Two-Phase 3D Printing Resin Floating on Immiscible Liquid

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Solution Overview

Problem

Urethane (meth)acrylates, despite their excellent properties, face limitations in 3D printing due to high viscosities, requiring large amounts of reactive diluents which lead to significant shrinkage and deviations from intended geometries in printed components.

Innovation Solution

A method utilizing a free-radically crosslinkable resin with urethane (meth)acrylates that floats on an immiscible liquid of higher density, allowing for layer-by-layer deposition with reduced reactive diluent usage, using photoactivatable initiators and isocyanate-functional compounds, and dual-cure systems to minimize shrinkage and enhance mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If large amounts of reactive diluents are added to reduce resin viscosity, then the resin becomes more suitable for 3D printing, but significant shrinkage occurs and deviations from intended geometries increase

Engineering Contradiction:
Improveresin processabilityVSAvoidgeometric accuracy
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The invention changes the physical parameters of the resin system by introducing a two-phase system with immiscible liquids of different densities. The crosslinkable resin forms a separate phase with higher density than the carrier liquid, allowing controlled deposition without requiring excessive reactive diluents. This parameter change enables the resin to maintain adequate viscosity for printing while minimizing shrinkage-induced geometric deviations.

Inventive Principle:
Principle #35Parameter changes

2Strength

If high concentration of urethane groups is used to achieve excellent mechanical properties, then the resin shows superior performance, but viscosity increases significantly

Engineering Contradiction:
Improvemechanical propertiesVSAvoidresin processability
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention segments the resin system into two distinct phases: a crosslinkable resin phase containing urethane (meth)acrylates and a separate carrier liquid phase. This segmentation allows the resin phase to maintain high urethane group concentration for excellent mechanical properties while the overall system remains processable due to the presence of the carrier liquid. The phases are immiscible, with the resin phase floating on the carrier liquid.

Inventive Principle:
Principle #1Segmentation

3Manufacturing precision

If a two-phase system with immiscible liquids is used, then shrinkage is reduced and geometric precision is improved, but the system complexity increases

Engineering Contradiction:
Improvegeometric accuracyVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention introduces a carrier liquid as an intermediary substance that facilitates the deposition process. The carrier liquid is immiscible with and has higher density than the crosslinkable resin, causing the resin to form a separate floating phase. This intermediary enables controlled layer-by-layer deposition with minimal shrinkage while maintaining relative system simplicity through straightforward phase separation based on density differences.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables the production of high-quality, mechanically robust products with low shrinkage and precise geometry, utilizing a two-phase stereolithography process with urethane (meth)acrylates and dual-cure chemistry to improve mechanical properties post-curing.

Implementation Method 1

the container containing the free-radically crosslinkable resin and a liquid which is not miscible with the free-radically crosslinkable resin and which has a higher density than the free-radically crosslinkable resin, so that the free-radically crosslinkable resin floats on the liquid

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 2

exposing and/or irradiating a selected area of a free-radically crosslinkable resin, corresponding to the respectively selected cross-section of the object

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP3727858B1Two phase 3D printing method
Publication Date: 2023.07.12 STRATASYS INC
  • EP3727858B1 patent drawingFigure 1~2

AI summary

An additive manufacturing method wherein the carrier (400) is within a vessel (100), the vessel contains the free-radically crosslinkable resin (300) and a liquid (200) which is immiscible with the free-radically crosslinkable resin (300) and has a higher density than the free-radically crosslinkable resin (300), such that the free-radically crosslinkable resin (300) floats on top of the liquid (200) and, prior to each step II), the distance between the carrier (400) and the free-radically crosslinkable resin (300) is altered such that a layer of the free-radically crosslinkable resin forms above the uppermost surface (420), viewed in vertical direction, of the previously deposited layer of the construction material (600) and at least partially forms contact with this uppermost surface (420) of the previously deposited layer of the construction material (600). The free-radically crosslinkable resin (300) comprises a urethane (meth)acrylate. The invention further relates to the use of a free-radically crosslinkable resin comprising a urethane (meth)acrylate as construction material in a two-phase 3D printing method.