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:
Jul. 15, 1980
Filed:
Oct. 19, 1978
Applicant:
Inventors:
Assignee:
Hoechst Aktiengesellschaft, Frankfurt, DE;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C09B / ;
U.S. Cl.
CPC ...
546 49 ; 1062 / ;
Abstract
Unsubstituted linear trans-quinacridone of the gamma-crystal modification is obtained by cyclization of 2,5-dianilino-terephthalic acid with the 2.5 to 4-fold quantity of polyphosphoric acid or of an acidic polyphosphoric acid methyl ester, followed by hydrolysis of the condensation product in water, intensive grinding of the aqueous crude quinacridone in the presence of an alcohol or ketone and heating of the resulting product to 80.degree. to 200.degree. C.