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

Vinyl-Functional UV-Curable Polyurethanes

Patent Title: ALKENYL ETHER POLYOLS

 Number/Link: WO2016038112 (German)

Applicant/Assignee: Henkel

Publication date: 17-03-2016

Gist”: Alkenylether-functional polyols are used in oligomeric PU adhesives.

Why it is interesting: Alkenylether-functional groups are highly reactive and can be cured by UV-initiated cationic polymerization. This has the advantage of being unsensitive to oxigen which allows for so-called “dark cure”, i.e. the continuing polymerization after a first pulse of UV light. According to this invention, vinyl functional polyols are prepared by polymerizing a hydroxyl- or amine functional vinyl ether, e.g. 4-hydroxybutylvinylether (HBVE) or 3-aminopropylvinylether with epoxides or cyclocarbonates. The polyols can then be reacted with isocyanates resulting in UV curable polyurethanes.  In an example HBVE is reacted with 1,4-butanedioldiglycidylether to make the vinyl-functional polyol which is then further reacted with isophorondiisocyanate to make the PU adhesive.

1,4-butandioldiglycidylether

1,4-butandioldiglycidylether