Method of dyeing a substrate comprising elastomeric fibre and non-elastomeric fibre, and a dyed subtrate comprising these fibres
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Solution Overview
Problem
Dyeing methods for substrates containing elastomeric fibers, such as spandex, often result in poor color fastness, leading to dye transfer during wear and washing due to the high affinity of elastomeric fibers for dyes, which is exacerbated by their low glass transition temperature.
Innovation Solution
A method involving dyeing substrates with elastomeric fibers containing less than 60°C glass transition temperature polymers and non-elastomeric companion fibers with higher glass transition temperature polymers, followed by treatment with a supercritical or liquefied carbon dioxide extraction medium at specific temperatures to selectively remove dye from elastomeric fibers, ensuring high color fastness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elastomeric fibers are dyed using conventional methods, then the fibers achieve sufficient color intensity, but the color fastness deteriorates due to dye transfer during wear and washing
Solution Approach 1:
The patent applies extraction by contacting the pre-dyed substrate with supercritical or liquefied carbon dioxide to selectively remove dye from elastomeric fibers while preserving dye in non-elastomeric companion fibers. This extraction process eliminates the harmful dye transfer from elastomeric fibers while maintaining the desired color intensity in the fabric, directly resolving the contradiction between color fastness and dye transfer.
Solution Approach 2:
The patent utilizes parameter changes by controlling temperature and pressure conditions during the extraction process. By operating at temperatures above the glass transition temperature of the elastomeric fiber polymer but below that of the companion fiber polymer, the method selectively modifies the dye affinity of elastomeric fibers, enabling dye removal while preserving dye in companion fibers, thus achieving high color fastness without dye transfer.
2Reliability
If the substrate is treated with chemical reduction clearing to improve color fastness, then dye transfer is reduced, but harmful chemicals and wastewater are generated
Solution Approach 1:
The patent replaces chemical reduction clearing with a physical extraction process using supercritical or liquefied carbon dioxide. This substitution eliminates the need for harmful chemicals and wastewater generation while achieving the same color fastness improvement, directly addressing the contradiction between color fastness and chemical waste.
Solution Approach 2:
The patent employs an inert carbon dioxide environment for the extraction process, replacing harmful chemical reducing agents. The carbon dioxide acts as a clean, inert medium that achieves dye removal without generating chemical waste, thereby resolving the contradiction between improving color fastness and avoiding chemical pollution.
3Reliability
If the extraction temperature is increased to remove more dye from elastomeric fibers, then color fastness improves, but dye may be removed from companion fibers
Solution Approach 1:
The patent applies local quality by exploiting the difference in glass transition temperatures between elastomeric fiber polymer and companion fiber polymer. By selecting an extraction temperature that is above Tg1 (elastomeric fiber) but below Tg2 (companion fiber), the method creates selective conditions that affect only the elastomeric fibers, enabling dye removal from these fibers while preserving dye in companion fibers, thus resolving the contradiction between color fastness and dye loss.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the extraction temperature within a specific range between the two glass transition temperatures. This parameter optimization enables selective dye extraction from elastomeric fibers without affecting companion fibers, achieving high color fastness while minimizing dye loss, thereby resolving the contradiction.
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 method achieves exceptionally high color fastness by concentrating dye in non-elastomeric fibers, reducing dye transfer and maintaining fabric quality without the need for chemical reduction clearing or wastewater generation.
Implementation Method 1
elastomeric fibre containing at least 30 wt. % of a first polymer having a glass transition temperature T1 of less than 60° C. and non-elastomeric companion fibre containing more than 50 wt. % of a second polymer having a glass transition temperature T2 that is at least 20° C. higher than T1
Implementation Method 2
contacting the pre-dyed substrate with an extraction medium at a temperature Te and a pressure Pe, to produce a high fastness dyed substrate, said extraction medium comprising at least 50 wt. % of supercritical or liquefied carbon dioxide
Implementation Method 3
Te exceeds Tg1,extraction and wherein Te is less than Tg2,extraction in case the companion fibre contains more than 50 wt. % of polymers having a glass transition temperature T2; Tg1,extraction representing the glass transition temperature of the first polymer in carbon dioxide at pressure Pe
Data Source
AI summary
A dyeing method comprising a) dyeing a substrate containing (i) elastomeric fiber containing at least 30 wt. % of a first polymer having a glass transition temperature T1 of less than 60° C. and (ii) non-elastomeric companion fiber containing more than 50 wt. % of a second polymer, said second polymer being polymer having no glass transition temperature or polymer having a glass transition temperature T2 that is at least 20° C. higher than T1, b) contacting the pre-dyed substrate with an extraction medium at a temperature Te and a pressure Pe, said extraction medium comprising at least 50 wt. % of supercritical or liquefied carbon dioxide; wherein Te exceeds Tg1,extraction and wherein Te is less than Tg2,extraction in case the companion 1 fiber contains more than 50 wt. % of polymers having a glass transition temperature T2; Tg1,extraction representing the glass transition temperature of the first polymer in carbon dioxide at pressure Pe; and Tg2,extraction representing the glass transition temperature of the second polymer in carbon dioxide at pressure Pe.