Indigo and ring dyeing process using high concentration of caustic and material produced thereof
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Solution Overview
Problem
Conventional indigo and sulfur continuous yarn dyeing methods fail to achieve a ring dye effect, where the outer periphery of the yarn is dyed while maintaining an internal white core, due to the formation of large molecules that hinder dye penetration, often requiring hazardous chemicals like potassium permanganate for removal.
Innovation Solution
A method involving immersion of yarns in a caustic bath followed by rinsing and dyeing in a single sulfur or indigo dye box, with controlled pH and temperature, to restrict dye penetration and achieve a ring dye effect without using multiple dye boxes or harsh chemicals, utilizing a series of stages including pre-treatment, dyeing, and washing to optimize dye distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sulfur and indigo dyeing processes are used, then the yarn becomes dyed, but the dye penetrates too deeply into the yarn core, preventing ring dye effect
Solution Approach 1:
The patent applies preliminary action by treating the yarn with a caustic bath before dyeing to open the yarn structure and create conditions for controlled dye penetration. This pre-treatment modifies the yarn surface to enable subsequent restriction of dye penetration to the outer layer only, achieving ring dye effect that would otherwise require multiple dye boxes or harsh chemicals.
Solution Approach 2:
The patent utilizes parameter changes by controlling pH levels, temperature, and immersion time in the caustic bath to precisely regulate dye penetration depth. By adjusting these parameters, the process achieves consistent ring dyeing where dye penetrates only 10-30% into the yarn cross-section, leaving the core white without requiring complex multi-box dyeing systems.
2Manufacturing precision
If multiple dye boxes are used to achieve ring dye effect, then dye penetration can be controlled, but the process complexity increases
Solution Approach 1:
The patent merges the functions of multiple dye boxes into a single dye box by using a caustic pre-treatment that enables controlled dye penetration in one immersion. The caustic-modified yarn structure allows the single dye box to achieve what traditionally required multiple sequential dyeing stages, simplifying the equipment while maintaining precise ring dyeing control.
Solution Approach 2:
The patent extracts the dye penetration control function from the multi-box system and transfers it to a chemical pre-treatment step. By removing the need for multiple mechanical dyeing stages and replacing them with a single caustic treatment followed by one dyeing step, the process eliminates complex equipment while preserving the ability to control dye distribution.
3Ease of manufacture
If harsh chemicals like potassium permanganate are used for color removal, then the worn look can be achieved, but environmental harm increases
Solution Approach 1:
The patent converts the potential harm of deep dye penetration into a benefit by using caustic pre-treatment to create a yarn structure that naturally limits dye penetration to the outer layer. This transforms what would be a problem (dye reaching the core) into an advantage (automatic ring dyeing), eliminating the need for harsh chemical removal processes and enabling environmentally friendly laser or manual abrasion methods.
Solution Approach 2:
The patent replaces the chemical-mechanical system of harsh chemical treatment and abrasion with a controlled chemical pre-treatment followed by limited dye penetration. By substituting the need for potassium permanganate and aggressive chemical removal with a controlled single-step dyeing process on caustic-treated yarn, the method achieves the same worn aesthetic effect without environmental damage.
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 method achieves consistent dye penetration of 10% to 35% of the yarn's cross-sectional area, allowing for a controlled ring dye effect, reducing the need for potassium permanganate and minimizing environmental impact, while ensuring the core remains undyed, facilitating laser or manual abrasion for color removal.
Implementation Method 1
The yarn is immersed for between 7 to 40 seconds in a caustic bath having a caustic concentration of 50 to 175 g/l
Implementation Method 2
The yarn is dyed in only one sulfur dye box when the yarn is open-end yarn and ring yarn or is dyed at least one indigo dye box
Implementation Method 3
Sulfur dye, once dyed on cellulosic fiber, forms a bigger molecule due to dye and cellulose bonding
Implementation Method 4
this large molecule covers the free sites of cellulose and forms a barrier for the indigo dye molecule to enter towards the core of the yarn
Implementation Method 5
The parameters which control the degree of ring dyeing for indigo and sulfur continuous yarns are indigo and sulfur dye properties, immersion time, air oxidation time
Data Source
AI summary
A method of ring dyeing a yarn comprises a series of steps, including providing a yarn chosen from the group consisting of open-end yarns and ring yarns. The yarn is immersed for between 7 to 40 seconds in a caustic bath having a caustic concentration of 50 to 175 g/l. The yarn is skyed after removal from the caustic bath. The yarn is rinsed in water after skying. The yarn is chosen from one of open-end yarn and ring yarn and is dyed in only one sulfur dye box when the yarn is open-end yarn and ring yarn or is dyed at least one indigo dye box when the yarn is open-end yarn. The yarn is washed in water after the dyeing step and thereafter the dyed yarn is dried.