Serially Curable Resins for Additive Manufacturing
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Solution Overview
Problem
Conventional additive manufacturing techniques, such as stereolithography and CLIP, face challenges in producing parts with a range of mechanical properties due to competing requirements during the dual cure process, where ingredients for easy processing may compromise strength and thermal stability, and rapid light polymerization can affect the mechanical properties of the finished product.
Innovation Solution
A method involving reactive blocked monomers and prepolymers, which are irradiated with light to form a scaffold, then heated or microwave-irradiated to regenerate and self-polymerize, producing three-dimensional objects with improved rigidity, thermal stability, and flame resistance, while reducing solvent out-gassing and stress relief through scaffold cleavage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low viscosity resin is used for easy processing by additive manufacturing, then ease of manufacture is improved, but green part strength deteriorates
Solution Approach 1:
The curing process is segmented into two distinct stages: first light-induced polymerization to create a green part with adequate strength, then heat-induced completion cure to achieve final mechanical properties. This segmentation allows optimization of resin viscosity for processing while using the second cure stage to develop full strength, resolving the contradiction between ease of manufacture and green part strength.
Solution Approach 2:
The light-induced polymerization performs a preliminary curing action that creates a sufficiently strong green part for handling and post-processing. This preliminary action allows the resin to be processed at low viscosity while the subsequent heat cure completes the polymerization to achieve final mechanical strength, thus resolving the contradiction between ease of processing and green part strength.
2Strength
If ingredients are added to provide strong green part, then green part strength is improved, but mechanical properties of finished part deteriorate
Solution Approach 1:
The invention changes the curing parameters by using two different energy sources (light and heat) with different activation mechanisms. The light-induced polymerization uses photoinitiators to create crosslinks for green part strength, while the heat-induced completion cure uses thermal energy to achieve optimal mechanical properties. This parameter change allows independent optimization of green part strength and finished part mechanical properties, resolving the contradiction between these two requirements.
3Productivity
If rapid light polymerization is used to increase productivity, then productivity is improved, but green strength and mechanical properties deteriorate
Solution Approach 1:
The polymerization process is segmented into two stages with different speed characteristics. The first light-induced stage provides rapid polymerization for high productivity and creates the green part structure. The second heat-induced stage completes the polymerization to achieve optimal mechanical properties and green strength. This segmentation allows the system to benefit from rapid light polymerization while ensuring adequate strength development in the completion cure stage.
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
The method produces three-dimensional objects with enhanced mechanical properties, thermal stability, and reduced solvent out-gassing, addressing the limitations of existing dual cure processes by optimizing the resin composition and curing steps.
Implementation Method 1
irradiating the build region with light through said optically transparent member to form a solid polymer scaffold from the reactive blocked monomer and/or prepolymer
Implementation Method 2
heating, microwave irradiating, or both heating and microwave irradiating, the three-dimensional intermediate sufficiently to degrade the scaffold and regenerate the monomer and/or prepolymer
Implementation Method 3
heating, microwave irradiating, or both heating and microwave irradiating, the three-dimensional intermediate
Data Source
AI summary
Provided is a method of forming a three-dimensional object, which may include the steps of: (a) providing a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region therebetween; (b) filling the build region with a polymerizable liquid that comprises a reactive blocked monomer and/or prepolymer comprising a self-polymerizing monomer and/or prepolymer blocked with a light-polymerizable blocking group; (c) irradiating the build region with light through said optically transparent member to form a solid polymer scaffold from the reactive blocked monomer and/or prepolymer and also advancing the carrier away from the build surface to form a three-dimensional intermediate; and then (d) heating and/or microwave irradiating, the three-dimensional intermediate sufficiently to degrade the scaffold and regenerate the monomer and/or prepolymer in de-blocked form, which monomer and/or prepolymer in turn self-polymerize, to form said three-dimensional object.