Latent Curable Composition for RTM Hardening
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Solution Overview
Problem
Current epoxy resin systems used in resin transfer molding (RTM) processes exhibit a flat hardening profile, lack temperature dependency, and often contain bisphenol A, which poses risks, necessitating the development of a system with a steeper hardening profile and longer pot life at room temperature while maintaining performance comparable to existing epoxy systems.
Innovation Solution
A heat-curable composition comprising a polymer obtained from the reaction of aromatic dialdehydes with acrylate compounds, optionally including α-(1′-hydroxyalkyl)acrylate groups and thiol compounds, which remains latently reactive at room temperature but rapidly hardens at elevated temperatures, achieving a steeper hardening profile and avoiding bisphenol A.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy resin systems are used in RTM processes, then good structural performance is achieved, but the hardening profile is flat and temperature dependency is low
Solution Approach 1:
The patent changes the chemical composition parameters by replacing bisphenol A-based epoxy resins with alternatives containing DGEBA, DGEBL, and specific hardeners (amines, anhydrides, carboxylic acids). This parameter change results in a steeper hardening profile with higher temperature dependency while maintaining structural performance
Solution Approach 2:
The invention uses composite resin systems combining multiple epoxy components (DGEBA, DGEBL) with various hardeners and optional additives. This composite approach achieves both good structural performance and improved hardening characteristics with better temperature dependency
2Productivity
If high-reactivity resin systems are used, then short cycle times are achieved, but pot life is reduced and room temperature stability is compromised
Solution Approach 1:
The patent creates a dynamic hardening system where the reaction rate adapts to temperature changes. At room temperature, the system remains stable with slow reaction, but at processing temperatures, the hardening rate increases dynamically, achieving short cycle times without sacrificing pot life
Solution Approach 2:
By selecting specific hardener-resin combinations and adjusting compositional parameters, the system achieves temperature-dependent reactivity that provides long pot life at room temperature while enabling rapid curing at processing temperatures for short cycle times
3Reliability
If bisphenol A-based epoxy resins are used, then good performance is achieved, but health and safety risks increase
Solution Approach 1:
The patent extracts and removes bisphenol A from the resin system while replacing it with alternative epoxy components (DGEBA, DGEBL) and safe hardeners. This elimination maintains performance reliability while removing the health and safety hazards associated with bisphenol A
Solution Approach 2:
The invention replaces the problematic bisphenol A-based resin with alternative compositions that achieve similar performance without the harmful effects, effectively substituting a safer, shorter-lived alternative that doesn't require long-term stability of the original system
4Stress or pressure
If injection resins with low viscosity are used, then flow resistance is reduced and charging pressure is lowered, but hardening control becomes more difficult
Solution Approach 1:
The patent adjusts the viscosity and hardening kinetics parameters through selective component choice. The resin system maintains low viscosity for easy flow and low charging pressure while the temperature-dependent hardening profile provides controllable curing characteristics that simplify rather than complicate the 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 solution enables shorter production cycles in composite materials and adhesive bonding by providing a composition that hardens quickly at moderate temperatures, addressing the limitations of existing epoxy systems with improved temperature dependency and safety.
Implementation Method 1
a curable composition comprises: a) at least one polymer (S) obtainable via reaction of at least one compound having two aldehyde groups and of at least one acrylate compound
Implementation Method 2
the composition comprises a polymer obtainable via reaction of certain compounds having two aldehyde groups with polyacrylate compounds having two or more acrylate groups, and also a compound which bears at least two thiol groups
Implementation Method 3
the composition is hardened by heating to temperatures of more than or equal to 60°C
Implementation Method 4
Systems with steeper hardening profile are desirable, i.e. with relatively high temperature dependency of hardening rate
Data Source
AI summary
The invention relates to a process for the curing of latently reactive, heat-curable compositions which do not harden at room temperature. The composition includes a polymer obtainable via reaction of certain compounds having two aldehyde groups with polyacrylate compounds having two or more acrylate groups, and also a compound which bears at least two thiol groups.