Flame Retardant Adhesive Composition with Synergistic Curing
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Solution Overview
Problem
Current epoxy resin-based adhesive compositions face challenges in achieving rapid curing at room temperature while maintaining high mechanical and adhesive strength, especially at elevated temperatures, and require a balance between flame retardancy, smoke, and toxic fume emission properties, which are crucial in industries like aerospace and automotive.
Innovation Solution
A curable two-component epoxy resin composition comprising a first part with a polyether amine epoxy curing agent, a secondary curative, a metal salt catalyst, and phosphorous-based flame retardants, combined with a second part containing epoxy resins, core-shell polymer toughening agents, and reactive diluents, where the total flame retardant content is less than 50 wt.-%, allowing for fast curing and enhanced mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large amounts of flame retardant compounds are added to achieve flame retardant properties, then flame retardancy is improved, but mechanical strength and handling properties deteriorate
Solution Approach 1:
The patent changes the chemical parameters of the flame retardant system by using a synergistic combination of phosphorous-based flame retardant (1-20 wt.-%) and nitrogen-containing compound (5-30 wt.-%), achieving effective flame retardancy at lower total concentrations than conventional single-component systems, thereby maintaining mechanical strength
Solution Approach 2:
The patent creates a composite flame retardant system by combining phosphorous-based compounds and nitrogen-containing compounds in specific ratios, where the synergistic interaction between the two components provides enhanced flame retardant efficiency at lower overall concentrations, preventing degradation of mechanical properties
2Productivity
If fast curing agents are used to achieve rapid curing at room temperature, then curing speed is improved, but adhesive strength and mechanical strength deteriorate
Solution Approach 1:
The patent segments the curing agent system into multiple functional components: a primary amine curing agent for fast initial curing, and additional curing agents to ensure complete crosslinking and maximum strength development, with each component serving a specific stage of the curing process
Solution Approach 2:
The patent employs a composite curing system combining multiple amine-based curing agents with different reactivities and molecular weights, creating a synergistic effect that provides both rapid initial cure and complete crosslinking for high final strength
3Ease of operation
If epoxy resin compositions are designed for room temperature curing, then ease of operation is improved, but curing time and shelf-life deteriorate
Solution Approach 1:
The patent adjusts the molecular weight and reactivity parameters of the amine curing agents to optimize the balance between room temperature curing capability and curing speed, using lower molecular weight amines with higher reactivity to achieve faster cure at ambient conditions
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 rapid curing with high mechanical and adhesive strength, excellent flame retardancy, low toxic smoke and fume emission, and favorable handling properties, meeting stringent industrial requirements.
Implementation Method 1
a first epoxy curing agent comprising at least one polyether amine and having an amine equivalent weight of at least 55 grams per mole of amine equivalents
Implementation Method 2
a metal salt catalyst
Implementation Method 3
at least one phosphorous-based first flame retardant; wherein the total amount of flame retardant is lower than 50 wt.-% of the total curable adhesive precursor
Data Source
AI summary
In one aspect of the present disclosure, there is provided an adhesive precursor, comprising a first part (A) comprising: a first epoxy curing agent comprising at least one polyether amine and having an amine equivalent weight of at least 55 grams per mole of amine equivalents; a second epoxy curing agent distinct from the first epoxy curing agent and/or a secondary curative; a metal salt catalyst; a toughening agent; optionally, at least one phosphorous-based first flame retardant; optionally, at least one second flame retardant distinct from the at least one first flame retardant; and a second part (B) comprising: a first epoxy resin; and/or a second epoxy-based resin distinct from the first epoxy resin; at least one phosphorous-based first flame retardant; optionally, at least one second flame-retardant distinct from the at least one first flame retardant; an epoxy-based reactive diluent; a core-shell polymer toughening agent; and optionally, a filler material; wherein the total amount of flame retardant is lower than 50 wt.-% of the total curable adhesive precursor.