Extra-fine Fiber Sheet Bead Formation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing extra-fine fiber sheets with nanometer-scale fibers are limited in achieving small fiber diameters and are prone to bead formation, especially when using low-molecular-weight polymers, which affects fiber fineness, straightness, and properties like liquid absorbability and peel resistance.
Innovation Solution
The use of a solvent-spinnable polymer with a weight average molecular weight of 5,000 to 100,000 as the main component and a high-molecular-weight polymer with a weight average molecular weight at least ten times larger as an accessory component, where the high-molecular-weight polymer is added to improve spinning ability and reduce bead formation, resulting in an extra-fine fiber sheet with an average fiber diameter of 10 to 500 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a low-molecular-weight polymer (weight average molecular weight of 100,000 or lower) is used to reduce fiber diameter, then fiber fineness is improved, but bead formation increases and fiber straightness deteriorates
Solution Approach 1:
The patent combines a low-molecular-weight polymer (weight average molecular weight 10,000 to 100,000) with a high-molecular-weight polymer (weight average molecular weight 1,000,000 to 10,000,000) in a specific ratio (95:5 to 50:50 by weight). The low-molecular-weight polymer enables formation of ultra-fine fibers with diameters of 10 to 500 nm, while the high-molecular-weight polymer acts as a viscosity modifier that suppresses bead formation and improves fiber straightness during electrospinning. This composite approach allows simultaneous achievement of small fiber diameter and high manufacturing precision.
Solution Approach 2:
The patent changes the molecular weight parameter of the polymer system by introducing a dual-polymer composition with widely different molecular weights. The low-molecular-weight polymer (10,000-100,000) provides the base for fine fiber formation, while the high-molecular-weight polymer (1,000,000-10,000,000) modifies the solution viscosity and spinning characteristics. By controlling the weight ratio and molecular weight parameters within specific ranges, the patent optimizes both fiber fineness and straightness.
2Stability of the object's composition
If the concentration of polymer solution is kept high to maintain solution stability, then solution stability is improved, but fiber fineness deteriorates
Solution Approach 1:
The patent changes the viscosity parameter of the polymer solution by adding a high-molecular-weight polymer component. This allows the use of lower polymer concentrations (0.1 to 10% by weight) while maintaining sufficient solution stability and viscosity for electrospinning. The high-molecular-weight polymer (1,000,000 to 10,000,000) compensates for the reduced concentration, enabling formation of ultra-fine fibers with diameters of 10 to 500 nm without compromising solution stability.
3Adaptability or versatility
If a polymer with low fiber formability is used, then polymer versatility is improved, but fiber quality deteriorates
Solution Approach 1:
The patent creates a composite spinning dope system combining two polymers with different properties. The low-molecular-weight polymer (10,000-100,000) provides versatility in polymer selection, while the high-molecular-weight polymer (1,000,000-10,000,000) acts as a universal viscosity modifier and fiber quality enhancer. This composite approach enables production of high-quality extra-fine fibers even with polymers that have low inherent fiber formability, as the high-molecular-weight component compensates for deficiencies in the low-molecular-weight polymer.
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 allows for the production of extra-fine fiber sheets with unattainable small fineness, excellent straightness, and enhanced liquid absorbability and peel resistance, while minimizing bead formation, even with polymers of low fiber formability.
Implementation Method 1
a high voltage is applied between the spinning nozzle and a counter electrode to accumulate charges in a dielectric material in the nozzle, thereby producing extra-fine fibers by means of an electrostatic repulsive force
Data Source
AI summary
Provided is an extra-fine fiber sheet including an extra-fine fiber assembly including extra-fine fibers having an average fiber diameter of 500 nm or smaller. The extra-fine fiber sheet includes an extra-fine fiber assembly. The assembly includes a solvent-spinnable polymer (A) having a weight average molecular weight of 5,000 to 100,000 as a main component and a polymer (B) having a weight average molecular weight equal to or more than 10 times as large as that of the polymer (A) as an accessory component; and the assembly includes constituent fibers having an average fiber diameter of 10 to 500 nm. The polymer (A) may be a non-conductive polymer, and the polymer (B) may be a thickening polymer.