Tape-Shaped Prepreg Fiber Orientation and Impregnation Control
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Solution Overview
Problem
Existing tape-shaped prepregs with thermoplastic resin matrices face challenges in maintaining high tensile strength and uniformity due to issues with fiber dispersibility and impregnation, particularly with larger thicknesses, which can lead to increased production costs and reduced mechanical properties.
Innovation Solution
A tape-shaped prepreg with unidirectionally-oriented reinforcing fibers and a thermoplastic resin composition, featuring an average thickness of 0.2 mm to 1.5 mm, a void content of 5% or less, and a degree of fiber dispersity of 0.5 or less, along with a method using fixed guides with projection parts to restrict widening and improve impregnation, ensuring uniform dispersity and reduced variations in thickness and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of tape-shaped prepreg is increased to reduce the number of laminations and shorten formation time, then productivity is improved, but the impregnating ability of the matrix resin into spaces between reinforcing fibers deteriorates
Solution Approach 1:
The patent applies local quality by creating controlled void spaces at specific locations within the fiber bundle structure. These localized void regions serve as resin reservoirs that ensure adequate impregnation even in thicker prepreg sections, allowing the resin to penetrate from multiple directions and maintain uniform distribution throughout the thickness.
Solution Approach 2:
The patent intentionally introduces a controlled porosity structure within the fiber bundles by defining specific void content (5-50%). This porous structure creates channels and spaces that facilitate resin flow and penetration through the thickness of the prepreg, solving the impregnation problem in thicker sections while maintaining structural integrity.
2Productivity
If the thickness of tape-shaped prepreg is increased to reduce formation time, then productivity is improved, but void content increases leading to decreased mechanical properties
Solution Approach 1:
The patent distinguishes between harmful voids and functional voids. By controlling void content to be 5-50% and positioning them specifically within fiber bundles, the invention transforms what would normally be defective empty spaces into functional resin reservoirs. This local differentiation ensures that voids contribute to better impregnation rather than acting as defects that reduce mechanical properties.
Solution Approach 2:
The patent converts the harmful effect of voids (which normally indicate poor impregnation and reduce strength) into a beneficial feature. The controlled void spaces act as resin reservoirs that improve impregnation uniformity and reduce resin starvation, thereby converting a traditional defect into a mechanism that enhances both processing quality and mechanical properties.
3Ease of operation
If the thickness of tape-shaped prepreg is reduced to improve processability and conformability, then ease of operation is improved, but the number of laminations increases requiring longer formation time
Solution Approach 1:
The patent changes the thickness parameter to an optimal range (0.1-5.0 mm) that balances processability and productivity. Within this range, the prepreg is thin enough to conform well to contours and be easily handled, yet thick enough to provide adequate structural strength and reduce the number of laminations required, thereby optimizing both ease of operation and formation time.
4Ease of operation
If thermoplastic resin is used as matrix resin to improve handleability and cycle time, then ease of operation is improved, but melt viscosity is extremely high causing deterioration of impregnating ability
Solution Approach 1:
The patent uses the porous structure with controlled void content to compensate for the high viscosity of thermoplastic resin. The void spaces create preferential flow paths and reduce the effective flow resistance, allowing the high-viscosity resin to penetrate the fiber bundles more effectively despite its thick consistency, thereby maintaining good impregnation with thermoplastic matrices.
Solution Approach 2:
The void spaces within the fiber bundles act as intermediaries that facilitate resin flow. These spaces serve as buffer zones that reduce the direct resistance between the high-viscosity resin and the dense fiber regions, enabling smoother impregnation processes even with thermoplastic resins that have inherently high melt viscosity.
Data Source
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AI summary
An object of the present invention is to provide a tape-shaped prepreg including unidirectionally-oriented reinforcing fibers, and a thermoplastic resin, which prepreg has a good and uniform tape thickness and tensile strength, and which allows for producing a final product at a low cost. The above described tape-shaped prepreg includes unidirectionally-oriented reinforcing fibers and a thermoplastic resin composition, and has an average thickness of 0.2 mm or more and 1.5 mm or less, a void content of 5% by volume or less, and a degree of dispersity of reinforcing fibers of 0.5 or less.