Supercritical Fluid Leather Processing to Reduce Water and Energy Use
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Solution Overview
Problem
Conventional leather dyeing methods require large amounts of water and processing agents, are energy-intensive, and struggle to achieve high dye depth and wet fastness, while also posing environmental sustainability challenges.
Innovation Solution
A dyeing and retanning process using a pressurized fluid in a supercritical state to penetrate the leather structure, combined with controlled pressure reduction to maintain leather quality, reducing the need for water and energy, and employing soluble or carried agents to achieve deep and fast color penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional wet dyeing methods are used, then leather can be colored, but large amounts of water are required and energy consumption is high
Solution Approach 1:
The patent changes the physical state of the dyeing medium from liquid (conventional water-based dyeing) to supercritical fluid state. By controlling temperature and pressure parameters to achieve supercritical state, the system eliminates the need for large amounts of water while reducing energy consumption through faster drying and reduced heating requirements.
Solution Approach 2:
The patent utilizes phase transition of the dyeing medium between liquid, supercritical, and gas states. The medium is heated and pressurized to supercritical state for dyeing, then depressurized to gas state for easy removal, eliminating water usage and associated energy costs for water heating and drying.
2Manufacturing precision
If conventional dyeing methods are used, then leather surface can be colored, but achieving high dye depth and wet fastness is difficult
Solution Approach 1:
The patent uses parameter changes (temperature and pressure control) to achieve supercritical state of the dyeing medium, which enhances penetration capability into leather structure. This allows deep and uniform dye penetration without requiring excessive amounts of dye or processing agents, improving both dye depth and wet fastness.
Solution Approach 2:
The supercritical fluid acts as an intermediary carrier that efficiently transports dye molecules deep into the leather structure. The unique properties of supercritical state (high density, low viscosity) enable effective penetration and uniform distribution of dye throughout the leather, achieving high dye depth and fastness with reduced agent quantities.
3Productivity
If rapid pressure reduction is used after supercritical dyeing, then processing time is reduced, but leather delamination may occur
Solution Approach 1:
The patent implements dynamic pressure control during the dyeing and depressurization process. Pressure is gradually reduced in controlled stages, allowing the leather structure to adapt and preventing sudden pressure differentials that could cause delamination. This dynamic approach maintains productivity while ensuring leather integrity.
Solution Approach 2:
The patent applies beforehand cushioning by implementing controlled, gradual pressure reduction protocols before complete depressurization. This staged approach prevents sudden structural stress on the leather, cushioning against potential delamination while still achieving rapid overall processing compared to conventional methods.
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 dyeing efficiency with improved wet fastness and reduced environmental impact by minimizing water usage and energy consumption, while preventing leather delamination and allowing for automated processing.
Implementation Method 1
use of a pressurized fluid which is soluble and/or transportable in the pressurized fluid at least when this is in the supercritical state
Implementation Method 2
the dissolved dyeing agent in combination with the pressurized fluid in the supercritical state can penetrate into the leather structure including at least part of the inner structure
Data Source
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AI summary
A method and an apparatus for processing of leather objects (30) comprising a process chamber (34), a controllable compressor (36) for pressurizing a fluid, a pressure reducing member (44), an inlet (54) for a processing agent (56) and a controller (40), wherein said process chamber (34) is configured in the form of a pressure chamber, said controllable compressor (36) for pressurizing a fluid is configured for introducing pressurized fluid into the process chamber (34) from a source of said fluid, controlled by the controller (40), and for providing a predefined pressure in the process chamber (34) in order to reach a supercritical state of said fluid, and wherein said inlet (54) for said processing agent (56) is configured for facilitating introduction of said processing agent (56) into the process chamber (34) prior to, during or subsequent to pressurization of the fluid, and wherein said pressure reducing member (44) is configured for gradually reducing the pressure of the pressurized fluid to reach a gaseous state subsequent to the processing of said leather objects (30).