Polyimide Fiber Assembly with Curved Structure for Lightweight Insulation
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Solution Overview
Problem
Polyimide fiber assemblies used in various applications, such as thermal insulation and sound absorption in aircraft, are heavy and have inadequate thermal insulation and sound absorbency due to high bulk density and low air retention, limiting their effectiveness and weight efficiency.
Innovation Solution
A polyimide fiber assembly with curved fibers of average diameters between 1 µm and 100 µm and bulk densities between 1 kg/m³ and 30 kg/m³ is produced by dissolving polyamic acid or polyimide in an organic solvent and using a gas flow intersecting with the discharge direction to spin the fibers, allowing for improved entanglement and air retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dry spinning method is used to produce polyimide fibers, then the fibers are curveless and high in bulk density, but the thermal insulation performance and sound absorbency are insufficient
Solution Approach 1:
The patent applies crimping treatment to the polyimide fibers to introduce curves and bends, transforming the straight fiber structure into a curved configuration. This curvature increases the air gaps between fibers, thereby improving thermal insulation performance and sound absorbency while maintaining the advantages of dry spinning production
Solution Approach 2:
The patent creates a porous structure by forming air gaps between the crimped fibers through loosening treatment. This porous configuration increases the amount of air retained in the fiber assembly, enhancing both thermal insulation and sound absorption properties without significantly increasing weight
2Ease of manufacture
If dry spinning method is used to produce polyimide fibers, then the fibers are curveless and high in bulk density, but the weight of the product increases
Solution Approach 1:
By crimping the fibers to create curves, the patent increases the volume occupied by the same mass of fiber, thereby reducing bulk density. This allows weight reduction while maintaining the manufacturing efficiency of dry spinning
Solution Approach 2:
The loosening treatment creates a porous structure with increased air content between fibers, reducing the overall density of the fiber assembly. This enables the product to be lighter while preserving the structural integrity and manufacturing advantages of dry spinning fibers
3Length of moving object
If the diameter of spun fibers is made smaller by raising the draw ratio, then the fiber diameter decreases, but the fibers are likely to be broken and the yield decreases
Solution Approach 1:
The patent applies crimping treatment during or after the spinning process to introduce curves into the fibers before final winding. This preliminary structural modification allows the use of appropriate draw ratios without excessive fiber breakage, as the crimped structure provides stress distribution that prevents breakage during subsequent handling
Solution Approach 2:
By introducing curves through crimping, the patent reduces the stress concentration that occurs in straight, thin fibers during drawing and winding operations. This allows for production of finer fibers with higher yield, as the curved structure distributes mechanical stresses more evenly throughout the fiber assembly
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 resulting polyimide fiber assembly achieves enhanced thermal insulation and sound absorbency while maintaining light weight, along with excellent flame retardance, heat resistance, and chemical resistance, making it suitable for applications like thermal insulating materials, flame-retardant mats, and heat-resistant garments.
Implementation Method 1
using a gas flow intersecting with the discharge direction to spin the fibers
Implementation Method 2
high bulk density, low in amount of air retained therein
Data Source
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AI summary
A polyimide fiber assembly of the present invention includes polyimide fibers having curved shapes with an average fiber diameter falling within a range of greater than 1 µm to not greater than 100 µm, the polyimide fiber assembly having a bulk density falling within a range of not less than 1 kg/m3 to not greater than 30 kg/m3. This makes it possible to realize a polyimide fiber assembly that is both excellent in thermal insulation performance and sound absorbency and light in weight. The polyimide fiber assembly of the present invention can be obtained by a production method comprising the steps of: (i) discharging a polymeric resin solution obtained by dissolving polyamic acid or polyimide in an organic solvent; and (ii) using external force to cause the polymeric resin solution thus discharged to fly in a direction of the external force, the external force being external force of gas from a direction intersecting with a discharge direction in which the polymeric resin solution is discharged, and then forming a polymeric resin into fibers by spinning while vaporizing the organic solvent contained in the polymeric resin solution.