Thermosetting Adhesive Low-Temperature Curing Automotive Bonding
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Solution Overview
Problem
Current thermally curable adhesives either harden at too high temperatures, making them unsuitable for bonding temperature-sensitive components, or lack tackiness, limiting their application in the automotive industry and other temperature-sensitive environments.
Innovation Solution
A thermally curable, meltable adhesive comprising epoxy-functionalized acrylonitrile/butadiene copolymer with multiple epoxy groups and the reaction product of phthalic anhydride and diethylenetriamine, which can be processed at lower temperatures and cures within the range of 110°C to 230°C, maintaining tackiness and achieving high shear strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermally curable adhesives are used to achieve high bonding strength, then shear strength is improved, but curing temperature becomes too high (above 130°C), making them unsuitable for temperature-sensitive components
Solution Approach 1:
The patent changes the chemical parameters of the adhesive system by using a modified epoxy resin with lower ring strain and a specific hardener combination (dicyandiamide with imidazole-metal salt complex), which alters the curing kinetics to enable effective curing at lower temperatures (starting from 110°C) while maintaining high bond strength
Solution Approach 2:
The patent creates a composite curing system combining multiple hardeners (dicyandiamide, imidazole, and metal salt) with the modified epoxy resin, where each component contributes specific properties that collectively enable low-temperature curing with high strength development
2Temperature
If latent-reactive adhesive products with low light-off temperatures (40°C) are used to bond temperature-sensitive components, then curing temperature is reduced, but the adhesive products lack tackiness
Solution Approach 1:
The patent modifies the epoxy resin structure to have lower ring strain, which changes the reactivity parameters to provide optimal tackiness at room temperature while maintaining the ability to cure at low temperatures (110°C and above), eliminating the tackiness problem of conventional low-temperature adhesives
3Loss of time
If conventional epoxy adhesives are used to achieve rapid curing at moderate temperatures, then curing time is reduced, but storage stability deteriorates to several months only
Solution Approach 1:
The patent introduces imidazole and metal salt complex as intermediary catalysts that mediate between the epoxy resin and dicyandiamide hardener, enabling rapid curing at moderate temperatures (110-150°C) while the imidazole-metal salt complex provides controlled reactivity that maintains long-term storage stability
Solution Approach 2:
The patent changes the chemical structure of the epoxy resin to have lower ring strain, which modifies the reaction kinetics to achieve faster curing rates at moderate temperatures while the modified structure provides enhanced storage stability exceeding one year at room temperature
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 adhesive achieves rapid curing, high shear strength, and excellent storage stability, allowing for effective bonding and sealing in the automotive industry, including on temperature-sensitive substrates, with cohesive fracture patterns and no brittle failure.
Implementation Method 1
thermally curable from 110 °C, viscoelastic, high-strength 1K adhesive after curing
Implementation Method 2
meltable, preferably pressure-sensitive adhesive
Data Source
AI summary
An adhesive – in particular thermally curable, meltable, preferably tacky – which is thermally curable from a temperature of 110 °C, has a storage stability of approximately one month at 60 °C and for more than one year at 23 °C, and an adhesive tape produced therefrom, comprising an epoxy-functionalized acrylonitrile/butadiene copolymer with an average of more than 1.5 epoxy groups per molecule and the ground reaction product of phthalic anhydride and diethylenetriamine, for use in the automotive industry both in body-in-white on oiled sheets and in the paint shop on KTL-coated or otherwise painted sheets, for bonding and/or sealing, for example for hem seam bonding, hem seam sealing, seam sealing, underlining bonding, hole sealing and much more.