Polyamide Particle Modified Benzoxazine Prepreg for Aircraft Composite CAI

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Solution Overview

Problem

Fiber-reinforced composite materials for aircraft applications require higher compressive strength after impact (CAI) and flexural modulus while maintaining high glass transition temperature and moisture resistance, which existing benzoxazine resin-based materials struggle to achieve simultaneously.

Innovation Solution

A prepreg comprising a reinforcing fiber layer impregnated with a resin composition containing benzoxazine, epoxy, and a curing agent with phenolic hydroxy groups, along with a surface layer containing polyamide resin particles, specifically polyamide 12 and polyamide 1010, to enhance interlaminar fracture toughness and CAI.

Engineering Contradictions & Design Principles

VSEngineering 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 interlaminar fracture toughness and CAI are insufficient

Engineering Contradiction:
Improvemoisture resistance and heat resistanceVSAvoidinterlaminar fracture toughness and CAI
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent uses a composite resin system combining benzoxazine resin (for moisture and heat resistance) with epoxy resin (for toughness) and polyamide resin particles (for impact resistance). This multi-component composite material allows simultaneous achievement of excellent moisture resistance, heat resistance, interlaminar fracture toughness, and CAI properties that cannot be obtained with benzoxazine resin alone.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent introduces polyamide resin particles with specific characteristics (melting point 150-200°C, particle size 1-10 μm) to modify the resin matrix properties. These parameter changes enable the material to achieve high interlaminar fracture toughness and CAI while maintaining the excellent moisture and heat resistance provided by the benzoxazine resin matrix.

Inventive Principle:
Principle #35Parameter changes

2Weight of moving object

If weight reduction is achieved through material selection, then weight is reduced, but it becomes difficult to achieve high CAI and flexural modulus simultaneously

Engineering Contradiction:
Improvematerial weightVSAvoidCAI and flexural modulus
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent optimizes the particle size of polyamide resin particles to 1-10 μm and controls their melting point range (150-200°C) to enable effective reinforcement at high temperatures. This parameter optimization allows weight reduction while maintaining or improving CAI and flexural modulus, as the particles provide reinforcement without excessive weight penalty.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite material combines lightweight benzoxazine resin with reinforcing polyamide particles to achieve high strength-to-weight ratio. The synergistic effect of the resin matrix and particle reinforcement enables weight reduction while simultaneously achieving high CAI and flexural modulus required for aircraft applications.

Inventive Principle:
Principle #40Composite materials

3Temperature

If glass transition temperature is maintained high to ensure high temperature characteristics, then heat resistance is improved, but it becomes difficult to achieve high interlaminar fracture toughness and CAI

Engineering Contradiction:
Improveglass transition temperatureVSAvoidinterlaminar fracture toughness and CAI
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The patent uses polyamide resin particles with melting points specifically controlled to 150-200°C, which is lower than the glass transition temperature of the cured benzoxazine-epoxy system. This parameter differentiation allows the particles to remain solid at service temperatures (maintaining high glass transition temperature characteristics) while providing impact resistance and interlaminar fracture toughness through their reinforcement effect.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite system combines high-glass-transition-temperature benzoxazine-epoxy resin matrix with polyamide particles that have lower melting points but higher thermal stability in the cured state. This composite structure enables the material to maintain high glass transition temperature for heat resistance while the polyamide particles provide enhanced interlaminar fracture toughness and CAI through their reinforcement effect.

Inventive Principle:
Principle #40Composite materials

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 proposed solution achieves high interlaminar fracture toughness, CAI, and flexural modulus while maintaining high glass transition temperature, enabling weight reduction and improved mechanical properties for aircraft applications.

Implementation Method 1

A decrease in the melting temperature of the polyamide resin particles occurs due to the presence of the compound having phenolic hydroxy groups that is the curing agent of the benzoxazine resin

Methodology Applied
Scientific EffectPhase transition (melting): Melting

Implementation Method 2

a curing agent having 2 or more phenolic hydroxy groups in a molecule

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentEP3072917B1Prepreg, fibre-reinforced composite material, and particle-containing resin composition
Publication Date: 2018.07.18 ENEOS CORP
  • EP3072917B1 patent drawingFigure 1(a)~1(b)
  • EP3072917B1 patent drawingFigure 2(a)~2(c)
  • EP3072917B1 patent drawingFigure 3(a)~3(b)

AI summary

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 a 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 a polyamide 12 resin particle and a polyamide 1010 resin particle.