Granted Patent
Utility
US 4,987,271 · App. 07/480,126
Method for purifying a polyoxyalkylene alcohol
Inventors:
Takashi Watabe, Hiromitsu Takeyasu, Takao Doi, Nobuaki Kunii
Patented Case
View Patent ↗
Granted: Jan 22, 1991
Filed: Feb 14, 1990
Inventors
Takashi Watabe
Hiromitsu Takeyasu
Takao Doi
Nobuaki Kunii
Assignee (at issue)
ASAHI GLASS CO., LTD.
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.