system by using two adhesives with different decomposition temperatures. This parameter differentiation allows for controlled thermal processing where the first adhesive decomposes at a lower temperature range, creating porosity and releasing gas, while the second adhesive remains stable and provides structural support, thereby enabling high-frequency induction heating without component damage.
2Productivity
If high-frequency induction heating is used to heat the adhesive, then heating efficiency is improved, but contamination and recycling issues arise
Solution Approach 1:
The adhesive system is divided into two functional layers: the first layer serves as a sacrificial adhesive that decomposes and releases gas to create porosity, while the second layer serves as the structural adhesive that maintains bonding. This segmentation allows the decomposing adhesive to be easily removed or degraded without affecting the structural integrity, thereby reducing contamination and facilitating recycling.
Solution Approach 2:
The first adhesive layer is designed to decompose and release gas during the heating process, effectively being discarded or transformed into harmless byproducts. This allows the second adhesive layer to remain as the functional bonding material, reducing overall contamination and enabling easier recovery and recycling of the structural adhesive without interference from the decomposed first layer.
3Strength
If heat-activated adhesive is used to bond plastic substrates, then adhesive strength is improved, but heating process becomes complex and time-consuming
Solution Approach 1:
The invention merges the functions of two adhesives into a single laminated structure, where the first adhesive provides controlled decomposition and gas release, and the second adhesive provides structural bonding. This combined structure simplifies the heating process by enabling simultaneous thermal processing of both layers, eliminating the need for separate heating steps and reducing overall process complexity while maintaining high adhesive strength.
Solution Approach 2:
The first adhesive undergoes a phase transition from solid to gas during heating, releasing gas that creates porosity and facilitates bonding. This phase transition occurs at a controlled temperature range, allowing for simplified heating processes that do not require precise temperature control beyond the decomposition point of the first adhesive, thereby reducing process complexity while maintaining strong bonds.
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
This approach enables controlled bonding and separation of plastic-plastic bonds without damaging components, maintaining high adhesive strength and facilitating clean recycling by precisely managing the adhesive's activation and deactivation temperatures.
Implementation Method 1
the bonding is effected by exposing the heat-activated bonded surface element to a first temperature (T1) at which simultaneous heat activation of the two heat-activated adhesives takes place
Implementation Method 2
the heating is achieved on the one hand by induced eddy currents in electrically conductive receptors
Implementation Method 3
adhesives that have little or no inherent tack at room temperature, but under the influence of heat the adhesive strength required for bonding to the respective bonding substrates build up
Implementation Method 4
the re-release is effected by the bonding point being exposed to the second temperature (T2), at which, under given conditions, only one of the heat-activatable layers loses its adhesive effect in the adhesive bond to such an extent that the adhesive bond separates
Data Source
Figure 1
AI summary
The invention relates to a method for gluing together and detaching again two substrate surfaces, wherein a surface element that can be glued by heat activation is used for gluing. The surface element that can be glued by heat activation comprises at least one electrically conductive sheet material and at least two layers made of different heat-activatable adhesive compounds, wherein the first heat-activatable adhesive compound layer is substantially located on the one side of the electrically conductive sheet material and the second heat-activatable adhesive compound is substantially located on the other side of the electrically conductive sheet material. The method is characterized in that the gluing is effected by exposing the surface element that can be glued by heat activation to a temperature T1, at which a simultaneous heat activation of the two heat-activatable adhesive compounds takes place. The detachment is effected by exposing the gluing site to a temperature T2, at which under predetermined conditions only one of the heat-activatable layers of the surface element that can be glued by heat activation loses the adhesive effect thereof in the adhesive bond so much that the adhesive bond is separated.