Polythiourethanes for 3D Printing

Patent Title:  THIOURETHANE POLYMERS, METHOD OF SYNTHESIS THEREOF AND USE IN ADDITIVE MANUFACTURING TECHNOLOGIES

 Number/Link: WO2017/160810

Applicant/Assignee:  Univ. Texas

Publication date: 21-September-2017

Gist”: Photolatent bases are used to catalyse the polythiol-polyisocyanate reaction

Why it is interesting: According to this invention reactive systems useful for additive manufacturing processes can be prepared from polythiols, diisocyanates and a photolatent base.  When irradiated the photolatent base will split off a non-nucleophilic base which will catalyse the thiol-isocyanate reaction. The systems can be prepared such that the resulting materials show improved mechanical properties over current 3D printed materials.  In an example 2,2′-(ethylenedioxy)diethanethiol and pentaerithritol tetrakis(3-mercaptopropionate) are reacted with HDI using 1,1-dimethyl-1-(2-hydroxypropyl)amine-p-nitrobenzimide (DANBA) as a photolatent base.

Example of pholatent base (DANBA)

Thiol-Crosslinked Poly(hydroxyurethanes)

Title: METHOD FOR PRODUCING OR CURING POLYMERS USING THIOL-ENE POLYADDITION REACTIONS

Number/Link: W2017/081120

Applicant/Assignee:  Henkel

Publication Date: 18-05-2017

“Gist”: Unsaturated PHU are crosslinked using polythiols

Why it is interesting: The invention is about poly(hydroxyurethanes) (PHU) containing alkylene groups that are crosslinked using thiol-ene ‘click’ polyaddition reactions. The unsaturated PHU are first prepared by aminolysis of cyclocarbonates using unsaturated amines. In an example di-trimethylolpropane is converted to di-trimethylolpropanedicarbonate using ethylchloroformiate.  The di-TMPDC is then reacted with 3-aminopropylvinylether to prepare the PHU, which is then crosslinked using pentaerithritol-tetra(3-mecaptopropionate) in the presence of a photoinitiator and UV light.  The invention is said to be useful for isocyanate-free adhesive- and coating systems.

Di-trimethylolpropanedicarbonate

PU-Acrylate/Epoxy IPN for 3D Printing

Patent Title: PHOTOCURABLE COMPOSITIONS FOR THREE-DIMENSIONAL PRINTING

 Number/Link:  WO 2016/153711

Applicant/Assignee: Dow

Publication date: 29-09-2016

Gist”: Acrylate-capped PU prepolymer is copolymerized with epoxides using UV radiation

Why it is interesting: This case is about UV-curable compositions to make flexible materials using additive manufacturing, especially stereolithography.  A prepolymer of an isocyanate and a ‘flexible’ polyol is capped with a hydroxy-functional acrylate, then mixed with a multifunctional epoxy, a multifunctional acrylate ‘monomer’ (a crosslinker also acting as reactive diluent) and two photoinitiators:  one radical and one cationic.  In the example a 6 to 8000 Mole weight diol is capped with TDI and then with hydroxyethyl acrylate.  The prepolymer is then mixed with 3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 1,6-hexanedioldiacrylate and two photoinitiators.  After UV curing the materials had a shore A hardness between about 60 and 80 and an elongation at break between about 70 and 200.

3,4-Epoxycyclohexylmethyl-3,4- epoxycyclohexane carboxylate

3,4-Epoxycyclohexylmethyl-3,4-
epoxycyclohexane carboxylate

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