# US 5,705,221 A · Method of depositing insoluble metal salt deposits on electrostatographic carrier surfaces

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- Number: US 5,705,221 A
- Document ID: US5705221A
- Status: Granted
- Kind: A
- Application number: 08/629,818
- Filed: 1996-04-10
- Granted: 1998-01-06
- Earliest claimed: 1996-04-10
- Assignees: Eastman Kodak Company
- Inventors: William Edward Yoerger
- Web page: https://patentgrep.com/patent/US5705221A

## CPC

- G03G 9/1134: {containing fluorine atoms}
- G03G 9/1133: {obtained by reactions only involving carbon-to-carbon unsaturated bonds}
- G03G 9/1139: {Inorganic components of coatings}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

A method of modifying the triboelectric charging propensity electrostatographic developer carrier particles, comprising the steps of: (A) providing a carrier particles that is uncoated or polymer coated; (B) mixing the carrier particles with either (i) an aqueous basic solution or (ii) an aqueous solution containing from 0.1 to 5.0 weight percent of a soluble acidic metal salt, based on the weight of the carrier particles to form a mixture; and (C) contacting the mixture with the solution, (i) or (ii), not used in step (B) thereby causing a precipitate of an insoluble salt to deposit on the carrier particles wherein the insoluble salt is (a) strontium carbonate; (b) insoluble metal hydroxides; (c) insoluble metal hydrated oxides; or (d) a mixture of two or more of (a), (b) and (c); provided that when a soluble strontium metal acid salt is used in step (B) (ii) and the carrier coating is other than a polyfluorocarbon, a reagent that provides a source of carbonate ions is also used in step (B).

## Claims

### Claim 1

A method of modifying the triboelectric charging propensity electrostatographic developer carrier particles, comprising the steps of:
(A) providing carrier particles that are polymer coated;
(B) mixing the carrier particles with either (i) an aqueous basic solution or (ii) an aqueous solution containing from 0.1 to 5.0 weight percent of a soluble acidic metal salt, based on the weight of the carrier particles to form a mixture; and
(C) contacting the mixture with the solution, (i) or (ii), not used in step (B) thereby causing a precipitate of an insoluble salt to deposit on the carrier particles wherein the insoluble salt is
(a) strontium carbonate;
(b) insoluble metal hydroxides;
(c) insoluble metal hydrated oxides; or
(d) a mixture of two or more of (a), (b) and (c);
provided that when a soluble strontium metal acid salt is used in step (B) (ii) and the carrier coating is other than a polyfluorocarbon, a reagent that provides a source of carbonate ions is also used in step (B).

### Claim 2 (depends on 1)

The method of claim 1 wherein the polymeric coating is selected from the group consisting of silicone resins, poly(vinylidene fluoride), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(methylmethacrylate) and poly(styrene-co-methylmethacrylate).

### Claim 3 (depends on 1, 2)

The method of any one of claims 1-2 wherein the acidic metal salt comprises a metal selected from the group consisting of Sr.sup.+2, Ba.sup.+2, Fe.sup.+3, La.sup.+3, Ni.sup.+2, Cu.sup.+2, Co.sup.+2, Mg.sup.+2, Ca.sup.+2, Mn.sup.+2, Sn.sup.+2, Al.sup.+3, Cr.sup.+3, and Zn.sup.+2.

### Claim 4 (depends on 3)

The method of claim 3 wherein the acidic metal salt is a mixture of metals selected from the group consisting of Sr.sup.+2, Fe.sup.+3, La.sup.+3, Ni.sup.+2, Cu.sup.+2, Co.sup.+2, Mg.sup.+2 and Al.sup.+3.

### Claim 5 (depends on 1)

The method of claim 1 wherein the base is KOH.