3D Printing Silicone Elastomers via Photopolymerizable Functional Groups
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Solution Overview
Problem
Existing additive manufacturing methods, such as 3D printing, struggle to produce objects with consistent quality and surface accuracy, particularly for silicone elastomers, due to issues like turbidity, inhomogeneities, and material damage caused by photoinitiators and high local photon densities.
Innovation Solution
A 3D printing method using a device with a print head that continuously determines its position and adjusts the dispensing of printing masses in real-time, allowing for precise placement of voxels or strands, and utilizing UV/VIS-induced crosslinking for silicone rubber masses to ensure accurate and high-quality object production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photopolymerizable materials with photoinitiators are used for 3D printing, then crosslinking and solidification can be achieved, but turbidity and inhomogeneities occur due to poor solubility in silicone masses
Solution Approach 1:
The patent changes the chemical parameters of the silicone mass by functionalizing it with photopolymerizable groups (acrylate, methacrylate, vinyl, epoxy, isocyanate, oxetane, or carbonyl groups). This modification enables the silicone to undergo photopolymerization while maintaining homogeneity, as the functional groups are chemically integrated into the silicone structure rather than being added as separate photoinitiators that cause turbidity.
Solution Approach 2:
The patent creates a composite material system where photopolymerizable functional groups are chemically bonded to the silicone polymer chains. This composite approach allows the material to exhibit both silicone elastomer properties and photopolymerization capability, achieving crosslinking without the turbidity issues associated with conventional photoinitiator additives.
2Reliability
If high functional density of photopolymerizable groups is used to counteract oxygen inhibition, then crosslinking rate improves, but the vulcanizate becomes non-elastic and brittle
Solution Approach 1:
The patent optimizes the functional density parameter by incorporating photopolymerizable groups at controlled concentrations (0.1-10 wt%, preferably 0.5-5 wt%). This moderate functional density is sufficient to achieve adequate crosslinking rates while maintaining the elastomeric network structure, preventing the material from becoming brittle.
Solution Approach 2:
The patent creates local crosslinked regions through photopolymerization while maintaining the overall elastomeric network. The crosslinking occurs selectively in illuminated areas, creating a heterogeneous structure with localized rigid crosslinked zones embedded in a flexible silicone matrix, preserving elastomeric properties while achieving sufficient crosslinking.
3Manufacturing precision
If pulsed femtosecond lasers are used for multiphoton polymerization, then precise solidification is achieved, but decomposition reactions and material damage occur due to extremely high local photon density
Solution Approach 1:
The patent changes the material's optical and chemical parameters by incorporating photopolymerizable functional groups that have optimized absorption characteristics. These functional groups allow the material to undergo polymerization at lower photon densities, reducing the risk of decomposition reactions while maintaining precise solidification capability.
Solution Approach 2:
The photopolymerizable functional groups act as intermediaries that mediate the energy transfer from laser photons to the silicone polymer chains. These functional groups have optimized energy absorption and transfer properties, enabling controlled polymerization without the extreme local photon densities that cause decomposition, thus protecting the material from damage.
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 object quality comparable to or exceeding that of injection-molded parts, with improved surface finish, edge sharpness, and dimensional stability, while avoiding issues like turbidity and material damage.
Implementation Method 1
utilizing UV/VIS-induced crosslinking for silicone rubber masses
Data Source
Figure 1
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Figure 3a~4d
AI summary
The invention relates to a method for producing an object (40) by using a 3D printing device (10), which has at least one printhead (22) with a discharge device (24), wherein the discharge device (24) is designed for placing printing compounds (42) at desired positions in order to produce the object (40) generatively. In particular, it is provided here that the position of the printhead (22) is continuously determined by a position measuring device (20), and that the printing compounds (42) are placed by the discharge device (24) in dependence on the continuously determined position of the printhead (22). Further aspects of the invention concern an elastomer part produced by the method, a 3D printing device (10) and a computer program that is designed for carrying out the method.