Polyamide Multifilament Strength-Elongation Balance
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Solution Overview
Problem
Existing polyamide multifilaments for stockings and knitted laces face issues with low fiber modulus and strength-elongation product, leading to unsatisfactory durability and appearance quality, while high modulus fibers are prone to breakage and fluffing during processing.
Innovation Solution
A polyamide multifilament with a tensile strength of 4.0-6.0 cN/dtex, a strength-elongation product of 10.0 cN/dtex or larger, and a yarn unevenness of 1.2 or less, featuring a fineness of 1.3-3.4 dtex, elongation of 30-50%, and a sum of crystal and rigid amorphous components content of 70-90%, which enhances durability, transparency, and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-modulus polyamide fibers are used to improve strength and durability, then the strength-elongation product increases, but the fibers become prone to breakage and fluffing during high-order processing
Solution Approach 1:
The patent precisely controls multiple parameters including tensile strength (4.0-6.0 cN/dtex), strength-elongation product (10.0 cN/dtex or larger), yarn unevenness (U% of 1.2 or less), single-filament fineness (1.3-3.4 dtex), elongation (30-50%), and crystallinity (70-90%). This multi-parameter optimization resolves the contradiction by finding the precise balance point where sufficient strength is achieved without excessive modulus that would cause processing problems.
Solution Approach 2:
The patent creates a composite structure within the fiber by controlling the sum of crystal and rigid amorphous components content to be 70-90%. This composite microstructure combines the strength benefits of crystalline regions with the flexibility and processability of amorphous regions, resolving the contradiction between strength and processability.
2Strength
If polyamide fibers with higher strength are used to improve durability, then the strength increases, but the softness and sense of transparency deteriorate
Solution Approach 1:
The patent optimizes the tensile strength parameter to a specific range (4.0-6.0 cN/dtex) rather than maximizing it, and controls the strength-elongation product to be 10.0 cN/dtex or larger. This balanced parameter selection ensures sufficient durability while maintaining the softness and transparency needed for comfort wear.
Solution Approach 2:
The patent applies different quality characteristics to different aspects of the fiber performance: high strength and durability in the mechanical properties, while maintaining low fineness (1.3-3.4 dtex) for softness and transparency. This local optimization of different properties resolves the contradiction between durability and comfort.
3Ease of operation
If the fineness of polyamide fibers is reduced to enhance transparency and softness, then the comfort wearability improves, but the strength and durability decrease
Solution Approach 1:
The patent reduces the single-filament fineness to a specific range (1.3-3.4 dtex) to enhance softness and transparency, but compensates for the strength loss by optimizing other parameters including tensile strength (4.0-6.0 cN/dtex), elongation (30-50%), and crystallinity (70-90%). This multi-parameter compensation strategy maintains durability despite reduced fineness.
Solution Approach 2:
The controlled composite structure of crystal and rigid amorphous components (70-90% total) provides reinforcement at the microstructural level, compensating for the reduced fineness and maintaining sufficient strength and durability in the ultra-fine fibers.
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 polyamide multifilament achieves high durability, attractive pattern retention, and excellent softness in knitted laces and stockings, with improved high-order process passage capability and appearance quality, enabling them to withstand practical use while maintaining softness and transparency.
Implementation Method 1
the sum of a content of crystals and a content of rigid amorphous components of 70-90%
Data Source
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AI summary
Provided is a polyamide multifilament characterized by having a tensile strength at 15% elongation of 4.0 to 6.0 cN/dtex, a strength-elongation product of 10.0 or more, and a yarn unevenness (U%) of 1.2 or less. The present invention provides a high-strength polyamide multifilament with which it is possible to obtain stockings having high softness, durability, and transparency, and a lace knit in which patterns have a beautiful appearance.