Carbon Fiber Prepreg Sizing for Adhesion and Storage Stability
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Solution Overview
Problem
Conventional epoxy resin combinations fail to achieve both high adhesion between carbon fibers and a matrix resin and long-term storage stability in carbon fiber-reinforced composite materials, as they do not simultaneously satisfy the requirements of strong interaction between the epoxy component and carbon fibers, suppression of reactions between the epoxy compound and the matrix resin, and high adhesion to the matrix resin.
Innovation Solution
A prepreg comprising sizing agent-coated carbon fibers with a thermosetting resin composition, where the sizing agent includes an aliphatic epoxy compound and an aromatic epoxy compound in specific ratios, and the thermosetting resin composition contains epoxy resins with multiple ring structures and latent hardeners, ensuring strong adhesion and stability during long-term storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a sizing agent with high reactivity epoxy compounds is used, then adhesion to carbon fibers is improved, but stability during long-term storage deteriorates
Solution Approach 1:
The sizing agent creates a protective outer layer rich in aromatic epoxy compounds that acts as a barrier, reducing the reactivity of the highly reactive aliphatic epoxy compounds in the inner layer. This local quality differentiation allows high adhesion at the fiber interface while maintaining storage stability at the outer surface.
Solution Approach 2:
The aromatic epoxy compounds serve as an intermediary layer between the highly reactive aliphatic epoxy compounds and the external environment (air, moisture). This intermediary protects the reactive aliphatic epoxy from premature reactions during storage while still allowing strong adhesion to carbon fibers.
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 solution provides excellent adhesiveness between carbon fibers and the matrix resin, maintains mechanical characteristics over time, and enhances the strength and heat resistance of the carbon fiber-reinforced composite material.
Implementation Method 1
the aliphatic epoxy compound and the aromatic epoxy compound are contained in a mass ratio of 52/48 to 80/20... excellent adhesiveness between carbon fibers and a matrix resin
Implementation Method 2
the thermosetting resin composition includes a thermosetting resin (D) and a latent hardener (E)... enhances the strength and heat resistance of the carbon fiber-reinforced composite material
Data Source
AI summary
Provided is a prepreg and a carbon fiber-reinforced composite material having excellent adhesiveness between carbon fibers and a matrix resin and excellent long-term storage stability. The present invention provides a prepreg that includes; sizing agent-coated carbon fibers coated with a sizing agent; and a thermosetting resin composition impregnated into the sizing agent-coated carbon fibers. The sizing agent includes an aliphatic epoxy compound (A) and an aromatic epoxy compound (B1). The thermosetting resin composition includes a thermosetting resin (D) and a latent hardener (E), and optionally includes an additive (F) other than the thermosetting resin (D) and the latent hardener (E). The (a)/(b) ratio is within a predetermined range where (a) is the height of a component at a binding energy assigned to CHx, C-C, and C=C and (b) is the height of a component at a binding energy assigned to C-O in a C1s core spectrum of the surfaces of the sizing agent-coated carbon fibers analyzed by X-ray photoelectron spectroscopy.