Epoxy Resin Composition for Composite Materials
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Solution Overview
Problem
Existing fiber-reinforced composite materials face challenges in achieving both excellent mechanical properties and appearance, particularly in applications like golf club shafts and fishing rods, where high strength, low coloring, transparency, and weather resistance are required.
Innovation Solution
A prepreg composition is developed, incorporating specific ratios of isocyanurate type epoxy resin, novolac type epoxy resin, glycidylamine type epoxy resin, dicyandiamide, a compound with a boiling point of 130°C or higher, and phenoxy resin, which balances mechanical properties and appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If dicyandiamide is used as a curing agent to improve resin strength, then mechanical properties are improved, but appearance deteriorates due to incomplete dissolution causing defects and coloring
Solution Approach 1:
The patent introduces a specific compound (with boiling point 130°C or higher, molecular weight 50-250, no epoxy group, no curing ability) as an intermediary substance. This compound acts as a mediator that facilitates the complete dissolution of dicyandiamide in the epoxy resin system, enabling both high mechanical strength and excellent appearance quality without the defects caused by incomplete dissolution
Solution Approach 2:
The patent optimizes the content ratio of dicyandiamide to the specific compound within 1:0.1 to 1:5. By controlling this parameter range, the system achieves complete dissolution of the curing agent while maintaining high resin strength and preventing appearance defects such as coloring and surface irregularities
2Manufacturing precision
If dicyandiamide content is reduced to improve appearance, then appearance quality is improved, but mechanical properties deteriorate due to low flexural strength and elastic modulus
Solution Approach 1:
The specific compound serves as a mediator that enhances the effectiveness of dicyandiamide. Even at low dicyandiamide content, the intermediary compound ensures complete dissolution and maximizes the curing efficiency, allowing the system to achieve both excellent appearance and high mechanical properties including flexural strength and elastic modulus
3Manufacturing precision
If self-polymerization of epoxy resin is used to improve appearance, then appearance quality is improved, but tacking property deteriorates due to insufficient tackiness
Solution Approach 1:
The specific compound acts as a mediator that bridges the gap between self-polymerization and tacking requirements. It enables the epoxy resin to undergo self-polymerization for excellent appearance while simultaneously providing sufficient tackiness through its interaction with the polymerization process, resolving the contradiction between appearance quality and handling 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 resulting prepreg and fiber-reinforced composite materials exhibit excellent mechanical properties, such as high flexural strength and elastic modulus, along with superior appearance characteristics like low coloring, transparency, and weather resistance, while also maintaining excellent tacking properties.
Implementation Method 1
thermosetting resins are mainly used in resin compositions for use in such fiber-reinforced composite materials... epoxy resins are preferably used from the viewpoint of mechanical properties, such as adhesion to reinforcing fibers
Data Source
AI summary
An object of the present invention is to provide a prepreg which has both excellent mechanical properties such as strength and elastic modulus and excellent appearance such as low-coloring property, transparency and weather resistance, and which also has an excellent tacking property, as well as to provide a fiber-reinforced composite material, a tubular fiber-reinforced composite material, a golf club shaft and a fishing rod, using the prepreg. The gist of the present invention is a prepreg including reinforcing fibers and a resin composition, wherein the resin composition contains the following component [A] to component [D]: component [A]: epoxy resins; component [B]: dicyandiamide; component [C]: a compound which has a boiling point of 130° C. or higher and a molecular weight m of 50 or more and 250 or less, which does not contain an epoxy group within the molecular structure, and which substantially does not have an epoxy resin curing ability; and component [D]: a phenoxy resin; and wherein the resin composition satisfies the following requirements (1) to (3): (1): the resin composition contains from 10 to 40 parts by mass of an isocyanurate type epoxy resin [A1], as the component [A], with respect to 100 parts by mass of the total epoxy resin: (2): the resin composition contains from 10 to 50 parts by mass of a novolac type epoxy resin [A2], as the component [A], with respect to 100 parts by mass of the total epoxy resin; and(3): the resin composition contains 10 parts by mass or less of a glycidylamine type epoxy resin [A3], as the component [A], with respect to 100 parts by mass of the total epoxy resin.