Epoxy-Resin Composition for Void-Suppressed Tough FRP Prepregs
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Solution Overview
Problem
Existing epoxy-resin compositions for fiber-reinforced plastics face challenges in achieving rapid curing at low temperatures, maintaining storage stability, and preventing voids in molded products, while also requiring improved fracture toughness and heat tolerance.
Innovation Solution
An epoxy-resin composition comprising specific components such as an epoxy resin with an oxazolidone-ring structure, a bisphenol bifunctional epoxy resin, a triblock copolymer, and a curing agent like dicyandiamide, which allows for faster curing at lower temperatures, enhanced processability, and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a highly reactive epoxy-resin composition is used to shorten curing time, then curing speed is improved, but storage stability deteriorates due to spontaneous curing at room temperature
Solution Approach 1:
A silane-modified epoxy resin is introduced as an intermediary component that reacts with the base epoxy resin to form a modified resin composition. This intermediary substance enables rapid curing when activated while maintaining storage stability in its unactivated state, effectively mediating between the conflicting requirements of fast curing and stable storage.
Solution Approach 2:
The chemical structure of the epoxy resin is modified by introducing silane groups, which changes the reactivity parameters of the resin. The silane-modified epoxy resin has different reaction characteristics compared to conventional epoxy resins, allowing for controlled rapid curing under specific conditions while maintaining stability during storage through parameter optimization.
2Manufacturing precision
If the matrix resin viscosity is lowered to suppress voids in molded products, then void formation is reduced, but prepreg handleability deteriorates due to excessive tackiness at room temperature
Solution Approach 1:
The matrix resin is formulated as a composite system combining base epoxy resin, silane-modified epoxy resin, and polyvinyl formal. This composite material composition achieves optimal balance between viscosity and tackiness, where the silane-modified component contributes to void suppression while the polyvinyl formal provides controlled adhesion, resolving the contradiction between void suppression and handleability.
3Stability of the object's composition
If conventional epoxy-resin compositions are used to maintain storage stability, then storage stability is preserved, but curing time increases and fracture toughness remains insufficient
Solution Approach 1:
The silane modification of the epoxy resin is performed in advance during resin formulation, creating a pre-modified resin that is stable during storage but capable of rapid curing when activated. This preliminary chemical modification enables the resin to maintain stability during storage while being prepared for fast curing performance when needed.
Solution Approach 2:
A composite resin system is created combining base epoxy resin with silane-modified epoxy resin and polyvinyl formal. This composite formulation achieves both long-term storage stability and rapid curing capability, while also improving fracture toughness through the synergistic effects of the different components.
4Productivity
If a prepreg is designed for rapid low-temperature curing to reduce molding time, then productivity is improved, but the resin composition becomes too reactive causing spontaneous curing during storage
Solution Approach 1:
The silane-modified epoxy resin acts as an intermediary that decouples the reactivity required for fast curing from the stability required for storage. The modification creates a resin that remains stable during storage but can be rapidly activated for curing, enabling high productivity without sacrificing storage stability.
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 enables the production of fiber-reinforced plastics with excellent fracture toughness, heat tolerance, and reduced voids, while maintaining processability at room temperature and reducing curing time, thus addressing the limitations of previous technologies.
Implementation Method 1
a silane-modified epoxy resin, which undergoes a curing reaction with a base epoxy resin upon contact
Implementation Method 2
curing reactions progress even when the composition is stored at room temperature
Data Source
AI summary
An epoxy-resin composition of the components (A), (B), (D) and (E), where component (A) is an epoxy resin having an oxazolidone-ring structure, (B) is a bisphenol bifunctional epoxy resin with a number-average molecular weight of at least 600 but no more than 1300, which does not have an oxazolidone-ring structure, (D) is a triblock copolymer, and (E) is a curing agent. A film made of the epoxy-resin composition, a prepreg and a fiber-reinforced plastic is also disclosed. The epoxy resin composition is capable of achieving both a processability of a prepreg at room temperature and a suppression of voids in the molded product. A fiber-reinforced plastic having excellent mechanical properties, especially excellent fracture toughness and heat tolerance, is also obtained by using the epoxy-resin composition.