# US 11,079,693 B2 · Electrophotographic photoreceptor, process cartridge, and image forming apparatus

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- Number: US 11,079,693 B2
- Document ID: US11079693B2
- Status: Granted
- Kind: B2
- Application number: 16/722,053
- Filed: 2019-12-20
- Published: 2020-10-01
- Granted: 2021-08-03
- Earliest claimed: 2019-04-01
- Assignees: FUJIFILM Business Innovation Corp.
- Applicants: FUJIFILM Business Innovation Corp.
- Inventors: Eri Kunisawa
- Web page: https://patentgrep.com/patent/US11079693B2

## CPC

- G03G 5/142: {Inert intermediate layers}
- G03G 5/144: {comprising inorganic material}
- G03G 5/047: characterised by the charge-generation layers or charge transport layers {(G03G5/0433 and G03G5/0436 take precedence)}
- G03G 5/102: {consisting of or comprising metals}
- G03G 5/14704: {comprising inorganic material}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An electrophotographic photoreceptor includes: a conductive substrate; an undercoating layer that contains inorganic particles surface-treated with a surface treatment agent, and is provided in contact with an outer peripheral surface of the conductive substrate; and a photosensitive layer provided on the undercoating layer, wherein, with respect to the outer peripheral surface of the conductive substrate, a proportion of an area being in contact with the inorganic particles is from 82% to 91%.

## Claims

### Claim 1

An electrophotographic photoreceptor comprising:
a conductive substrate;
an undercoating layer that contains inorganic particles surface-treated with a surface treatment agent, and is provided in contact with an outer peripheral surface of the conductive substrate; and
a photosensitive layer provided on the undercoating layer,
wherein, with respect to the outer peripheral surface of the conductive substrate, a percentage of an area of the outer peripheral surface being in a state of contact with the inorganic particles is from 82% to 91% when a total area of the outer peripheral surface is considered to be 100%,
an area of the outer peripheral surface of the conductive substrate in a state of not being in contact with the inorganic particles is an area that is more than 5 μm from a surface of a closest inorganic particle of the inorganic particles,
the total area of the outer peripheral surface of the conductive substrate consists of a sum of the area being in the state of contact with the inorganic particles and the area in the state of not being in contact with the inorganic particles,
a content of the inorganic particles in the undercoating layer is 75% by weight or more, and
the conductive substrate has a thickness of 0.2 mm to 1.5 mm.

### Claim 2 (depends on 1)

The electrophotographic photoreceptor according to claim 1,
wherein, when halftone full page images with an image density of 50% are continuously formed on 2 million sheets of A4 paper, a rate of decrease in a value of current flowing from the undercoating layer to the conductive substrate is 20% or less.

### Claim 3 (depends on 1)

The electrophotographic photoreceptor according to claim 1,
wherein a content of the inorganic particles in the undercoating layer is 78% by weight or more.

### Claim 4 (depends on 1)

The electrophotographic photoreceptor according to claim 1,
wherein the conductive substrate has a thickness of 0.4 mm to 0.8 mm.

### Claim 5 (depends on 1)

A process cartridge that is detachable from an image forming apparatus, the process cartridge comprising:
the electrophotographic photoreceptor according to claim 1.

### Claim 6 (depends on 1)

An image forming apparatus comprising:
the electrophotographic photoreceptor according to claim 1;
a charging unit that charges a surface of the electrophotographic photoreceptor;
an electrostatic latent image forming unit that forms an electrostatic latent image on a charged surface of the electrophotographic photoreceptor;
a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer including toner to form a toner image; and
a transfer unit that transfers the toner image onto a surface of a recording medium.

### Claim 7 (depends on 1)

The electrophotographic photoreceptor according to claim 1,
wherein the undercoat layer is obtained by coating the conductive substrate with an undercoating layer-forming coating liquid having an elastic recovery amount of 0.30 Pa·sec or more and less than 0.90 Pa·sec, and the elastic recovery amount is an amount of change in shear viscosity due to application of a shear stress with shear rate of 0.1 sec−1 after applying a shear stress with shear rate of 1,000 sec−1 to the undercoating layer-forming coating liquid.

### Claim 8 (depends on 7)

The electrophotographic photoreceptor according to claim 7,
wherein the elastic recovery amount is from 0.50 Pa·sec to 0.85 Pa·sec.

### Claim 9 (depends on 7)

The electrophotographic photoreceptor according to claim 7,
wherein the elastic recover amount is from 0.55 Pa·sec to 0.80 Pa·sec.