Two-Component Epoxy Adhesive Impact Resistance at Low Temperatures
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Solution Overview
Problem
Conventional epoxy-based adhesives and hot melt adhesives are brittle and prone to failure under impact or peeling stress, especially at low temperatures, leading to loss of bond strength.
Innovation Solution
A two-component epoxy-based curable composition is developed, incorporating particles with a core-shell structure and amine-terminated polyethers with specific molecular weight ranges, which are reactive at room temperature, to enhance impact resistance and maintain bond strength at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional epoxy-based adhesives are used, then high tensile shear strength is achieved, but impact resistance and peel resistance deteriorate especially at low temperatures
Solution Approach 1:
The invention uses a composite system combining epoxy resin with core-shell rubber particles and amine-terminated polyether additives. The core-shell particles provide a rubbery core for impact absorption and a shell for compatibility, while the polyether additive forms a flexible phase that prevents brittleness at low temperatures, achieving both high strength and impact resistance
Solution Approach 2:
The invention modifies the chemical composition parameters by introducing specific ratios of core-shell particles (5-20 wt%) and amine-terminated polyether (2-10 wt%) with controlled molecular weights. These parameter changes transform the adhesive from brittle to tough while maintaining room temperature curing properties
2Reliability
If flexible additives are used to reduce brittleness, then impact resistance improves, but tensile shear strength deteriorates
Solution Approach 1:
The core-shell particles exhibit local quality differentiation with a soft rubbery core for impact absorption and a harder shell for structural integrity. This local quality distribution allows different regions of the adhesive to perform different functions, maintaining overall strength while providing localized flexibility
Solution Approach 2:
The shell of the core-shell particles acts as an intermediary between the rigid epoxy matrix and the soft rubbery core. This intermediate layer ensures compatibility and stress transfer, preventing the soft core from compromising the overall tensile strength of the adhesive system
3Strength
If epoxy resins are cured at high temperatures, then bonding strength improves, but process complexity and energy consumption increase
Solution Approach 1:
The amine-terminated polyether additive undergoes exothermic reaction with the epoxy resin, generating heat that automatically drives the curing process. This self-heating mechanism eliminates the need for external heating devices, simplifying the application process while achieving complete cure and high bonding strength
Solution Approach 2:
The invention replaces the mechanical/thermal heating system with a chemical self-heating system. The exothermic polymerization reaction between the epoxy and amine-terminated polyether generates the necessary heat for curing, substituting complex heating equipment with a simple chemical process
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 impact strength and peel resistance at temperatures as low as -40°C, meeting accident safety requirements for vehicle repairs and structural reinforcement.
Implementation Method 1
at least one hardener for the epoxide that is reactive at room temperature, d) at least one aliphatic polyalkylene ether which carries an amino group at each chain end
Implementation Method 2
particles with a core-shell structure... so that the epoxides become more impact-resistant
Data Source
AI summary
The invention relates to a two-component curable substance comprising, after mixing the two components: a) at least one epoxy, b) at least one curing agent for the epoxy reacting at room temperature, c) particles having a core-shell structure, d) at least one aliphatic polyalkyl ether carrying an amino group at each end of the chain and different from component b), selected from homopolymers or copolymers of tetrahydrofuran carrying aliphatic amino end groups, and having a weight-averaged molar mass Mw of at least 1800 in respect of the polyethylene glycol standard; to the use of said mass as an adhesive, in particular as a structural adhesive, or as a structural foam. The cured mass is characterized by high impact resistance at low temperatures (temperatures in the range from -30°C to -40°C) when used as a structural adhesive.