Reactive TPU for AM

Patent Title: REACTIVE THERMOPLASTIC POLYURETHANE BASED ON BLOCKED ISOCYANATES

 Number/Link: WO2018/149977

Applicant/Assignee:  BASF

Publication date: 23 August 2018

Gist”: Low molecular weight TPU with blocked isocyanate groups is useful for 3D printing

Why it is interesting: The invention is related to relatively low MW ( up to 40,000Da) thermoplastic polyurethanes with thermolabile end groups and a melting point of about 100ºC (pref).  The TPU has a low melt viscosity and after de-blocking (at pref. about 150ºC) the isocyanate groups can react with chain extender present, resulting in increased MW and related properties. The TPU can be prepared by partially blocking diisocyanates (with e.g. caprolactam) and then reacting in one shot or prepolymer system with polyols and chain extenders. In powder form the TPUs are said to be useful in additive manufacturing (AM) processes.

caprolactam

Caprolactam

Thermoplastic Polythiourethanes for 3D Printing

Patent Title: THIOURETHANE POLYMERS, METHOD OF SYNTHESIS THEREOF AND USE IN FUSED FILAMENT FABRICATION PRINTING

 Number/Link:  WO2018/035102

Applicant/Assignee:  University of Texas

Publication date: 22 February 2018

Gist”: Polythiourethanes from diisocyanates and dithiols are used in FFF printing

Why it is interesting: Fused Filament Fabrication (FFF), which is actually the same thing as  Fused Deposition Modeling (FDM) is a popular and cheap additive manufacturing technology in which a thermoplastic filament is molten and ‘printed’ in layers. Many off-the-shelf thermoplastics can be used in FFF but these often do not have the correct melt characteristics resulting in printed objects of poor quality. According to this invention FFF-optimized thermoplastics can be prepared by reacting dithiols with diisocyanates into polythiourethanes.  The reaction is carried out in an aprotic solvent and catalysed by a non-nucleophilic base. In an example 2,2′-(ethylenedioxy)diethanethiol is reacted with HDI in DMF and catalysed by triethylamine. FFF printed parts of this polymer are said to show high toughness and less water uptake compared to TPU and polyamides.

polythiourethane

Polythiourethane according to the invention

 

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