Cryogenic Leather Finishing Layer Removal
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Solution Overview
Problem
Current methods for removing finishing layers from tanned and finished leathers are inadequate, as they result in significant material loss and reduction in commercial value, especially for high-fashion leathers, leading to disposal rather than reuse, and waste of water and chemicals.
Innovation Solution
A process involving quick freezing of finished leather using a cryogenic inert material, such as liquid nitrogen, carbon dioxide snow, or dry ice, to detach the surface polymeric layer without damaging the underlying leather, allowing for the recovery and reuse of high-value leathers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If shaving processes are used to remove the surface layer, then the finishing layer can be removed, but a thickness of even 1 mm is removed which significantly reduces the commercial value of high-fashion leathers
Solution Approach 1:
The invention changes the physical state parameter of the polymeric finishing layer by applying cryogenic cooling, transforming it from a solid adhesive state to a fractured state. This parameter change enables selective removal of the thin surface layer (a few microns) without mechanically damaging the underlying leather, thus resolving the contradiction between removing the finishing layer and preserving the leather thickness.
Solution Approach 2:
The invention utilizes the phase transition of the polymeric finishing layer from solid to fractured state through cryogenic cooling. By applying liquid nitrogen or dry ice, the temperature of the polymeric layer is dropped below its glass transition temperature, causing it to fracture and detach from the leather substrate. This phase transition mechanism allows precise removal of the thin finishing layer without removing significant amounts of the underlying leather material.
2Loss of energy
If finished leathers are disposed of in landfills, then commercial value is preserved, but large amounts of water and chemicals used in processing become useless
Solution Approach 1:
The invention enables the recovery and reuse of high-value tanned leather by selectively removing only the polymeric finishing layer. The cryogenic process allows the underlying leather to be recovered in good condition and reused for new products, thereby preventing the waste of water and chemicals used in the tanning process while maintaining the commercial value of the leather product.
Solution Approach 2:
By changing the temperature parameter of the polymeric finishing layer through cryogenic cooling, the invention creates a selective removal process that distinguishes between the finishing layer and the underlying leather. This parameter-based differentiation enables the recovery of the leather substrate for reuse, transforming a waste disposal problem into a resource recovery solution.
3Loss of substance
If thin polymeric films are deposited to provide waterproof properties, then the finishing layer provides desired functional properties, but the layer thickness of a few microns cannot be removed by conventional methods
Solution Approach 1:
The invention applies cryogenic cooling to induce a phase transition in the thin polymeric finishing layer, transforming it from a solid adhesive state to a fractured state. This phase transition enables the removal of extremely thin layers (a few microns) that cannot be removed by conventional mechanical shaving methods, thus resolving the contradiction between removing thin layers and the feasibility of the removal process.
Solution Approach 2:
The invention replaces conventional mechanical shaving processes with a cryogenic-based removal process. Instead of using mechanical force that removes excessive material, the cryogenic method uses temperature-induced phase transition to selectively fracture and remove only the thin polymeric finishing layer, thereby enabling the removal of ultra-thin layers with precision and control.
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
Enables the removal of thin finishing layers without reducing the commercial value of the leather, facilitating its reuse and aligning with circular economy principles by reconditioning the tanned leather for further processing.
Implementation Method 1
subjecting the finished leather to a quick freezing... step B is carried out by employing a cryogenic inert material
Implementation Method 2
quick freezing... causes the surface polymeric layer to break and detach from the leather
Implementation Method 3
subjecting the finished leather to a quick freezing... employing a cryogenic inert material
Data Source
Figure 1~2
Figure 3a~4b
Figure 5a~6b
AI summary
A process for removing a finishing layer from finished leather, comprising the following steps: A. providing a finished leather comprising a surface polymeric layer applied on said leather; B. subjecting the finished leather to a quick freezing; C. removing the surface polymeric layer from the finished leather, wherein step B is carried out by employing a cryogenic inert material.