Sizing agent, sizing agent-adhered carbon fibers and method for producing same, aqueous dispersion of sizing agent, prepreg and method for producing same, and method for producing carbon fiber-reinforced composite material
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Solution Overview
Problem
Carbon fiber-reinforced composite materials using super engineering plastics as matrix resins face issues with void formation due to insufficient spreadability of sizing agents and handling properties, leading to poor quality products with voids and mechanical weaknesses.
Innovation Solution
A sizing agent with specific heat weight loss characteristics and surfactant content is applied to carbon fibers, ensuring excellent spreadability and handling performance, and is used in a prepreg production method that minimizes voids by controlling the decomposition and volatilization of the sizing agent during high-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sizing agent is applied to carbon fibers to improve handling properties, then handling properties improve, but spreadability deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the heat weight loss characteristics of the sizing agent (specifically setting heat weight loss at 250°C to 10% or less and at 350°C to 65% or more) to achieve optimal balance between handling properties and spreadability. This quantitative parameter control allows the sizing agent to provide sufficient protection during handling while minimizing interference with fiber spreading and resin impregnation processes.
2Productivity
If the amount of sizing agent adhered to carbon fibers is reduced to improve spreadability, then spreadability improves, but handling properties deteriorate
Solution Approach 1:
The patent resolves this contradiction by changing the qualitative parameters of the sizing agent itself rather than simply adjusting the quantity. By specifying precise heat weight loss characteristics (10% or less at 250°C, 65% or more at 350°C), the invention enables effective handling protection with minimal sizing agent content, thereby maintaining both handling properties and spreadability simultaneously.
Solution Approach 2:
The sizing agent functions as a temporary protective layer that serves its purpose during handling and processing, then decomposes completely at high molding temperatures (65% or more heat weight loss at 350°C). This disposable nature allows minimal sizing agent application while ensuring adequate handling protection and complete removal during molding to prevent void formation.
3Ease of operation
If a sizing agent is used to improve handling properties, then handling properties improve, but voids form in the molded product due to gas generation
Solution Approach 1:
The patent applies preliminary action by designing the sizing agent to decompose in a specific sequence during heating: first losing minimal weight (10% or less) at 250°C during handling and resin impregnation, then rapidly decomposing (65% or more) at 350°C during molding. This staged decomposition ensures the sizing agent provides protection when needed and eliminates gas generation issues during high-temperature molding by complete decomposition before resin solidification.
Solution Approach 2:
The invention uses parameter changes by precisely controlling the thermal decomposition characteristics of the sizing agent through specific heat weight loss parameters. By setting the decomposition profile (10% or less at 250°C, 65% or more at 350°C), the sizing agent transitions from a protective state during handling to a complete decomposition state during molding, preventing void formation while maintaining handling properties.
4Temperature
If super engineering plastics are used as matrix resins for high heat resistance, then heat resistance improves, but impregnation becomes difficult due to high molding temperature requirements
Solution Approach 1:
The sizing agent acts as an intermediary substance that facilitates the interaction between carbon fibers and high-temperature matrix resins. By providing optimal surface characteristics and controlled decomposition behavior, the sizing agent enables effective resin impregnation even at high molding temperatures required for super engineering plastics, bridging the gap between fiber and resin without compromising heat resistance.
Solution Approach 2:
The patent applies parameter changes by controlling the heat weight loss characteristics of the sizing agent to match the processing requirements of super engineering plastics. The specific decomposition profile (10% or less at 250°C, 65% or more at 350°C) ensures the sizing agent remains stable during resin impregnation at elevated temperatures but decomposes completely during final molding, enabling successful impregnation with high-heat-resistant resins.
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 produces carbon fiber-reinforced composite materials with significantly reduced voids and improved mechanical properties, maintaining excellent handling and fiber spreadability even with high-heat matrix resins like super engineering plastics.
Implementation Method 1
a sizing agent is applied to the carbon fibers to form sizing agent-adhered carbon fibers
Implementation Method 2
The voids are presumed to be the gas generated by the decomposition or volatilization of the sizing agent
Implementation Method 3
The voids are presumed to be the gas generated by the decomposition or volatilization of the sizing agent
Implementation Method 4
the matrix resin, which is melted and fluidized by being heated to a high temperature, proceeds to fill the gaps between the carbon fibers
Data Source
AI summary
Use of a sizing agent having a heat weight loss B-1 of 65% or more as determined by a specific measurement method, or a sizing agent containing a surfactant and a compound represented by formula (1):