PU-Acrylate/Epoxy IPN for 3D 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

epoxycyclohexane carboxylate


Vinyl-Functional UV-Curable Polyurethanes


 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.



Urethane-Acrylate Hybrids From Thiol-Ene Chemistry


 Number/Link: US2015/0232422

Applicant/Assignee: Dymax Oligomers and Coatings

Publication date: 20-08-2015

Gist”: A dihydroxythiol is reacted with an acrylate and then with diisocyanate and hydroxyacrylate

Why it is interesting: This invention relates to radically polymerizable urethane oligomers which are useful as adhesives or coatings. The oligomers are prepared in two stages:  first a dihydroxy thiol is reacted with an acrylate resulting in a diol which is then reacted with an excess diisocyanate and then with hydroxyacrylates.  For example: thioglycerol is reacted with phenyltioethylacrylate.  The resulting diol is then further reacted with TDI and subsequently with polycaprolactonacrylate and hydroxyethylacrylate resulting in the structure below. The urethane oligomers can be used for coatings or adhesives which are said to have improved properties over the existing art, like improved thermal resistance.

A urethane-acrylate oligomer according to the invention

A urethane-acrylate oligomer according to the invention

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