Centrifugal Spinning of Composite Fine Fiber Strands
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Solution Overview
Problem
Existing methods of centrifugal spinning for producing nanofibers face challenges with low fiber strength, high defect rates, and increased solvent costs due to the need for high polymer concentrations and low molecular weights, which compromise fiber quality and production efficiency.
Innovation Solution
A fiber strand composition comprising a first polymer and a second polymer with a higher molecular weight, where the second polymer is 1.5 times higher, is centrifugally spun using a polymer solution with a concentration of at least 10% by weight, and the fibers are then bonded to a substrate using thermal, chemical, or adhesive methods to form a fibrous web, optimizing fiber strength and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high polymer concentration is used in centrifugal spinning, then fiber production efficiency is improved, but fiber strength decreases and defect rates increase
Solution Approach 1:
The patent uses a composite polymer system consisting of both high molecular weight polymer (providing strength) and low molecular weight polymer (providing processability and spinability). This composite approach allows the fiber to achieve both high strength and high production efficiency by combining the advantages of different polymer molecular weights in a single fiber structure.
2Ease of manufacture
If low molecular weight polymer is used, then fiber spinability and processability are improved, but fiber strength decreases
Solution Approach 1:
The patent combines low molecular weight polymer (for spinability and ease of manufacture) with high molecular weight polymer (for strength) to create a composite fiber system that achieves both processability and mechanical strength simultaneously.
Solution Approach 2:
The patent optimizes the molecular weight distribution parameters of the polymer blend, specifically using a ratio where the high molecular weight polymer is 1.5 times the low molecular weight polymer. This parameter optimization allows the fiber to maintain both spinability and strength by carefully controlling the molecular weight distribution.
3Loss of substance
If high polymer concentration is used, then solvent costs decrease, but fiber defect rates increase
Solution Approach 1:
The composite polymer system allows the use of high polymer concentration (reducing solvent content and costs) while maintaining low defect rates because the high molecular weight component provides structural integrity that prevents fiber breaking and defects during high-speed centrifugal spinning.
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
This approach enhances fiber strength, reduces defect rates, and decreases solvent costs by maintaining high polymer concentrations while achieving nano-scale diameters and continuous fiber lengths, improving the overall efficiency of the centrifugal spinning process.
Implementation Method 1
centrifugally expelling the polymer solution through orifices in at least one spinneret while rotating the spinneret at a speed of at least 2500 rpm
Implementation Method 2
drawing down a fiber diameter of the fine fiber strands through centrifugal force
Implementation Method 3
thermally, chemically, or adhesively bonding at least a portion of the plurality of fine fiber strands to the substrate
Data Source
AI summary
In embodiments, the present invention provides a plurality of fine fiber strands made from a first polymer and a second polymer where the second polymer has a higher molecular weight than the first polymer. In preferred embodiments, the fine fiber strands have an average diameter of less than 2 micron, and the fine fiber strands have a length of at least 1 millimeter.