Die-Coated Slurry Impregnation for Uniform Thick Fiber Sheets
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Solution Overview
Problem
Existing methods for producing prepregs face challenges in achieving uniform impregnation of resin particles on fiber sheets due to issues with controlling the width of fiber strands, tension during conveyance, and variations in basis weight, particularly for thick fiber sheets.
Innovation Solution
An apparatus comprising a conveying device, a coating device with a die that includes a slurry supply channel, manifold, and slit, and an impregnation device that applies an external force to uniformly impregnate fiber sheets with slurry, along with a drying device to remove solvent, ensuring angles between device components facilitate uniform slurry application and prevent clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a slurry impregnation method is used to produce prepreg, then the production process is simplified compared to hot melt method, but it becomes substantially difficult to accurately control the basis weight of resin particles due to variations in strand width, tension during conveyance, and particle concentration
Solution Approach 1:
The slurry application system is segmented into multiple independent spray nozzles that can be individually controlled. Each nozzle applies slurry to a specific zone of the fiber sheet, allowing localized adjustment of resin distribution. This segmentation enables precise control of basis weight by independently managing slurry application in different regions, overcoming the problem of uniform but uncontrolled resin distribution in conventional single-tank methods
Solution Approach 2:
The invention changes key parameters including slurry particle concentration (controlled within ±5%), spray pressure, nozzle-to-sheet distance, and conveyance speed. By precisely controlling these parameters and maintaining strand width variation within ±10%, the system achieves accurate basis weight control while preserving the simplified slurry impregnation process
2Ease of operation
If fibers are twisted or entangled to form strands, then the fiber sheet can be handled more easily, but it becomes difficult to control the width of the strand to be constant
Solution Approach 1:
The invention introduces a dynamic tension control system with variable speed rollers that adjust roller spacing and rotational speed during conveyance. This dynamic adjustment compensates for natural variations in strand width caused by fiber twisting and entanglement, maintaining constant effective strand width throughout the slurry application process while preserving the handled nature of stranded fibers
Solution Approach 2:
A feedback control system uses sensors to detect real-time strand width variations and automatically adjusts conveyance tension and slurry application rate. The system maintains strand width within ±10% by continuously monitoring and adjusting process parameters, allowing the use of naturally twisted and entangled fibers without sacrificing width control
3Strength
If a thick fiber sheet is used, then the product meets higher strength requirements, but it becomes difficult to impregnate the fiber sheet with resin uniformly throughout its thickness
Solution Approach 1:
The slurry application system is segmented into multiple spray nozzles arranged at different heights and angles to target different zones of thick fiber sheets. This multi-zone segmentation ensures uniform resin distribution throughout the entire thickness, achieving consistent impregnation even in sheets requiring high strength
Solution Approach 2:
The invention transitions from single-plane slurry application to three-dimensional multi-angle spraying. Nozzles are positioned to spray from multiple dimensions (different heights and angles), ensuring resin penetrates uniformly throughout the thickness of thick fiber sheets while maintaining surface quality
4Productivity
If the production rate is increased, then productivity improves, but the uniformity of slurry impregnation becomes more difficult to maintain
Solution Approach 1:
The invention implements continuous slurry circulation and recycling systems that maintain constant particle concentration and distribution characteristics. The closed-loop system continuously recirculates slurry through filtration and concentration control, ensuring uniform impregnation quality is maintained even at high production rates where residence time is reduced
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 apparatus enables the production of slurry-impregnated sheets with uniform resin impregnation in high yield, preventing resin deposition and ensuring stable production over time, even for thick sheets.
Implementation Method 1
heating the sheet to dry the organic solvent
Implementation Method 2
further heating the sheet at a high temperature to melt the thermoplastic resin to integrate into the reinforcing-fiber sheet
Data Source
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AI summary
Provided is an apparatus for producing a slurry-impregnated sheet capable of producing a slurry-impregnated sheet having a uniform slurry impregnation amount in a high yield. An apparatus for producing a slurry-impregnated sheet of the present invention is an apparatus for producing a slurry-impregnated sheet constituted of a fiber sheet or a porous sheet impregnated with a slurry prepared by dispersing particles in a solvent, the apparatus including: a conveying device configured to convey the fiber sheet or the porous sheet; a coating device configured to meter and apply the slurry to the fiber sheet or the porous sheet; and an impregnation device disposed downstream of the coating device in a sheet conveyance direction and configured to apply an external force to the fiber sheet or the porous sheet to impregnate the fiber sheet or the porous sheet with the particles, in which the coating device includes a die.