3D-Printed Silicone Curing via Thermal Post-Treatment
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Solution Overview
Problem
Existing additive manufacturing methods for silicones face challenges with high viscosities making accurate dosing difficult and crosslinking reactions that are not spatially controlled, leading to issues with achieving isotropic mechanical properties and full curing of large 3D-printed structures, particularly with light-promoted curing which has limited penetration and can introduce molecular tension.
Innovation Solution
A method using thermally promoted free radical curing or silanol condensation curing steps in the post-processing of 3D-printed silicone products, with a composition comprising silicone building blocks bearing alkenyl groups, crosslinking agents with thiol groups, and free radical photoinitiators, to achieve homogeneous curing and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If light-promoted curing is used for 3D-printed silicone, then curing can be initiated, but light penetration is limited and cannot cure large structures fully
Solution Approach 1:
The patent changes the curing mechanism from light-promoted to thermally promoted free radical curing. By using thermal energy instead of light, the curing process can penetrate throughout the entire volume of the silicone structure, solving the limitation of light penetration in large structures. The thermal curing method allows complete curing regardless of the structure's size or complexity.
Solution Approach 2:
The patent replaces the optical system (light promotion) with a thermal system (thermal promotion). This substitution enables the curing process to overcome the penetration depth limitations of light by using heat, which can effectively transmit through the entire silicone matrix to initiate and complete the crosslinking reaction throughout the whole structure.
2Manufacturing precision
If light-promoted curing is used, then surface curing can be achieved, but molecular tension is introduced and mechanical properties are reduced
Solution Approach 1:
The patent replaces light-promoted curing with thermally promoted curing to eliminate the introduction of molecular tension. Thermal promotion allows for more uniform and controlled crosslinking without the rapid curing that causes tension and defects, thereby improving the mechanical properties of the final silicone product.
Solution Approach 2:
The patent changes the curing initiation mechanism from optical to thermal parameters. This parameter change allows for controlled, uniform curing throughout the structure without the rapid surface curing that creates molecular tension and compromises mechanical strength. The thermal process enables slower, more uniform crosslinking that preserves material integrity.
3Ease of manufacture
If polysiloxanes are used for additive manufacturing, then silicone material can be processed, but high viscosities make accurate dosing difficult
Solution Approach 1:
The patent modifies the physical parameters of the polysiloxane by incorporating functional groups (alkenyl and thiol groups) that enable chemical crosslinking. This chemical modification allows the material to maintain processability while providing a mechanism for controlled curing, addressing the dosing accuracy issues through improved material characterization and formulation.
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 results in 3D-printed silicones with consistent Shore A hardness across the structure, enhanced mechanical properties such as Young's modulus, elongation at break, tensile strength, and tear strength, and ensures full curing of large products without the limitations of light-promoted curing.
Implementation Method 1
a) at least one silicone building block bearing a plurality of alkenyl groups (A); b) at least one crosslinking agent bearing a plurality of thiol groups (B); c) at least one free radical photoinitiator (D)
Implementation Method 2
post-curing treatment that comprises at least one further curing step other than light-promoted curing, preferably either heat promoted radical curing or silanol condensation curing
Implementation Method 3
post-curing treatment that comprises at least one further curing step other than light-promoted curing, preferably either heat promoted radical curing or silanol condensation curing
Data Source
AI summary
A method for preparing a 3D-printed silicone comprising: a) preparation of a 3D model of a preproduct; b) additive manufacturing of the preproduct according to the 3D model of the preproduct using an additive manufacturing device and an additive manufacturing composition comprising: i) at least one silicone building block bearing a plurality of alkenyl groups (A); ii) at least one crosslinking agent bearing a plurality of thiol groups (B); iii) at least one free radical photoinitiator (D); c) post-curing treatment that comprises at least one further curing step other than light-promoted curing, preferably either heat promoted radical curing or silanol condensation curing; wherein the ratio of thiol groups to alkenyl groups in the additive manufacturing composition is in the range from 0.5:1 to 5:1.