Structural Adhesive Composition Latent Curing Agent
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Solution Overview
Problem
Current structural adhesive compositions face challenges in achieving optimal bond strength, ease of application, and extended pot life for bonding various substrate materials, particularly in applications like wind turbine blades and automotive components.
Innovation Solution
A one-component (1K) and two-component (2K) structural adhesive composition is developed, comprising an epoxy-capped flexibilizer, a heat-activated latent curing agent, rubber particles with a core/shell structure, and an adduct of an epoxy compound and a dimer acid, which provides enhanced mechanical properties and controlled curing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional structural adhesive compositions are used, then bond strength is achieved, but pot life is limited and application complexity increases
Solution Approach 1:
The adhesive system is divided into two separate components: Component A containing the epoxy resin and Component B containing the curing agent. This segmentation allows each component to remain stable independently, preventing premature reaction and extending pot life while maintaining bond strength when mixed.
Solution Approach 2:
A latent curing agent is introduced as an intermediary that remains inactive at room temperature but activates at elevated temperatures. This mediator enables controlled curing timing, extending the working pot life at ambient conditions while achieving complete cure and bond strength at elevated temperatures.
2Strength
If conventional structural adhesive compositions are used, then bond strength is achieved, but ease of application deteriorates due to mixing requirements
Solution Approach 1:
By segmenting the adhesive into pre-mixed Component A (epoxy resin with all modifiers) and Component B (curing agent), the system eliminates the need for users to perform complex multi-component mixing, improving ease of application while maintaining the bonded strength through proper formulation of each segment.
Solution Approach 2:
The adhesive system is designed to be self-curing through the latent curing mechanism, eliminating the need for external catalysts or complex processing steps. Users simply apply and allow thermal curing to occur, simplifying the application process while achieving full bond strength.
3Duration of action of moving object
If epoxy-capped flexibilizer and latent curing agent are used, then pot life is extended and ease of application improves, but bond strength may be compromised
Solution Approach 1:
The curing agent is designed to change its reactivity parameters with temperature: remaining latent (low reactivity) at room temperature to extend pot life, then becoming highly reactive at elevated curing temperatures to achieve full bond strength. This parameter change resolves the contradiction between extended pot life and adequate bond strength.
Solution Approach 2:
The adhesive system combines multiple materials with complementary properties: epoxy resin for strength, flexibilizer for toughness, and latent curing agent for controlled reactivity. This composite approach ensures both extended pot life through latent curing and adequate bond strength through the synergistic combination of materials that activate at curing 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 composition offers improved bond strength, ease of application, and extended pot life, making it suitable for diverse applications such as bonding wind turbine blades and automotive components with enhanced mechanical properties like tensile strength and impact resistance.
Implementation Method 1
a heat-activated latent curing agent comprising dicyandiamide and a reaction product of reactants comprising an epoxy compound and an imidazole
Implementation Method 2
an epoxy-capped flexibilizer comprising a reaction product of reactants comprising (i) an epoxy compound, (ii) an anhydride and/or a diacide, and (iii) a polyol
Data Source
AI summary
Disclosed herein are compositions including (a) a first component comprising (1) an epoxy-adduct that is the reaction product of reactants comprising a first epoxy compound, a polyol, and an anhydride and/or a diacid and (2) a second epoxy compound; (b) rubber particles having a core/shell structure and/or graphenic carbon particles; and (c) a second component that chemically reacts with the first component at ambient or slightly thermal conditions. Also disclosed herein are compositions including (a) an epoxy-capped flexibilizer; (b) a heat-activated latent curing agent; and optionally (c) rubber particles having a core/shell structure and/or graphenic carbon particles; (d) an epoxy/CTBN adduct; and/or (e) an epoxy/dimer acid adduct. The heat-activated latent curing agent may include at least one reaction product of reactants including an epoxy compound and an amine and/or an alkaloid.