Thermoplastic Prepreg for Thin Complex Shapes
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Solution Overview
Problem
Conventional prepregs are unsuitable for thin molded products and complicated shapes due to limitations in isotropic mechanical properties and processing restrictions, leading to increased economic burdens and reduced flexibility in lamination.
Innovation Solution
A prepreg comprising reinforcing fibers with specific fiber lengths and two-dimensional orientation angles, impregnated with a thermoplastic resin, allowing for improved isotropic mechanical properties and enhanced workability, enabling the production of thin molded products with complex shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If continuous reinforcing fibers are used in their original form, then superior mechanical properties are obtained, but they are unsuitable for shaping into complicated shapes and require time-consuming lamination steps
Solution Approach 1:
The continuous reinforcing fibers are cut into discontinuous lengths of 3-15mm to enable shaping into complicated forms while maintaining adequate mechanical properties. This segmentation allows the fibers to conform to complex geometries during molding without requiring extensive lamination operations.
Solution Approach 2:
The fiber length parameter is optimized to a specific range (3-15mm) to balance mechanical strength requirements with formability. This parameter change enables the material to be shaped into complicated forms while retaining sufficient reinforcement effectiveness.
2Strength
If prepregs are laminated with attention to lamination angle, then superior mechanical properties are obtained, but the process requires time and effort increasing economic burden
Solution Approach 1:
The discontinuous fibers are uniformly dispersed throughout the resin matrix with controlled orientation angles (10-80 degrees), creating a homogeneous structure that provides isotropic mechanical properties. This homogeneity eliminates the need for complex lamination angle considerations, significantly reducing lamination time and effort.
Solution Approach 2:
Instead of requiring precise control of lamination angles for every layer, the invention uses a sufficient amount of discontinuous fibers with randomized orientation that collectively provide the necessary mechanical properties without exact angular precision, reducing the stringency of the lamination process.
3Ease of manufacture
If discontinuous reinforcing fibers are used, then shaping into complicated shapes is enabled, but mechanical properties such as specific strength and specific rigidity are poor
Solution Approach 1:
The invention creates local density variations in the fiber distribution, with higher fiber concentration in regions requiring greater strength. The discontinuous fibers are distributed to achieve optimal local reinforcement while maintaining overall formability for complicated shapes.
Solution Approach 2:
The invention uses a composite structure combining discontinuous reinforcing fibers with a resin matrix, where the specific combination of fiber length (3-15mm), orientation (10-80 degrees), and matrix composition achieves both shaping capability and adequate mechanical properties.
4Ease of manufacture
If resin flows greatly at the time of molding, then shaping is facilitated, but isotropic mechanical properties are impaired and mechanical properties decline
Solution Approach 1:
The reinforcing fibers are pre-dispersed and pre-oriented within the resin matrix before molding, creating a structured composite that maintains fiber orientation during the molding process. This preliminary arrangement ensures that even with resin flow, the fibers remain positioned to provide isotropic mechanical properties.
Solution Approach 2:
The invention uses a sufficient quantity of shorter discontinuous fibers that can accommodate resin flow without requiring precise positioning, accepting some resin movement while maintaining adequate mechanical properties through the high volume of reinforcement material.
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
A prepreg is disclosed, comprising a reinforcing fiber base material impregnated with a thermoplastic resin, wherein the reinforcing fiber base material may comprise from 0 to 50% by mass of reinforcing fibers each having a fiber length of more than 10 mm, from 50 to 100% by mass of reinforcing fibers each having a fiber length of from 2 to 10 mm, and from 0 to 50% by mass of reinforcing fibers each having a fiber length of less than 2 mm, wherein the average of two-dimensional orientation angles each formed by a reinforcing filament (a) and a reinforcing filament (b) intersecting the reinforcing filament (a) may be from 10 to 80°, the thickness h0 (mm) at 23°C may be 0.03 to 1 mm, and the tensile strength σ may be 0.01 MPa or more. The prepreg can be applied for thin molded products which have been considered unsuitable as a laminated molded product and can provide molded products that have a complicated shape and have isotropically high mechanical properties.