Structural Adhesive Composition for Bonding Dissimilar Materials
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional epoxy structural adhesives used in the automotive and aerospace industries have high adhesive strength and impact-resistance but low elongation, making them unsuitable for bonding heterogeneous materials with different thermal expansion coefficients, particularly lightweight materials in future automobiles.
Innovation Solution
A structural adhesive composition combining an epoxy resin with a urethane resin formed using a specific polyol, rubber particles or microfibers, a modified epoxy resin, an adhesion promoter, a filler, and a catalyst, which improves elongation and impact-resistance while maintaining mechanical properties, allowing for better bonding of dissimilar materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional epoxy resin is used for structural adhesive, then adhesive strength and impact-resistance are improved, but elongation is reduced making it unsuitable for bonding heterogeneous materials
Solution Approach 1:
The patent creates a composite adhesive system by incorporating rubber particles (5-20 wt%) and microfibers (0.1-10 wt%) into the epoxy resin matrix. This composite structure allows the adhesive to maintain the high strength and impact-resistance of epoxy while gaining the elongation and flexibility from rubber particles and microfibers, enabling it to bond heterogeneous materials with different thermal expansion coefficients
Solution Approach 2:
The patent modifies the physical and chemical parameters of the epoxy resin by controlling the size distribution of rubber particles (0.1-10 μm) and microfibers (1-100 μm), and by optimizing their content ratios. These parameter changes transform the rigid epoxy structure into a more flexible composite system that can accommodate dimensional changes from thermal expansion while maintaining bonding strength
2Strength
If epoxy resin with high impact-resistance is used for bonding steel sheets, then impact-resistance is improved, but elongation remains smaller than 5% preventing absorption of thermal expansion dimensional changes
Solution Approach 1:
The patent incorporates rubber particles as flexible inclusions within the epoxy matrix. These rubber particles act as flexible elements that can deform and absorb dimensional changes caused by thermal expansion, allowing the adhesive to maintain both high impact-resistance and sufficient elongation for bonding steel sheets in automotive applications
3Strength
If nanoparticles are added to epoxy resin to improve impact-resistance and adhesion, then mechanical properties are improved, but elongation suitable for bonding dissimilar materials is not achieved
Solution Approach 1:
The patent uses nanoparticles as fillers within the epoxy matrix to locally enhance mechanical properties and impact-resistance, while simultaneously incorporating rubber particles and microfibers as separate phases that provide macro-level flexibility and elongation. This multi-scale approach allows different regions of the adhesive to perform different functions: nanoparticles for strength enhancement and rubber/microfibers for elongation
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 enhanced adhesion and impact-resistance with high elongation, enabling effective bonding of diverse materials in automotive and aerospace applications by introducing flexibility and controlled polarity through the urethane resin and rubber particles, thus addressing the limitations of conventional epoxy adhesives.
Implementation Method 1
the polyol contains a hydroxyl-functional group (—OH) represented by a following Chemical Formula 1... the functional group may be introduced to a branched chain of an urethane main structure. This may secure the flexibility of the structural adhesive composition prepared using the urethane resin and at the same time, improve the adhesive strength by controlling the polarity.
Implementation Method 2
The epoxy resin is an intermediate (prepolymer) of a thermosetting resin, and reacts with a curing agent to form a three-dimensional network structure as a cured product of the epoxy resin showing an inherent properties of an epoxy.
Data Source
AI summary
A structural adhesive composition having high elongation and impact resistance contains an epoxy resin, a urethane resin formed by using a polyol comprising a long chain as a functional group, and an epoxy curing agent.