3D Printing of High‐Performance Isocyanate Ester Thermosets

Abstract

High-performance materials for 3D printing are increasingly desired to meet more and more requirements from various fields including aerospace and high-tech equipment. In this study, 3D printing of isocyanate ester thermosets with high performances, such as excellent mechanical properties and thermal resistance, is realized with a facile method. A precursor of acrylate isocyanate ester with good photocuring capability is first synthesized with the reaction of tolylene-2,4-diisocyanate and hydroxypropyl acrylate. Then, mixed with diluent NeoRad U-6282 and photoinitiator Irgacure 819, it forms ultraviolet curable resins for 3D printing. The digital light processing 3D printing of the resins results in high-precision 3D structures, which finally turn out highperformance thermoset materials after the cross-linking of isocyanate groups at elevated temperature. 3D printing of isocyanate ester thermosets with high printing accuracy, excellent mechanical properties, and good heat resistance will expand the applications of 3D printing by meeting the high demands from many industries on both mechanical and thermal performance.

Reconfigurable Polymer Networks for Digital Light Processing 3D Printing

“…Therefore, the intermedia state during the post-treatment is thermally stable even placed at 140 °C in the absence of amine, and it can be reactivated and transformed into another state with the readdition of amine (Figure S3). In contrast, the intermediate state is nonexistent or unstable in the previously reported two-stage curing system. − …”

“…So far, there have been some attempts to remanipulate the properties of the printed objects by changing the polymer network structures. − One method is to employ a photothermal dual-curing resin to achieve an interpenetration network through two orthogonal polymerization mechanisms. − For example, an acrylate–cyanate resin was developed to get a 3D product with excellent thermostability . During 3D printing, the acrylate was photoinitiated and cured into a green part, which was swollen with the unreacted liquid cyanate.…”

“…Subsequently, the cyanate moiety polymerized into a second network, which provided both high mechanical strength and a high glass transition temperature. Another strategy is designing a photocurable single homogeneous network with reactive groups, − such as hydroxyl groups, on the side chains or the main chains. A transesterification reaction between the hydroxyl and ester functional groups upon heating imparts an extra cross-linking into the printed objects .…”

Investigating inexpensive polymeric 3D printed materials under extreme thermal conditions

“…This can be done, e.g. by a two-stage curing process for a resin composed of a photocurable and a thermally curable component [20,21], or by developing new resins [22,23] for 3D printed thermosets with high glass transition temperature.…”

3D Printable All-Polymer Epoxy Composites

“…Additive manufacturing technologies for thermoplastics are quite robust; the 3D printing of thermosets, however, especially those with higher service temperatures, is still under development. ,, The printing methods of thermosets can be classified primarily by three curing types: photocuring, thermal curing, and hybrid. Several photocurable thermosets, including epoxy resins, are compatible with stereolithography and digit light processing. − Though these two approaches can generate printed parts with high resolution, the selection of photocurable materials is limited, and the heat resistance and thermal stability of photocured resins are also usually inferior to the resins cured at high temperatures. , …”