Carpet Recycling by Selective Backing Decomposition
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Solution Overview
Problem
Current carpet recycling methods are inefficient and labor-intensive, with low yield and contamination issues, particularly in separating face fibers from backing materials, which are difficult to decompose due to their design for durability.
Innovation Solution
A process involving heating the carpet to a temperature below the melting point of the face fibers but above the thermal decomposition temperature of the backing material, making the backing more friable, followed by mechanical liberation of the backing from the face fibers, allowing for effective separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shearing method is used to recover face fiber, then most of the non-face fiber portion is separated from the face fiber, but the method is labor intensive and requires manual feeding of carpet pieces
Solution Approach 1:
The patent replaces manual shearing operations with an automated thermal-mechanical system. Carpet is fed continuously through a heating zone that thermally degrades the backing material, then through a refining zone with mechanical elements that separate face fibers from degraded backing. This substitution eliminates manual labor while maintaining separation quality through controlled thermal degradation followed by mechanical refinement.
Solution Approach 2:
The patent changes the physical-chemical parameters of the backing material by heating it to a temperature sufficient to degrade the backing but below the melting point of the face fiber. This parameter change (temperature control) transforms the backing from a durable, bonded state to a degraded, separable state, enabling automated processing without manual intervention.
2Productivity
If shearing method is used with careful cutting depth adjustment, then face fiber recovery is maximized, but cutter wear is significant and costly
Solution Approach 1:
The patent replaces mechanical cutting blades with a thermal degradation process. Instead of using sharp cutters that wear from contact with carpet materials, the system uses controlled heating to chemically degrade the backing material, followed by gentle mechanical refinement. This eliminates cutter wear while maximizing face fiber recovery through selective thermal degradation.
Solution Approach 2:
The patent changes the state of the backing material through controlled thermal degradation at temperatures below the face fiber melting point. This parameter change (temperature control) allows separation without mechanical cutting, eliminating cutter wear while maintaining high face fiber recovery yields.
3Productivity
If whole carpet shredding is used, then the entire carpet is processed efficiently, but backing polypropylene fibers remain intermixed with face fibers and latex/filler contamination remains on fiber ends
Solution Approach 1:
The patent applies selective thermal degradation by controlling the heating temperature to be sufficient to degrade the backing material (polypropylene, latex, inorganic fillers) but below the melting point of the face fiber (nylon, polyester). This parameter control transforms the backing into a degraded state that separates easily from the intact face fibers, achieving both efficient processing and high fiber purity.
Solution Approach 2:
The patent applies different thermal treatments to different parts of the carpet structure. The backing material undergoes thermal degradation while the face fibers remain intact due to their higher melting points. This localized differential treatment based on material properties enables separation of face fibers from backing contaminants while maintaining processing efficiency.
4Duration of action of stationary object
If carpet is designed for durability with strong bonding between face fiber and backing, then carpet survives decades of wear, but the carpet becomes difficult to deconstruct for recycling
Solution Approach 1:
The patent uses controlled thermal degradation to change the chemical structure of the backing material. By heating to temperatures that degrade the backing but below the face fiber melting point, the durable bonds between backing and face fiber are selectively broken, enabling easy deconstruction for recycling while the carpet maintains its service life during use.
Solution Approach 2:
The patent converts the durability of the backing material, which normally resists degradation, into a benefit for recycling. The same strong bonds that protect the carpet during use are selectively broken through controlled thermal degradation at specific temperatures, transforming the durable backing into easily separable degraded material while preserving face fiber integrity.
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 enhances the recovery of high-quality face fibers with higher yields compared to traditional methods, reduces contamination, and minimizes manual labor and operating costs, while also vaporizing malodorous and pathogenic contaminants.
Implementation Method 1
heating the carpet to a temperature below the melting point of the face fibers but above the thermal decomposition temperature of the backing material, making the backing more friable
Implementation Method 2
applying mechanical force to the carpet so as to liberate the friable backing material from the face fiber material
Data Source
AI summary
Methods for the recycling of carpet are disclosed that produce clean face fiber suitable for industrial use. The methods allow the recovery of face fiber material, for example a polyester or a polyamide, from carpets that includes a face fiber material and a backing material, and include the steps of heating the carpet to a temperature lower than the melting point of the face fiber material, but higher than the initial thermal decomposition temperature of the backing material, for a time and at a temperature sufficient to thermally decompose, pyrolyze, or oxidize at least a portion of the backing material, rendering the backing material friable, that is more friable than the untreated backing; and applying mechanical force to the carpet so as to liberate the friable backing material from the face fiber material.