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

 

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)