Microstructured Curved Surfaces for Mold Release

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Solution Overview

Problem

Current methods struggle to produce superhydrophobic, 3-dimensionally curved surfaces using mold-related processes, as existing technologies face challenges in maintaining mechanical stability and uniform hydrophobicity, especially when components need to be easily removable from molds, leading to issues with structural integrity and self-cleaning effectiveness.

Innovation Solution

The solution involves aligning microstructuring elements on curved surfaces in a specific manner, ensuring parallelism and consistent spacing to facilitate easy removal from molds while maintaining mechanical stability and uniform hydrophobicity, with structuring elements having the same size and distance between adjacent sides, aligned parallel to the removal direction, and a macrostructure for additional protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If microstructured surfaces are produced using conventional mold-related processes, then superhydrophobic surfaces can be generated, but the components cannot be easily removed from molds and mechanical stability is compromised

Engineering Contradiction:
Improvemechanical stabilityVSAvoiddemoldability
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The microstructured surface is divided into discrete structuring elements (protrusions, pillars, or recesses) that are distributed across the surface. This segmentation allows the mold to release the component easily while maintaining the functional integrity of each individual structure, resolving the contradiction between easy demolding and mechanical stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The microstructures are designed with specific local characteristics (height, diameter, spacing) that vary according to the functional requirements of different surface regions. This local optimization ensures that each area maintains appropriate mechanical properties and hydrophobicity while allowing uniform demolding across the entire component.

Inventive Principle:
Principle #3Local quality

2Reliability

If hierarchical structures are used to achieve superhydrophobicity, then hydrophobic effect is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvehydrophobic effectVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The microstructured surface serves multiple functions simultaneously: it provides hydrophobicity through the Cassie-Baxter effect, maintains mechanical stability through the distributed structuring elements, and enables easy demolding through the specific geometric configuration. This multi-functionality reduces the need for separate manufacturing steps while achieving superior hydrophobic performance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If regular surface structures are produced using lithography or embossing, then manufacturing precision is improved, but the surfaces lack the mechanical stability and hydrophobic uniformity needed for reliable performance

Engineering Contradiction:
Improvesurface structure precisionVSAvoidmechanical stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The microstructured surface design allows the structures to self-align and self-stabilize during the molding process. The geometric configuration of the structuring elements inherently maintains uniform spacing and orientation, eliminating the need for complex post-processing or precise alignment procedures while ensuring reliable mechanical and hydrophobic properties.

Inventive Principle:
Principle #25Self-service

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 configuration allows for the creation of superhydrophobic surfaces with consistent water contact angles, ensuring reliable demolding and enhanced mechanical stability, even on complex geometries, while maintaining the self-cleaning effect and hydrophobic properties.

Implementation Method 1

The latter is characterized by the fact that the liquid cannot penetrate the surface structure; an air cushion forms between the structures. Water droplets thus easily form a static contact angle of over 150°

Methodology Applied
Scientific EffectCassie-Baxter wetting: Wetting

Implementation Method 2

an air cushion forms between the structures

Methodology Applied
Scientific EffectAir cushion effect: Air Lubrication

Implementation Method 3

To produce particularly effective and hydrophobic surfaces, hierarchical structures or specific aspect ratios are necessary

Methodology Applied
Scientific EffectSuperhydrophobicity: Hydrophobe

Implementation Method 4

Biological surfaces, such as the lotus leaf, are often used as models

Methodology Applied
Scientific EffectLotus leaf effect: Lotus Leaf Effect

Data Source

PatentEP3774253B1Microstructured object
Publication Date: 2023.08.09 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3774253B1 patent drawingFigure 1
  • EP3774253B1 patent drawingFigure 2
  • EP3774253B1 patent drawingFigure 3

AI summary

The invention relates to an object with an at least partially curved surface having a microstructure of structuring elements which are aligned in such a way that the object can be easily removed from its mold during its production. The invention relates to a mold or a molded part for the structured object, which comprises the negative of the microstructure on the surface thereof, and to the use of a microstructure for producing a surface having a high static water edge angle. The invention also relates to a method for producing a mold or a molded part for the microstructured object.