3D-Patterned Microstructure R2R Curing for Reliable Demolding

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Solution Overview

Problem

Current roll-to-roll (R2R) manufacturing of complex 3D-patterned microstructures using UV-curable materials faces challenges such as poor adhesion, non-wetting, and frictional properties, along with a short flexible mold lifetime and low repeatability, due to incompatibility between mold materials and structural materials, leading to inefficient and costly production.

Innovation Solution

A method involving a two-step UV curing process with a flexible mold layer, where a UV-curable material is partially cured at a low intensity and then fully cured, using a demolding angle of at least 80 degrees, to enhance mold repeatability and lifetime, and achieve improved microstructure formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a flexible mold is used in UV-R2R manufacturing of 3D microstructures, then the mold can conform to complex patterns and enable continuous production, but the mold lifetime and repeatability are short due to incompatibility between mold materials and structural materials

Engineering Contradiction:
Improvecontinuous production capabilityVSAvoidmold lifetime and repeatability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the UV curing parameters by implementing a two-step curing process: first curing at low UV intensity to allow demolding, then completing the curing process after demolding. This parameter change resolves the contradiction by enabling the mold to be removed before full curing, preventing adhesion issues that limit mold lifetime, while still achieving complete curing of the microstructure for continuous production capability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary UV curing at low intensity before demolding to create a partially cured state that maintains structural integrity during mold removal. This preliminary action prevents the uncured material from adhering to the flexible mold, thereby extending mold lifetime and repeatability while enabling continuous production

Inventive Principle:
Principle #10Preliminary action

2Speed

If UV-curable materials are used for R2R manufacturing, then fast curing (seconds to minutes) is achieved compared to thermal curing, but poor adhesion, non-wetting, and frictional properties result due to incompatibility with mold materials

Engineering Contradiction:
Improvecuring speedVSAvoidadhesion and frictional properties
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent applies partial UV curing action by using low UV intensity during the first curing step, which is insufficient to fully cure the material but adequate to create a demoldable state. This partial action prevents excessive adhesion to the mold while maintaining fast curing benefits, and the remaining curing is completed after demolding to achieve full performance

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent segments the UV curing process into two distinct phases: first curing at low intensity before demolding, and second curing after demolding. This segmentation allows optimization of each phase for its specific purpose, resolving the contradiction between fast curing speed and proper adhesion properties by preventing premature full curing that causes mold adhesion issues

Inventive Principle:
Principle #1Segmentation

3Device complexity

If a demolding angle of less than 80 degrees is used in conventional UV-R2R systems, then the apparatus design is simpler, but the flexible mold lifetime and repeatability are reduced

Engineering Contradiction:
Improveapparatus design simplicityVSAvoidmold repeatability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by performing low-intensity UV curing before demolding to create a partially cured state that prevents adhesion between the microstructure and mold. This preliminary anti-adhesion action counteracts the adhesion forces that would otherwise limit mold repeatability, enabling successful demolding even with simpler apparatus designs

Inventive Principle:
Principle #9Preliminary anti-action

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 3D-patterned microstructures with enhanced adhesive, frictional, and optical properties, along with increased flexible mold lifetime and repeatability, enabling cost-effective large-scale production of complex microstructures.

Implementation Method 1

subjecting the raw casting to a first curing step at a UV intensity of 10,000 mW/cm2 to provide a partially cured casting comprising a partially cured UV-curable material; subjecting the partially cured casting to a second curing step to provide a fully cured casting comprising a fully cured UV-curable material

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP4354222A1Method of roll-to-roll (R2R) manufacturing of a 3d-patterned microstructure, use of a 3d-patterned microstructure, and an apparatus for manufacturing a 3d-patterned microstructure
Publication Date: 2024.04.17 MAX PLANCK GESELLSCHAFT ZUR FOERDERUNG DER WISSENSCHAFTEN EV
  • EP4354222A1 patent drawingFigure 1a~1b
  • EP4354222A1 patent drawingFigure 2
  • EP4354222A1 patent drawingFigure 3

AI summary

The present invention relates to a method of roll-to-roll (R2R) manufacturing of a 3D-patterned microstructure. Further, the present invention relates to a 3D-patterned microstructure obtained by the method. In addition, the present invention relates to a use of a 3D-patterned microstructure manufactured according to the method. Furthermore, the present invention relates to an apparatus for manufacturing a 3D-patterned microstructure, the apparatus being configured to carry out the method.