3D Spacer Fabric Membrane Coating via Dynamic Doctor Knife
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Solution Overview
Problem
The production of filtration membranes using 3D textiles faces challenges due to the irregular surface uniformity, thickness variability, and roughness, leading to uneven coating deposits and operational issues such as uneven porosity and difficulty in backwashing.
Innovation Solution
A method is developed to measure the variation in thickness, roughness, and tapering of 3D spacer fabrics in real-time during the casting process, allowing for precise adjustment of the casting head distance to ensure uniform polymer coating application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thick layer of coating is applied to compensate for the variability of thickness and roughness of 3D textiles, then the coating can cover the irregular surface, but this results in a significant increase in raw material use and creates irregular coating deposits
Solution Approach 1:
The patent applies a doctor knife with adjustable angle and position to dynamically adapt the coating process to the irregular 3D textile surface. The doctor knife can be moved closer to the casting head or its angle adjusted to compensate for surface variations without requiring a uniformly thick coating layer, thus reducing raw material consumption while maintaining coating uniformity.
Solution Approach 2:
The patent changes the parameters of the coating process by adjusting the doctor knife angle (α) and its distance from the casting head. These parameter adjustments allow the system to accommodate surface irregularities of 3D textiles without applying excessive coating material, optimizing both coating uniformity and material efficiency.
2Manufacturing precision
If a thick layer of coating is applied to compensate for textile variability, then surface coverage is improved, but the coating deposit through the membrane becomes irregular with thicker regions having smaller embedded regions and thinner regions having thick deposits
Solution Approach 1:
The patent replaces simple gravity-based coating with a controlled mechanical system using a doctor knife. This mechanical intervention allows precise control over coating thickness and distribution, ensuring uniform coating deposits across the 3D textile surface by mechanically removing excess coating material and adjusting the coating head position.
Solution Approach 2:
The doctor knife acts as an intermediary between the casting head and the 3D textile surface. It mediates the coating process by controlling the polymer solution distribution, ensuring that the coating is applied uniformly across irregular surfaces without directly contacting the textile, thus simplifying the overall control mechanism.
3Ease of manufacture
If conventional casting is performed on 3D textiles without adjustment, then the process is simple, but the membrane exhibits uneven surface porosity, difficulty of backwashing in some regions, and unevenly sized filtration channels
Solution Approach 1:
The patent introduces dynamic adjustment capabilities to the casting process, including adjustable doctor knife angle and position, and adjustable casting head distance from the textile surface. These dynamic adjustments maintain process simplicity while significantly improving membrane performance uniformity by adapting to surface variations in real-time.
Solution Approach 2:
The doctor knife serves multiple functions: it controls coating thickness, compensates for surface irregularities, and ensures uniform polymer distribution. This multi-functional tool maintains ease of manufacture by using a single device that performs multiple correction functions, rather than requiring complex multi-component systems.
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 results in filtration membranes with uniform coatings, improved pore size consistency, enhanced surface porosity, and efficient backwashing capabilities, reducing raw material usage and operational issues.
Implementation Method 1
a polymer solution is applied by means of an injection process by means of a casting module
Implementation Method 2
precipitation in an aqueous bath and drying at elevated temperature
Implementation Method 3
drying at elevated temperature
Data Source
AI summary
The current invention relates to a method for the production of a filtration membrane envelope comprising a 3D spacer fabric interposed between two membrane layers cast onto said 3D spacer fabric, wherein said method comprises a casting step, wherein during said casting step a polymer solution is applied to the outer surface of said 3D spacer fabric, wherein said polymer is applied by means of an injection process by means of a casting module and wherein said excess of coating material is removed by a casting head comprising a casting head, wherein prior or during the casting process the variation in thickness, roughness and/or tapering of the fabric is measured and the distance between the 3D fabric and the casting head is adjusted based on said measurement.