Polythiourethanes for 3D Printing


 Number/Link: WO2017/0267804

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)

Rigid Thermoplastic Polyurethanes


 Number/Link: WO2017/146948  WO2017/146949

Applicant/Assignee: Eastman Chemical

Publication date: 31 august 2017

Gist”: A “rigid”, high Tg polyester diol is extended with 4,4′ MDI

Why it is interesting: Rigid, high modulus TPUs have been known for a long time – see e.g. Upjohn’s classic patent on ‘Isoplast’ from 1981. These materials are high hardblock TPUs made from diisocyanates, chain extenders with only a small amount of high molecular weight diol as an impact modifier. According to the current invention however, rigid TPUs can be made using less than 40% (w/w) of diisocyanate, a high Tg polyester diol and optionally some chain extender.  The polyester is prepared from ‘rigid’ diols like isosorbide or 1,4-cyclohexanedimethanol together with a ‘rigid’ diacid like terephthalic acid, such that the diol has a MW of more than 400 Dalton and a Tg of more than 40°C. The diisocyanate is pref. 4,4-MDI. The rigid TPUs have a Tg of more than 145°C and a tensile modulus of 1 GPa or higher. They are said to be less moisture sensitive than conventional rigid TPUs.


Viscoelastic Polyurethane Elastomers


Number/Link: US2017/0233519

Applicant/Assignee: Dow

Publication Date: 17 august 2017

“Gist”: Viscoelastic foams are prepared from MDI, castor oil and a hydrophilic polyether polyol.

Why it is interesting: According to this invention energy absorbing foams with relatively low density and a low hardness and resilience in the temperature range from about -10 to +40°C, can be produced by reacting a blend of hydrophilic and hydrophobic polyols containing castor oil, about 0.5 pbw water and some catalyst and chain extender with MDI.  The examples show foams of about 500 kg/m³ with hardness below shore 50A and ball rebound below 15% at both -10 and +23°C. The foams are said to be useful for impact-protective garments.

Castor oil

Castor oil component

Non-Isocyanate Polyurethane Flexible Foams



Applicant/Assignee: Faurecia

Publication Date: 3 august 2017

“Gist”: Flex foams from a blend of two polyfunctional cyclocarbonates, a polyamine and HFC blowing agent.

Why it is interesting: While non-isocyanate polyurethanes are well known by now, examples of NIPU foams, especially flexible foams are rare. According to this case NIPU foams ‘having good resilience and low density’ can be prepared by reacting two polyfunctional carbonates A and B with a polyamine in the presence of a blowing agent and a catalyst. Cyclocarbonate A is (pref) trimethylolpropaneglycidylether carbonate and B is a polyetherpolyol with the OH groups replaced by glycidylcarbonate groups, for example an alkoxyalated trimethylolpropaneglycidylether carbonate. The polyamine is e.g. 1,6 diaminohexane.  The ratio A:B is preferably about 60:40.  In the examples no value for the resilience is given (but my guess based on the Tg is that it is probably not very high) and the lowest moulded density achieved is 140 kg/m³. So still a long way to go..

Glycidylether carbonate of alkoxylkated trimethylolpropane

PCM Containing PU Gels

Title: Temperature Regulating Polyurethane Gels

Number/Link: US2017/0210961

Applicant/Assignee: Technogel

Publication Date: 27 july 2017

“Gist”: Fatty acid ester PCMs are incorporated into Technogel-type gels without encapsulation

Why it is interesting: Polyurethane gels have been discussed before in this blog. The current invention is about “Technogel-type”  gels, made at low NCO-index and high functionality, that contain phase change materials (PCMs). The PCMs are esters of fatty acids that can be blended in molten state with the low EO polyol to form a clear solution, which is then reacted with isocyanate to form the gel. Despite not being encapsulated or forming a separate phase, the PCMs can reversibly melt and crsytallize while in the fluid phase of the gel. In the examples blends of lauryl laurate (C12-C12) and myristyl myristate (C14-C14) are used as PCM such that the phase change temperature is about 22-38°C.  The gels are said to be useful for ‘close to body’ comfort applications especially for use in matresses to improve sleeping comfort.

Lauryl laurate