Two-Step Dyeing Process for Artificial Leather Color Uniformity
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Solution Overview
Problem
Existing methods for dyeing artificial leather composed of ultrafine fibers and polymeric elastomers fail to achieve uniform coloration, resulting in color unevenness between the fibers and elastomers, particularly in light to medium colors, due to insufficient dye retention after reduction cleaning.
Innovation Solution
A two-step dyeing process is employed, where the artificial leather is first dyed using a specific dye concentration and temperature, followed by a second dyeing step with a lower temperature and reduced dye concentration, ensuring consistent dyeability for both ultrafine fibers and polymeric elastomers, thereby maintaining color continuity and fastness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-step dyeing method is used, then ultrafine fibers can be colored effectively, but polymeric elastomers cannot be colored effectively, resulting in color unevenness
Solution Approach 1:
The dyeing process is divided into two distinct steps: first dyeing the artificial leather with a disperse dye to color the ultrafine fibers, then performing a second dyeing step with a different dye concentration and temperature to color the polymeric elastomers. This segmentation allows each component to be dyed under optimized conditions, achieving uniform coloration across both ultrafine fibers and polymeric elastomers.
Solution Approach 2:
The invention changes the dyeing parameters between the two steps: the first step uses higher temperature and higher dye concentration for ultrafine fiber dyeing, while the second step uses lower temperature and lower dye concentration (0.1% to 30% of the first step concentration) for polymeric elastomer dyeing. This parameter adjustment enables effective dyeing of both materials without color unevenness.
2Manufacturing precision
If reduction cleaning treatment is performed after single-step dyeing, then color developing ability is improved, but dye quantity becomes insufficient, leading to insufficient coloring of polymeric elastomers
Solution Approach 1:
The reduction cleaning treatment is performed as a preliminary step before the second dyeing step, not after. This allows the polymeric elastomers to be prepared for dyeing while ensuring sufficient dye quantity is available in the subsequent second dyeing step. The preliminary reduction cleaning removes excess dye from the first step without depleting the dye supply needed for effective polymeric elastomer coloring in the second step.
3Reliability
If high dye concentration is used in second dyeing step, then polymeric elastomers can be colored, but color unevenness occurs with ultrafine fibers
Solution Approach 1:
The invention uses lower dye concentration (0.1% to 30% of the first step concentration) and lower temperature in the second dyeing step compared to the first step. This parameter reduction prevents over-dyeing of the ultrafine fibers while ensuring sufficient dye penetration into the polymeric elastomers, maintaining color uniformity across both components.
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 produces artificial leather with no color unevenness between ultrafine fibers and polymeric elastomers, achieving high washing, rubbing, and light fastness, even in red shades, thus enhancing surface quality and commercial value.
Implementation Method 1
artificial leather constituted mainly of a fibrous base containing ultrafine fibers with a filament fineness of 2 decitex or less and a polymeric elastomer is dyed using a dye
Implementation Method 2
a first dying step in which artificial leather constituted mainly of a fibrous base containing ultrafine fibers with a filament fineness of 2 decitex or less and a polymeric elastomer is dyed using a dye and a subsequent second dyeing step
Data Source
AI summary
A dyed artificial leather includes a fibrous base containing ultrafine fibers with a filament fineness of 2 decitex or less and a polymeric elastomer, and characterized in that the lightness difference ΔL* between the ultrafine fibers and the polymeric elastomer represented by the following equation meet the requirement of −16≤ΔL*≤5: ΔL*=(average lightness L* of ultrafine fibers)−(average lightness L* of polymeric elastomer). A production method for dyed artificial leather includes a first dying step in which artificial leather constituted mainly of a fibrous base containing ultrafine fibers with a filament fineness of 2 decitex or less and a polymeric elastomer is dyed using a dye and a subsequent second dyeing step performed at a dye concentration that is 0.1% to 30% of the dye concentration (owf) in the first dyeing step.