Polyurethane-Modified Epoxy Resin Composition for Impact Resistance
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Solution Overview
Problem
Epoxy resin cured products exhibit low rupture elongation, fracture toughness, and peel strength, limiting their suitability for applications requiring improved fatigue resistance, impact resistance, and heat retention in composite materials and structural adhesives.
Innovation Solution
A polyurethane-modified epoxy resin composition is developed, comprising a low-concentration polyurethane-modified epoxy resin, a polyurethane-unmodified epoxy resin, a solid epoxy resin with a bisphenol structure, and an amine-based curing agent, with specific weight percentages and molecular weight ranges to achieve enhanced mechanical properties and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyurethane-modified epoxy resin is used to improve rupture elongation and fracture toughness, then impact resistance is improved, but glass transition temperature decreases and heat resistance is insufficient
Solution Approach 1:
The patent changes the concentration parameter of polyurethane modification from conventional high concentration to low concentration (0.1-15 mass%). This parameter change allows the resin to maintain improved impact resistance while preserving the high glass transition temperature and heat resistance characteristics of the base epoxy resin
Solution Approach 2:
The patent creates a composite resin system by combining low-concentration polyurethane-modified epoxy resin with unmodified epoxy resin and solid epoxy resin. This composite approach allows the polyurethane component to provide impact resistance enhancement while the majority epoxy resin matrix maintains high heat resistance and glass transition temperature
2Reliability
If polyurethane concentration is increased to improve peel strength and adhesive property, then fatigue resistance is improved, but viscosity increases and processability deteriorates
Solution Approach 1:
The patent optimizes the polyurethane concentration parameter to a low range (0.1-15 mass%), which provides sufficient peel strength and fatigue resistance improvement while maintaining the resin viscosity at acceptable levels for good processability and impregnation characteristics
Solution Approach 2:
The patent applies partial modification by using low concentrations of polyurethane rather than full modification. This partial action is sufficient to improve adhesive properties and fatigue resistance while avoiding the excessive viscosity increase that would compromise processability
3Temperature
If conventional epoxy resin is used to maintain heat resistance, then glass transition temperature is high, but rupture elongation and fracture toughness are low
Solution Approach 1:
The patent creates a composite system where unmodified epoxy resin (providing high glass transition temperature and heat resistance) is combined with polyurethane-modified epoxy resin (providing improved fracture toughness and rupture elongation). The synergistic combination allows both high heat resistance and improved mechanical toughness to be achieved simultaneously
Solution Approach 2:
The patent applies local quality by introducing polyurethane modification at specific low concentrations (0.1-15 mass%) rather than uniformly throughout the entire resin system. This localized modification provides fracture toughness improvement at the molecular level while the bulk resin maintains its high glass transition temperature and heat resistance properties
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 achieves a glass transition temperature of 110°C or more, an Izod impact strength of 30 kJ/m² or more, and improved storage stability, making it suitable for adhesives, coatings, and composite materials while maintaining heat resistance.
Implementation Method 1
a polyol compound (b) and a polyisocyanate compound (c) are caused to react with each other
Data Source
AI summary
Provided is a polyurethane-modified epoxy resin composition having satisfactory operability of processing, such as casting or impregnation, in a composition state. The epoxy resin composition includes, as essential components, the following components (A) to (D): (A) a low-concentration polyurethane-modified epoxy resin containing a polyurethane having an epoxy resin added to each of both terminals thereof and/or one terminal thereof; (B) a polyurethane-unmodified epoxy resin that is liquid at 30° C.; (C) a solid epoxy resin having a bisphenol structure, the resin having a glass transition temperature or a melting point of 50° C. or more; and (D) an amine-based curing agent that is dicyandiamide or a derivative thereof, wherein the epoxy resin composition includes the component (A) at from 3.0 wt % to 30.0 wt %, and the component (C) at from 0.1 wt % to 40.0 wt % with respect to the total of the components (A) to (D).