Method for decolorization of dyed polyester fiber
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Solution Overview
Problem
Current methods for decolorizing polyester fibers are inefficient, often requiring high temperatures, large solvent consumption, and environmental harm, with existing technologies failing to completely remove dyes without inducing side reactions or purity issues.
Innovation Solution
A method using an ether-alcohol solvent heated to its boiling point to generate a fresh gas for dye extraction, which is then condensed and reused, effectively decolorizing polyester fibers at a lower temperature and reducing solvent usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high temperature is used for dye removal, then dye decomposition is achieved, but pyrolysis side reactions occur and fiber purity deteriorates
Solution Approach 1:
The patent changes the temperature parameter from high temperature (conventional method) to low temperature (below glass transition temperature of polyester fiber) processing. This parameter change allows dye removal through solvent extraction without causing pyrolysis side reactions, thus resolving the contradiction between dye removal efficiency and preventing harmful side reactions
Solution Approach 2:
The patent introduces a solvent as an intermediary substance to facilitate dye removal. The solvent acts as a mediator that extracts dye from polyester fiber at low temperature, avoiding direct thermal decomposition and pyrolysis side reactions while achieving effective decolorization
2Object-affected harmful factors
If solvent extraction is used for dye removal, then dye decomposition is prevented, but solvent consumption increases and environment is polluted
Solution Approach 1:
The patent implements solvent recovery by condensing and reusing the solvent after extraction. This closed-loop system reduces solvent consumption and minimizes environmental pollution while maintaining the benefit of preventing dye decomposition through gentle extraction
Solution Approach 2:
The system achieves self-service through automatic solvent condensation and recycling. The solvent that evaporates during extraction is condensed and returned to the extraction system, creating a self-sustaining process that reduces external solvent input and waste discharge
3Productivity
If high temperature processing is applied, then dye extraction efficiency is improved, but energy consumption increases
Solution Approach 1:
The patent changes the temperature parameter from high to low (below glass transition temperature), which reduces energy consumption for heating. The low temperature processing achieves adequate dye extraction efficiency through extended contact time and solvent effectiveness, resolving the contradiction between extraction efficiency and energy consumption
4Quantity of substance
If conventional decolorization methods are used, then dye removal is achieved, but fiber hue and purity are compromised
Solution Approach 1:
The patent changes multiple parameters including temperature (below glass transition temperature), solvent type, and processing time to achieve selective dye removal. These parameter changes enable complete dye removal while preserving fiber hue and purity, resolving the contradiction between quantity of dye removed and manufacturing precision of fiber quality
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 complete dye removal from polyester fibers with reduced solvent consumption and processing costs, while maintaining fiber purity and hue, addressing the inefficiencies of previous methods.
Implementation Method 1
heating the ether-alcohol solvent up to a boiling point of the ether-alcohol solvent to continuingly generate a fresh gas
Implementation Method 2
extracting the dye from the polyester fiber via the fresh gas and forming an extracting condensate containing the dye; reflowing the extracting condensate back into the ether-alcohol solvent
Data Source
AI summary
A method for decolorization of a dyed polyester fiber is provided. The method for decolorization of a dyed polyester fiber includes step of: providing an ether-alcohol solvent and a polyester fiber containing a dye; heating the ether-alcohol solvent up to a boiling point of the ether-alcohol solvent to continuingly generate a fresh gas; wherein a temperature of the fresh gas ranges from 90° C. to 200° C. which is between a glass transition temperature of the polyester fiber and a melting point of the polyester fiber; extracting the dye from the polyester fiber via the fresh gas and forming an extracting condensate containing the dye; reflowing the extracting condensate back into the ether-alcohol solvent; repeating the steps mentioned above to obtain a decolorized polyester fiber.