Solvent-Assisted Reactive Dye Bath for Low-Water Textile Dyeing
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Solution Overview
Problem
In solvent-assisted dyeing processes for textiles using reactive dyes, there is a challenge in minimizing water consumption and avoiding environmentally harmful pretreatments while maintaining dyeing depth, uniformity, and color fastness, as existing methods often result in reduced fixation rates and waste due to hydrolysis and require water-intensive processes.
Innovation Solution
A reactive dye bath comprising a non-polar organic solvent, an aqueous dye solution, a surfactant, and a co-surfactant, which allows for a one-step dyeing and fixation process without additional salt or water-intensive pretreatments, using a dye emulsion with specific ratios and recovery methods to enhance dye uptake and fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water is used as the main dyeing medium in traditional reactive dyeing processes, then good dyeing depth and color fastness can be achieved, but high water consumption and discharge of highly polluted wastewater occur
Solution Approach 1:
The patent changes the fundamental parameter of the dyeing medium from water to organic solvent (such as dimethyl carbonate, ethyl methyl carbonate, or propylene carbonate). This parameter change enables the dyeing process to achieve similar dyeing depth and color fastness while dramatically reducing water consumption and eliminating the discharge of highly polluted wastewater, as the organic solvent can be recovered and reused through distillation
Solution Approach 2:
The patent implements a solvent recovery system where the organic solvent used in the dyeing process is recovered through distillation and reused. This eliminates the need to discharge polluted wastewater, as the solvent is continuously recycled. The system transforms the linear water-consumptive process into a circular solvent-recovery process, significantly reducing environmental pollution
2Reliability
If pre-padding with aqueous sodium carbonate solution is performed before solvent assisted dyeing, then fixation reaction can be promoted, but hydrolysis of reactive dye increases causing reduced fixation rate and dye wasting
Solution Approach 1:
The patent inverts the conventional sequence and approach by eliminating the aqueous pre-padding step entirely. Instead of adding base to water and then introducing dye, the system uses organic solvent as the medium from the start, promoting the fixation reaction through the organic solvent environment itself. This inversion prevents the hydrolysis problem that occurs when reactive dyes are exposed to aqueous basic conditions before dyeing
Solution Approach 2:
The organic solvent acts as an intermediary medium that facilitates both the dyeing and fixation reactions without causing hydrolysis. Solvents like dimethyl carbonate, ethyl methyl carbonate, or propylene carbonate provide a non-aqueous basic environment that promotes the fixation reaction between reactive dye and fiber while preventing the hydrolysis that occurs in water-based systems
3Productivity
If cationic modifiers are used for textile pretreatment to improve dyeing performance, then dye utilization increases, but water consumption increases and environmental adverse effects occur
Solution Approach 1:
The patent extracts and eliminates the water-intensive cationic modification pretreatment step from the dyeing process. By using organic solvent as the dyeing medium from the beginning, the system achieves good dyeing performance and dye utilization without requiring the separate water-based pretreatment step, thereby eliminating the associated water consumption and environmental adverse effects
Solution Approach 2:
The organic solvent serves multiple functions simultaneously: it acts as the dyeing medium, promotes the fixation reaction, and eliminates the need for separate pretreatment steps. This multi-functionality achieves high dye utilization while avoiding the water consumption and environmental problems associated with traditional cationic modification pretreatment
4Speed
If salt is added to accelerate dyeing in water bath systems, then dyeing speed increases, but water consumption and wastewater pollution increase
Solution Approach 1:
The patent changes the medium parameter from water to organic solvent, which inherently provides faster dyeing speed without requiring salt addition. The organic solvent environment facilitates quicker penetration and fixation of reactive dyes into fibers, achieving high dyeing speed while avoiding increased water consumption and wastewater pollution associated with salt-based acceleration methods
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 achieves high dyeing depth, uniformity, and color fastness without special pretreatments, with efficient solvent recovery and reduced water consumption, resulting in a more environmentally friendly and energy-efficient dyeing method.
Implementation Method 1
a reactive dye bath, which comprises of a dye emulsion composed of an organic solvent, an aqueous dye solution, a surfactant and a co-surfactant
Implementation Method 2
a surfactant and a co-surfactant
Implementation Method 3
The main principle of this process for dyeing with a reactive dye using an organic solvent that replaces part of the water medium (i.e., a solvent assisted dyeing method) is based on the use of the reverse micelle theory. Reverse micelles are nanoscale spherical aggregates that are self-assembled from water, an oil and a surfactant at a specific ratio under certain conditions. There is a stable aqueous microenvironment, i.e., so-called water-pool, in the interior region of the micelle.
Data Source
AI summary
The present invention relates to a reactive dye bath and a dyeing process for textiles. The reactive dye bath for textiles comprises an organic solvent, an aqueous dye solution, a surfactant and a co-surfactant. The reactive dye bath or the dyeing process of the present invention allows for full up-take of the dye without subjecting the textiles to any special pre-treatment and without the addition of a salt for accelerating dyeing, so as to obtain dyed textiles with a higher dyeing depth, uniformity and fastness.