Ultrafine Polyamide Multifilament Elongation and Transparency Balance
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Solution Overview
Problem
Existing methods for producing ultrafine high-strength polyamide multifilaments, such as those described in Patent documents 1 and 2, result in nylon yarns with elongation degrees less than 38%, leading to inferior high-order process passage capability and product quality in stockings and woven fabrics, while consumers demand increased softness and transparency while maintaining durability.
Innovation Solution
Developing an ultrafine high-strength polyamide multifilament with a total fineness of 4.0 to 6.0 dtex, single fiber fineness of 1.2 dtex or less, a strength-elongation product of 9.1 cN/dtex or more, and an elongation degree of 40 to 50%, along with a yarn unevenness of 1.2 or less, and sulfuric acid relative viscosity of 2.5 to 3.5, which is used to produce stockings and woven fabrics with improved softness, durability, and lightweightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If ultrafine high-strength polyamide multifilament is produced by heating and additional stretching, then softness and transparent appearance are improved, but elongation degree decreases to less than 38%, resulting in inferior high-order process passage capability
Solution Approach 1:
The invention changes the processing parameters by controlling the draw ratio to 2.0 or more and the taking-up speed to 3000 m/min or more, while maintaining specific spinning conditions. This parameter optimization achieves both high transparency and sufficient elongation degree (38% or more), resolving the contradiction between transparent appearance and process passage capability
Solution Approach 2:
The invention introduces dynamic control of the taking-up speed during the spinning process, maintaining it at 3000 m/min or more to achieve the desired balance between transparency and elongation. This dynamic parameter control allows the system to simultaneously satisfy both requirements that were previously conflicting
2Illumination intensity
If total fineness is reduced to achieve ultrafine characteristics, then softness and transparent appearance are improved, but strength decreases, affecting durability
Solution Approach 1:
The invention creates a composite structure through the interaction of ultrafine fibers with optimized crystallinity and molecular orientation. By controlling the draw ratio and taking-up speed, the invention achieves a composite effect where the ultrafine structure provides transparency while the enhanced molecular alignment compensates for strength loss, maintaining durability
Solution Approach 2:
The invention changes the physical parameters of the fiber structure by controlling the draw ratio to 2.0 or more and taking-up speed to 3000 m/min or more. These parameter changes transform the molecular structure to achieve both ultrafine characteristics and sufficient strength, resolving the contradiction between transparency and durability
3Shape
If single fiber fineness is reduced to 1.2 dtex or less, then softness is improved, but yarn unevenness increases, affecting product quality
Solution Approach 1:
The invention implements process feedback by carefully controlling the relationship between draw ratio and taking-up speed. The taking-up speed is maintained at 3000 m/min or more in response to the draw ratio of 2.0 or more, creating a feedback-controlled system that ensures uniform yarn structure and minimizes yarn unevenness while achieving ultrafine softness
Data Source
AI summary
A polyamide multifilament, characterized in having a total fineness of 4.0-6.0 dtex, a single yarn fineness of 1.2 dtex or below, a strength-elongation product of 9.1 or above, and an elongation degree of 40-50%. Provided is a polyamide fiber having a small total fineness and single fiber fineness while having a high strength-elongation product and exhibiting a low unevenness (U%) in the longitudinal direction. Also provided are: a stocking exhibiting an excellent higher-order process passability and productivity and exhibiting an excellent softness, durability, and transparent feel; and a fabric exhibiting an excellent softness and durability.