PLA Fiber Dissolution for Quality-Preserving Textile Separation

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Solution Overview

Problem

Existing textile recycling methods struggle to effectively separate and reuse polylactic acid (PLA) fibers from blends without damaging other fibers, leading to degraded mechanical properties and reduced quality, especially when elastane is present.

Innovation Solution

A chemical recycling method involving the use of a PLA solvent, such as alkyl lactate, to dissolve PLA fibers while preserving non-PLA fibers by maintaining their physical and chemical properties through solid-liquid separation and subsequent treatment to recover lactic acid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If mechanical recycling is used to separate fibers, then fiber recovery is achieved, but fiber quality and mechanical properties are degraded

Engineering Contradiction:

Improvefiber recoveryVSAvoidmechanical properties

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent replaces mechanical recycling methods with a chemical recycling approach using solvent-based dissolution. The PLA fibers are selectively dissolved in a solvent system, allowing separation from non-PLA fibers without mechanical stress. This chemical method preserves fiber integrity and mechanical properties while achieving high recovery yields.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the separation mechanism from mechanical to chemical by utilizing differential solubility parameters. PLA fibers are selectively soluble in the chosen solvent system under controlled conditions, while non-PLA fibers remain insoluble. This parameter-based differentiation enables quality-preserving separation and recovery.

Inventive Principle:

Principle #35Parameter changes

2Strength

If chemical recycling is used to separate PLA fibers, then fiber quality is preserved, but separation efficiency from blends is reduced

Engineering Contradiction:

Improvefiber qualityVSAvoidseparation efficiency

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent extracts PLA fibers from blends by exploiting their selective solubility. The solvent system is specifically chosen to dissolve PLA while leaving non-PLA fibers intact. This extraction approach achieves both high separation efficiency and fiber quality preservation by targeting only the PLA component for removal.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a solvent system as an intermediary medium to enable selective separation. The solvent acts as a mediator that selectively interacts with PLA fibers, dissolving them while non-PLA fibers remain unaffected. This intermediary allows efficient separation without direct mechanical or chemical damage to the fiber structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If elastane is present in the fiber blend, then textile performance is improved, but recycling processability is compromised

Engineering Contradiction:

Improvetextile performanceVSAvoidrecycling processability

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent extracts elastane from the blend by utilizing its insolubility in the chosen solvent system. Since elastane does not dissolve under the recycling conditions, it remains in the solid residue while PLA fibers are selectively removed. This extraction approach enables recycling of elastane-containing textiles without compromising processability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies local quality differentiation based on solubility characteristics. Different fiber types in the blend are treated differently: PLA fibers are soluble and are removed, while elastane and non-PLA fibers are insoluble and remain. This localized selective interaction enables successful recycling despite the presence of elastane.

Inventive Principle:

Principle #3Local 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

The method achieves high yields in recovering undamaged non-PLA fibers and lactic acid, allowing for their reuse in textile applications, with minimal impact on the fibers' quality and properties.

Implementation Method 1

A chemical recycling method involving the use of a PLA solvent, such as alkyl lactate, to dissolve PLA fibers

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 2

solid-liquid separation and subsequent treatment to recover lactic acid

Methodology Applied

Scientific EffectSolid-liquid separation: Sedimentation

Data Source

PatentUS20250376569A1Method for isolating fibers polylactic acid-based from a mixture of textile fibers and recovery of the latter no longer containing polylactic acid

Publication Date: 2025.12.11 NOOSA

AI summary

Method for treating a blend of textile fibres comprising PLA textile fibres and non-PLA textile fibres wherein the blend of fibres is introduced into a tank with a PLA solvent in a PLA/lactic ester mass ratio of between 0.05 and 0.6, at a temperature between 100 and 130° C. to recover the solution containing the dissolved textile fibres containing PLA and to subject them to a treatment to recover the lactic acid, wherein the non-PLA textile fibres are separated from the lactic ester solvent to recover and process them for reuse.