Process and plant for recycling textiles
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Solution Overview
Problem
Current recycling processes for polyester-cotton textiles are costly, time-consuming, and environmentally inefficient, often requiring shredding, depolymerization of polyester into monomers, and subsequent processing of cellulose pulp, which results in significant loss of cotton fiber quality and incomplete garment recycling due to the removal of non-textile elements.
Innovation Solution
A process that depolymerizes polyester in a basic aqueous solution under controlled conditions, allowing the recovery of cellulosic staple fibers like cotton without shredding or dissolving them into pulp, while maintaining the mechanical properties of the fibers and allowing for the detachment of non-textile elements like zippers and buttons, using a circulating depolymerization solution at specific temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fabric is shredded before depolymerization, then polyester can be effectively depolymerized, but the process becomes time-consuming and costly
Solution Approach 1:
The patent applies preliminary action by treating the fabric with a size-reducing agent before depolymerization to reduce fiber entanglement and improve solution penetration, thereby eliminating the need for time-consuming shredding while maintaining effective polyester depolymerization
2Ease of manufacture
If cellulose pulp is processed to obtain regenerated cellulose fibers, then usable fibers are produced, but the degree of polymerization is significantly lost
Solution Approach 1:
The patent extracts polyester from the fabric through selective depolymerization while preserving the cellulose structure, allowing direct recovery of cellulose fibers without converting them to pulp and regenerated fibers, thus maintaining their degree of polymerization and mechanical properties
Solution Approach 2:
The patent changes the chemical parameters of the treatment solution and process conditions to enable selective depolymerization of polyester while preserving cellulose integrity, avoiding the harsh conditions that would degrade cellulose into pulp
3Productivity
If non-textile elements are removed before processing, then complete garment recycling is achieved, but additional processing steps and costs are incurred
Solution Approach 1:
The patent merges the depolymerization step with the separation of non-textile elements, allowing both polyester dissolution and detachment of metal/plastic components to occur simultaneously in the same treatment process, thereby achieving complete garment recycling without additional processing steps
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 process efficiently recycles cotton fibers with preserved mechanical properties, enabling their reuse in yarn production and allows for the complete recycling of garments without pre-removal of non-textile elements, reducing waste and operational costs.
Implementation Method 1
a process for recycling waste blend fabrics comprising polyester and cellulosic staple fibers, preferably cotton fibres, the process including a depolymerization of the polyester in a basic aqueous solution
Implementation Method 2
circulating at least once said amount of depolymerizing solution through said fabrics
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
A process of treatment of waste blend textiles comprising polyester fibers and cotton fibres depolymerizes polyester in a controlled environment to obtain treated textile comprising cotton staple fibers suitable to be recycled into cotton yarns.