All posts tagged open time

Prepregs from Glass Fiber and Reactive Polyurethane Powder

Title: PREPREGS AND MOLDINGS PRODUCED THEREFROM

 Number/Link: US2014065911

Applicant/Assignee: Evonik

Publication date: 6-03-2014

“Gist”: A reactive polyurethane powder is prepared from a mixture of a  solid polyester polyol and a solid dimerised IPDI and subsequently used to make glass fiber prepregs.

Why it is interesting:  A polyurethane powder is made from (pref.) a mixture of  a solid (at room temperature) polyster polyol and a solid, blocked isocyanate.  The isocyanate is preferably an “internally” blocked IPDI.  Internally blocked meaning that the isocyanate contains uretidinedione groups.  The powder is scattered over a fibrous support and heated to over melting temperature but below curing temperature to make the prepreg.  Prepregs made with PU powder instead of the conventional resins have the advantage of being non-sticky, non-toxic and of having a very high storage stability (45 days in the examples).

Prepreg production with reactive PU powder

Prepreg production with reactive PU powder

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by Gerhard Bleys on March 11, 2014  •  Permalink
Posted in composites, Isocyanates and Prepolymers
Tagged , , , , , , , ,

Posted by Gerhard Bleys on March 11, 2014

https://purpatents.com/2014/03/11/prepregs-from-glass-fiber-and-reactive-polyurethane-powder/

Polyurethane/Polyurea Elastomers from 2,4′-MDI and MDA

Title: MOLDED POLYURETHANE ELASTOMER PARTS MADE OF DIPHENYLMETHANE DIISOCYANATE-BASED NCO PREPOLYMERS AND METAL SALT COMPLEXES, AND A METHOD FOR PRODUCING SAME

 Number/Link: US2013267655

Applicant/Assignee: Bayer

Publication date: 10-10-2013 (priority PCT/DE)

“Gist”: Molded PU/PUA elastomers are prepared from a 2,4′-MDI based prepolymer cured with blocked MDA

Why it is interesting: A prepolymer with an NCO content between 3 to 7% is prepared from MDI containing more than 97% of the  2,4′ isomer together with a diol with an OH value of about 100.  (e.g a PTMEG or a polycaprolacton).  The prepolymer is then cured with a salt-complexed diphenylmethanediamine (“blocked MDA”). Because of it’s relatively low viscosity and long potlife the system allows for the production of thick-walled, bubble-free molded elastomers.  Probably because there is less premature polyurea phase separation (due the 2,4′-MDI) the system cures homogeneously.

4,4'-MDA

4,4′-MDA

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by Gerhard Bleys on October 15, 2013  •  Permalink
Posted in Adhesives-Coatings, Elastomers, Isocyanates and Prepolymers
Tagged , , , , ,

Posted by Gerhard Bleys on October 15, 2013

https://purpatents.com/2013/10/15/polyurethanepolyurea-elastomers-from-24-mdi-and-mda/

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