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. 26, 1995
Filed:
Feb. 17, 1995
Jean F Grollier, Paris, FR;
Marie F Bosq, Clichy, FR;
Jean Cotteret, Verneuil-sur-Seine, FR;
Arnaud De Labbey, Aulnay-sous-Bois, FR;
L'Oreal, Paris, FR;
Abstract
Process for preserving the dyeing capacity of 5,6-dihydroxyindole or of its derivatives corresponding to the formula (I): ##STR1## in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which are identical or different, denote hydrogen or a C.sub.1 -C.sub.4 lower alkyl, R.sub.1, R.sub.2 and R.sub.3 denoting hydrogen when R.sub.4 denotes alkyl in an aqueous medium, characterized in that the pH of the aqueous medium is adjusted to a value pH.sub.C of between 5 and 10 by employing a pH-regulating agent containing two components (A) and (B), the component (A) being chosen from pH-regulating agents which have a dissociation constant K.sub.CA in aqueous solution at 25.degree. C., such as pk.sub.CA, that is: