Pasty Polyurethane 3D Printing: Dual Cure for Interlayer Adhesion
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Solution Overview
Problem
Existing 3D printing methods using polymeric materials face challenges with insufficient interlayer adhesion and deformation due to low viscosity of reactive liquid compositions.
Innovation Solution
A method utilizing a pasty polyurethane composition with a specific viscosity factor, which is radiation and heat curable, ensuring dimensional stability and good interlayer adhesion through thixotropic behavior and dual curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reactive liquid printable compositions are used for 3D printing, then the material can be printed in a layer-by-layer manner, but the low viscosity leads to deformation of the printed part and poor resolution
Solution Approach 1:
The patent changes the viscosity parameter of the printable composition by formulating it as a pasty polyurethane composition with specific viscosity characteristics. This allows the material to maintain sufficient viscosity for dimensional stability during printing while still being printable in a layer-by-layer manner, thereby resolving the contradiction between printability and resolution.
2Stability of the object's composition
If fully cooled and solidified layers are printed upon, then the structural integrity is maintained, but the interlayer adhesion becomes insufficient
Solution Approach 1:
The patent applies preliminary radiation curing to the printed layers before printing the next layer. This preliminary action partially cures the polyurethane composition, creating a stable surface for the next layer while leaving some uncured portions that maintain good wettability and adhesion. This resolves the contradiction between structural integrity and interlayer adhesion.
Solution Approach 2:
The patent uses a composite printable composition that combines cured and uncured polyurethane portions. The cured portions provide structural integrity while the uncured portions maintain wettability and adhesion properties, creating a composite structure that satisfies both requirements.
3Adaptability or versatility
If elastomeric properties are provided in polymeric 3D printing materials, then the material flexibility is improved, but the interlayer adhesion and dimensional stability deteriorate
Solution Approach 1:
The patent changes the physical state parameter of the material from liquid to pasty, and controls the viscosity through formulation. This allows elastomeric polyurethane materials to maintain dimensional stability during printing while preserving their elastomeric properties, resolving the contradiction between flexibility and dimensional stability.
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 achieves a stable 3D structure with excellent interlayer adhesion and mechanical properties, along with a smooth surface finish, by maintaining the form until complete curing.
Implementation Method 1
the thixotropic behaviour ensures that the printed layer is already dimensional stable
Implementation Method 2
at least one monomer and/or prepolymer that is polymerizable by exposure to radiation, preferably a (meth)acrylate
Implementation Method 3
curing the printed layers of the reactive curable printable composition, preferably by heating
Data Source
AI summary
The present invention lies in the field of 3D printing methods. In particular, the invention relates to 3D printing methods for the production of a 3D part in a layer-by-layer manner, wherein the printable composition is a pasty polyurethane composition comprising at least one polyisocyanate resin, at least one monomer and/or prepolymer that is polymerizable by exposure to radiation and at least one photoinitiator, wherein the pasty polyurethane composition has a viscosity factor (1.5/15) of at least 2 at application temperature.