Carbon Fiber Composite Material with Controlled Bundle Segmentation
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Solution Overview
Problem
Existing fiber-reinforced composite materials using thermoplastic resins face challenges in achieving high mechanical strength and thin, homogeneous products due to limitations in fiber volume content and orientation, particularly with random mats and thermoplastic stamping molding methods, which result in long processing times and poor surface quality.
Innovation Solution
A composite material comprising carbon fibers with an average length of 10-100 mm and a thermoplastic resin, where carbon fibers are two-dimensionally randomly oriented, with a specific carbon fiber bundle ratio and critical single fiber number, achieved through cutting, opening, and spraying processes to ensure uniform fiber distribution and orientation, allowing for efficient fiber impregnation and press forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fiber volume content is increased to improve mechanical physical property, then strength is improved, but it is difficult to increase fiber volume content in a random mat using cut fibers
Solution Approach 1:
The invention segments fiber bundles into individual fibers or short fiber segments through controlled cutting, while maintaining bundle structure for reinforcement. This segmentation allows increased fiber volume content without compromising the random mat's manufacturability, as the segmented fibers can be effectively distributed and impregnated with thermoplastic resin.
Solution Approach 2:
The invention creates a composite structure combining carbon fiber bundles with thermoplastic resin matrix. This composite approach enables high fiber volume content by leveraging the synergistic effect where the resin matrix binds the fiber segments, achieving both strength improvement and manufacturability.
2Strength
If chopped fiber bundles are used to improve mechanical physical property, then strength is improved, but layer thickness must be more than 2 to 3 mm to obtain homogeneity
Solution Approach 1:
The invention applies local quality by controlling fiber bundle segmentation at different scales: maintaining larger bundles for strength reinforcement while creating smaller segments for homogeneity. This multi-scale segmentation allows achieving both mechanical strength and thin layer thickness (less than 2-3 mm) with uniform fiber distribution.
3Productivity
If thermoplastic resin is used as matrix instead of thermosetting resin, then processing time is reduced, but viscosity is higher and impregnation time is long
Solution Approach 1:
The invention applies preliminary action by pre-heating the thermoplastic resin and preparing the fiber mat structure before impregnation. This preliminary preparation reduces the actual impregnation time needed, overcoming the high viscosity issue and enabling fast impregnation that matches the reduced molding time advantage of thermoplastic resins.
4Productivity
If thermoplastic stamping molding is used to reduce processing time, then molding time is reduced to about 1 minute, but fiber orientation is not aligned and surface quality is poor
Solution Approach 1:
The invention applies parameter changes by controlling temperature, pressure, and fiber mat density during the stamping molding process. These parameter optimizations enable the fast molding process to achieve proper fiber alignment and surface quality while maintaining the 1-minute molding time advantage of thermoplastic stamping molding.
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 solution enables the production of thin, isotropic composite materials with excellent mechanical strength and surface quality, suitable for various applications, including automotive and electronic components, while reducing processing time and maintaining fiber length.
Implementation Method 1
a thermoplastic resin generally has a higher viscosity than a thermosetting resin
Implementation Method 2
heating chopped fibers, which are previously impregnated with a thermoplastic resin, at a temperature of more than the melting point
Implementation Method 3
cutting, opening, and spraying processes to ensure uniform fiber distribution and orientation
Implementation Method 4
press forming
Data Source
AI summary
A composite material includes: carbon fibers having an average fiber length of more than about 10 mm and about 100 mm or less; and a thermoplastic resin. The carbon fibers are substantially two-dimensionally-randomly oriented. The composite material includes a carbon fiber bundle (A) in a ratio of more than 0 volume % and less than about 30 volume % to a total volume of the carbon fibers, the carbon fiber bundle (A) including the carbon fibers of a critical single fiber number defined by formula (1) or more. An average number (N) of the carbon fibers in the carbon fiber bundle (A) satisfies formula (2).Critical single fiber number=600/D (1)1.0×104/D2<N<2.5×104/D2 (2)D is an average fiber diameter (μm) of the carbon fibers.