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METHOD FOR THE DIRECT PREPARATION OFLAKED AZO PIGMENTS

IP.com Disclosure Number: IPCOM000024099D
Original Publication Date: 1979-Oct-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 166K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed is a direct method for preparing laked azo pigments which are useful in photoelectrophoretic systems. The process involves the preparation of an aqueous solution of a beta hydroxy naphthoic acid coupler in the form of a calcium salt, followed by coupling a diazotized amine into the solution and obtaining the calcium lake directly as a finely dispersed pigment. This process can be accomplished despite the low equilibrium solubility of the calcium salt of the beta hydroxy

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XEROX DISCLOSURE JOURNAL

METHOD FOR THE DIRECT PREPARATION Proposed Classification

OFLAKED AZO PIGMENTS U.S. Cl. 96/1 W~F~So1o~~ mt. CI. G03g

Disclosed is a direct method for preparing laked azo pigments which are useful in photoelectrophoretic systems. The process involves the preparation of an aqueous

solution of a beta hydroxy naphthoic acid coupler in the form of a calcium salt, followed by coupling a diazotized amine into the solution and obtaining the calcium lake directly as a finely dispersed pigment. This process can be accomplished despite the low equilibrium solubility of the calcium salt of the beta hydroxy

naphthoic acid (BON) in view of the unanticipated property of this salt to remain in a supersaturated solution for a sufficient period of time for the coupling~4aking reaction to occur. In one embodiment the reaction mechanism can be illustrated by the following equation: CH

3

BON Acid COO

+ N

+ HNO

       2~(R~N2 Cl) Calcium Acetate COOH NH

4OH N Ca

NH 2 ~y~~OH ,/

COO /

CH

wherein R is an aromatic radical.

Volume 4 Number 5 September/October 1979 559

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