A method to recycle a fibrous carpet product
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Solution Overview
Problem
Current methods for recycling carpet products are inefficient and often require separation of different polymer materials, leading to incomplete recycling and high costs, as well as the need for additional adhesives that compromise mechanical properties.
Innovation Solution
A method for recycling polyester carpet products by direct extrusion, utilizing a polyester adhesive with specific crystallinity and viscosity properties that allows co-extrusion with high molecular weight polyester yarns without prior separation, enabling the production of a homogeneous recycled material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If latex-based adhesive is used to bind yarns to backing, then strong adhesion is achieved, but complete recycling becomes impractical due to chemical cross-linking
Solution Approach 1:
The patent changes the chemical parameters of the adhesive from chemically cross-linked latex to thermoplastic polymers with specific melting points. This allows the adhesive to maintain strong binding properties during carpet use, then transition to a melt state at controlled temperatures for recycling, enabling complete material recovery without chemical separation processes
Solution Approach 2:
The invention utilizes the phase transition of thermoplastic adhesives from solid to melt state. During recycling, heating the carpet product causes the thermoplastic adhesive to melt and flow, separating the yarns and backing materials. This phase change enables complete disassembly of the carpet components for full recycling, eliminating the permanent bonding characteristic of cross-linked latex
2Adaptability or versatility
If dissimilar materials are used for primary and secondary layers, then functional requirements are met, but separation of components is required for recycling
Solution Approach 1:
The patent applies homogeneity by making the adhesive layer compositionally matched to the yarns and backing (all thermoplastic polymers). This allows the entire carpet structure to be processed together in a single recycling operation through melting, eliminating the need to separate dissimilar materials and recover them through different processes
3Stability of the object's composition
If yarns and backing are strongly embedded in chemically cross-linked adhesive, then mechanical stability is improved, but component separation becomes difficult
Solution Approach 1:
The invention changes the thermal parameters of the adhesive system by using thermoplastic polymers with defined melting points instead of chemically cross-linked materials. This allows the carpet to maintain mechanical stability at service temperatures while enabling easy component separation through controlled heating that melts the adhesive, releasing the embedded yarns and backing
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 approach allows for reliable and efficient recycling of polyester carpet products, overcoming the challenges of material separation and adhesion, while maintaining mechanical properties and reducing energy and raw material costs.
Implementation Method 1
the carpet product is a substantially pure polyester carpet product wherein the polymer yarns comprise polyester having a molecular weight (i.e. Mw, the weight average molecular weight) above 50,000 g/mol (in practice below 100,000 g/mol) and a melting point between 180 and 300°C
Implementation Method 2
the method comprising homogenising the carpet product by extrusion
Implementation Method 3
homogenising the carpet product by extrusion
Data Source
Figure 1~2
AI summary
The present invention pertains to a method for recycling a carpet product, the carpet product comprising a fibrous sheet comprising polymer yarns, wherein at least one surface of the sheet is provided with a layer of polymer adhesive, wherein the carpet product is a substantially pure polyester carpet product, wherein the polymer yarns comprise polyester having a molecular weight above 50,000 g/mol and a melting point between 180 and 300°C, the adhesive is a polyester adhesive having a crystallinity between 5% and 35% and a viscosity of 5-55 Pa.s at 150°C, the method comprising homogenising the carpet product by extrusion. The invention also pertains to recycled polymer obtainable by this method, to fibres comprising this recycled polymer material, to fibrous products comprising these fibres and to polyester adhesive.