Epoxy-Cured Polyurethane Resin for Humidity-Resistant 3D Printing
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Solution Overview
Problem
Existing stereolithography techniques using (meth)acrylate blocked polyurethanes and polyureas face issues with thermal performance due to reactive blocking agents like tert-butylaminoethyl methacrylate (TBAEMA), which can lead to unwanted side reactions and humidity sensitivity, limiting their effectiveness in additive manufacturing.
Innovation Solution
The use of reactive blocked polyisocyanates and polyfunctional epoxy compounds, catalyzed by secondary or tertiary amines, to form oxazolidinones, allowing for a dual cure process that enhances thermal performance and reduces sensitivity to humidity, with optional additives like photoinitiators, polyols, and fillers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If (meth)acrylate blocked polyurethanes and polyureas are used in stereolithography, then additive manufacturing can be performed, but thermal performance deteriorates due to unwanted side reactions from reactive blocking agents like TBAEMA
Solution Approach 1:
The patent removes the problematic reactive blocking agent (TBAEMA) from the system and replaces it with a non-reactive blocking agent that does not cause unwanted side reactions. This extraction of the harmful component while retaining the essential blocking function resolves the thermal performance issue while maintaining additive manufacturing capability.
Solution Approach 2:
The patent changes the chemical parameters of the blocking agent from reactive (TBAEMA) to non-reactive, thereby altering the thermal stability characteristics of the system. This parameter change eliminates the side reactions that degrade thermal performance while preserving the photopolymerization functionality needed for stereolithography.
2Ease of manufacture
If (meth)acrylate blocked polyurethanes and polyureas are used in stereolithography, then additive manufacturing can be performed, but reliability deteriorates due to humidity sensitivity
Solution Approach 1:
The patent extracts the humidity-sensitive reactive blocking agent (TBAEMA) from the system and replaces it with a humidity-resistant non-reactive blocking agent. This removal of the vulnerable component eliminates the humidity sensitivity that compromises reliability while maintaining the essential photopolymerization function.
Solution Approach 2:
The patent changes the chemical parameters of the blocking agent to eliminate humidity sensitivity. By selecting a non-reactive blocking agent with appropriate hydrophobicity or steric hindrance, the system achieves resistance to humidity while preserving additive manufacturing capability.
3Strength
If isocyanate concentration is increased to achieve more rigid reactive blocked polyurethanes, then rigidity improves, but concentration of reactive blocking agent increases leading to more side reactions
Solution Approach 1:
The patent removes the source of side reactions by replacing the reactive blocking agent with a non-reactive one. This allows increasing isocyanate concentration to achieve desired rigidity without proportionally increasing side reactions, as the blocking agent no longer participates in unwanted chemical reactions.
Solution Approach 2:
The patent changes the reactivity parameter of the blocking agent from high (reactive) to low (non-reactive), thereby decoupling the relationship between isocyanate concentration and side reaction concentration. This enables independent optimization of rigidity through isocyanate concentration without the penalty of increased side reactions.
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 dual cure process improves the thermal stability and humidity resistance of three-dimensional objects, enabling more robust and reliable additive manufacturing processes.
Implementation Method 1
irradiating a resin composition of the invention with actinic radiation or light, thereby forming a three-dimensional intermediate
Implementation Method 2
The use of reactive blocked polyisocyanates and polyfunctional epoxy compounds, catalyzed by secondary or tertiary amines, to form oxazolidinones
Data Source
AI summary
Provided are methods of forming a three-dimensional object that include irradiating a resin composition of the invention with actinic radiation or light, thereby forming a three-dimensional intermediate, and then further reacting the three-dimensional intermediate to form the three-dimensional object. In some embodiments, resin compositions of the invention include a polyisocyanate such as, e.g., a reactive blocked polyisocyanate; a polyfunctional epoxy compound; a photoinitiator; optionally, a catalyst; optionally, a polyol and/or a polyamine chain extender; optionally, a reactive diluent; optionally, a pigment or dye; and optionally, a filler. Related resin compositions are also provided herein. Further, provided are three-dimensional objects formed by a method of the invention, including, e.g., objects formed of a polymer having at least one oxazolidinone linkage.