Coating Spray-Dyeing Method for Zero-Discharge Denim Fabric Processing
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Solution Overview
Problem
Traditional denim fabric dyeing methods consume large amounts of water, energy, and generate significant pollution due to the use of sulfur dyes, resulting in poor color hue, brightness, and durability issues.
Innovation Solution
An environmentally-friendly processing method involving high-temperature steam treatment, plasma drying, coating spray-dyeing, and specific chemical formulations to eliminate the need for water-based washing and reduce the use of corrosive auxiliaries, achieving zero discharge and improved colorfastness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional sulfur dyestuff dip-dyeing method is used, then denim fabric can be dyed, but a large amount of water and sodium sulfide are consumed, generating significant sewage pollution
Solution Approach 1:
The patent changes the fundamental parameter of the dyeing medium from water-based to oil-based (using white oil as carrier), and changes the chemical state of the dye from reduced sulfur dye to sulfur-containing compound. This parameter change eliminates the need for water and sodium sulfide, achieving zero discharge of harmful wastewater while maintaining dyeing effectiveness
Solution Approach 2:
The patent replaces the traditional mechanical dip-dyeing process with a coating-based application method. The dye composition is applied as a coating on the fabric surface and then cured through heating, substituting the water-based diffusion mechanism with a thermal curing mechanism, thereby eliminating water consumption and sewage generation
2Use of energy by moving object
If traditional dip-dyeing with sulfur dyestuff is used, then fabric can be dyed, but the process requires high temperature and multiple washing/soaping steps, consuming huge amounts of electricity and steam
Solution Approach 1:
The patent performs preliminary action by pre-mixing the sulfur-containing compound with white oil and applying it as a coating before curing. The fabric is pre-treated with the dye composition and then cured in one heating step, eliminating the need for multiple repeated dip-dyeing cycles and subsequent washing/soaping steps, thereby reducing overall energy consumption
Solution Approach 2:
The patent merges multiple traditional separate processes (dyeing, drying, and color development) into a single curing step. The coating application and thermal curing are combined in one operation, and the color development occurs simultaneously during curing, eliminating the need for separate washing and soaping steps, thus improving productivity while reducing energy use
3Illumination intensity
If sulfur dyestuff is used for dyeing, then denim fabric can be dyed, but the color lacks hue and brightness, and the fabric becomes crisp during storage
Solution Approach 1:
The patent changes the chemical parameter of the dye from traditional sulfur dye to a sulfur-containing compound with specific molecular structure, and changes the physical parameter of the carrier from water to white oil. This parameter change results in superior color brightness and hue while maintaining fabric softness during storage, overcoming the limitations of traditional sulfur dyes
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 zero effluent discharge, enhances dye pick-up by over 15%, improves colorfastness, and produces denim fabric with a soft hand feel and vibrant color, meeting SGS testing standards while avoiding formaldehyde and other harmful substances.
Implementation Method 1
increasing the temperature inside the drying barrel with high-temperature steam for 10-15 min
Implementation Method 2
performing plasma drying treatment on surfaces of the warp yarns at normal pressure for 10-15 min
Implementation Method 3
increasing the temperature inside the drying barrel to a high operation temperature within the range of 135-150° C. first, maintaining the temperature for 30 min
Implementation Method 4
performing spray-dyeing operation, and obtaining a semi-finished product C
Implementation Method 5
increasing the temperature inside the drying chamber to a temperature within the range of 170-190° C., maintaining the temperature for 10 min
Implementation Method 6
performing sizing operation at a yarn speed of 30 m/min and a tank temperature of over 95° C.
Data Source
AI summary
The present invention relates to the field of denim fabric processing, specifically to an environmentally-friendly processing method for dyeing denim fabric with zero discharge. The method includes: step 1, a treatment of white warp yarns; step 2, a primary drying operation; step 3, a coating spray-dyeing operation; step 4, a secondary drying operation; step 5, a sizing operation; step 6, a ternary drying operation; and step 7, a doffing operation. In the present application, as warp yarns are dyed using the coating spray-dyeing technology, highly corrosive auxiliaries such as sodium hydrosulfite and sodium sulfide are not needed in the dyeing process, and the dyed warp yarns are not required to be treated in a washing tank, so that zero effluent discharge is achieved.