Granted Patent
Utility
US 4,978,779 · App. 07/321,496
Preparation of methylene diphenylene diisocyanates and polymethylene polyphenylene poly (isocyanates) using an organic sulfonic acid promoter
Inventors:
Edward T. Shawl, Haven S. Kesling, Jr., Frank J. Liotta, Jr.
Patented Case
View Patent ↗
Granted: Dec 18, 1990
Filed: Mar 9, 1989
Inventors
Edward T. Shawl
Haven S. Kesling, Jr.
Frank J. Liotta, Jr.
Assignee (at issue)
Arco Chemical Technology, L.P.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.