Spun-dyed Para-aramid Filament Yarn Drying Tension Control
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Solution Overview
Problem
Spun-dyed para-aramid filament yarns with increased dye concentration tend to form defects that lead to nep formation and color fading when used to manufacture slivers and textile fabrics, resulting in inferior quality products.
Innovation Solution
A process involving the preparation of a spin dope with 17.5 to 18.5% para-aramid polymer and 4 to 15% dyestuff by weight, followed by spinning, coagulation, neutralization, washing, and drying under tension between 0.2 to 0.8 cN/dtex, which reduces defect formation and color fading in the resulting yarns and fabrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the concentration of dyestuff in the filament yarn is increased to achieve deeper color, then the color intensity is improved, but the filament yarn forms intermittent defects that extend along the center of the filament fiber axis
Solution Approach 1:
The patent applies parameter changes by precisely controlling the spin dope composition (17.5-18.5% para-aramid polymer, 4-15% dyestuff) and drying tension (0.2-0.8 cN/dtex) to optimize both color intensity and defect prevention. This resolves the contradiction by finding the optimal parameter range that achieves deep color without excessive defect formation.
2Illumination intensity
If spun-dyed para-aramid filament yarn with high dye concentration is used to manufacture sliver, then the color depth is improved, but the sliver exhibits neps and color fading
Solution Approach 1:
The patent applies preliminary action by performing drying under controlled tension (0.2-0.8 cN/dtex) during the manufacturing process itself, rather than after. This preliminary drying step prevents nep formation and color fading before they can occur during subsequent sliver manufacturing, thereby maintaining color stability while achieving deep color.
3Illumination intensity
If the concentration of dyestuff is increased to achieve deeper color in filament yarn, then the color intensity is improved, but the resulting staple fiber yarn exhibits increased nep formation and color fading
Solution Approach 1:
The patent applies parameter changes by optimizing the spin dope composition and drying tension to prevent nep formation at its source. By controlling the drying tension (0.2-0.8 cN/dtex) and dyestuff concentration (4-15%), the process achieves deep color without generating neps that would otherwise transfer to staple fiber yarn and fabric.
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 process produces spun-dyed para-aramid filament yarns that are less susceptible to defects, resulting in slivers and textile fabrics with reduced nep formation and color fading, maintaining the desired color intensity throughout the manufacturing process.
Implementation Method 1
spinning the spin dope through a spinneret to obtain spun filaments
Implementation Method 2
coagulating the spun filaments to obtain coagulated filaments
Implementation Method 3
neutralizing the coagulated filaments to obtain neutralized filaments
Implementation Method 4
drying the washed filaments to obtain dried filaments
Implementation Method 5
during drying the filaments are hold under a tension in a range from 0.2 to 0.8 cN/dtex
Data Source
AI summary
Manufacturing a spun-dyed para-aramid filament yarn includes (a) preparing a spin dope comprising a para-aramid polymer, at least one dyestuff and concentrated sulfuric acid, (b) spinning the spin dope through a spinneret to obtain spun filaments, (c) coagulating the spun filaments to obtain coagulated filaments, (d) neutralizing the coagulated filaments to obtain neutralized filaments, (e) washing the neutralized filaments to obtain washed filaments, and (f) drying the washed filaments to obtain dried filaments. In step a) the spin dope includes 17.5 to 18.5% by weight of a para-aramid polymer with respect to the weight of the spin dope, and 4 to 15% by weight of the at least one dyestuff with respect to the weight of the para-aramid polymer plus the at least one dyestuff. In step f) the filaments are hold under a tension in a range from 0.2 to 0.8 cN/dtex.