Method for recycling polyester fabric
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Solution Overview
Problem
Conventional methods for recycling polyester fabrics fail to effectively remove both dye and water repellent, leading to poor recycling quality and limited use due to excessive residual water repellent, which causes issues such as fiber breakage and deepening of fabric color.
Innovation Solution
A method involving a composite solvent of water and acetic acid is used to extract dye and water repellent, followed by a liquid state polycondensation reaction to increase intrinsic viscosity and remove residual impurities, resulting in a polyester fabric with an L value of at least 60 and water repellent content of no more than 500 ppm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional solvents are used for extraction, then dye removal efficiency is improved, but water repellent cannot be effectively removed
Solution Approach 1:
The patent uses a composite solvent system consisting of organic solvent and water in a specific ratio (95:5 to 50:50 by weight) to simultaneously remove both dye and water repellent. This composite approach overcomes the limitation of conventional single solvents that can only remove dye effectively while leaving water repellent residues.
Solution Approach 2:
The patent optimizes the composition ratio of organic solvent to water in the composite solvent system. By adjusting this parameter within the specified range, the extraction efficiency for both dye and water repellent is maximized, resolving the contradiction between dye removal and water repellent removal effectiveness.
2Illumination intensity
If high concentration of water repellent remains on polyester fabric, then recycling quality is improved in terms of color, but fiber strength deteriorates due to breakage
Solution Approach 1:
The patent controls the water repellent content to be within a specific range (not more than 500 ppm, preferably 10-300 ppm) after recycling. This parameter control ensures that enough water repellent remains to maintain fabric brightness and color, while removing sufficient amounts to prevent fiber breakage and maintain strength.
Solution Approach 2:
The patent establishes a feedback mechanism by measuring and controlling the residual water repellent content within the specified range. This feedback control allows optimization of both fabric appearance (brightness) and mechanical properties (strength) by adjusting the extraction process parameters.
3Manufacturing precision
If solid state polymerization is performed on recycled polyester fabric, then intrinsic viscosity is improved, but color deepening occurs and solid residue removal becomes difficult
Solution Approach 1:
The patent employs liquid state polycondensation instead of solid state polymerization. By transitioning the polyester to liquid state through melting and performing polycondensation in this phase, the process achieves effective intrinsic viscosity improvement and complete solid residue removal without the color deepening problem associated with solid state polymerization.
Solution Approach 2:
The patent replaces the solid state polymerization mechanism with liquid state polycondensation. This substitution of the physical state and chemical process mechanism enables better control over color stability and more effective removal of solid residues while achieving the desired intrinsic viscosity enhancement.
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 effectively recycles polyester fabrics with improved quality, reducing water repellent content and increasing intrinsic viscosity, thereby facilitating easier recycling and lowering manufacturing costs while ensuring high process safety.
Implementation Method 1
performing an extraction operation including infiltrating the polyester fabric with the composite solvent and extracting the dye and the water repellent to remove the dye and the water repellent from a material of the polyester fabric
Implementation Method 2
carrying out a liquid state polycondensation reaction on the polyester fabric so that an intrinsic viscosity of the polyester fabric is increased
Data Source
AI summary
A method for recycling a polyester fabric is provided. The method includes providing a polyester fabric that is dyed and has dye and water repellent attached thereon, providing a composite solvent containing water and acetic acid mixed with each other, performing an extraction operation including infiltrating the polyester fabric with the composite solvent and extracting the dye and the water repellent, and carrying out a liquid state polycondensation reaction on the polyester fabric so that an intrinsic viscosity of the polyester fabric is increased and residual impurities of the polyester fabric are further removed.