Leather processing utilizing super-critical or near super-critical co2 value
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Solution Overview
Problem
Conventional leather processing methods are inefficient, water-intensive, and environmentally unfriendly, particularly in dyeing and finishing stages, and struggle with improving lower-grade leathers to high-quality standards without generating significant waste.
Innovation Solution
A method utilizing supercritical or near-supercritical CO2 to process leather, including drying, fat-liquoring, dyeing, coating, and waterproofing, under increased pressure and temperature, allowing for a complete dehydration and impregnation cycle with minimal chemicals and no wastewater, using a stand-alone apparatus with a CO2 pump, autoclave, and integrated cooling/heating system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional water-based and chemical-intensive processing methods are used, then leather can be processed through multiple stages (tanning, drying, dyeing, finishing), but significant water consumption, chemical waste, and environmental pollution occur
Solution Approach 1:
The patent changes the physical state and properties of the processing medium from liquid water to supercritical CO2 by adjusting pressure and temperature parameters. This transformation enables the CO2 to penetrate leather effectively while avoiding water-related waste and chemical pollution, thus resolving the contradiction between productivity and environmental harm
Solution Approach 2:
The patent utilizes the phase transition of CO2 between supercritical and gaseous states. By controlling pressure and temperature, CO2 transitions to a supercritical state for processing, then returns to gaseous state for easy separation and recycling. This phase transition mechanism eliminates water waste and chemical residues while maintaining high processing efficiency
2Manufacturing precision
If intensive chemical treatments are applied to improve lower-grade leather quality, then leather quality can be enhanced, but more chemicals and time are consumed
Solution Approach 1:
The patent employs precise control of supercritical CO2 parameters (pressure, temperature, density) to achieve uniform penetration and treatment of leather. This parameter control enables consistent quality improvement across different leather grades without requiring multiple sequential chemical treatments, thereby reducing processing time while enhancing manufacturing precision
3Reliability
If multiple separate processing steps are used for dehydration, fat-liquoring, re-tanning, and dyeing, then each step can be optimized, but the overall process becomes complex and time-consuming
Solution Approach 1:
The patent merges multiple separate processing steps (dehydration, fat-liquoring, re-tanning, dyeing) into a single integrated supercritical CO2 processing system. Different functional agents are introduced into the supercritical CO2 medium to perform multiple operations simultaneously or sequentially in one continuous process, reducing device complexity while maintaining reliable process control through unified parameter management
Solution Approach 2:
The supercritical CO2 medium serves multiple functions throughout the processing sequence: it acts as a drying agent for dehydration, a carrier for fat-liquoring agents, a medium for re-tanning compounds, and a vehicle for dye penetration. This multi-functionality eliminates the need for separate processing equipment and simplifies the overall system while maintaining precise control over each functional stage
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-quality leather with improved tensile strength, softness, and color homogeneity, reducing environmental impact by minimizing water and chemical usage, and enabling efficient processing of various leather types, including low-grade and synthetic materials.
Implementation Method 1
processing leather by subjecting the leather to super critical CO2 under increased pressure of >7.3 MPa (73 bar), a temperature of >30° C.
Implementation Method 2
fat-liquoring leather by (b1) solvent exchange, or (b2) directly
Implementation Method 3
dyeing leather by contacting the leather with at least one dye in the presence of supercritical CO2
Implementation Method 4
dyeing tanned and dried leather, or fat-liquored leather, or finished leather
Implementation Method 5
under increased pressure of >7.3 MPa (73 bar)
Implementation Method 6
a temperature of >30° C.
Implementation Method 7
integrated cooling/heating system
Data Source
AI summary
A method for processing natural or synthetic leather by using super-critical CO2. The leather can be dried leather, low grade leathers, thin leather, crust leathers, finished leathers, wet blue leathers, and tanned leather, as well as synthetic leather. In a second aspect the invention relates to leather obtained by said method, and in a third aspect to a stand-alone apparatus for performing said method.