Partially Reversible Thermosets for Additive Manufacturing Recycling
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Solution Overview
Problem
Conventional additive manufacturing techniques are slow and produce parts with limited mechanical properties, making them unsuitable for real-world applications beyond prototyping, and there is a need for sustainable chemistry approaches to enhance the recyclability of additively manufactured products.
Innovation Solution
A method involving the recycling of additively manufactured articles or recovered coating materials using a resin comprising a reactive blocked prepolymer, crosslinker, photoinitiator, and optional additives, where the preformed material is comminuted and combined with a reactive blocking agent to regenerate a reactive prepolymer, which can be extracted and reused, enabling the creation of recyclable light-polymerizable resins for additive manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional additive manufacturing techniques are used, then parts can be produced, but the production speed is slow and mechanical properties are limited
Solution Approach 1:
The patent changes the chemical parameters of the resin system by using thermosetting prepolymers with specific functional groups (epoxy, carboxyl, hydroxyl) that enable both rapid curing and superior mechanical properties. The resin composition parameters are optimized to achieve fast production speed while maintaining high strength parts
Solution Approach 2:
The patent employs composite resin formulations combining thermosetting prepolymers with specific crosslinking agents and fillers. This composite approach enables the resin to exhibit both rapid curing characteristics for high productivity and enhanced mechanical properties for structural applications
2Strength
If thermoset resins are used to improve mechanical properties, then parts gain strength, but the materials become difficult to recycle
Solution Approach 1:
The patent implements a recovery system where used thermoset parts are ground into particles, and the thermosetting prepolymer is extracted and purified. This recovered prepolymer can be reused to formulate new resin compositions, creating a circular economy that maintains both high mechanical properties and recyclability
Solution Approach 2:
The patent extracts the thermosetting prepolymer from cured parts through solvent extraction processes. This separation allows the valuable prepolymer component to be recovered and reused, while the crosslinked network structure that provides mechanical strength remains in the spent particles
3Productivity
If resin is used to produce parts, then additive manufacturing can proceed, but unreacted resin and coating materials are wasted
Solution Approach 1:
The patent enables the system to serve itself by recovering and reusing resin materials. The unreacted resin and coating materials are collected, processed to recover the thermosetting prepolymer, and fed back into the manufacturing process, eliminating waste and reducing the need for fresh resin
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 allows for the regeneration of reactive prepolymers from recycled materials, enhancing the recyclability and sustainability of additive manufacturing processes while improving the mechanical properties of produced parts, enabling their use in real-world applications.
Implementation Method 1
light polymerizing a single-cure resin in an additive manufacturing (or coating) process
Implementation Method 2
said preformed article comprised of at least 70, 80 or 90 percent by weight of a crosslinked polymer, said crosslinked polymer consisting essentially of said reactive blocked prepolymer, said crosslinker, and said reactive diluent when included, in light polymerized, cross-linked, thermoset form
Implementation Method 3
heating said mixture (e.g., to a temperature of from 40, 60 or 70° Celsius to 90, 100, or 120° Celsius, or more) for a time sufficient to form a regenerated reactive prepolymer
Implementation Method 4
the method further includes (d) extracting said regenerated reactive prepolymer from said mixture into a solvent
Data Source
AI summary
Provided herein is a method of recycling reactive prepolymers from additively manufactured articles or recovered coating material that comprises a crosslinked polymer formed from a single-cure resin comprising a reactive blocked prepolymer and a crosslinker, by forming and recovering a regenerated reactive prepolymer. Light-polymerizable resins, methods of making recyclable objects from such resins, and methods for sustainable manufacturing are also provided.