Sizing agent, reinforcement fiber tow, fiber-reinforced resin-molding material, and fiber-reinforced composite material
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Solution Overview
Problem
Existing sizing agents used for reinforcement fiber tows struggle to balance excellent chopping properties with sufficient separation properties, leading to issues such as sub-tows separating during processing and entanglement of carbon fiber filaments.
Innovation Solution
A sizing agent comprising a blend of epoxy resin (component A) with a viscosity of 1 to 180,000 Pa·s and an aliphatic ester compound (component B) with a freezing point of 50° C. or lower, in a mass ratio of 0.5 to 20, applied to reinforcement fiber tows to enhance both chopping and separation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sizing agent with high bundling property is used to improve chopping property, then chopping property is improved, but separation property deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the viscosity of the epoxy resin (1 to 180,000 Pa·s at 30°C) and the freezing point of the aliphatic ester compound (50°C or lower) to achieve optimal balance between bundling and separation properties. By adjusting these physical parameters, the sizing agent provides sufficient bundling for good chopping property while maintaining separation capability during processing.
Solution Approach 2:
The patent uses a composite sizing agent formulation combining epoxy resin (component A) and aliphatic ester compound (component B) in a mass ratio of 0.5 to 20. This composite approach allows the epoxy resin to provide bundling strength for chopping while the aliphatic ester compound enables separation, resolving the contradiction between these two opposing requirements.
2Ease of operation
If the amount of sizing agent is reduced or low bundling property sizing agent is used to secure separation property, then separation property is improved, but chopping property deteriorates
Solution Approach 1:
The patent addresses this contradiction by optimizing the viscosity parameter of the epoxy resin and the freezing point parameter of the aliphatic ester compound. These parameter adjustments ensure that even at reduced sizing agent amounts, the formulation maintains adequate bundling for chopping while preserving separation capability.
Solution Approach 2:
The composite formulation of epoxy resin and aliphatic ester compound in specific ratios enables the sizing agent to provide both bundling and separation functions simultaneously, eliminating the need to compromise between chopping property and separation property.
3Productivity
If carbon fiber tow is chopped without sufficient sub-tow integration, then chopping is easier, but sub-tows separate during processing causing entanglement
Solution Approach 1:
The patent applies preliminary action by applying the sizing agent to the carbon fiber tow before chopping. The sizing agent pre-integrates the sub-tows through the epoxy resin component, ensuring they remain integrated during subsequent processing operations, thus preventing separation and entanglement while maintaining chopping efficiency.
Solution Approach 2:
The composite sizing agent with epoxy resin and aliphatic ester compound provides both integration strength for process stability and controlled separation capability, resolving the contradiction between chopping efficiency and process stability in carbon fiber tow handling.
Data Source
AI summary
A sizing agent is provided, the sizing agent includes a component (A) and a component (B), wherein a mass ratio A/B of the component (A) to the component (B) is 0.5 to 20, and a proportion of a total mass of the component (A) and the component (B) with respect to a total mass of the sizing agent is 80% by mass or more, wherein the component (A) is an epoxy resin having a viscosity of 1 to 180,000 Pa·s at 30° C., and the component (B) is an aliphatic ester compound having a freezing point of 50° C. or lower.