Polyamide Particle Prepreg for Composite Toughness
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Solution Overview
Problem
Fiber-reinforced composite materials for aircraft applications require high compressive strength after impact (CAI), flexural modulus, and glass transition temperature while maintaining excellent moisture and heat resistance, which existing methods using benzoxazine resin struggle to achieve simultaneously.
Innovation Solution
A production method involving a prepreg with a resin composition containing benzoxazine, epoxy, and a curing agent with phenolic hydroxy groups, along with polyamide resin particles of varying melting temperatures to enhance interlaminar fracture toughness and adhesiveness between fiber layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If benzoxazine resin is used to achieve excellent moisture resistance and heat resistance, then moisture resistance and heat resistance are improved, but toughness deteriorates
Solution Approach 1:
The patent uses a composite resin system combining benzoxazine resin with epoxy resin and polyamide resin particles. The benzoxazine resin provides moisture and heat resistance, while the epoxy resin and polyamide particles compensate for the toughness deficiency, creating a synergistic composite material that achieves all required mechanical properties simultaneously.
Solution Approach 2:
The patent introduces polyamide resin particles with specific melting points (150-220°C) that are lower than the curing temperature. These particles melt during curing to enhance toughness and adhesion, then solidify to provide reinforcement. This parameter change in particle melting temperature allows the system to achieve high toughness without sacrificing the heat resistance provided by benzoxazine resin.
2Strength
If multiple resin components are blended to improve toughness, then toughness is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of using complex multi-component resin systems, the patent simplifies the approach by using benzoxazine resin combined with polyamide resin particles of controlled melting points. The particle melting temperature parameter is optimized to 150-220°C, which is lower than the curing temperature but high enough to maintain structural integrity during service. This single-parameter optimization achieves toughness improvement without requiring multiple resin components.
3Strength
If polyamide resin particles with low melting temperature are used to enhance adhesion, then adhesion is improved, but peeling between fiber layers increases
Solution Approach 1:
The patent optimizes the melting temperature of polyamide resin particles to a specific range (150-220°C) that is lower than the curing temperature but higher than room temperature. This parameter optimization ensures particles melt during curing to enhance adhesion, then solidify to provide peeling resistance. The specific melting point range prevents premature melting during storage and handling, maintaining composition stability.
Solution Approach 2:
The polyamide resin particles are distributed throughout the resin composition, creating local regions of enhanced adhesion where particles melt during curing. However, the overall composition maintains peeling resistance through the benzoxazine resin matrix and the solidified particle structure. This local quality enhancement without global compromise resolves the adhesion-peeling contradiction.
4Reliability
If heating temperature is increased to improve curing, then curing is improved, but variability in physical properties increases
Solution Approach 1:
The patent uses polyamide resin particles with melting points (150-220°C) that serve as thermal indicators during curing. The curing temperature is set higher than the particle melting point to ensure complete curing, but the particle melting provides a thermal reference that reduces variability. The particles melt at a consistent temperature, providing a reliable thermal marker that ensures uniform curing across different batches, thereby reducing physical property variability.
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 method achieves high interlaminar fracture toughness, CAI, and flexural modulus while maintaining high glass transition temperature, reducing material weight and variability in physical properties due to heating conditions.
Implementation Method 1
a surface layer provided on at least one surface of the reinforcing fiber layer and containing (A) a benzoxazine resin, (B) an epoxy resin, (C) a curing agent having 2 or more phenolic hydroxy groups in a molecule, and (D) polyamide resin particles having an average particle size of 5 to 50 μm, wherein the polyamide resin particles include (D1) a first polyamide resin particle and (D2) a second polyamide resin particle having a higher melting temperature measured in a composition constituting the surface layer than the first polyamide resin particle has
Implementation Method 2
a resin composition with which the space between fibers of the reinforcing fibers is impregnated and which contains (A) a benzoxazine resin, (B) an epoxy resin, and (C) a curing agent having 2 or more phenolic hydroxy groups in a molecule
Implementation Method 3
a step of stacking a prepreg plurally and heating the prepregs to cure a resin
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
A production method for a fiber-reinforced composite material comprises: a step of stacking a prepreg plurally to obtain a prepreg-stacked body; and a step of heating the prepreg-stacked body to cure a resin, wherein the prepreg comprises: a reinforcing fiber layer including reinforcing fibers and a resin composition with which the space between fibers of the reinforcing fibers is impregnated and which contains (A) a benzoxazine resin, (B) an epoxy resin, and (C) a curing agent having 2 or more phenolic hydroxy groups in a molecule; and a surface layer provided on at least one surface of the reinforcing fiber layer and containing (A) to (C) components, and (D) polyamide resin particles having an average particle size of 5 to 50 µm, wherein the polyamide resin particles include (D1) a first polyamide resin particle and (D2) a second polyamide resin particle having a higher melting temperature measured in a composition constituting the surface layer than the first polyamide resin particle has.