Which Aromatic Diamine could be recommended to replace (MDA) 4,4' Methylenedianiline suspected as acute hazardous substance ?
Throughout many years 4,4'-Methylenedianiline (MDA) was widely used in production of a great variety of Materials : Polyurethanes, Polyimides, as a Hardener for Epoxy Resins... and other Advances Polymer Materials.
But about 15 years ago the US Occupational Safety and Health Administration (OSHA) - pronounced that MDA presents a significant risk to humans as a carcinogen.
Since then there were many attempts to find an adequate replacement to MDA. And there were found some combinations of Diamines - providing almost the same level of properties, HOWEVER - at much higher price.
So, the question is: What is the present state of the Problem ?
The question about "present state" is too comprehensive. List of suitable diamines for polyimides production is presented in US8808804 (to Boing) . As a rule, introduction of electron-withdriwing substituents in aniline lead to suppressing of carcinogen properties. So, replacement of -CH2- bridge by C=O, -S-, -SO-, -SO2-, -C(CF3)2-, -PO(OPh)- is suitable. Price for such polyimides will be unavoidable higher in comparison to -CH2- derivatives because the last originate from very cheap H2CO and aniline precursors.
3,4'-ODA (3,4'-diaminodiphenylether, CAS#2657-87-6, Hazard Codes:
Xi:Irritant) is perspective substituent for MDA. TEIJIN is only bulk seller of high quality 3,4'-ODA and try now to improve synthesis route for 3,4'-ODA in term of purity of target product.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20020024447.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750020356.pdf
https://polycomp.mse.iastate.edu/files/2012/01/7-Polyimide-Resins.pdf
http://www.teijin.com/products/chemicals/dape.html
Dear Dr. Rogoza:
Please accept my sincere gratitude for your comprehensive List of Diamines to be used in place of MDA and all the other information concerning the subject as well.
All the best to you, Leonid
Hi,
Networks cured with Diamino Diphenyl Sulfone are display comparable (not rigorously identical) properies than networks cured with MDA.
see:
Molecular analysis of the viscoelastic properties of epoxy networks as deduced from the study of model systems. Journal of Non-Crystalline Solids, Volumes 131–133, Part 2, 2 June 1991, Pages 898-905
Effect of structure on glass transition temperature of amine crosslinked epoxiesJournal of Polymer Science Part B: Polymer Physics
Volume 25, Issue 6, June 1987, Pages: 1219–1234, V. Bellenger, J. Verdu and E. Morel
regards
Hi, Emmanuel,
thank you very much for these references about epoxy-networks.
Best Regards, Leonid
Commercially available alternatives for MDA, especially in PU chemistry, are Addolink 1604, Ethacure 100 and Ethacure 300. The structures you can find in the internet. Nearly all kinds of subtitution at the aromatic ring lowers the carcinogenic risk. Ester groups like in Addolink are especially effective.
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