Epoxy Adhesive Viscosity Control for Spray Application
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Solution Overview
Problem
One-component heat-curing epoxy resin adhesives used in the automotive industry are highly viscous at room temperature, making them difficult to apply as a spray and requiring higher temperatures, which complicates the painting process and can lead to contamination issues during the KTL process.
Innovation Solution
A one-component heat-curing epoxy resin composition with a specific formulation including epoxy resin, latent hardener, airgel particles, and toughness modifiers, which maintains low viscosity at application temperatures (40-70°C) and provides high wash-resistance and impact peel strength, allowing for efficient application and bonding without significant contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the adhesive is applied at room temperature, then the viscosity is very high making spray application difficult, but heating to reduce viscosity complicates the painting process and may cause contamination
Solution Approach 1:
The patent modifies the chemical composition parameters of the adhesive by incorporating specific additives and modifying the epoxy resin structure, which changes the viscosity-temperature relationship. This allows the adhesive to maintain low viscosity at room temperature for easy spray application without requiring external heating, thus avoiding process complexity and contamination risks
Solution Approach 2:
The patent introduces intermediary substances (additives and modifiers) that mediate between the epoxy resin and the application process. These intermediaries reduce viscosity and improve sprayability while maintaining wash resistance, eliminating the need for heating equipment and complex process control
2Ease of operation
If the adhesive is heated to reduce viscosity for spray application, then the application ease improves, but wash resistance decreases at higher temperatures
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating temperature-stable modifiers and additives that maintain the adhesive's wash resistance properties across a wide temperature range. This allows room temperature application with good wash resistance, eliminating the trade-off between application ease and reliability
Solution Approach 2:
The patent creates a composite adhesive system combining epoxy resin with multiple additives and modifiers. This composite formulation achieves synergistic effects where the combination of components provides both low viscosity for spray application and maintained wash resistance, without requiring temperature elevation
3Strength
If conventional epoxy adhesives are used, then good bonding strength is achieved, but very high viscosity prevents easy spray application
Solution Approach 1:
The patent modifies the viscosity parameter through chemical composition changes, incorporating additives and modifiers that reduce viscosity while preserving the bonding strength. This allows the adhesive to be easily sprayed while maintaining conventional epoxy's strong bonding capabilities
Solution Approach 2:
The patent develops a composite adhesive formulation that combines epoxy resin with viscosity-reducing additives and strength-maintaining modifiers. This composite achieves both low viscosity for spray application and high bonding strength, resolving the contradiction between ease of operation and strength
Data Source
AI summary
The invention relates to single-component thermosetting epoxy resin adhesives, comprising: a) at least one epoxy resin having, on average, more than one epoxy group per molecule; b) at least one latent hardener for epoxy resins; and c) 2-7 wt% aerogel particles, relative to the total weight of the single-component thermosetting epoxy resin adhesive, wherein the epoxy resin adhesive has a viscosity of 1000-4000 Pas, in particular 1000-3500 Pas, at 25 °C, wherein the viscosity is oscillographically determined by means of a rheometer having a heatable plate (MCR 301, AntonPaar) (gap 1000 µm, measurement plate diameter: 25 mm (plate/plate), deformation 0.01 at 5 Hz, temperature: 25 °C). The epoxy resin adhesives are characterized in that they can be easily applied in the temperature range from 40 °C to 70 °C and are scouring-resistant, even at higher temperatures.