Two-Component Polyurethane Composition for Fast, Low-Tack 3D Printing
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Solution Overview
Problem
Existing 3D printing technologies using two-component polyurethane compositions face challenges in achieving rapid curing without viscosity increase, nozzle clogging, and excessive tackiness, limiting printing speed and flexibility in producing large-scale models with desired mechanical properties.
Innovation Solution
A two-component polyurethane composition comprising a tri- or higher functional polyol with low to moderate molecular weight, di- or tri-functional polyether or polyester polyol, and a polyisocyanate, which allows for moderate viscosity build-up after mixing and quick curing post-application, reducing tackiness, and enabling fast 3D printing cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If highly reactive two-component compositions are used for rapid curing, then printing speed is improved, but viscosity increases significantly causing nozzle clogging and mixing difficulties
Solution Approach 1:
The composition is divided into two separate components (polyol component and polyisocyanate component) that are mixed immediately before application. This segmentation allows each component to be stored and handled separately with stable, low viscosity, while achieving rapid curing only after mixing at the point of use, thus avoiding nozzle clogging during storage and transport.
Solution Approach 2:
The reactive components are prepared and stored separately in advance with optimized formulations that ensure low viscosity and stable storage. The actual curing reaction is initiated only when the components are mixed immediately before application, allowing preliminary preparation without the constraints of rapid viscosity increase.
2Productivity
If heating is applied to accelerate curing reaction, then printing speed is improved, but viscosity control becomes difficult and nozzle clogging increases
Solution Approach 1:
The formulation parameters of both components are optimized to achieve rapid curing at ambient temperature without requiring external heating. The polyol component contains specifically selected polyols with appropriate molecular weights and functionalities, while the polyisocyanate component is formulated to react rapidly with these polyols, enabling fast curing while maintaining manageable viscosity through compositional design rather than thermal acceleration.
3Ease of manufacture
If thermoplastic materials are used for 3D printing, then ease of processing is improved, but chemical resistance, heat resistance and mechanical properties are limited
Solution Approach 1:
The material undergoes a phase transition from a liquid state during printing to a solid crosslinked network after curing. The two-component polyurethane composition is applied in a liquid, low-viscosity state that allows easy processing and shaping, then rapidly cures through chemical reaction to form a solid material with superior chemical resistance, heat resistance, and mechanical properties, combining the advantages of both thermoplastic processing and thermoset performance.
4Manufacturing precision
If residence time in mixer is increased to achieve homogeneous mixing, then mixing quality is improved, but viscosity increases due to progressive curing reducing application time
Solution Approach 1:
The mixing process is segmented into a static mixing section followed by a dynamic mixing section. The static mixer provides initial homogenization with minimal residence time, while the dynamic mixer (attached to the printhead) completes the mixing process at the point of application. This segmentation allows sufficient mixing time for homogeneity without exposing the reactive components to prolonged contact that would cause excessive viscosity increase.
Solution Approach 2:
A static mixer acts as an intermediary element between the component storage and the application point. This static mixer provides a controlled environment for initial mixing with defined residence time, preventing excessive curing while achieving homogeneous mixing before the material reaches the dynamic mixer and printhead for final application.
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 composition enables efficient, fast 3D printing of large-scale models with reduced tackiness and adjustable mechanical properties, reducing waste and processing time, suitable for industries like automobile, marine, and aeronautics.
Implementation Method 1
The chemical basis of such printing materials are e.g. RTV-2 silicones, two-component epoxy materials or two-component polyurethanes. Two-component materials are advantageous, if not essential, in such processes, as the highly reactive constituents such as hardener and binder are initially present separately and begin to cure only during or after the mixing of the two components.
Implementation Method 2
such two-component compositions already begin to react upon mixing, resulting in a rapid increase in viscosity. This is a problem for 3D printing, since a homogeneous mixture must be obtained and therefore a certain residence time in a static or dynamic mixer is needed.
Data Source
AI summary
A two-component polyurethane compositions including (i) a polyol component A comprising a tri- or higher functional polyol P1 having an OH equivalent weight of from 60 g/mol to 250 g/mol and a di- or tri-functional polyether or polyester polyol P2 which is different from the polyol P1; and (ii) an isocyanate component B comprising at least one polyisocyanate I. Polyurethane compositions have surprisingly been found to be suitable for 3D printing processing, where they provide printed 3D objects with reduced tackiness even shortly after the printing. In addition, the invention provides processes for the production of three dimension objects form such compositions as well as three dimensional objects prepared accordingly and the use of corresponding compositions in 3D printing processes.