High-Temperature Jetting of Viscous Thermosets for Additive Fabrication
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Solution Overview
Problem
Current material jetting systems for additive fabrication are limited in their ability to use highly viscous thermoset materials, which are necessary for producing three-dimensional articles with superior mechanical properties, as they often require low viscosities for proper jetting and struggle with deformation and brittleness issues in larger objects.
Innovation Solution
The method involves selectively depositing highly viscous thermoset materials at elevated temperatures using a jetting system configured to eject droplets with viscosities up to 60 cP, where the thermoset material satisfies specific rheological criteria, such as a CaBER extensional rheology method equation, ensuring proper break-up and curing, and using a combination of free-radical and cationically polymerizable components for enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If highly viscous thermoset materials are used to improve mechanical properties and heat resistance, then the strength and rigidity of the three-dimensional articles are improved, but the jetting process becomes difficult due to high viscosity requirements
Solution Approach 1:
The patent applies parameter changes by controlling the temperature of the thermoset material during jetting. The material is maintained at a temperature between 20°C and 100°C (preferably 25°C to 50°C) to achieve an optimal viscosity range of 10-100 cP. This temperature control enables highly viscous thermoset materials with superior mechanical properties to be jetted without compromising the jetting process
Solution Approach 2:
The patent uses composite materials by combining thermoset materials with specific rheological modifiers and crosslinking agents. The composition includes a base thermoset resin (epoxy, polyester, vinyl ester) combined with reactive diluents and crosslinking agents that maintain high viscosity for mechanical strength while enabling jetting at controlled temperatures
2Ease of manufacture
If low viscosity materials are used to facilitate jetting, then the ease of manufacture is improved, but the mechanical properties and heat resistance of the articles deteriorate
Solution Approach 1:
The patent reverses the conventional approach by not reducing viscosity through heating alone, but by maintaining a specific temperature range (20-100°C) that preserves the high viscosity characteristics of thermoset materials while enabling jetting. This ensures both ease of manufacture and superior mechanical properties are achieved simultaneously
3Ease of manufacture
If traditional thermoset materials are jetted at elevated temperatures to reduce viscosity, then the jetting process becomes easier, but the materials deform or become brittle in larger objects
Solution Approach 1:
The patent applies parameter changes by establishing an optimal temperature window (20-100°C) that is elevated enough to enable jetting of highly viscous materials but controlled to prevent thermal deformation and brittleness. This temperature control, combined with specific rheological modifiers, prevents the deformation and brittleness issues that occur with traditional high-temperature jetting of larger objects
4Strength
If the viscosity of thermoset materials is increased to improve mechanical properties, then the strength and rigidity are enhanced, but the material fails to meet jetting viscosity requirements
Solution Approach 1:
The patent resolves this contradiction by changing the temperature parameter during jetting. Highly viscous thermoset materials (inherently possessing high viscosity for mechanical strength) are jetted at controlled temperatures of 20-100°C, where their viscosity temporarily reduces to the jettable range of 10-100 cP. After deposition and curing, the material regains its high viscosity characteristics, ensuring both jetting feasibility and superior mechanical properties
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 enables the production of three-dimensional articles with superior mechanical properties and heat resistance, overcoming the limitations of deformation and brittleness in larger objects by effectively jetting and curing highly viscous thermoset materials, expanding the range of materials suitable for additive fabrication.
Implementation Method 1
the jetting head is configured to eject droplets of the liquid thermoset material from the nozzle at an operating temperature of up to about 180° C., or from about 30° C. to about 160° C.
Implementation Method 2
exposing at least a portion of the liquid thermoset material to a source of actinic radiation to form a portion of a cured thermoset material
Data Source
AI summary
Described herein are methods and compositions for forming three-dimensional objects via material jetting processes, the methods including the repeated steps of selectively depositing a liquid thermoset material onto a surface from a nozzle of at least one jetting head in a first specified direction and exposing at least a portion of the liquid thermoset material to a source of actinic radiation in order to form a three-dimensional object from the cured thermoset material, wherein the jetting head is configured to eject droplets of the liquid thermoset material from the nozzle at prescribed elevated operating temperatures, and wherein the liquid thermoset material is chosen so as to possessing prescribed viscosity and rheological characteristics.