The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 12, 1978
Filed:
Jan. 06, 1977
Vasanth R Kamath, Tonawanda, NY (US);
Gary A Harpell, Kenmore, NY (US);
Pennwalt Corporation, Philadelphia, PA (US);
Abstract
A process for the free-radical polymerization of vinyl aromatic monomers in at least two thermally distinct polymerization stages each between the temperatures of about 70.degree. C and 150.degree. C in the presence of at least two free-radical initiators, one of which initiators is particularly effective at the lowest temperature stage and has the formula ##STR1## wherein R is an alkylene, alkynylene or alkenylene diradical, R.sub.1 is alkyl, alkenyl, alkyn or alkoxy and Rhd 2 is lower alkyl and R.sub.3 is hydrogen or a lower alkyl and a second of which initiators has a 10 hour half-life temperature of at least about 80.degree. C which temperature is at least about 15.degree. C above the 10 hour half-life temperature of the compound of the above formula.