# US 2018/0321618 A1 · Liquid electrophotographic ink developer unit

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- Number: US 2018/0321618 A1
- Document ID: US20180321618A1
- Status: Published application
- Kind: A1
- Application number: 15/773,962
- Filed: 2016-01-27
- Published: 2018-11-08
- Earliest claimed: 2016-01-27
- Assignees: Hewlett-Packard Development Company, L.P.
- Applicants: Hewlett-Packard Development Company, L.P.
- Inventors: Guang Jin Li; Stanley J. Kozmiski; Seongsik Chang; Daniel Tanchangco; David Sabo; Thomas Anthony; Omer Gila
- Web page: https://patentgrep.com/patent/US20180321618A1

## CPC

- G03G 15/10: using a liquid developer
- C08L 75/04: Polyurethanes
- G03G 13/10: using a liquid developer {, e.g. liquid suspension}
- G03G 15/0233: {Structure, details of the charging member, e.g. chemical composition, surface properties}
- G03G 15/0818: {characterised by the structure of the donor member, e.g. surface properties}
- G03G 2215/0861: Particular composition or materials
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## Abstract

The present disclosure relates to a liquid electrophotographic ink developer unit. The unit comprises a developer roller, and a secondary roller that co-operates with the developer roller. The developer roller is formed of a material having a specific resistivity of less than 1×106 Ω·cm. The secondary roller is formed of a material having a specific resistivity of 1×104 to 1×109 Ω·cm.

## Claims

### Claim 1

A liquid electrophotographic ink developer unit, said unit comprising
a developer roller, and
a secondary roller that co-operates with the developer roller,
wherein the developer roller is formed of a material having a specific resistivity of less than 1×106 Ω·cm, and
wherein the secondary roller is formed of a material having a specific resistivity of 1×104 to 1×109 Ω·cm.

### Claim 2 (depends on 1)

A unit as claimed in claim 1, wherein the developer roller is formed from a material having a specific resistivity of 1×103 to 1×105 Ω·cm.

### Claim 3 (depends on 1)

A unit as claimed in claim 1, which comprises two secondary rollers, wherein the secondary roller is formed of a material having a specific resistivity of 1×104 to 1×109 Ω·cm.

### Claim 4 (depends on 1)

A unit as claimed in claim 1, wherein the developer roller comprises a polymer composition comprising a conductive filler dispersed in a polymer resin matrix, wherein the polymer composition has a specific resistivity of less than 1×106 Ω·cm.

### Claim 5 (depends on 4)

A unit as claimed in claim 4, wherein the conductive filler is selected from carbon nanotubes, graphene, carbon fibre, carbon black, metal particles, conductive oxide particles and intrinsic conductive polymer (ICP) particles.

### Claim 6 (depends on 5)

A unit as claimed in claim 5, wherein conductive filler is carbon black and the concentration of carbon black in the polymer is 0.1 to 20% in weight.

### Claim 7 (depends on 1)

A unit as claimed in claim 1, wherein the secondary roller is formed of a material that has a specific resistivity of 1×105 to 5×106 Ω·cm.

### Claim 8 (depends on 1)

A unit as claimed in claim 1, wherein the secondary roller comprises an outer coating formed of a material having a specific resistivity of 1×104 to 1×109 Ω·cm.

### Claim 9 (depends on 8)

A unit as claimed in claim 8, wherein the coating has a thickness of 20 μm to 2 mm.

### Claim 10 (depends on 8)

A unit as claimed in claim 8, wherein the secondary roller comprises a metal core that is coated with said coating.

### Claim 11 (depends on 10)

A unit as claimed in claim 10, wherein the coating is a ceramic coating.

### Claim 12 (depends on 11)

A unit as claimed in claim 11, wherein the coating is formed of alumina-titania.

### Claim 13 (depends on 1)

A unit as claimed in claim 1, wherein the nip resistance between the developer roller and the secondary roller is 3×102 Ohm to 3×105 Ohm.

### Claim 14

A liquid electrophotographic ink developer unit, said unit comprising
a developer roller, and
a secondary roller that co-operates with the developer roller,
wherein the developer roller is formed of a material having a specific resistivity of less than 1×106 Ω·cm, and
wherein the secondary roller comprises a metal core that is coated with a ceramic coating.

### Claim 15

A liquid electrophotographic printer comprising a developer roller, and
a secondary roller that co-operates with the developer roller,
wherein the developer roller is formed of a material having a specific resistivity of less than 1×106 Ω·cm, and
wherein the secondary roller is formed of a material having a specific resistivity of 1×104 to 1×109 Ω·cm.