XNBR-Epoxy Adhesive Reduces Meander Formation
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Solution Overview
Problem
The challenge in hem-flange bonding during the curing of crash durable adhesives is meander formation, which leads to cracks and subsequent corrosion issues due to thermal stresses from differing thermal expansion rates in material structures.
Innovation Solution
Incorporating high molecular weight carboxylated acrylonitrile butadiene rubber-epoxy adducts (XNBR-epoxy adducts) into the adhesive composition to reduce meander formation, with a preferred composition containing at least 4-12 wt% rubber-epoxy adducts, providing improved heat stability and tackiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional crash durable adhesives are used for hem-flange bonding, then adhesive strength is achieved, but meander formation occurs during curing due to thermal stresses
Solution Approach 1:
The patent modifies the adhesive composition by incorporating rubber-epoxy adducts with specific molecular weight parameters (Mw > 60,000 Da and Mn > 10,000 Da) to change the rheological and thermal properties of the adhesive, thereby reducing meander formation while maintaining bonding strength
Solution Approach 2:
The patent creates a composite adhesive system by combining conventional crash durable adhesive components with rubber-epoxy adducts, leveraging the complementary properties of both materials to achieve both strength and reduced meander formation
2Reliability
If adhesive composition is optimized for strength, then bonding durability is improved, but heat stability deteriorates leading to increased meander formation
Solution Approach 1:
The patent changes the thermal and rheological parameters of the adhesive by adding rubber-epoxy adducts, which improve heat stability and reduce thermal expansion differences, thereby reducing meander formation during curing while maintaining bonding durability
3Stability of the object's composition
If high molecular weight rubber-epoxy adducts are added to reduce meander formation, then heat stability is improved, but viscosity increases
Solution Approach 1:
The patent carefully selects and controls the molecular weight parameters of the rubber-epoxy adducts (Mw > 60,000 Da and Mn > 10,000 Da) to achieve the optimal balance between heat stability improvement and viscosity control, ensuring the adhesive remains workable
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
Significantly reduces meander formation, enhancing hem-flange bonding performance and preventing corrosion by maintaining mechanical characteristics and improving thermal stability without compromising adhesive properties.
Implementation Method 1
meander formation in a joint part during the curing of the adhesives... due to thermal stresses from differing thermal expansion rates in material structures
Data Source
AI summary
The invention relates to an adhesive composition having an added component of rubber-epoxy such as XNBR-epoxy adducts. It was found that the new adhesive composition significantly reduces meander formation in the making of automotive parts.