Sealed Indigo Dyeing Line With Inert Atmosphere for Better Fixation
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Solution Overview
Problem
Continuous dyeing with indigo for denim fabrics is challenging due to high consumption of hydrosulfite and caustic soda, bath salinity, and dependence on external variables, leading to inefficiencies and pollution, especially in large-scale production where maintaining chemical equilibrium and achieving consistent color shades is difficult.
Innovation Solution
A device for continuous dyeing with indigo operates in an inert environment, using foam-distributing devices to apply indigo dye in a sealed system, reducing the need for multiple tanks and minimizing oxidation, allowing for flexible temperature and concentration operations, and enabling better dye fixation and reduced waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional continuous dyeing with indigo is performed using multiple tanks and open oxidation, then dye fixation is achieved, but consumption of hydrosulfite and caustic soda is high and bath salinity increases
Solution Approach 1:
The patent applies an inert atmosphere (nitrogen or carbon dioxide) in the dyeing tanks to prevent oxidation of the reduced indigo dye during the dyeing process. This eliminates the need for extensive oxidation steps and reduces consumption of chemical reducing agents (hydrosulfite and caustic soda) while maintaining effective dye fixation. The inert environment allows the dye to remain in reduced state longer, improving efficiency and reducing chemical waste.
2Manufacturing precision
If multiple dyeing tanks and oxidation passages are used, then color shade consistency is achieved, but device complexity and production time increase
Solution Approach 1:
The patent merges multiple separate dyeing tanks and oxidation passages into a single integrated tank where both dyeing and oxidation occur simultaneously in an inert atmosphere. This consolidation reduces the number of separate units required while maintaining color shade consistency through controlled oxidation using hydrogen peroxide added directly to the dye bath, thereby simplifying the overall device structure and reducing production time.
Solution Approach 2:
The patent changes the chemical parameters of the dyeing process by using hydrogen peroxide oxidation instead of air oxidation, and by maintaining an inert atmosphere throughout the process. These parameter changes allow for more precise control over the oxidation stage, ensuring consistent color shades while reducing the need for multiple processing stages and complex equipment configurations.
3Reliability
If traditional open oxidation method is used, then dye intensification occurs, but oxidation of reduced dye by atmospheric oxygen leads to high chemical consumption
Solution Approach 1:
The patent uses an inert atmosphere (nitrogen or carbon dioxide) to control the oxidation process, preventing uncontrolled oxidation by atmospheric oxygen. This allows for more efficient dye intensification with reduced consumption of chemical reducing agents, as the oxidation can be better controlled and timed, minimizing waste of hydrosulfite and caustic soda while achieving the desired color intensity.
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 significantly reduces the consumption of hydrosulfite and caustic soda, enhances dye fixation, and improves color consistency, making the process more economical and environmentally friendly while allowing for greater flexibility in dyeing conditions.
Implementation Method 1
using foam-distributing devices to apply indigo dye
Implementation Method 2
operates in an inert environment, using foam-distributing devices to apply indigo dye in a sealed system, reducing the need for multiple tanks and minimizing oxidation
Implementation Method 3
must not only be reduced in an alkaline solution (leuco)
Implementation Method 4
followed, after squeezing, by a passage in air to allow the leuco to oxidize, become blue and then insoluble
Data Source
AI summary
A device (100) is described, together with a continuous dyeing process with indigo and reduction dyes for warp yarn chains (3) and/or fabrics. The device (100) comprising at least one hermetically sealed dyeing compartment (1), and at least one hermetically sealed compartment (2) for the diffusion and fixing of the dye on the yarn (3). The compartment (2) is situated downstream of the dyeing compartment (1) and is functionally and hermetically connected to the dyeing compartment (1) by means of a tunnel (4). Means (12) are present inside the compartments (1, 2) and tunnel (4), for the entry of inert gas or deoxygenated air. One or more means (14, 14′) for the direct application of the dye onto the yarn (3) are also present inside the dyeing compartment (1), whereas at least one tank (8) for humidifying the environment and at least one means (7) for heating the yarn (3) leaving the dyeing compartment (1), are present in the compartment (2).