Foamable Adhesive Sheet Timing for Stronger Bonded Joints
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Solution Overview
Problem
Adhesive compositions with foaming agents face issues where the adhesive strength decreases, leading to inferior reliability and durability of adhered members, despite the foaming start temperature and curing start temperature having a predetermined relationship.
Innovation Solution
A method involving the use of a thermally expandable microcapsule as a foaming agent, where the slope of the foaming ratio-time curve and the slope of the DSC curve are controlled to ensure the foaming agent expands before the curing reaction of the thermosetting resin, maintaining adhesive layer thickness and enhancing adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a foaming agent is added to adhesive composition, then foamability is improved, but adhesive strength decreases
Solution Approach 1:
The patent controls the foaming start temperature T1 and curing start temperature T2 to satisfy T1 ≤ T2, ensuring proper sequence of foaming followed by curing. This temperature parameter control resolves the contradiction by optimizing the thermal processing conditions to maintain both foamability and adhesive strength
Solution Approach 2:
The foaming agent is designed to expand before the curing reaction occurs. By performing the foaming action preliminary to curing, the adhesive composition achieves proper foam structure formation while maintaining sufficient adhesive strength through subsequent curing
2Productivity
If foaming start temperature T1 is lower than curing start temperature T2, then foaming occurs before curing, but adhesive strength may still decrease
Solution Approach 1:
The patent uses differential scanning calorimetry (DSC) to measure and control the relationship between foaming start temperature T1 and curing start temperature T2. This feedback mechanism ensures that the heating conditions properly satisfy T1 ≤ T2, resolving the contradiction by providing precise thermal process control
Solution Approach 2:
The patent optimizes the specific temperature values and their relationship (T1 ≤ T2) to ensure proper sequencing. By carefully controlling these thermal parameters, the invention maintains both foaming performance and adhesive strength
3Strength
If adhesive layer thickness is maintained during foaming, then adhesive strength is improved, but foaming expansion may be restricted
Solution Approach 1:
The foaming agent expands preliminary to the curing reaction, allowing maximum volumetric expansion while the adhesive is still in a flexible, uncured state. This preliminary foaming action resolves the contradiction by achieving both充分的膨胀 and subsequent strength development through curing
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 method improves adhesive strength, resulting in enhanced reliability and durability of the adhered members by ensuring the foaming agent expands sufficiently before the curing reaction occurs.
Implementation Method 1
the foaming agent is a thermally expandable microcapsule
Implementation Method 2
curing the adhesive composition by heating
Data Source
Figure 1A~2
Figure 3~4
Figure 5~6
AI summary
The present disclosure provides a method for producing a product, the method comprising: a placing step of placing an adhesive composition, including a thermosetting resin and a foaming agent, between a first member and a second member; and an adhering step of adhering the first member and the second member by foaming and curing the adhesive composition by heating, wherein the foaming agent is a thermally expandable microcapsule; A < B when following conditions are satisfied, in a foaming ratio-time curve where time is on a horizontal axis and a foaming ratio of the foaming agent is on a vertical axis, when a differential scanning calorimetry is carried out to the foaming agent, using a differential scanning calorimeter including a camera, under heating conditions in the adhering step, a slope of a tangent line to the curve at a top of a peak, on a longer time side of the peak, is regarded as A, and in a DSC curve where time is on a horizontal axis and a heat flow is on a vertical axis, when a differential scanning calorimetry is carried out to the adhesive composition under the heating conditions in the adhering step, a slope of a tangent line to the curve at a top of an exothermic peak, on a longer time side of the exothermic peak, is regarded as B; and the adhesive composition is heated so that T1 < T2 when following conditions are satisfied in the adhering step, in a foaming ratio-time curve where time is on a horizontal axis and a foaming ratio of the foaming agent is on a vertical axis, when a differential scanning calorimetry is carried out to the foaming agent, using a differential scanning calorimeter including a camera, time corresponding to a top of a peak is regarded as T1, and in a DSC curve where time is on a horizontal axis and a heat flow is on a vertical axis, when a differential scanning calorimetry is carried out to a composition where the foaming agent is excluded from the adhesive composition, time corresponding to a top of an exothermic peak is regarded as T2.