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:
May. 26, 1981
Filed:
Oct. 29, 1979
Derek H Barton, Gif-sur Yvette, FR;
Irena Y Bronstein-Bonte, Newton, MA (US);
Lloyd D Taylor, Lexington, MA (US);
Polaroid Corporation, Cambridge, MA (US);
Abstract
Polymeric optical filter agents and photographic products and processes using same are disclosed. The polymeric optical filter agents are pH-sensitive optical filter agents comprising polymeric backbone units having the following hydrazone moiety: ##STR1## where R is a group which can provide a double bond for conjugation with the ##STR2## portion of the moiety to provide light-absorbing capability for the agent at a pH above its pKa, and X represents a substituent of R providing at least one electron-withdrawing group. The polymeric pH-sensitive optical filter agents have a highly colored light-absorbing form at a pH above the pKa and are substantially non-absorbing at a pH below the pKa. The polymeric optical filter agents are useful in photographic film units and processes for the protection of photoexposed photosensitive elements against the occurence of fogging during in-light development.