Prepreg Production via Vertical Coating and Pressure Gradient
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Solution Overview
Problem
Current methods for producing prepregs, such as the hot-melt process and pultrusion methods, face challenges like high production costs, low speed, and clogging issues due to fuzz generation, which hinder efficient impregnation of reinforcing fiber sheets with matrix resins, especially when producing sheet-like materials.
Innovation Solution
A method involving a coating device with a liquid pool and a narrowed section that increases liquid pressure to prevent fuzz clogging and ensure uniform impregnation, using a unidirectional reinforcing fiber sheet that passes vertically downward through the coating section, where the cross-sectional area of the liquid pool decreases continuously, and the narrowed section has a smaller cross-sectional area, enhancing impregnation efficiency and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hot-melt process is used to impregnate reinforcing fiber sheets with matrix resin, then the impregnation can be achieved, but the production speed is low and production cost is high
Solution Approach 1:
The patent replaces the conventional hot-melt process with a pultrusion-based continuous production system. The reinforcing fiber sheet is continuously fed through a die filled with liquid matrix resin, and impregnation is achieved through the combined action of liquid resin flow and ultrasonic vibration, eliminating the need for repeated heating and pressing cycles.
Solution Approach 2:
The die is pre-filled with liquid matrix resin before the reinforcing fiber sheet enters. This preliminary preparation of the resin environment allows immediate impregnation upon fiber entry, enabling continuous production without intermittent heating and resin application steps.
2Productivity
If ultrasonic vibration is applied at the outlet of a manifold in pultrusion method, then impregnation efficiency is improved, but fuzz generation causes clogging
Solution Approach 1:
The patent introduces ultrasonic vibration in the vertical direction (thickness direction of the fiber sheet) while the fiber sheet moves horizontally through the die. This multi-dimensional approach enhances resin penetration into the fiber structure without disrupting the horizontal flow of fibers, reducing fuzz generation that would cause clogging.
Solution Approach 2:
Ultrasonic vibration is applied to the reinforcing fiber sheet during impregnation to enhance the penetration of liquid matrix resin into the fiber structure. The high-frequency vibration loosens the fiber arrangement temporarily, allowing better resin infiltration, and then the fibers return to their original arrangement, minimizing fuzz generation.
3Reliability
If the cross-sectional area of the liquid pool decreases continuously, then liquid pressure increases to prevent clogging, but uniform impregnation becomes more difficult
Solution Approach 1:
The die structure is designed with different cross-sectional area profiles at different locations. The inlet portion has a larger cross-sectional area for resin supply, the middle portion has a gradually decreasing area to build pressure, and the outlet portion maintains appropriate area for uniform impregnation. This localized variation in geometry optimizes both pressure generation and impregnation uniformity.
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
This approach significantly reduces fuzz clogging, allows for high-speed continuous production of prepregs, and ensures uniform impregnation of the reinforcing fiber sheet with matrix resin, enhancing the mechanical properties and efficiency of the prepreg production process.
Implementation Method 1
the cross-sectional area of the liquid pool decreases continuously, and the narrowed section has a smaller cross-sectional area, enhancing impregnation efficiency
Implementation Method 2
a unidirectional reinforcing fiber sheet that passes vertically downward through the coating section
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The present invention relates to a method of producing a prepreg, in which a matrix resin is applied to a reinforcing fiber sheet. An object of the present invention is to provide a method of producing a prepreg, in which the sheet can continuously run without clogging of generated fuzz even at a high running speed and in which the reinforcing fiber sheet can be efficiently impregnated with the matrix resin. The spirit of the present invention is a method of producing a prepreg (1c), including: allowing a reinforcing fiber sheet (1a) to pass substantially vertically downward through the inside of a coating section (20) storing a matrix resin (2) to apply the matrix resin (2) to the reinforcing fiber sheet (1a); and then applying a resin film (3) to a primary impregnate prepreg (1b) withdrawn from the coating section (20); wherein the coating section (20) includes a liquid pool and a narrowed section which are in communication with each other; wherein the liquid pool has a portion whose cross-sectional area decreases continuously along a running direction of the reinforcing fiber sheet, and wherein the narrowed section has a slit-like cross-section and has a smaller cross-sectional area than the top side of the liquid pool.