Epoxy Resin Composition for Pre-Cured Bonding Without Metal Joining
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Solution Overview
Problem
Existing thermosetting one-component epoxy resin compositions used in vehicle bodywork construction lack sufficient lap shear strength at room and elevated temperatures, such as 180°C, without additional metal joining techniques, and exhibit premature failure due to fatigue under dynamic movement.
Innovation Solution
A thermosetting one-component epoxy resin composition comprising a specific blend of liquid and solid epoxy resins, a latent curing agent, a core-shell polymer, and a terminally blocked polyurethane polymer, optimized with specific weight ratios and additives to enhance mechanical strength, lap shear strength, impact peel, glass transition temperature, and fatigue resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If partial curing is performed by induction heating before final curing, then the bonding process becomes faster and less expensive, but the lap shear strength achieves too low values
Solution Approach 1:
The patent modifies the chemical composition parameters of the epoxy resin system by incorporating specific rubber modifiers (core-shell polymers and polyurethane polymers) that alter the curing kinetics and mechanical properties. This enables the adhesive to achieve sufficient lap shear strength even with limited energy input during partial curing, while maintaining the productivity benefit of reduced curing time
Solution Approach 2:
The patent creates a composite adhesive system by combining epoxy resin with rubber modifiers (core-shell polymers and polyurethane polymers). This composite formulation enhances both the mechanical strength and flexibility of the adhesive, allowing it to withstand dynamic movements and achieve high lap shear strength values even when only partially cured before final curing
2Reliability
If additional metal joining techniques are used, then the mechanical strength and reliability are improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent develops a universal adhesive formulation that performs multiple functions: it provides strong bonding, flexibility for dynamic movements, and sufficient strength during partial curing. This multi-functional adhesive eliminates the need for additional metal joining techniques, simplifying the overall bonding process while maintaining high reliability
Solution Approach 2:
The patent replaces mechanical joining systems (welding, riveting) with an enhanced chemical bonding system. The modified epoxy resin composition achieves such high mechanical strength and fatigue resistance that it can fully substitute for traditional mechanical joining techniques, reducing device complexity and manufacturing cost
3Strength
If the adhesive is fully cured at high temperature, then the mechanical strength is maximized, but the adhesion fails at 180°C without additional metal joining techniques
Solution Approach 1:
The patent modifies the thermal and mechanical parameters of the adhesive by incorporating rubber modifiers that enhance high-temperature stability. This compositional change allows the adhesive to maintain adhesion and mechanical strength at service temperatures up to 180°C, eliminating the need for additional metal joining techniques even at elevated 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 composition achieves high lap shear strength values at both room and elevated temperatures, improved mechanical properties, enhanced impact resistance, and increased fatigue resistance, allowing for effective bonding without additional metal joining techniques.
Implementation Method 1
at least one core-shell polymer D1; and at least one terminally blocked polyurethane polymer D2
Data Source
Figure 1
AI summary
The invention relates to a thermosetting one-component epoxy resin composition comprising at least one liquid aromatic epoxy resin A1, at least one solid epoxy resin A2, at least one curing agent B for epoxy resins, at least one core-shell polymer D1 and at least one terminally blocked polyurethane polymer D2. The weight ratio of the at least one liquid epoxy resin A1 to the at least one solid epoxy resin A2 (A1/A2) is from 1.75 - 3.75 and wherein the weight ratio of the at least one core-shell polymer D1 to the at least one terminally blocked polyurethane polymer D2 (D1/D2) is from 1.2 - 4. The epoxy resin compositions that have sufficient lap shear strength without additional metal joining techniques after preliminary curing. Furthermore, the fully cured epoxy resin compositions provide good values for mechanical strength, lap shear strength, impact peel, glass transition temperature (Tg) and fatigue resistance.