Carrier and developer

Patent metadata

Field	Value
Publication number	US-9285699-B2
Application number	US-201414267825-A
Country	US
Kind code	B2
Filing date	May 1, 2014
Priority date	May 1, 2014
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

Disclosed is a carrier suitable for use with an electrophotographic developer and an electrophotographic developer containing the carrier. In particular, the carrier is powder coated and comprises a copolymer of cyclohexylmethacrylate and dimethylaminoethylmethacrylate.

First claim

What is claimed is:

1. A powder coated carrier for an electrophotographic developer comprising:
(a) a ferrite core; and
(b) a coating comprising:
(i) a copolymer of cyclohexylmethacrylate and dimethylaminoethylmethacrylate, wherein the copolymer contains from about 0.8 to about 1.0 wt % dimethylaminoethylmethacrylate;
(ii) a melamine-formaldehyde resin; and
(iii) carbon black present in an amount of from about 9.2 to about 9.7 wt % of the coating;

said coating being present in an amount of from about 0.85 to about 1.25 wt % of the carrier;
said coated carrier having a conductivity of from about 8.9 to about 9.5 [log(mho/cm)], wherein the carrier core has a surface roughness of from about 0.163 to about 0.167 m 2 /g as measured by the BET (Brunauer Emmett Teller) method.

2. A carrier according to claim 1 wherein the melamine-formaldehyde resin is present in an amount of from about 8 to about 12 wt % of the coating.

3. A carrier according to claim 1 wherein the carrier core has an average particle diameter when measured by laser diffraction of from about 30 to about 45 μm.

4. A carrier according to claim 1 wherein the carrier core has a conductivity of from about 7.25 to about 8.50 [Log(mho/cm)] at 500 v DC.

5. A carrier according to claim 1 wherein the carrier core comprises:
(a) a mixture of iron oxide, manganese oxide, lithium oxide;
(b) a mixture of iron oxide, manganese oxide, magnesium oxide, and strontium oxide;
(c) a mixture of iron oxide, manganese oxide, magnesium oxide, and calcium oxide; or
(d) a mixture thereof.

6. A developer composition comprising:
(a) an emulsion aggregation toner comprising:
(i) an amorphous polyester resin;
(II) a crystalline polyester resin;
(iii) a wax; and
(iv) a colorant; and

(b) a powder coated carrier comprising
(i) a ferrite core; and
(ii) a coating comprising:
(A) a copolymer of cyclohexylmethacrylate and dimethylaminoethylmethacrylate, wherein the copolymer contains from about 0.8 to about 1.0 wt % dimethylaminoethylmethacrylate;
(B) a melamine-formaldehyde resin; and
(C) carbon black present in an amount of from about 9.2 to about 9.7 wt % of the coating;

said coating being present in an amount of from about 0.85 to about 1.25 wt % of the carrier;
said coated carrier having a conductivity of from about 8.9 to about 9.5 [Log(mho/cm)], wherein the carrier core has a surface roughness of from about 0.163 to about 0.167 m 2 /g as measured by the BET (Brunauer Emmett Teller) method, and further wherein the carrier exhibits a triboelectric (Q/m) at 8% Toner Concentration of at least about 32 microCoulombs/gram (μC/g).

7. A developer according to claim 6 wherein the melamine-formaldehyde resin is present in an amount of from about 8 to about 12 wt % of the coating.

8. A developer according to claim 6 wherein the carrier core has an average particle diameter when measured by laser diffraction of from about 30 to about 45 μm.

9. A developer according to claim 6 wherein the carrier core has a conductivity of from about 7.25 to about 8.5 [Log(mho/cm)] at 500 v DC.

10. A developer according to claim 6 wherein the carrier core comprises:
(a) a mixture of iron oxide, manganese oxide, lithium oxide;
(b) a mixture of iron oxide, manganese oxide, magnesium oxide, and strontium oxide;
(c) a mixture of iron oxide, manganese oxide, magnesium oxide, and calcium oxide; or
(d) a mixture thereof.

11. A developer according to claim 6 wherein the amorphous resin is of the formula

wherein m is from about 5 to about 1000.

12. A developer according to claim 6 wherein the amorphous resin is terpoly-(propoxylated bisphenol A-fumarate)-terpoly(propoxylated bisphenol A-terephthalate)-terpoly-(propoxylated bisphenol A-2-dodecylsuccinate).

13. A developer according to claim 6 wherein the crystalline resin is of the formula

wherein b is from about 5 to about 2000 and d is from about 5 to about 2000.

14. A developer according to claim 6 wherein the crystalline resin is poly(nonane-dodecanoiate).

15. A carrier for an electrophotographic developer made by a process which comprises:
(a) preparing a latex copolymer of cyclohexylmethacrylate and dimethylaminoethylmethacrylate, wherein the copolymer contains from about 0.8 to about 1.2 wt % dimethylaminoethylmethacrylate;
(b) preparing dry particles of the copolymer having a particle size of from about 80 to about 120 nm;
(c) preparing a carrier coating by mixing the dry copolymer particles with:
(i) carbon black, present in an amount of from about 9.2 to about 9.7 wt % of the carrier coating; and
(ii) a melamine-formaldehyde resin;

(d) mixing the carrier coating with ferrite cores;
(e) heating the mixture of carrier coating and ferrite cores at a temperature of from about 385 to about 405° F. for a period of from about 20 to about 30 minutes, thereby fusing the carrier coating to the ferrite core; and
(f) screening the coated carrier particles;
said coated carrier particles having:
(1) a coating weight of from about 0.85 to about 1.25 wt %; and
(2) a conductivity of from about 8.9 to about 9.5 [Log(mho/cm)]; and
wherein the cores have a surface roughness of from about 0.163 to about 0.167 m 2 /q as measured by the BET (Brunauer Emmett Teller) method.

16. A carrier according to claim 15 wherein fusing is done in a rotary kiln.

17. A carrier according to claim 15 wherein fusing is performed for a period of from about 20 to about 30 minutes.

18. A carrier according to claim 15 wherein the melamine-formaldehyde resin is present in an amount of from about 8 to about 12 wt % of the coating.

Assignees

• Xerox Corp

Inventors

• Kelly Bernard A
• Dombroski Thomas C
• Giannetto Brian S
• Moore Brian E
• Spencer Lloyd D
• Veregin Richard P N
• Moffat Karen A
• Enright Thomas E
• Farrugia Valerie M
• Hawkins Michael S
• Bashir Wafa F

Classifications

• G03G9/1137

  being crosslinked · CPC title

• G03G9/1133 Primary

  obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• G03G9/1135

  obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• G03G9/08755

  Polyesters · CPC title

• G03G9/1139

  Inorganic components of coatings · CPC title