Substrate-Based Additive Fabrication Resin Curing
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Solution Overview
Problem
Substrate-based additive fabrication processes face challenges in developing hybrid liquid radiation curable resins that achieve excellent mechanical properties and rapid curing, as cationically polymerizable components polymerize slowly, leading to issues with adhesive and cohesive strength, and existing formulations often result in incomplete peeling or cohesive failure.
Innovation Solution
A method involving coating a substrate with a layer of liquid radiation curable resin comprising 30-80 wt% cationically curable compounds, exposing it to actinic radiation, and controlling the separation delay time to achieve a storage shear modulus of greater than 9.0 x 10^5 Pa, ensuring proper adhesion and peeling from the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cationically polymerizable components are used in liquid radiation curable resin, then mechanical properties of the cured layer are improved, but polymerization speed decreases leading to incomplete curing
Solution Approach 1:
The patent modifies the chemical composition parameters of the liquid radiation curable resin by incorporating cationically polymerizable compounds in specific concentrations (0.1-10 wt%, preferably 0.5-5 wt%). This parameter change enables the resin to achieve both good mechanical properties and adequate curing speed by balancing the slow polymerization characteristic of cationic systems with the rapid initial cure provided by free radical photopolymerization.
2Strength
If cationically polymerizable components are used to improve mechanical properties, then adhesive strength may improve, but separation and peeling from substrate becomes difficult
Solution Approach 1:
The patent carefully controls the concentration of cationically polymerizable compounds within specific ranges (0.1-10 wt%, preferably 0.5-5 wt%) to balance adhesive strength and peelability. This parameter optimization ensures that the cured layer achieves sufficient adhesion to the substrate while maintaining enough flexibility and controlled curing to allow for successful separation and peeling during the layer-by-layer fabrication process.
3Productivity
If the resin is cured rapidly to improve build speed, then productivity increases, but cohesive strength may be insufficient leading to layer failure
Solution Approach 1:
The patent employs free radical photopolymerization as a preliminary action that provides rapid initial curing of the liquid radiation curable resin. This preliminary fast cure establishes the basic structural framework and prevents layer collapse, enabling high build speed. The subsequently slower cationic polymerization then continues in the background to develop full mechanical strength and cohesive properties, resolving the contradiction between build speed and cohesive strength.
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 allows for the formation of three-dimensional objects with excellent mechanical properties by balancing adhesive and cohesive strength, enabling successful peeling and building of parts without cohesive failure.
Implementation Method 1
selectively exposing the layer of liquid radiation curable resin to actinic radiation, provided by a source of actinic radiation, thereby forming a cured layer
Data Source
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AI summary
The invention relates to a substrate-based method for forming a three-dimensional object by additive fabrication by coating a liquid radiation curable resin comprising from 30 to 80 wt% of cationically curable compounds on a substrate, contacting the liquid radiation curable resin with a previously cured layer, selectively exposing the layer of liquid radiation curable layer to actinic radiation thereby forming a cured layer, separating the cured layer at the substrate, and repeating the steps a sufficient number of time in order to build up a three-dimensional object.